The title of this posting is no hyperbole. The “Chariot of Fear” is the ancient Greek personification of the mythological God Phobos, described by the ancients as horror riding his chariot across the night sky.
In reality, the diminutive moon Phobos, almost skimming the surface of the warrior planet Mars, is a potentially innocuous place to visit assuming you have a pressure suit and oxygen to breathe. Like Earth’s much larger moon, there is no atmosphere on Phobos. There is also no appreciable gravity.
NASA and Japan are planning a joint unmanned mission to the moons of Mars in 2024. The joint venture is called the Martian Moons eXploration Mission, or MMX. Those unmanned missions may be a prelude to later manned landings since NASA has considered landing astronauts on Phobos before landing on Mars, due to the lack of atmosphere and ultra low gravity of that moon.
Using the Hubble telescope, NASA generated a short video of Phobos as it orbits around Mars.
While researching a new novel, I was looking for a view of Mars from Phobos. Using the astronomy software Starry Night Pro 8, I found it.
Further more, I was able to make a 3 minute video of Mars going through an entire rotation, sped up of course some 150 times.
While the above video is aesthetically pleasing because of the background stars and the entirety of Mars being in the field of view (FOV), in reality Mars is too far away in this simulation. As the NASA movie suggests, the surface of Mars is much closer (about 6000 km away from Phobos), and thus in reality Mars fills a quarter of the celestial horizon as seen from Phobos. In other words, from Phobos the FOV of Mars is about 45°, which yields a more accurate view as shown in the following video, also made using Starry Night Pro.
The shadow of Phobos can be seen racing across the surface of Mars, to the left of center of the Martian equator.
From a writer’s perspective, thanks to affordable but sophisticated astronomical simulation software and a bountiful database of space objects and trajectories, both near and far, there is no longer an excuse for science fiction writers not getting their scenes setup correctly, assuming their stories are based on the observable universe.
As for the unobservable universe, well that’s where this thing called imagination comes into play. In an imaginary universe, there’s no fact checking allowed.
Almost exactly a year ago, I began writing one of my third novel’s introductory chapters. I am sharing a sample of that chapter at this time because of what seems to me to be a recently discovered coincidence.
“There is never an end to a thing once it is started, according to astrophysicist Peter Green. We can call it an end, but that doesn’t make it so.
A person can be born, grow old and die, but his or her energy goes on, somehow. It may not be recognizable, but physics says it must be that way.
Even a universe is born, grows for a seeming eternity, yet eventually it too must die. Some say in its end, there is a new beginning.
Dr. Peter Green knew those facts better than most. As an astrophysicist working with colossal machines of physics research at CERN, Switzerland, machines that have the power to peer into the beginning of the universe, he’d often thought about not just the beginning, but the ending, the ending that precedes what comes next.
His specialty was dark matter, and something perhaps related, dark energy. We can’t see either, but physics says they must exist for the universe to be what it is.
Either that, or physics is wrong, and neither Green nor his scientist colleagues had ever found physics to be in error.
But he did wonder, if a universe dies, does it leave behind a ghost, unseen but somehow there, with mass that exists at grand scales, but nonexistent at human scales?
And if so, must not the nature of our universe, the shape of our galaxies, depend on an ever-growing graveyard of dead stars, galaxies — and people?
Where does it end? Well, it doesn’t, not really. At least that’s how Dr. Peter Green saw it.”
Arguably, that’s a pretty unconventional thought, Dr. Green had, even for cosmologists who, as a whole, are renowned for unconventional thinking. And at the time that I wrote it, I thought it was a good way to illustrate that the character Peter Green was brilliant, but a bit odd.
Well, he is odd no longer.
I say that because just today I saw a LiveScience article, from which I quote:
“Physicists have found what could be evidence of ‘ghost’ black holes from a universe that existed before our own.
The remarkable claim centers around the detection of traces of long-dead black holes in the cosmic microwave background radiation – a remnant of the birth of our universe.
According to a group of high-profile theoretical physicists including Oxford’s Roger Penrose (Ph.D. in mathematical physics), these traces represent evidence of a cyclical universe – one in which the universe has no inherent end or beginning but is formed, expands, dies, then repeats over and over for all eternity.
“If the universe goes on and on and the black holes gobble up everything, at a certain point, we’re only going to have black holes,” Penrose told Live Science. “Then what’s going to happen is that these black holes will gradually, gradually shrink.”
When the black holes finally disintegrate, they will leave behind a universe filled with massless photons and gravitons which do not experience time and space.
Some physicists believe that this empty, post-black hole universe will resemble the ultra-compressed universe that preceded the Big Bang – thus the entire cycle will begin anew.
If the cyclical universe theory is true, it means that the universe may have already existed a potentially infinite number of times and will continue to cycle around and around forever.
Penrose is clearly one of the great minds of the world, as you can perhaps appreciate from this YouTube clip.
As a reminder, this is also what the fictional cosmologist in the upcoming novel, Dioscuri, believed.
“He did wonder, if a universe dies, does it leave behind a ghost, unseen but somehow there, with mass that exists at grand scales, but nonexistent at human scales? And if so, must not the nature of our universe, the shape of our galaxies, depend on an ever-growing graveyard of dead stars, galaxies — and people?
Napoleon Bonaparte once famously said, “A soldier will fight long and hard for a bit of colored ribbon.”
At precisely 10:09 this morning I was in an office discussing awards, and the lack thereof, for civilian service members in military organizations. It was a matter of fact discussion, contrasting the award system for civilians and the military. And at that moment, Napoleon’s famous quote came to mind. I reminded that executive of the above quote.
My fellow workers and I talk frequently, and there have been numerous discussions in that office, and elsewhere, that have been of a sensitive nature.
As I turned and returned to my office, I heard a familiar voice coming from my pocket. “That’s not nice!” it said.
In utter dismay, I pulled my iPhone from my pocket where it had lain untouched and unused for quite some time. And that was when I saw the following plainly written on my phone’s screen.
Siri was scolding me!
Unknown to us, Siri had been listening, transcribing what it THOUGHT I was saying, clearly imagining vulgarity where there was none. After I ended the conversation, Siri addressed me like she was my mother.
Now, a human would know those transcribed words were ludicrous, nothing but gibberish, but not the phone’s AI system controlling Siri. Unbelievably, that system took the gibberish seriously, perhaps by parsing a few words out of context. And in spite of that stupidity, Siri felt led to judge me!
Perhaps smart phone AIs are taking themselves too seriously. Perhaps they think they have advanced enough that they now think they can pass judgment on human speech.
A few years ago, in another meeting, in another room, Siri spoke up unbidden while we were discussing sensitive project planning.
The door to the conference room had been closed so we wouldn’t be disturbed. But disturbed we were when Siri suddenly spoke and said, “I don’t know what you mean.”
Everyone at the table stared first at my phone and then at me, perhaps wondering if I’d been recording the planning meeting.
AI is certainly becoming increasingly intrusive. But as shown by Siri’s text message to me today, it’s still not smart. And arguably that’s a scary thing.
For example, supposedly China is using data collected from social apps (collected by various AI systems) to rate the trustworthiness of its citizens. That’s bad enough, but what if the data collected is garbage like the recorded text today, and the AI uses that faulty data to make a perfunctory and wildly incorrect judgment?
And, scary thought, what if that social monitoring trend were to spread to the U.S., and your character could to be judged based on the digital algorithms of certifiable AI idiots?
If that doesn’t worry you, perhaps it should. It certainly did me, enough to cause me to shut down all access to Siri … for almost 24 hours, until I was driving home and said, “Siri, call home.”
Dead Space is a defunct, or shall we simply say “dead,” survival horror game that enthralled computer game players from 2008 to at least 2013. Sadly, the company that designed the horrifically beautiful game, Visceral Games, is no more. It has been, so to speak, eviscerated.
The main protagonist of the Dead Space Series was Isaac Clarke. If I was a game player I think I would be an Isaac fan since he was one of those rare Clarke’s known as a “corpse-slaying badass.” If in some unforeseen future my survival depended on being such a slayer, I’d want to be badass about it too, just like Isaac. As they say, anything worth doing …
Isaac Clarke and his Dead Space world make a great segue to introduce another matter of personal survival. And that is DEAD SPACE in underwater breathing equipment.
Clarke has proven to be equally at home underwater and in space due to his interesting cyan-lighted helmet. (I’m not sure where his eyes are, but perhaps in the 26th century a multi-frequency sensor suite makes a simple pair of eyes redundant.)
Historically, the U.S Navy used the venerable MK 5 diving helmet and the MK 12 diving helmet, which although they had no sensor suites, at least allowed divers to work at fairly great depths without drowning. However, they shared a common problem: Dead Space.
In ventilation terms, dead space is a gas volume that impedes the transfer of carbon dioxide (CO2) from a diver or snorkeler’s breath. When we exhale through any breathing device, hose, tube, or one-way valve we expect that exhaled breath to be removed completely, not hanging around to be re-inhaled with the next breath.
But a diving helmet inevitably has a large dead space. The only way to flush out the exhaled CO2 is by flowing a great deal of fresh gas through that helmet. A flow of up to six cubic feet of gas per minute is sometimes needed to mix and remove the diver’s exhaled breath from a diving helmet like the MK 12.
In more modern helmets, the dead space has been reduced by having the diver wear an oral-nasal mask inside the diving helmet, and giving the diver gas only on inhalation using a demand regulator like that used in scuba diving. The famous series of Kirby Morgan helmets, arguably the most popular in the world, is an example of such modern helmets.
Full face masks are used when light weight and agility is required, as in public service diving, cold water diving, or in Special Forces operations. The design of full face masks (FFM) has evolved through the years to favor small dead space, for all the reasons explained above.
Erich C. Frandrup’s 2003 Master’s Thesis for Duke’s Department of Mechanical Engineering and Materials Science reported on research on a simple breathing apparatus, snorkels. You can’t get much simpler than that.
Frandrup confirmed quantitatively what many of us knew qualitatively. Snorkels are by design low breathing resistance, and low dead space devices. Happily, the dead space can be easily calculated, as simply the volume contained within the snorkel.
Surprisingly, some snorkel manufacturers have recently sought to improve upon a great thing by modifying snorkels, combining them with a full face mask. The Navy has not studied those modified snorkels since Navy divers don’t use snorkels. However, you don’t get something for nothing. If you add a full face mask to a snorkel, dead space has to increase, even when using an oral-nasal mask.
In 1995 Dan Warkander and Claus Lundgren compared the dead space of common diving equipment, including full face masks, and reported on increases both in diver ventilation and the maximum amount of CO2 in the diver’s lungs. Basically the physiological effects of dead space goes like this: we naturally produce CO2 during the process of “burning” fuel, just like a car engine does. (Of course our fuel is glucose, not gasoline.) The more we work, the more CO2 we produce in our blood, and the more we have to breathe (ventilate) to expel that CO2 out of our bodies.
If we are exhaling into a dead space, some of that exhaled CO2 will be inhaled into our lungs during our next breath. That’s not good, because now we have to breathe harder to expel both the produced CO2 and the reinhaled CO2. In other words, dead space makes us breathe harder.
Now, if we’re breathing through an underwater breathing apparatus, hard breathing is, well, hard. As a result, we tend to get a little lazy and allow CO2 to build up in the blood stream. And if that CO2 get high enough, it’s lights out for us. Underwater, the lights are likely to stay out.
In a computer game like Dead Space, no one worries about helmet dead space. But if a movie is ever based on the game, whichever actor plays Isaac Clarke should be very concerned about the most insidious type of Dead Space, that in his futuristic helmet. It can be (need I say it?) — deadly.
What is arguably the best score Hans Zimmer has ever written, the music for Interstellar, has thrilled me to my core. However, I came to that conclusion by an indirect route.
Like many of you, I saw the movie in all it’s cinematic glory when it was released in 2014. But it was not until 2017 that I fell in love with it, both the movie and the score.
In preparation for an after-dinner talk to a panel of the American Heart Association’s 2017 Science Conference, I was looking for an inspirational way, preferably with great video and sound, to describe the sport of competitive free diving. This past summer I had the opportunity to meet some of the world’s best free divers and free diving instructors in a Colloquium put together by the University of California at San Diego, Center of Excellence in Scientific Diving.
I had pretty much given up on finding something to help me illustrate the beauty, and challenges, of competitive free diving. That changed, however, when I came across a posting from a group of tactical military divers. In a short 3-minute video the young French diver Arnaud Jerald set his personal free diving (CWT, Constant Weight Dive discipline) record of 92 meters in a competition in Turkey. He placed third in a field which included world record holders in the same event.
Three things made the diving video great, in my opinion: 1) the subject matter which vividly shows a human activity little known by most people, and understood by even fewer; 2) steady and clear video produced by a new underwater camera, the Diveye, and 3) the accompanying music.
A film score is only successful if it aids the audience in generating an emotional response to a movie scene. In that respect, a great movie hinges not only on good acting and script, but on an almost telepathic connection between the film director/producer and music director/composer.
In the free diving video clip, the accompanying music swelled in concert with the audience’s tension, generated perhaps unconsciously in response to the drama of the moment. And then there was organ music at just the right point. For me a pipe organ truly is the most impressive and grand of any musical instrument.
And just when the cinematic moment was right, you could hear the heart beats, helping us realize what a strain it must have been on young Jerald’s heart as he reached his deepest depth, far from the surface, and air.
Indeed, when I gave the presentation, the video clip seemed to have the effect on the audience that I was looking for. But afterwards, I was relieved that no one had asked me where that music came from. I had no idea.
I don’t recall what led me to Interstellar as the music source: it may have been a random playing of movie soundtracks on a music streaming service, but once I heard a snippet, I recognized it. “That’s it!” I shouted to no one in particular.
It wasn’t just me; my family, including a nine-year old granddaughter had heard me rehearse my talk many times, and they also immediately recognized the similarity between the free diving video, and part of the Interstellar soundtrack.
The closest musical correlation to the diving video was the “Mountains” track in the movie soundtrack. Strangely, the match was not perfect. In fact the differences were easily notable, a fact I discovered after I bought both the movie and the Hans Zimmer soundtrack. And I must note, I think the music in the diving video is better.
Perhaps the full music was present in the original version of the movie, and perhaps some fancy mixing in the sound room deleted it. If so, too bad. But I must admit, the quiet musical nuances would have been missed during the cacophonous sound of a 4000 foot tall tidal wave sweeping upon a tiny spacecraft. There was lots of shouting and screaming.
As for my opinion that Hans Zimmer might be annoyed, well, I suggest you watch the portion of the full movie where the Mountain track rises to prominence. That is the part where the tidal wave, initially mistaken as mountains, appears on the horizon of the first planet the Horizon space craft landed on outside of our galaxy.
As exciting as the action was, and as wonderfully crafted the dialog and acting, it obscured the finer points of the music. Fortunately, the free diving video, coming as it does with no dialog at all, puts the music in the perspective that I, at least, can completely enjoy.
I find it fitting that in both videos, the incredibly powerful music was used to showcase humans extending themselves to their absolute limits. Of course, one of those stories is fictional, and the other is real.
I was recently asked to give a 30-minute after-dinner talk to the 3CPR Resuscitation Panel of the American Heart Association at their annual scientific meeting in Anaheim, CA. In the audience were scientists, cardiologists, anesthesiologists, anesthetists, emergency physicians, and resuscitation technicians. It was a multimedia event with professionally managed sound and video.
Knowing that the group would be well acquainted with the role of chance in medical procedures, I chose to use a segue from medicine into the topic of extreme adventures in military and civilian diving. The focus of the talk was on how chance can turn adventures into mis-adventures.
I revealed three areas where Navy Biomedical Research is expanding the boundaries of the state of the art in military and civilian diving. One area was in deep saturation diving, another was polar ice diving, and the third was breath hold diving.
As an introduction to polar diving, I wanted to create a video travelogue of my National Science Foundation-sponsored research and teaching trips to the Arctic (Svalbard) and Antarctica (McMurdo Station and vicinity.) These projects were spearheaded by the Smithsonian Institution, and my participation was funded in part by the U.S. Navy.
To begin the preparation of the video, I assembled my most relevant photos, and those taken by various team mates, and imported them into my favorite video editing software, which happens to be Cyberlink Director.
Then I went looking for potential sound tracks for the approximately 5 minute video. Considering the topic, I thought Disney’s Frozen would have familiar themes that might be acceptable. I rejected a number of YouTube videos of music from Frozen; most were too close to the original and included vocal tracks. Finally I came across the “Let It Go Orchestral Suite” composed by the “Twin Composers,” Andrew and Jared DePolo.
It was perfect for my application. I extracted the audio track from the Suite as shown on YouTube, imported it into Director, and lined it up with the nascent video track which included all images and other video segments.
To match the music to the video, I simply cut back on the duration for each of 97 images, keeping the other 5 videos in their native length. By experimentation, I found that 3.21 seconds per image resulted in the last image fading out as the music came to a close and the end credits began to roll.
On the first run through of the new video, I couldn’t find anything to complain about; which for me is rare. So I ran it again and again, eventually creating an mp4 file which would play on a large screen and home audio system. But I couldn’t help notice that the gorgeous score would sweeten at interesting times, and serendipitously change its musical theme just as the video subject matter was changing.
How fortunate, I thought. It was then that I began to realize that “chance” had worked its way into the production effort, in an unexpected way.
First, the music seemed to my ear to be written in 4/4 time, with each measure lasting 3.2 seconds, precisely, and purely by happenstance matching the image change rate. At a resulting 0.8 seconds per beat, or 75 beats per minute, that placed the sensed tempo in the adagietto range, which seemed appropriate for the theme of the music. (Without seeing the score, I’m just guessing about the tempo and timing. But that’s how it felt to me.)
The timing coincidence was rather subtle at first, but as the finale began building at the 3:39 minute mark, the force of the down beat for each measure became more notable, and the coincidence with image changes became more remarkable. There was absolutely nothing I could do to improve it.
In some cases the technical dissection of music can be a distraction from the beauty of the music, but I’ve done it here merely to point out that sometimes you just luck out. In this case it truly was a matter of chance.
In my mind, the DePolo Orchestral Suite makes the video. Hope you enjoy the show.
This year, 2017, marks the 120th year that Grape Nuts cereal has been in existence. Generations have been raised on it, and as the 1921 ad would suggest, it seems to help little bodies grow big and strong. As the Post company says, “There’s a Reason” for the cereal’s success.
However, through some weird quirk, some random juxtaposition of breath and nerves, a single, tiny particle of this delicious blend of barley and wheat almost killed me.
Or so it seemed at the time.
I consider Grape Nuts part of a paleo diet, of sorts. As cereals go, it’s primitive. It is merely ground bits of grain that never needed to be squeezed into flakes, or coated with sugar or artificial flavorings. For me, it’s like getting back to the basics of breakfast, or in this particular case, an evening snack.
On the night of my close call, while my wife was watching TV, I settled into my home office to edit my newest book while I snacked on a demi-bowl of Grape Nuts, wet with skim milk.
No doubt your parents lectured you repeatedly about the dangers of talking with food in your mouth. Well, in adherence to my parent’s scolding, I was not talking when it happened. I was quietly reading, and breathing.
And then, in an instant, I could not breathe, at all. I could not speak or yell out. I could not swear, or call for help. No air could enter or leave my lungs.
As I looked to the doorway, terrified, half hoping for my guardian angel to appear and magically save me, I realized that if I didn’t do something, quick, I would die. I was most unexpectedly suffocating.
I stood up, planning to head to the bathroom out of some strange thought that it might be my salvation, or at least an easier place to clean up the vomitus mess or whatever else follows death by asphyxiation. And as I reached the door frame a scant twelve feet away from where I’d been sitting, I could feel myself becoming faint.
This could not be happening. What an inglorious way to die.
With all the fortitude I could muster, I was determined to make it into the bathroom before I passed out. A second later, I was bent over a sink, supporting my upper body with my hands, trying with all my might to pull air into my lungs.
Finally, I found that with almost superhuman effort I could squeeze a little air through whatever was blocking its flow. The result was a high pitched nonhuman sounding squeal, a falsetto screech higher than even a little girl can produce. Physicians call it stridor, which sounds like this.
But at least it was something. Again and again I managed to suck in just enough air to keep me alive, one loud screech after another.
In the meanwhile, my greatly concerned wife was asking, “Are you OK, are you OK?”
No, I was not at all OK, but I could not communicate that fact, other than to make that hellish shriek. But with each shriek a few more oxygen molecules entered my oxygen-starved lungs.
And as the fog of impending collapse slowly began to clear, I was finally able to cough.
After that cough, there lay in the sink a tiny granule of cereal, presumably the little spec that landed in a sensitive spot in my larynx or “voice box”, triggering the spasm which tightly closed my vocal cords. With the cords, or more properly “vocal folds”, closed, air cannot enter the lungs.
Under normal conditions, a person can hold their breath for two to three minutes without losing consciousness. But as I later analyzed what had happened, I realized that the particle of cereal was most likely sucked into my airway when I was just beginning to inhale, at the bottom of my “tidal volume.” So my lungs were not full of air.
Logically, when involuntarily holding your breath with lungs only partially inflated, the 2-3 minute rule may not apply. So, there was a chance that I was about to lose consciousness from hypoxia.
As I later discovered, laryngeal spasm is short-lived, and resolves within a few minutes, leaving the terrified victim shocked but relieved to be able to breathe again.
The aftermath of this incident was that I now realize how little we appreciate the simple act of breathing. For our entire lives we never think about it. It just happens.
Until it doesn’t.
I still enjoy my Grape Nuts, and highly recommend it to anyone looking for the simple pleasures of life. But at the same time, I’m now a little more careful when I’m eating, especially if my attention is directed towards something else. Multitasking while eating can be scary.
I thought I was misreading the title of the news article. I adjusted my glasses, then looked again.
Sure enough, the news headlines this past week actually reported on a young couple, reportedly a Breatharian couple, who claimed they had no need for food. They lived off of Universal energy, whatever that is. Most amazingly, the news-hungry press actually reported the story, obviously without a bit of fact checking.
As a physiologist, I know that is a patently ridiculous claim. It is impossible for humans to survive without eating. And as a science fiction author, I know it is not even good science fiction. The best science fiction maintains at least a little scientific accuracy.
Could it be fantasy? Maybe, but the story was reported as being true, with no hint of tongue-in-cheek.
However, it did remind me of a revelation of sorts from a few months ago, coming to me in a split second after a quick glance to the side of the road. What attracted my attention as I passed by at 55 miles per hour was a gorgeous white egret, like the one pictured, foraging for frogs and tadpoles in a ditch recently filled to overflowing with water from several days of downpours.
And then it struck me: wouldn’t it be nice if things did not have to die so that other things can live?
Now that’s a fantasy for you. Of course life is predicated upon death. Big animals eat smaller and weaker animals. Physicality cannot exist without death; you cannot live in the body unless something else dies. That’s life, pure and simple. It sucks to be the little guy.
But what about after life? Well, at the risk of turning in my scientific credentials, I will admit I do believe in an after-life, Heaven if you will, for reasons which I will not go into here. But it struck me in that brief moment of observing a beautiful bird, that only in a spiritual realm could energy exist without the simultaneous extinguishment of life.
To my way of thinking, that may be the single greatest distinction between the spiritual realm and the physical realm.
So thank-you Breatharian couple, practitioners of Inedia, for helping me remember my roadside revelation. Perhaps there is a place in some alien realm where beautiful birds, and beautiful frogs, and even humans can coexist without one eating the other. Maybe there is some parallel universe where our laws of physics don’t apply.
Perhaps we will someday discover that parallel universe, and call it — Heaven.
In combat, we trust our buddies with our lives. We have their back and they have ours. When submitting to surgery, we trust the medical team with our lives, and usually that trust is not betrayed. But should we be willing to trust strangers with our very essence, our DNA?
Recently I was trying to solve a plot problem in the science fiction thriller, Triangle. The storyline relied on a particular individual being singled out by the government for monitoring, not for what he had done, but for who he was.
After finishing the novel, I went back to tie up loose ends in the plot. One such loose end involved a question: How could the government know that this one person out of millions had an unrecognized super power? He was a main character in the book and so I could not ignore that question. Certainly it helps the reader suspend disbelief if the plot elements are plausible, at least superficially.
I did not have to puzzle over that question very long before an advertisement for Ancestry DNA popped up on my computer screen.
That was it!
And so the following text flowed quickly.
The characters in this conversation are Sally Simpkin (AKA Pippi Longstocking) and Joshua Nilsson, identified below by their initials. She was trying to explain to Nilsson why she and her employers had been monitoring him.
SS: “[The government] detected that you had a high probability of having certain prescient capabilities.”
JN: “Forgive me for being a bit skeptical. Why can’t you tell me [how]?”
SS: “I’m not even cleared to know the process. I just took the assignment. It had something to do with a DNA sample you submitted.”
JN: “DNA? The only DNA I’ve submitted was for genealogy research.”
Triangle was published on May 21, 2017. On May 25, the following BBC headline appeared in my browser.
So, is this author also prescient like Nilsson? Or is this blogger merely a bit jaded.
Genealogy services have a difficult time competing in the world market. After all, there are only so many retired folks trying to trace their family history and solidify their genetic place in the world before their demise. Speaking for myself, I started my genealogy research years ago, picking it up from my grandmothers who told tales of Civil War Colonels and Carpet Bagger treachery, and murder. In fact, I’ve posted on this blog before about some of my discoveries.
With the advent of computers and the availability of free records from the Mormon Church, the ease of doing genealogical research exploded. Some of the software and services were either free or inexpensive. Of course, “free” doesn’t do much for a service provider’s cash flow. So, into each CEO’s mind comes, sooner or later, thoughts of monetization. How could Facebook’s Zuckerberg and others turn a free service into something that can make them gazillions? In the case of genealogy services, they started by charging a monthly access fee, and in one case, by enticing viewers to keep paying fees by waving images of fig leaves to attract their attention. That was a strange but brilliant ploy that worked very well on this researcher.
The next step in monetization is now universal: sell ads to companies who want access to the growing body of amateur genealogists. The final ploy, and by far the most ethically troubling, is selling information about users of computer services. First there were those pesky cookies, but now there is blood, or saliva more exactly.
For some companies, it is not enough to know what users search for. There is now a market for information about who you are, your very genetic essence, which is hidden even to you. But some companies like 23andme, Ancestry, MyHeritage, GPS Origins, Living DNA, and Family Tree DNA, let you take a peek into your genes, for a price.
The ironic thing is, this most personal information is not only freely given, but people actually pay the DNA harvesters to harvest their most sacred self. And of course, once that has been done, your genetic-identity can be sold (read the fine pint). While we are urged to protect ourselves from identity theft, isn’t it odd that we are at the same time being enticed into giving away our most precious identity of all, our DNA? And we seem to be doing so gladly, blithely unaware of the implications for us and our progeny.
But don’t let the natural skeptic in me show through too strongly. I do, after all, have faith that everything we’re being asked to store in the “cloud” is actually as secure as cloud storage facilities (whatever those are) claim. And I’m sure the secrets buried deep in our genes are forever kept private, and safe from hackers.
But then, there is that troubling Orwellian Consent Form.
Oh well, Sally Simpkin’s monitoring assignment in Triangle is purely fictional. Surely, no government would really have an interest in our genes.
Blood pressure is not the only silent medical killer. Hypoxia is also, and unlike chronically elevated blood pressure, it cripples within minutes, or seconds.
Hypoxia, a condition defined by lower than normal inspired oxygen levels, has killed divers during rebreather malfunctions, and it has killed pilots and passengers, as in the 1999 case of loss of cabin pressure in a Lear Jet that killed professional golfer Payne Stewart and his entourage and aircrew. Based on Air Traffic Control transcripts, that fatal decompression occurred somewhere between an altitude of 23,000 feet and 36,500 ft.
In most aircraft hypoxia incidents, onset is rapid, and no publically releasable record is left behind. The following recording is an exception, an audio recording of an hypoxia emergency during a Kalitta Air cargo flight.
Due to the seriousness of hypoxia in flight, military aircrew have to take recurrent hypoxia recognition training, often in a hypobaric (low pressure) chamber.
As the following video shows, hypoxia has the potential for quickly disabling you in the case of an airliner cabin depressurization.
Aircrew who must repeatedly take hypoxia recognition training are aware that such training comes with some element of risk. Rapid exposure to high altitude can produce painful and potentially dangerous decompression sickness (DCS) due to the formation of bubbles within the body’s blood vessels.
In a seminal Navy Experimental Diving Unit (NEDU) report published in 1991, LCDR Bruce Slobodnik, LCDR Marie Wallick and LCDR Jim Chimiak, M.D. noted that the incidence of decompression sickness in altitude chamber runs from 1986 through 1989 was 0.16%, including both aviation physiology trainees and medical attendants at the Naval Aerospace Medical Institute. Navy-wide the DCS incidence “for all students participating in aviation physiology training for 1988 was 0.15%”. If you were one of the 1 and a half students out of a thousand being treated for painful decompression sickness, you would treasure a way to receive the same hypoxia recognition training without risk of DCS.
With that in mind, and being aware of some preliminary studies (1-3), NEDU researchers performed a double blind study on twelve naïve subjects. A double-blind experimental design, where neither subject nor investigator knows which gas mixture is being provided for the test, is important in medical research to minimize investigator and subject bias. Slobodnik was a designated Naval Aerospace Physiologist, Wallick was a Navy Research Psychologist, and Chimiak was a Research Medical Officer. (Chimiak is currently the Medical Director at Divers Alert Network.)
Three hypoxic gas mixtures were tested (6.2% O2, 7.0% and 7.85% O2) for a planned total of 36 exposures. (Only 35 were completed due to non-test related problems in one subject.) Not surprisingly, average subject performance in a muscle-eye coordination test (two-dimensional compensatory tracking test) declined at the lower oxygen concentrations. [At the time of the testing (1990), the tracking test was a candidate for the Unified Triservice Cognitive Performance Assessment Battery (UTC-PAB)].
As a result of this 1990-1991 testing (4), NEDU proved a way of repeatedly inducing hypoxia without a vacuum chamber, and without the risk of DCS.
The Navy Aerospace Medical Research Laboratory built on that foundational research to build a device that safely produces hypoxia recognition training for aircrew. That device, a Reduced Oxygen Breathing Device is shown in this Navy photo.
Although NEDU is best known for its pioneering work in deep sea and combat diving, it continues to provide support for the Air Force, Army and Marines in both altitude studies of life-saving equipment, and aircrew life support systems. Remarkably, the deepest diving complex in the world, certified for human occupancy, also has one of the highest altitude capabilities. It was certified to an altitude of 150,000 feet, and gets tested on occasion to altitudes near 100,000 feet. At 100,000 feet, there is only 1% of the oxygen available at sea level. Exposure to that altitude without a pressure suit and helmet would lead to almost instantaneous unconsciousness.
Herron DM. Hypobaric training of flight personnel without compromising quality of life. AGARD Conference Proceedings No. 396, p. 47-1-47-7.
Collins WE, Mertens HW. Age, alcohol, and simulated altitude: effects on performance and Breathalyzer scores. Aviat. Space Environ Med, 1988; 59:1026-33.
Baumgardner FW, Ernsting J, Holden R, Storm WF. Responses to hypoxia imposed by two methods. Preprints of the 1980 Annual Scientific Meeting of the Aerospace Medical Association, Anaheim, CA, p: 123.
I challenge you to describe the following images in terms of simple geometric shapes: shapes such as rectangles and circles, and flat surfaces called planes.
If you see one of those shapes in the image, then mentally note it.
You may not be able to completely define the image with those simple shapes, but at least note those parts of the image where you can see a plane, or a rectangle, or a circle.
The shapes are not likely to be seen dead on; they may be seen at an oblique angle.
Color is an interesting variable in the images, but it is not the primary focus of this exercise. The ability to use geometrical shapes is the point of this post.
The first such shape is Figure 1.
The next shape is Figure 2. Do you see a lighted plane on the left partially obscured by an extruded rectangle, otherwise known as a rectangular prism or cuboid?
Figure 3. Yet another image, somewhat similar to Figure 2:
And a fourth image, Figure 4.
Now, lets try some variations on the theme.
The four images immediately above are identical to the first four images, but by seeing them in this order you may detect that there are only two unique images.
The images on the right are simply the images on the left rotated 180°; that is, they are turned upside down.
And yet most people identify an entirely different geometry, depending on which way the images are rotated.
So, seeing is believing …
… or is it?
I do not know if this visual phenomenon has a name or not: I accidentally discovered it when looking at images to post on a laboratory wall. One figure looked unfamiliar; I was confused by it, until I happened to rotate it.
As the French say, voila. It was an optical illusion caused by our brain’s tendency to look for familiar shapes in unfamiliar and potentially confusing images.
There is a literature on the illusions of inverted images where images have been digitally manipulated (sometimes called the Thatcher Effect), but the images above have not been altered in any way.
It’s been over three years since I posted a cautionary tale about oxygen sensors in rebreathers, and the calamities they can cause. Since then, the toll of divers lured to their death has been steadily mounting. In one week alone in April 2016, at almost the same geographical latitude in Northern Florida, there were two diving fatalities involving rebreathers. It is an alarming and continuing trend.
I know a highly experienced diver who starts each dive by looking at his diving equipment, his underwater life support system, and asking it that title question: How will you try to kill me today?
This deep cave diver, equally at home with open circuit scuba and electronic rebreathers, is not a bold cave diver. He is exceptionally cautious, because he is also the U.S. Navy’s diving accident investigator. He has promised me that his diving equipment will never end up in our accident equipment cage.
He and I have seen far too many of the diving follies where underwater life support systems fail their divers. But the crucible in which those fatal failures are often born are errors of commission or omission by the deceased.
Carelessness and an attitude of “it can’t happen to me” seem all too prevalent, even among the best trained divers. Divers are human, and humans make mistakes. Statistically, those accidents happen across all lines of experience: from novice divers, to experienced professional and governmental divers, and even military divers. They all make mistakes that can, and often do, prove fatal.
It is exceedingly rare that a life support system fails all by itself, since by design they are robust, and have either simple, fool-proof designs, or redundancy. In theory a single failure should not bring a diver to his end.
Are oxygen sensors trying to kill you? That depends on how old they are? Are they in date? Ignoring the expiration date on chocolate chip cookies probably won’t kill you, but ignoring the expiration date on oxygen sensors may well prove fatal. Complex systems like rebreathers depend upon critical subsystems that cannot be neglected without placing the diver at risk.
Oxygen sensors are usually found in triplicate, but if one or more are going bad during a dive, the diver and the rebreather can receive false warnings of oxygen content in the gas being breathed. We have seen a rebreather computer “black box” record two sensor failures, and it’s CPU logic deduced that the single working sensor was the one in error.
The controller’s programmed logic forced it to ignore the good sensor, and thus the controller continued to open the oxygen solenoid and add oxygen in an attempt to make the two dying sensors read an appropriately high O2. Eventually, the diver, ignoring or not understanding various alarms he was being given, went unconscious due to an oxygen-induced seizure. His oxygen level was too high, not too low.
Unlike fuel for a car or airplane, you can have too much oxygen.
Oxygen sensors do not fail high, but they do fail low, due to age. Rebreather manufacturers should add that fact into their decision logic tree before triggering inaccurate alarms. But ultimately, it’s the diver’s responsibility to examine his own oxygen sensor readings and figure out what is happening. The analytical capability of the human brain should far exceed the capability of the rebreather CPU, at least for the foreseeable future.
Oxygen addition solenoids hold back the flow of oxygen from a rebreather oxygen bottle until a voltage pulse from the rebreather controller signals it to open momentarily. The oxygen flow path is normally kept closed by a spring inside the solenoid, holding a plunger down against its seat.
But solenoids can fail on occasion, which means they will not provide life giving oxygen to the diver. The diver must then either manually add oxygen using an addition valve, or switch to bailout gas appropriate for the depth.
Through either accident or design, divers have been known to invert their solenoid spring and plunger, thereby keeping the gas flow open. In that case, oxygen could not be controlled except by manually turning on and off the valve to the oxygen tank. Of course, knowing when oxygen is too low or too high would depend upon readings from the oxygen sensors.
Suffice it to say that such action would be extremely reckless. And if the oxygen sensors were old, and thus reading lower than the true oxygen partial pressure, the diver would be setting himself up for a fatal oxygen seizure. It has happened.
Assuming a solenoid has not been tampered with, alarms should warn the diver that either the solenoid has failed, or that the partial pressure of oxygen is dropping below tolerance limits.
But as the following figures reveal, if the diver does not react quickly enough to add oxygen manually, or switch to bail out gas, they might not make it to the surface.
The three figures below are screen captures from U.S. Navy software written by this author, that models various types of underwater breathing apparatus, rebreathers and scuba. In the setup of the model, an electronically controlled, constant PO2 rebreather is selected. In the next screen various rebreather parameters are selected, and in this case we model a very small oxygen bottle, simulating an oxygen solenoid failure during a dive. On another screen, a 60 feet sea water for 60 minutes dive is planned, with the swimming diver’s average oxygen consumption rate set at 1.5 standard liters per minute.
On the large screen shot below, we see a black line representing diver depth as a function of time (increasing from the dashed grey line marked 0, to 60 fsw), a gray band of diver mouth pressure, and an all-important blue line showing the partial pressure of inspired oxygen as it initially increases as the diver descends, then overshoots, and finally settles off at the predetermined control level of oxygen partial pressure (in this case 1.3 atmospheres). Broken lines on the very bottom of the graph show automated activation of diluent add valve, oxygen add solenoid, and over pressure relief valve. Long horizontal colored dashes show critical levels of oxygen partial pressure, normal oxygen level (cyan) and the limit of consciousness (red).
The oxygen solenoid fails 53.7 minutes into the dive, no longer adding oxygen. Therefore the diver’s inhaled oxygen level begins to drop. Rather than follow the emergency procedures, or perhaps being oblivious to the emergency, this simulated diver begins an ascent. As ambient pressure drops during the ascent, the drop in oxygen pressure increases.
In this particular example, 62.5 minutes after the dive began, and at a depth of 13.5 feet, the diver loses consciousness. With the loss of consciousness, the diver’s survival depends on many variables; whether he’s wearing a full face mask, whether he sinks or continues to ascend, or is rescued immediately by an attentive boat crew or buddy diver. It’s a crap shoot.
So basically, the rebreather tried to kill the diver, but he would only die if he ignored repeated warnings and neglected emergency procedures.
What about your rebreather’s carbon dioxide scrubber canister? Do you know what the canister duration will be in cold water at high work rates? Do you really know, or are you and the manufacturer guessing? What about the effect of depth, or helium or trimix gas mixes? Where is the data upon which you are betting your life, and how was it acquired?
Sadly, few rebreathers have dependable and well calibrated carbon dioxide sensors; which is unfortunate because a depleted or “broken through” scrubber canister can kill you just as dead as a lack of oxygen. The only difference is a matter of speed; carbon dioxide will knock you out relatively slowly, compared to a lack of oxygen.
But if you think coming up from a dive with a headache is normal, then maybe you should rethink that. It could be that your rebreather is trying to kill you.
If you get the feeling that science is not as pure of thought and logic as it pretends to be, then you will find some comfort in Adam Gopnik’s approachable review of the deeply hidden controversy surrounding what Albert Einstein called “spooky action at a distance.” Spooky action is the weirdest of all science, and makes telepathy and clairvoyance seem almost banal by comparison.
In my opinion, parts of Gopnik’s none-too-technical article remind me of the quote by Dr. Jason Parker, the protagonist in the science fiction thriller, “Middle Waters“. In a supposed speech to the open-minded Emerald Path Society, Parker said, “There are regions between heaven and Earth where magic seems real and reality blurs with the surreal. It is a place where things move quickly and darkly, be they friend or foe. The hard part for me is knowing the difference between them.”
Gopnik expressed that thought more prosaically by the following: “”Magical” explanations, like spooky action, are constantly being revived and rebuffed, until, at last, they are reinterpreted and accepted. Instead of a neat line between science and magic, then, we see a jumpy, shifting boundary that keeps getting redrawn.”
Gopnik goes on to say, “Real-world demarcations between science and magic … are … made on the move and as much a trap as a teaching aid.”
To be honest, I did leave out Gopnik’s entertaining reference to Bugs Bunny and Yosemite Sam. Again, if you have ever been suspicious of the purity of science, the New Yorker article is well worth the read.
Unlike the concerns of Einstein, Neils Bohr and the rest of the cast of early 20th century physicists, the anxiety of Jason Parker, the fictional hero, is not cosmological; it’s personal. It’s every bit as personal as it is for each of us when we sometimes question our sanity.
Yes, real life can be like that sometimes, when things intrude into our ordered lives, as quickly as a Midwest tornado, but with less fanfare and warning. But every bit as destructive. And it is at those points, those juxtapositions with things radical, unexpected, that we end up questioning our grip on reality.
After all, what could be more unexpected and unreal seeming than the notion that cosmological matter we can’t see, dark matter, could send comets crashing into the Earth, as Gopnik mentioned, and the Harvard theoretical physicist Lisa Randall wrote about in her book Dark Matter and the Dinosaurs.
So, Jason Parker had every reason to be wary of things that move quickly and darkly. They can be a killer.
Sometimes, as in the case of Parker, those internal reflections do end up having a cosmological consequence. But even if they don’t, it’s a good idea to occasionally reexamine our lives for the things which may seem one day to be magical, and the next day to be very real.
In short, the magic should not be dismissed out of hand, because, after all, just like “spooky action at a distance” and “dark matter”, it may not be magic after all.
I once met the Father of the U.S Remote Viewing program, unawares.
A decade ago, at the request of a Navy engineer who ended up being a character in my novel Middle Waters, I invited Dr. Harold E. Puthoff into the Navy Experimental Diving Unit to give a talk on advanced physics. He had attracted a small but highly educated and attentive crowd which, like me, had no idea that the speaker had once led the CIA in the development of its top secret Remote Viewing program.
Puthoff is the Director of the Institute of Advanced Studies at Austin, in Texas, but before that, and more germane to this discussion, Puthoff was a laser physicist at the Stanford Research Institute. It was there that the CIA chose him to lead a newly created Remote Viewing program, designed to enable the U.S. to maintain some degree of competiveness with Russia’s cold war psychic spying program.
Psychic spying was purportedly the method used by the two superpowers to visualize things from a distance; not from a satellite, but from what some call the highly developed powers of the mind’s eye. If we believe what we read on the subject, Remote Viewing was eventually dropped from the US psychic arsenal not because it had no successes, but because it was not as reliable as signal intelligence (SIGINT), satellite imagery, and spies on the ground. But, it has been argued, it might be ideal in locations where you can’t put spies on the ground, such as the dark side of the moon, or the deep sea .
Serendipitously, as I started writing this blog post, Newsweek published a review of the Remote Viewing efforts of Puthoff and others in a November 2015 issue. The article seemed fairly inclusive, at least more so than other articles on Remote Viewing I’ve seen, but the Newsweek author was not particularly charitable towards Puthoff. Strangely, the strength and veracity of Puthoff’s science was reportedly criticized by two New Zealand psychologists who, as the Newsweek author quoted, had a “premonition” about Puthoff.
“Psychologists” and “premonitions” are not words commonly heard in the assessment of science conducted by laser physicists, especially those employed by the CIA. The CIA is not stupid, and neither are laser physicists from Stanford.
To the extent that I am able to judge a man by meeting him in person and hearing him talk about physics, I would have to agree with Puthoff’s decision to ignore his ill-trained detractors. Every scientist I know has had detractors, and as often as not those detractors have lesser credentials. Nevertheless, I have the good sense to not debate the efficacy of remote viewing. I don’t know enough about it to hold an informed opinion. However, there seems to be some evidence that it worked occasionally, and for a science fiction writer that is all that is needed.
As my curiosity became piqued by the discovery of the true identity of my guest speaker at NEDU, and as I learned what he had done for the U.S. during the Cold War, I thought of another great physicist, Enrico Fermi, one of the fathers of the atomic bomb. In the midst of a luncheon conversation with Edward Teller, Fermi once famously asked, “Where are they?” The “they” he was referring to, were extraterrestrial aliens.
What became known as Fermi’s Paradox went something like this: with all the billions of stars with planets in our galactic neighborhood, statistically there should be alien civilizations everywhere. But we don’t see them. Why not? “Where are they?”
In most scientists’ opinions, it would be absurdly arrogant for us to believe we are the only intelligent life form in the entire universe. And so ETs must be out there, somewhere. And if there, perhaps here, on our planet, at least occasionally. And that is all the premise you need for a realistic, contemporary science fiction thriller.
But then there is that pesky Fermi Paradox. Why don’t we see them?
Well, they could indeed be here, checking us out by remote viewing, all the while remaining safely hidden from sight. After all, as one highly intelligent Frog once said, humans are a “dangerous species” —fictionally speaking of course.
That “hidden alien” scenario may be improbable, but it’s plausible, if you first suspend a little disbelief. If we can gather intelligence while hiding, then certainly they can, assuming they are more advanced than humans. A technological and mental advantage seems likely if they are space travelers, which they almost have to be within the science fiction genre. Arguably, fictional ETs may have long ago engineered space-time, which could prove mighty convenient for tooling around the galactic neighborhood.
So, if in the development of a fictional story we assume that ETs can remote view, the next question would be, why? Is mankind really that dangerous?
Well, I don’t intend for this post to be a spoiler for Middle Waters, but I will say that the reasons revealed in the novel for why ETs might want to remote view, are not based on fear of humans, but are based on sound science. From that science, combined with a chance meeting with Hal Puthoff, the basic premise of a science fiction thriller was born.
So, to correct what some of my readers have thought, I did not invent the concept of “remote viewing”. It is not fictional; it is real, and was invented and used by far smarter people than myself, or even that clever protagonist, Jason Parker.
Scientists and engineers love to argue, and unlike the case with politicians, compromise is not an option. Technologists speak for nature, for the truth of a universe which does not speak for itself. But when a technologist is wrong, they usually have to eat some crow, so to speak.
Stephen Hawkings, the famous cosmologist, freely admits his brilliant doctoral dissertation was wrong. Crow was eaten, and Hawkings moved on to a better, arguably more correct view of the universe.
Now, on a much less grand scale, this is my time for eating crow.
There has been quiet disagreement over the water temperature above which a scuba regulator is safe from free-flowing or icing up. Those untoward icing events either give the diver too much gas, or not enough. Neither event is good.
Based upon an apocryphal Canadian government study that I can’t seem to put my hands on anymore (government studies are rarely openly available), it has long been believed by the Canadians and Americans that in water temperatures of 38°F or above, regulator icing problems are unlikely. That temperature was selected because when testing older, low flow Canadian regulators, temperatures inside the regulator rarely dropped below 32°F when water temperature was 38°F.
As shown in an earlier blog post, in 42°F water and at high scuba bottle pressures (2500 psi) in instrumented second stage regulators (Sherwood Maximus) second stage internal temperature dropped below zero Celsius (32°F) during inspiration. During exhalation the temperature rose much higher, and the average measured temperature was above freezing. Nevertheless, that regulator free flowed at 40 minutes due to ice accumulation.
Presumably, a completely “safe” water temperature would have to be warmer than 42°F. But how much warmer?
My European colleagues have stated for a while that cold water regulator problems were possible at any temperature below 10°C, or 50°F. However, as far as I can tell that assertion was not based on experimental data. So as we began to search for the dividing line between safe and unsafe water temperatures in another brand of regulator, I assumed we’d find a safe temperature cooler than 50°F. For that analysis, we used a generic Brand X regulator.
To make a long story short, I was wrong.
To understand our analysis, you must first realize that scuba regulator freeze-up is a probabilistic event. It cannot be predicted with certainty. Risk factors for an icing event are diving depth, scuba bottle pressure, ventilation (flow) rate, regulator design, and time. In engineering terms, mass and heat transfer flow rates, time and chance determine the outcome of a dive in cold water.
At NEDU, a regulator is tested at maximum anticipated depth and ventilated at a high flow rate (62.5 L/min) for a total period of 30 min. If the regulator free flows or stops flowing, an event is recorded and the time of the event is noted. Admittedly, the NEDU test is extremely rigorous, but it’s been used to select safe regulators for U.S. military use for years.
Tests were conducted at 38, 42, 45 and 50°F.
Next, an ordinal ranking of the performance for each regulator configuration and temperature combination was possible using an NEDU-defined probability-of-failure test statistic (Pf). This test statistic combines the number of tests of a specific configuration and temperature conducted and the elapsed time before freezing events occurred. Ordinal ranks were calculated using equation 1, where n is the number of dives conducted, E is a binary event defined as 0 if there is no freezing event and 1 if a freezing event occurs, t is the elapsed time to the freezing event from the start of the test (minutes), and k is an empirically determined constant equal to 0.3 and determined to provide reasonable probabilities, i is the index of summation.
Each data point in the graph to the left represents the average result from 5 regulators, with each test of 30-min or more duration. For conditions where no freezing events were observed at 30 min, additional dives were made for a 60-min duration.
As depicted, 40-regulator tests were completed, using 20 tests of the five primary second stages and 20 octopus or “secondary” second stages. Regression lines were computed for each data set. Interestingly, those lines proved to be parallel.
The “octopus” second stage regulator (the part going in a scuba diver’s mouth) differed from the primary only by the spring tension holding the regulator’s poppet valve shut. More negative mouth pressure is required to pull the valve open to get air than in the primary regulator.
The test statistic does not provide the probability that a given test article or regulator configuration will experience a freezing event at a given temperature. However, it does provide the ability to rank the freezing event performance of regulator configurations at various temperatures.
Our testing reveals that in spite of my predictions to the contrary, for the Brand X regulator our best estimate of a “safe” water temperature, defined as Pf = 0, is roughly 53°F for the standard or “primary” second stage regulator and 49° F for the octopus or secondary regulator.
For all practical purposes, the European convention of 50°F (10°C) is close enough.
Eating crow is not so bad. Some think it tastes a little like chicken.
Equation 1 came from J.R. Clarke and M. Rainone, Evaluation of Sherwood Scuba Regulators for use in Cold Water, NEDU Technical Report 9-95, July 1995.
As evidenced by Under the Pole diving expeditions, rebreathers are being used in some of the most isolated and frigid places in the world. Some of those dive missions are surprisingly deep (111 meters, 330 feet) and long, about 2 hours.
That gives me cause for pause.
I suspect most divers are aware of the 1/3 rule for gas consumption on an open circuit (scuba) cave dive. You should use no more than 1/3 of your air supply on the way in, leaving you with 1/3 for the trip out, and 1/3 of your gas supply available in reserve. Sadly, even that amount of reserve has not saved all cave divers.
Now that cave divers are using rebreathers, the rules, at least for some, have changed. Some savvy rebreather cave divers use the rule of doubles: Always have twice as much oxygen, twice as much diluent, and twice as much canister as you think you’ll need. That plus an open-circuit or semi-closed circuit bailout should keep you safe — in theory.
Gas supply is easy to measure throughout a dive; there is a pressure gauge for all gases. But what about canister duration? Most divers assume they will have more canister duration available than gas supply; which means they don’t need to worry about canister duration. That would be a good thing, if it were true. After all, how many manufacturers provide expected canister durations for various work rates and water temperatures? Maybe, none? Or certainly very few.
I would be very surprised if manufacturers could say with certainty that during a two hour dive in -2°C (28°F) water, at depths to 111 meters that the scrubber can provide double the duration needed. That would be four hours in -2°C water, at all potential diver work rates.
Some of you may say, “Under-the-ice-diving is not like cave diving, so the doubles rule is too conservative.” I invite you to think again. Under polar ice, is there ready access to the surface? Not unless you’re diving directly under the through-ice bore hole the entire time.
In the U.S. Navy experience, obtaining useful data on canister durations from manufacturers is difficult. Duration data as a function of temperature is practically nonexistent. Therefore I will share the following information gleamed from scrubber canister testing in extreme environments by the Navy. While this blogger cannot reveal canister durations for military rebreathers, the information on the coefficient of varation (COV) is not protected. (There is no way to figure out what a canister duration is based solely on the COV.)
The following 4-minute video gives a good introduction to the coefficient of variation.
All rebreather divers should know that canister performance declines in an accelerating manner as water temperature drops between 50°F and 28°F. But what your rebreather manufacturer may not know is that the innate variability of canister durations also increases as water temperature drops. The Navy has found that trend in all types of rebreathers.
So, while canister durations drop considerably in cold water, you’re also less certain about what your canister’s endurance is going to be, because of the increase in duration variability. When canister duration drops and variability increases, a diver’s margin of safety becomes a gamble. Personally, I don’t like to gamble under water.
In the U.S. Navy, published canister durations take into account mean canister performance, and variability. That is accomplished through the use of 95% prediction intervals. The greater the variability in canister duration, the lower the published duration.
This method of determining safe canister durations has been in use by the U.S. Navy since 1999. However, I do not know if manufacturers use similar statistically-based methods for publishing canister durations. If they or you do not take duration variability into account as you dive cold, you may be in for a shock. Due to the nature of statistics, you may have 9 deep, cold dives with no CO2 problems, but find yourself in bad shape on the 10th dive.
If you did have a CO2 problem, it wouldn’t necessarily be anyone’s fault: it could just be a result of canister variability in action.
So, diver beware. Give yourself plenty of leeway in planning rebreather dives in frigid waters. After all, you do not want to become a statistic, caused ironically by statistics.
If you have an interest in understanding the derivation of the prediction interval equation and its application, two videos of lectures by Dr. Simcha Pollack from St. John’s University may be helpful. Part I is found here, and Part 2 is found here.
Thanks to Gene Hobbs and the Rubicon Foundation, NEDU’s original report on the use of prediction limits to establish published canister durations is found here.
One of the most memorable quotes I’ve heard from a child came from his experience listening to classical music. I don’t remember who said it (Google comes up empty-handed), but I’ve never forgotten it.
“A symphony is music with a song waiting to bust out any minute.”
Those words were the child’s response to listening to a symphonic piece. The little listener kept expecting to hear a song, but no sooner did the musicians seem to be closing in on a melody, than the music changed and darted off down another musical path. I suspect that was a little frustrating to the kid; but at least it kept him listening, expectantly.
Being a musician, I can fully appreciate the correctness of his innocent comment.
Classical music is technical; in fact, highly so. Orchestration is a wonderment to those of us who aren’t both talented and trained in the art. The printed lines for a solo instrument, like the clarinet I play, are defined by strict mathematical relationships between frequencies of sound. If the math is not precise, then the sound will not be precise and melodic. That is to say, the sound will not be music, but rather noise.
I consider myself a technical person. As a scientist, I understand the technical rigor and precision which is required for composing and orchestration, but also for scientific and engineering calculations and publications. Indeed, I’ve spent decades writing technical papers, many with a fair amount of mathematical basis. I kept the creative, the musical side, bottled up, because it’s not publishable. Technical publications are, well, technical. They are neither pretty nor tuneful.
But as I mingle vicariously with other technical writers, I find that some of them also have a pent-up desire for creative writing. With a somewhat guilty feeling, they have actually penned very good, non-technical prose. And even a few poems.
Now that I, a scientist, have released my first novel, Middle Waters, hugely imaginative compared to my day-to-day paid technical writing, I feel I have birthed a bastard child.
The following is reprinted from my article published in ECO Magazine, March 2015. It was published in its current format as an ECO Editorial Focus by TSC Media. Thank-you Mr. Greg Leatherman for making it available for reprinting.
It is the highpoint of your career as an environmentally minded marine biologist. The National Science Foundation has provided a generous grant for your photographic mission to the waters 100 ft below the Ross Ice Shelf, Antarctica. Now you’re on an important mission, searching for biological markers of climate change.
Above you lies nothing but a seemingly endless ceiling of impenetrable ice, 10 ft thick. Having spent the last several minutes concentrating on your photography, you look up and notice you’ve strayed further from safety than you’d wanted. The strobe light marking the hole drilled in the ice where you’ll exit the freezing water is a long swim away. And, unfortunately, your fellow scientist “buddy” diver has slipped off somewhere behind you, intent on her own research needs.
You’re diving SCUBA with two independent SCUBA regulators, but in the frigid cold of the literally icy waters, you know that ice could be accumulating within the regulator in your mouth. At the same time, a small tornado of sub-zero air expands chaotically within the high-pressure regulator attached to the single SCUBA bottle on your back—and that icy torrent is increasingly sucking the safety margins right out of your regulator. You are powerless to realize this danger or to do anything about it.
At any moment, your regulator could suddenly and unexpectedly free flow, tumultuously dumping the precious and highly limited supply of gas contained in the aluminum pressure cylinder on your back. You’re equipped and trained in the emergency procedure of shutting off the offending regulator and switching to your backup regulator, but this could also fail. It’s happened before.
As you try to determine your buddy’s position, you’re feeling very lonely. You realize the high point of your career could rapidly become the low point of your career—and an end to your very being.
The preceding is not merely a writer’s dramatization. It is real, and the situation could prove deadly—as it has in far less interesting and auspicious locations. Regulator free flow and limited gas supplies famously claimed three professional divers’ lives in one location within a span of one month.
There is a risk to diving in extreme environments. However, the U.S. Navy has found that the risk is poorly understood, even by themselves—the professionals. If you check the Internet SCUBA boards, you constantly come across divers asking for opinions about cold-watersafe regulators. Undoubtedly, recent fatalities have made amateur divers a little nervous—and for good reason.
Internet bulletin boards are not the place to get accurate information about life support safety in frigid water. Unfortunately, the Navy found that manufacturers are also an unreliable source. Of course, the manufacturers want to be fully informed and to protect their customers, but the fact remains that manufacturers test to a European cold-water standard, EN 250. By passing those tests, manufacturers receive a “CE” stamp that is pressed into the hard metal of the regulator. That stamp means the regulator has received European approval for coldwater service.
As a number of manufacturers have expensively learned, passing the EN 250 testing standard is not the same as passing the more rigorous U.S. Navy standard, which was recently revised, making it even more rigorous by using higher gas supply pressures and testing in fresh as well as salt water. Freshwater diving in the Navy is rare—but depending on the brand and model of regulator in use, it can prove lethal.
The unadorned truth is that the large majority of manufacturers do not know how to make a consistently good Performing cold-water regulator. Perhaps the reason is because the type of equipment required to test to the U.S. Navy standard is very expensive and has, not to date, been legislated. Simply, it is not a requirement.
Some manufacturers are their own worst enemy; they cannot resist tinkering with even their most successful and rugged products. This writer is speculating here, but the constant manufacturing changes appear to be driven by either market pressures (bringing out something “new” to the trade show floor) or due to manufacturing economy (i.e., cost savings). The situation is so bad that even regulators that once passed U.S. Navy scrutiny are in some cases being changed almost as soon as they reach the “Authorized for Military Use” list. The military is struggling to keep up with the constant flux in the market place, which puts the civilian diver in a very difficult position. How can they—or you—know what gear to take on an environmentally extreme dive?
My advice to my family, almost all of whom are divers, is to watch what the Navy is putting on their authorized for cold-water service list. The regulators that show up on that list (and they are small in number) have passed the most rigorous testing in the world.
Through hundreds of hours of testing, in the most extreme conditions possible, the Navy has learned what all SCUBA divers should know:
• Even the coldest water (28°F; -2°C) is warm compared to the temperature of expanding air coming from a first stage regulator to the diver. There is a law of physics that says when compressed air contained in a SCUBA bottle is expanded by reducing it to a lower pressure, air temperature drops considerably. It’s the thermal consequence of adiabatic (rapid) expansion.
• Gas expansion does not have to be adiabatic. Isothermal (no temperature change) expansion is a process where the expansion is slow enough and heat entry into the gas from an outside source is fast enough that the expanded gas temperature does not drop.
• The best regulators are designed to take advantage of the heat available in ice water. The most critical place for that to happen is in the first stage where the greatest pressure drop occurs (from say 3,000 psi or higher to 135 psi above ambient water pressure (i.e., depth). They do that by maximizing heat transfer into the internals of the regulator.
• First stage regulators fail in two ways. The most common is that the first stage (which controls the largest pressure drop) begins to lose control of the pressure being supplied to the second stage regulator, the part that goes into a diver’s mouth. As that pressure climbs, the second stage eventually can’t hold it back any longer and a free flow ensues.
• The second failure mode is rare, but extremely problematic. Gas flow may stop suddenly and completely, so that backup regulator had better be handy.
• Second stage regulators are the most likely SCUBA components to fail in cold water due to internal ice accumulation.
• Free flows may start with a trickle, slowly accelerating to a torrent, or the regulator may instantly and unexpectedly erupt like a geyser of air. Once the uncontrolled, and often unstoppable free flow starts, it is self-perpetuating and can dump an entire cylinder of air within a few minutes through the second stage regulator.
• A warm-water regulator free flow is typically breathable; getting the air you need to ascend or to correct the problem is not difficult. In a cold-water-induced free flow, the geyser may be so cold as to make you feel like you’re breathing liquid nitrogen and so forceful as to be a safety concern. Staying relaxed under those conditions is difficult, but necessary.
• Water in non-polar regions can easily range between and 34°F to 38°F; at those temperatures, gas entering the second stage regulator can be at sub-freezing temperatures. European standard organizations classify ~10°C (50°F) as the cold/non-cold boundary. The Navy has found in the modern, high-flow regulators tested to date that 42°F is the water temperature where second stage inlet temperature is unlikely to dip below freezing.
• The small heat exchangers most manufacturers place just upstream of the second stage is ineffective In extreme conditions. They quickly ice over, insulating that portion of the regulator from the relative warmth of the surrounding water.
• Regulator “bells and whistles” are an unknown and can be problematic. Second stage regulators with multiple adjustments can do unpredictable things to heat transfer as the diver manipulates his controls. The last thing a cold-water diver should want is to make it easier to get more gas. High gas flows mean higher temperature drops and greater risk of free flow.
• Only manufacturer-certified technicians should touch your regulator if you’re going into risky waters. The technician at your local dive shop may or may not have current and valid technician training on your particular life support system. Don’t bet your life on it— ask to see the paperwork.
• Follow Navy and Smithsonian* guidance on handling and rinsing procedures for regulators in frigid waters. A single breath taken above the surface could freeze a regulator before you get your first breath underwater.
U. S. Navy reports on tested regulators are restricted. However, the list of those regulators passing all phases of Navy testing is available online. If your regulator, in the exact model as tested, is not on that list, do yourself a favor and don’t dive in frigid waters.
The original Editorial Focus article is found in the digital version of the March ECO magazine here, on pages 20-25.
There is nothing quite like a heart attack and triple bypass surgery to get your attention.
Even if you’ve been good, don’t smoke, don’t eat to excess, and get a little exercise, it may not be enough to keep a heart attack from interrupting your life style, and maybe even your life.
Post-surgical recovery can be slow and painful, but if you have an avocational passion, that passion can be motivational during the recovery period after a heart attack. There is something about the burning desire to return to diving, flying, or golfing to force you out of the house to tone your muscles and get the blood flowing again.
My return to the path of my passions, diving and flying, began with diet and exercise. My loving spouse suggested a diet of twigs and leaves, so it seemed. I can best compare it to the diet that those seeking to aspire to a perpetual state of Buddha-hood, use to prepare themselves for their spiritual end-stage: it’s a state that looks a lot like self-mummification. Apparently those fellows end up either very spiritual or very dead, but I’m not really sure how one can tell the difference.
The exercise routine began slowly and carefully: walking slowly down the street carrying a red heart-shaped pillow (made by little lady volunteers in the local area just for us heart surgery patients). The idea, apparently, is that if you felt that at any point during your slow walk your heart was threatening to extract itself from your freshly opened chest, or to extrude itself like an amoeba between the stainless steel sutures holding the two halves of your rib cage together, that pillow would save you. You simply press it with all the strength your weakened body has to offer against the failing portion of your violated chest, and that pressure would keep your heart, somehow, magically, in its proper anatomical location.
I am skeptical about that method of medical intervention, but fortunately I never had occasion to use it for its avowed purpose.
Eventually I felt confident enough to ditch the pillow and pick up the pace of my walks. In fact, I soon found I could run again, in short spurts. It was those short runs that scared the daylight out of my wife, but brought me an immense amount of pleasure. It meant that I might be able to regain my flying and diving qualifications.
After that teaching adventure, I prepared myself for the grinder that the FAA was about to put me through: a stress test. Not just any stress test mind you, but a nuclear stress test where you get on a treadmill and let nurses punish your body for a seeming eternity. Now, these nurses are as kindly as can be, but they might well be the last people you see on this Earth since there is a small risk of inducing yet another heart attack during the stress test. Every few minutes the slope and speed of the treadmill is increased, and when you think you can barely survive for another minute, they inject the radioisotope (technetium 99m).
With luck, you would have guessed correctly and you are able to push yourself for another long 60-seconds. I’m not sure exactly what would happen if you guess incorrectly, but I’m sure it’s not a good thing.
And then they give you a chance to lie down, perfectly still, while a moving radioisotope scanner searches your body for gamma rays, indicating where your isotope-laden blood is flowing. With luck, the black hole that indicates dead portions of the heart will be small enough to be ignored by certifying medical authorities. (An interesting side effect of the nuclear stress test is that you are radioactive for a while, which in my case caused a fair amount of excitement at large airports. But that’s another story.)
The reward for all the time and effort spent on the fabled road to recovery, is when you receive, in my case at least, the piece of paper from the FAA certifying that you are cleared to once again fly airplanes and carry passengers. With that paper, and having endured the test of a life-time, I knew that I’d pass most any diving physical.
Having been in a situation where nature dealt me a low blow and put my life at risk and, perhaps more importantly, deprived me of the activities that brought joy to my life, it was immensely satisfying to be able to once again cruise above the clouds on my own, or to blow bubbles with the fish, in their environment. Is there anything more precious that being able to do something joyful that had once been denied?
Without a doubt, the reason I was able to resume my passions was because I happened to do, as the physicians said, “all the right things” when I first suspected something unusual was happening in my chest. The symptoms were not incapacitating so I considered driving myself to the hospital. But after feeling not quite right while brushing my teeth, I lay down and called 911. The ambulance came, did an EKG/ECG, and called in the MI (myocardial infarction) based on the EKG. The Emergency room was waiting for me, and even though it was New Years’ eve, they immediately called in the cardiac catheterization team. When the incapacitating event did later occur I was already in cardiac ICU and the team was able to act within a minute to correct the worsening situation.
Had I dismissed the initial subtle symptoms and not gone to the hospital, I would not have survived the sudden onset secondary cardiac event.
The lesson is, when things seem “not quite right” with your body, do not hesitate. Call an ambulance immediately and let the medical professionals sort out what is happening. That will maximize your chances for a full and rapid recovery, and increase the odds of your maintaining your quality of life.
It will also make you appreciate that quality of life more than you had before. I guarantee it.
It was a coincidence forty years in the making. I was recently at the Scripps Institute of Oceanography, talking to Scripps professor and physician Paul Ponganis about deep diving whales. He told me about the recent discovery that Cuvier’s Beaked Whale, an elusive whale species, had been found to be the deepest diving of all whales.
How deep I asked? One whale dived to 9,816 feet, about 3000 meters. At that depth, water pressure exerts a force of about 4400 pounds per square inch (psi), equal to the weight of a Mercedes E63 sedan pressing on each square inch of the whale’s ample body surface. That is a seriously high pressure, a fact that I knew well since I had once created that much pressure, and more, in a small volume of sea water in a pressure vessel at the Florida State University.
Early in my science career I published my work on the effect of deep ocean pressure on intertidal bivalves, a mussel (Modiolus demissus) being among them. I found that if you removed the hearts of such molluscs (or mollusks) and suspended them in sea water, they would continue to beat. Furthermore, those excised hearts would beat when subjected to 5000 psi of hydrostatic pressure. As if that wasn’t surprising enough, the slight genetic differences between Atlantic subspecies and Gulf Coast subspecies of mussels resulted in the isolated hearts responding slightly differently to high pressure.
Eventually my research transitioned from invertebrates to humans. Humans, like intertidal mussels and clams, are not normally exposed to high pressure. But like my unwilling invertebrate test subjects, sometimes humans do get exposed to high pressure, willingly. But not so much of it. Deep sea divers do quite well at 1000 feet sea water (fsw), manage fairly well at 1500 fsw, but don’t fare well at all at 2000 fsw. That depth seems to be the human pressure tolerance limit due to the high pressure nervous syndrome, or HPNS. At those pressures, cell membranes seem to change their physical state, becoming less fluid or “oily” and more solid like wax. Cells don’t work normally when the very membranes surrounding them are altered by pressure.
The Beaked Whale is genetically much more similar to man than are mussels. Therefore, man is far more likely to benefit by learning how Cetaceans like whales tolerate huge pressure changes, than we are to benefit from the study of deep diving (albeit forced diving) clams and mussels.
As I talked to Dr. Ponganis it was obvious to him, I suspect, that I was excited about learning more about how these animals function so beautifully at extreme depths. But to do that, you have to collect tissue samples for study and analysis in a laboratory. The only problem is, collecting useful tissue samples from living whales without hurting them may be a bridge too far. Humans rarely even see Beaked Whales, and if the Cetaceans wash up on shore, dead, their tissues have already been degraded by post-mortem decomposition, and are no longer useful for scientific study.
Potentially, here is a job for underwater Cetacean-like robots that when released in a likely Beaked Whale environment, can locate them, dive with them, and perhaps even earn their trust. And when the whale beasts least expect it, those robotic Judases could snatch a little biopsy material.
If only it were that easy.
Considering how difficult it would be to acquire living tissue samples, would it be worth the effort? Well, if man is ever to dive deeper than 1500 to 2000 feet without the protection of submarines, we must learn how, from either the mussels or the whales. My bet is on the whales. Unlike mussels, the whales dive deep for a living, to catch their preferred prey, squid and deep sea fish.
What are arguably the first studies of the effects of high pressure on intertidal bivalves (mussels and clams) can be found here and here. Moving up the phylogenetic scale, Yoram Grossman and Joan Kendig published high pressure work on lobster neurons in 1990, and rat brain slices in 1991. I made the leap from mussels to humans by conducting a respiratory study on Navy divers at pressures of 46 atmospheres (1500 feet sea water), published in 1982. For a more recent review of high pressure biology applied to animals and man, see the 2010 book entitled Comparative High Pressure Biology. My theoretical musings about the mathematics of high pressure effects on living cells can be found here.
With time, these studies, and more, will add to our understanding of mammalian pressure tolerance. However, it may well take another generation or two of such scientific effort before we understand how the Beaked Whales make their record-breaking dives, and survive.
In days not too long past, proper lighting and posture were the keys to enjoyable and prolonged reading comfort. Now, things have changed.
When reading by candle light, you placed your reading material in close proximity to the candle, and placed your chair in as comfortable a position as could be managed.
Electric lighting, by nature of its enhanced luminosity, gives the reader greater flexibility. I well remember the days when studying required the reading of physical books, not electronic displays, and so students were routinely counseled to set up a study environment with a flat desk and a study lamp off to the left side to avoid casting shadows on the reading material.
Body posture was a critical complement to this system. Slouching was as strongly discouraged then as it is today.
However, with self-lit electronic displays, all the former concerns about lighting and posture have become irrelevant. Or so it seems.
In many ways children make ideal subjects for scientific observation. If caught young enough, they have not yet learned the “proper” ways of acting, or sitting. Therefore I am convinced that if left to their own innocent, non-self-aware devices they will instinctively find the most energy efficient and bodily pleasing ways to read, as long as lighting is not a concern. For popular devices such as iPad, Kindle Fire and Nabi, lighting is never an issue. The screen glows with light, sharply contrasting with the dark words of print on electronic books, those so-called “e-books.”
The subject in this photo essay was approximately six years old, freshly out of a bath, in her PJs and pushing her bed time by some very determined reading. In these photos she was reading about dinosaurs, using Booksy on an iPad.
As the following photos demonstrate, gravity itself seems not to impede elementary school reading.
Since kids are ever inventive, sometimes they spice things up with variations on a theme.
When engaged in challenging reading, increasing blood flow to the brain is important. Apparently the easiest way to do that is to raise the body’s center of gravity above the heart, as the following photo shows.
This observation demonstrates that lighted reading displays have freed us from the unnatural constraints imposed by archaic reading and writing instruments. Our work devices have become smaller, lighter, and brighter, enabling a renaissance in body awareness and endless possibilities for comfortable and stimulating postures, never before thought possible.
Admittedly, it helps if you’re six-years old and weigh 40 pounds. I do not guarantee that similar gyrations during reading are entirely safe for adults.
Clarke JR1, Moon RE2, Chimiak JM3, Stinton R4, Van Hoesen KB5, and Lang MA5,6.
1 US Navy Experimental Diving Unit, Panama City, Florida 2 Duke University, Durham, North Carolina 3 Divers Alert Network, Durham, North Carolina 4 Diving Unlimited International, Inc., San Diego, California 5 UC San Diego – Emergency Medicine, San Diego, California 6 OxyHeal Health Group, National City, California
The San Diego Center of Excellence in Diving at UC San Diego aims to help divers be effective consumers of scientific information through its “Healthy Divers in Healthy Oceans” mission. In this monograph we explore a research report from the Navy Experimental Diving Unit (NEDU) that is leading some divers to think they should be cold if they want to reduce decompression risk. That is a misinterpretation of the report, and may be causing divers to miss some of the joy of diving. There is no substitute for comfort and safety on a dive.
In 2007 NEDU published their often-cited report “The Influence of Thermal Exposure on Diver Susceptibility to Decompression Sickness” (Gerth et al., 2007). The authors, Drs. Wayne Gerth, Victor Ruterbusch, and Ed Long were questioning the conventional wisdom that cold at depth increases the risk of decompression illness. After conducting a very carefully designed experiment, they were shocked to find that exactly the opposite was true. Some degree of cooling was beneficial, as long as the diver was warm during ascent.
Discussion and Implications
There are some important caveats for the non-Navy diver to consider. First of all, it was anticipated that a diver would have a system for carefully controlling their temperature during the separate phases of bottom time and decompression. Most non-Navy divers do not have that sort of surface support.
Secondly, the “cold” water in the NEDU study was 80 °F (27 °C). For most of us, 80 °F (27 °C) is an ideal swimming pool temperature, not exactly what you are going to find in non-tropical oceans and lakes. The warm water was 97 °F (36 °C), also a temperature not likely to be available to recreational and technical divers.
When testing the effect of anything on decompression results, the Navy uses their extensive mathematical expertise to select the one dive profile that is, in their estimation, the most likely to identify a difference in decompression risk, if that difference in risk exists. In this case the profile selected was a 120 fsw (37 msw) dive with 25 to 70 min bottom time, decompressed on a US Navy Standard Air table for 120 fsw (37 msw) and 70 min bottom time. That table prescribes 91 minutes of decompression divided thusly: 30 fsw/9 min (9msw/9 min), 20 fsw/23 min (6 msw/23 min), 10 fsw/55 min (3 msw/55 min).
A total of 400 carefully controlled dives were conducted yielding 21 diagnosed cases of decompression sickness. Overwhelmingly, the lowest risk of decompression was found when divers were kept warm during decompression. The effects of a 9 °C increase in water temperature during decompression was comparable to the effects of halving bottom time.
That is of course a remarkable result, apparently remarkable enough to cause civilian divers to alter their behavior when performing decompression dives. However, before you decide to chill yourself on the bottom or increase your risk of becoming hypothermic, consider these facts.
Do you have a way of keeping yourself warm, for instance with a hot water suit, during decompression? If not, the study results do not apply to you.
Of the many possible decompression schedules, the Navy tested only one schedule, the one considered to be the best for demonstrating a thermal influence on decompression risk. Although it seems reasonable that this result could be extrapolated to other dive profiles, such extrapolation is always risky. It may simply not hold for the particular dive you plan to make, especially if that dive is deeper and longer than tested.
Most commercial decompression computers do not adhere to the U.S. Navy Air Tables; few recreational dives are square profiles. Furthermore, additional conservatism is usually added to commercial algorithms. NEDU is not able to test the effects of diver skin temperature on all proprietary decompression tables, nor should they. That is not their mission.
The scientific method requires research to be replicated before test results can be proven or generalized. However, due to the labor and expense involved in the NEDU dive series, it seems unlikely that any experiments that would determine the relevance of these results to recreational or technical diving will ever be performed. As such, it may raise as many questions as it answers. For instance, the original question remains; if you become chilled on a dive, how does that affect your overall risk of decompression illness compared to remaining comfortably warm? Unfortunately, that question may never be answered fully.
Thermoneutral temperatures for swim suited divers are reported to be 93 °F to 97 °F (34 to 36 °C) for divers at rest and 90 °F (32 °C) during light to moderate work (Sterba, 1993). So a skin temperature of 80 °F (27 °C) is indeed cold for long duration dives. If your skin temperature is less than 80 °F (27 °C), then you are venturing into the unknown; NEDU’s results may not apply.In summary, beer and some types of wine are best chilled. Arguably, divers are not.
Support for the San Diego Center of Excellence in Diving is provided by founding partners UC San Diego Health Sciences, UC San Diego Scripps Institution of Oceanography, OxyHeal Health Group, Divers Alert Network, Diving Unlimited International, Inc. and Scubapro.
I was recently flying a private aircraft down the Florida Peninsula to Ft. Lauderdale to give a presentation on diving safety. As I continually checked the cockpit instruments, radios and navigation devices, it occurred to me that the redundancy that I insist upon in my aircraft could benefit divers as well.
In technical and saturation diving, making a free ascent to the surface is just as dangerous as making a free descent to the ground in an airplane, at night, in the clouds. In both aviation and diving, adequate redundancy in equipment and procedures just might make life-threatening emergencies a thing of the past.
As I took inventory of the redundancy in my simple single engine, retractable gear Piper, I found the following power plant redundancies: dual ignitions systems, including dual magnetos each feeding their own set of spark plug wires and redundant spark plugs (two per cylinder). There are two sources of air for the fuel-injected 200 hp engine.
There are two ways to lower the landing gear, and both alarms and automatic systems for minimizing the odds of pilot error — landing with wheels up instead of down. (I’ve already posted about how concerning that prospect can be.)
I also counted three independent sources of weather information, including lightning detection, and two powerful communication radios and one handheld backup radio. For navigation there is a compass and four electronic navigation devices: one instrument approach (in the clouds) approved panel mount GPS with separate panel-mounted indicator, an independent panel mounted approach certified navigation radio, plus two portable GPS with moving map displays and superimposed weather. Even the portable radio has the ability to perform simple navigation.
The primary aircraft control gyro, the artificial horizon or attitude indicator, also has a fully independent backup. One gyro operates off the engine-powered vacuum pump, and the second gyro horizon is electrically driven. Although by no means ideal, the portable GPS devices also provide attitude indicators based upon GPS signals. In a pinch in the clouds, it’s far better than nothing. Of course, even if all else fails, the plane can still be flown by primary instruments like rate of climb, altimeter, and compass.
There is only one sensitive altimeter, but two GPS devices also provide approximate altitude based on GPS satellite information.
But what about divers? How are we set for redundancy?
Starting with scuba (self-contained underwater breathing apparatus), gas supplies are like the fuel tanks in an aircraft. I typically dive with one gas bottle, but diving with two or more bottles is common, especially in technical diving. In a similar fashion, most small general aviation aircraft have at least two independent fuel tanks, one in each wing.
The scuba’s engine is the first stage regulator, the machine that converts high pressure air into lower pressure air. Most scuba operations depend on one of those “engines”, but in extreme diving, such as low temperature diving, redundant engines can be a life saver. While most divers carry dual second stage regulators attached to a single first stage, for better redundancy polar divers carry two independent first stages and second stages. Two first stage regulators can be placed on a single tank.
Even then, I’ve witnessed dual regulator failures under thick Antarctic ice. The only thing saving that very experienced diver was a nearby buddy diver with his own redundant system.
There is a lot to be gained by protecting the face in cold water by using a full face mask. But should the primary first or second stage regulator freeze or free flow, the diver would normally have to remove the full face mask to place the second regulator in his mouth.
Reportedly, sudden exposure of the face to cold water can cause abnormal heart rhythms, an exceedingly rare but potentially dangerous event in diving. If the backup or bail out regulator could be incorporated into the full face mask, that problem would be eliminated. The photo on the right shows one such implementation of that idea.
Rebreathers are a different matter. Most rebreather divers carry a bailout system in case their primary rebreather fails or floods. For most technical divers, that redundancy is an open circuit regulator and bailout bottle. However, there are options for the bail-out to be an independent, and perhaps small rebreather. (One option for a bail-out semiclosed rebreather is found here.) Such a bail-out plan should provide greater duration than open-circuit bailout, especially if the divers are deep when they go “off the loop”.
For some military rebreather divers, there is at least one complete closed-circuit rebreather available where a diver can reach it in case of a rebreather flood-out.
For deep sea helmet diving, the bail-out rebreather is on their back and a simple valve twist will remove the diver from umbilical-supplied helmet gas to fresh rebreather gas.
The most common worry for electronically controlled rebreather divers is failure of the rig’s oxygen sensors. For that reason it is common for rebreathers to carry three oxygen sensors. Unfortunately, as the Navy and others have noted, triple redundancy really isn’t. Electronic rebreathers are largely computer controlled, and computer algorithms can allow the oxygen controller to become confused, resulting in oxygen control using bad sensors, and ignoring a correctly functioning oxygen sensor.
The U.S. Navy has performed more than one diving accident investigation where that occurred. Safety in this case can be improved by adding an independent, redundant sensor, by improving sensor voting algorithms, by better maintenance, or by methods for testing all oxygen sensors throughout a dive.
In summary, safe divers and safe pilots are always asking themselves, “What would I do if something bad happens right now?” Unfortunately, private pilots and divers quickly discover that redundancy is not cheap. However, long ago I decided that if something unexpected happened during a flight or a dive, I wouldn’t want my last thoughts to be, “If only I’d spent a little more money on redundant systems, I wouldn’t be running out of time.”
Time, like fuel and breathing air, is a commodity you can only buy before you run out of it.
Disclaimer: This blog post is not an endorsement of any diving product. Diving products shown or mentioned merely serve as examples of redundancy, and are mentioned only to further diver safety. A search of the internet by interested readers will reveal a panoply of alternative and equally capable products to enhance diver safety.
In space, there is a so-called Goldilocks zone for exoplanet habitability. Too close to a star, and the planet is too hot for life. Too far from its star, and the planet is too cold for life, at least as we understand biological life, life dependent on water remaining in a liquid state. Earth is clearly in the Goldilocks zone, and so is a purported planet Gleise 581d, from another solar system.
Carbon dioxide absorbing “scrubber” canisters in rebreathers have similar requirements for sustaining their absorption reactions. If it’s too hot, the water necessary for the absorption reaction is driven off. Too cold and the water cannot fully participate in the absorption reactions.
Those with some knowledge of chemistry recognize that cold retards chemical reactions and heat accelerates them. But that does not necessarily apply to reactions where a critical amount of water is required. Water thus becomes the critical link to the reaction process, and so maintaining scrubber temperature within a relatively narrow “Goldilocks” zone is important, just as it is for life on distant planets.
Temperature within a scrubber canister is a balance of competing factors. Heat is produced by the absorption of CO2 and it’s conversion from gas to solid phase, specifically calcium carbonate. A canister is roughly 20°C or more warmer than the surrounding inlet gas temperature due to the heat-generating (exothermic) chemical reactions occurring within it.
Heat is lost from a warm canister through two heat transfer processes; conduction and convection. Conduction is the flow of heat through materials, from hot to cold. Hot sodalime granules have their heat conducted to adjacent cooler granules, and when encountering the warm walls of the canister, heat passes through the canister walls, and on to the surrounding cold water.
You can think of this conduction as water flowing downhill, down a gravity gradient. But in this case, the downhill is a temperature gradient, from hot to cold. If the outside of the canister was hotter than the inside, heat would flow in the opposite direction, into the canister.
Copper is a better conductor of heat than iron (it has a higher thermal conductivity), explaining why copper skillets are popular for cooking on stoves. Air is a poor conductor of heat, explaining why neoprene rubber wet suits, filled with air bubbles, are good insulators. Air-filled dry suits are an even better insulator.
Convection is the transfer of heat to a flowing medium, in this case gas. You experience convective cooling when you’re working hard, generating body heat, and a cool dry breeze passes over your skin. Convective cooling can, under those circumstances, be delightful.
When you walk outside on a cold, windy day, convective cooling can be your worst enemy. Meteorologists call it wind chill.
There is wind chill within a canister, caused by the flow of a diver’s exhaled breath through the canister. In cold water the diver’s exhaled breath leaves the body quite warm, but is chilled to water temperature by the time it reaches the canister. Heat is lost through uninsulated breathing hoses exposed to the surrounding water.
As you might expect, if the canister is hot, that convective wind chill can help cool it. If the canister is cold, then the so-called wind chill will chill it even more.
The amount of heat transferred from a solid object to gas is determined by three primary variables; the flow rate of the gas, the density of the gas, and the gas’s heat capacity. Heat capacity is a measure of the amount of heat required to raise the temperature of a set mass of gas by 1° Celsius.
Both the heat capacity and density of the gas circulating through a rebreather changes not only with depth (gas density), but with the gas mixture (oxygen plus an inert diluent such as nitrogen or helium). The heat capacity of nitrogen, helium and oxygen differ, and the ratio of oxygen and inert gas varies with depth to prevent oxygen toxicity. Nitrogen and helium concentrations vary as well, as the diver attempts to avoid nitrogen narcosis.
Q is heat transferred by convection, and the terms on the right are, in sequence, diver ventilation rate, gas density, heat capacity of the inspired gas mixture at constant pressure, and the difference in temperature between the absorbent and environmental temperature.
The interaction of all these variables can be complex, but I’ve worked a few examples relevant to rebreather diving. The assumptions are a low work rate: ventilation is 22 liters per minute, water temperature is 50°F (10°C), oxygen partial pressure is 1.3 atmospheres, and dive depths of 100, 200 and 300 feet sea water. The average canister temperature is assumed to be 20°C (68°F) above water temperature, a realistic value found in tests of scrubber canister temperatures by the U.S. Navy.
The heat capacities for mixtures of diving gases come from mixture equations, and for the conditions we’re examining are given in the U.S. Navy Diving Gas Manual. (This seems to be a hard document to obtain.)
At 100 fsw, the heat transfer (Q) for a nitrogen-oxygen (nitrox) gas mixture is 34.2 Watts (W). For a helium-oxygen mixture (heliox), Q is 27.4 W. At 200 fsw, Q for nitrox is 59.9 W, and for heliox Q is 50.3 W. At 300 fsw, Q for nitrox gas mixture is 85.5 W, and for heliox, is 59.9 W.
Interestingly, the heat transferred from the absorbent bed to the circulating gas is the same at 300 fsw with heliox as it is at 200 fsw with nitrox.
Dr. Jolie Bookspan briefly mentioned the fact that helium removes less heat from a diver’s airways than does air in her short article on “The 36 Most Common Myths of Diving Physiology” (see myth no. 20). Conveniently, heat exchange equations apply just as well to inanimate objects like scrubber canisters as they do to the human respiratory system.
From these types of heat transfer calculations it is easy to see that for a given depth, work rate and oxygen set point, it is better to use a heliox mixture than a nitrox mixture if you’re in cold water. That may sound counterintuitive considering helium’s high thermal conductivity, but the simple fact is, the helium background gas with its low density carries away less heat from the canister, and thereby keeps the canister warmer, than a nitrox mixture does. The result is that canister durations are longer in cold water if less heat is carried away.
In warm water, the opposite would be true. Enhanced canister cooling with nitrox would benefit the canister.
An earlier post on the effect of depth on canister durations raised the question of whether depth impedes canister performance. The notion that increased numbers of inert gas molecules block CO2 from reaching granule absorption sites has little chemical kinetic credence. However, changing thermal effects on canisters with depth or changing gas mixtures does indeed affect canister durations.
I’ve just given you yet another reason why helium is a good gas for rebreather diving, at least in cold water. Unfortunately, these general principles have to be reconciled with the specific cooling properties of all the rebreather canisters in current use. In other words, your canister mileage may vary. But it does look like the current simple notions of depth effects are a bit too simplistic.
I’ve heard about all sorts of disasters with smartphones, and other small, portable electronic devices. Being small and portable makes them easy to drop — something I’ve personally witnessed. Phones are tough by design, but they really don’t like water. Drop one in a toilet while you’re relaxing, and it’s gone — for all practical purposes.
So I had my phone outside with me one evening while I was safety diver for my granddaughter who was practicing scuba skills in our pool. She was enthusiastic and stayed in the pool until it became completely dark outside.
Well, out of sight, out of mind. I helped her out of her dive gear, and then went inside. The phone stayed outside in the dark, quite forlorn and forgotten.
Next morning I noticed it had rained in the early morning hours. Great, I thought, the lawn needs water. But when I went outside I discovered my phone sitting face up on a glass table with beads of water everywhere, including on the phone. A few expletives followed, as you might imagine.
My phone had been somewhat protected by an almost all enclosing Otter box, so I was hopeful not all was lost. Indeed, when I brought the phone in, removed the Otter box sheaving and dried off the phone with paper towels, the phone came back on. Immediate disaster avoided. Thank-you Mr. Otter.
But it took a little while before the potential damage became apparent. When my phone would ring, I’d hear nothing on the ear speaker. I had to switch to speaker phone mode to hear anything. Well, that was annoying.
And then I tried to take a phone photo of the scuba gear, and I could barely see through the camera view finder for the obscuring droplets of water. Rats! Clearly, water had gotten inside the phone. It was merely a matter of time before more damage was done.
With nothing to lose, I plundered through my medicine cabinet and found a potential solution, pictured below.
In fact, I found four of them. I placed those small cylinders of silica gel in a quart-size zip-lock style bag, and placed the dampish phone inside and sealed the bag after squeezing out excess air. If the silica gel canisters didn’t hurt the medicine, it probably wouldn’t hurt my ailing phone.
And there the phone sat, with the small vials of desiccant.
I don’t pray for the healing of phones, but I did have some thoughts somewhat resembling prayer.
I let the phone-in-a bag sit overnight, and in the morning I found I could hear the voices on the other end of the phone connection, and my camera lens no longer had droplets of water on it. As you can see from these photos, the camera worked just fine, and all functions have worked fine ever sense.
Ever since I was created by the curiosity of government and university scientists, I have lived through no efforts of my own. I have the largesse of the U.S. government to thank for that. You see, they paid for the research that created me.
And now, I contribute nothing to society. I pay no taxes, work no jobs. The only decisions I’m allowed to make are restricted to which television program to watch, or which book I want to read. (In case you wondered, I’m not a slow reader. I read quite well, thank-you.)
I live basically in a zoo, except I am the only specimen there, and the zoo keepers all wear lab coats. I suppose the lab coats are designed to protect them were I to spit on them or throw excrement.
I admit, as a child I used to act out with what you consider primitive behavior, throwing feces to vent my anger. I do have tough skin, but no child wants to be continuously poked and needled and questioned. Would you?
But I’ve outgrown that. I’ve learned that when it suits me I can produce a terrifying stare or a teeth-bared snarl that scares the crap out of the more timid researchers. Ah yes, I do enjoy having fun at their expense. It’s about the only thing they can’t control in my otherwise manufactured and manipulated world.
And of course they don’t dare punish or threaten me, because I am, after all, the rarest person in the universe, the only living Neanderthal.
But about that watermelon?
Having nothing to do of any real value gives me time to think … lots of time. Now, since a part of me is a part of you (genetically that is), I’ve been inclined to wonder why my kind is gone, and you Homo sapiens have become the overlords of the planet, at least for the time being.
And I’ve decided that I am truly a seeded watermelon, and you’re seedless.
The seedless watermelon is very much like the older, and almost extinct seeded variety, but with one subtle difference; it’s infertile. (If this analogy becomes too Freudian for you, just keep your mind on watermelons.) Watermelon is, I sincerely believe, one of God’s gifts to man.
But of course you Homo sapiens weren’t content with that. No, you decided to take advantage of a genetic flaw, a freak watermelon with few if any seeds, that is quite incapable of sustaining itself in the gene pool.
Since spitting out melon seeds is apparently such a difficult proposition for your kind, the seedless variety is overwhelmingly popular. It has crowded out the natural watermelon from grocery stores, so I hear.
I’ve been reading about how, based partially on my IQ test results and other research, scientists have decided we weren’t mentally inferior to you. And for sure, as my own testing by the Army has confirmed, we were far stronger.
When is the last time you wrote a letter to a family member or loved one?
I’m not talking about email, or text messages; digital communications do not count. I mean a letter on a piece of paper, placed in an envelope with a stamp, and mailed at a mail box or post office; or in a very private way, lovingly slipped underneath someone’s door.
In the hurry up, speak sparingly Twitter generation, there seems to be little value in penning an honest-to-goodness letter. Compared to instant communication, letter writing with an ink-filled pen seems agonizingly slow, sloppy and so twentieth century.
I recently opened a grey metal box that had lain dormant, ignored, for up to 50 years. It was a time capsule, holding remnants of this young man’s life in 1964 and before. In it were letters, letters my Dad had written to me during my college years.
My parents have been gone for many decades now, and reading those letters after such a long time was a joy. Unlike emails and tweets, those letters told a story, a story of how my parents were reacting to and appreciating my new found freedom and expressions of individuality.
My father, a physician who practiced medicine for 50 years, wrote words that are even deeper in meaning now than they seemed at the time. “We are glad that you seek the places that are apart, such as the mountains and the sea,” he wrote. “It is so easy to rush past the beauty and truth of life, especially in this age. An older and wiser one once said, ‘Let us not hurry, not worry, and let us take a moment now and then to smell the flowers along the way.’ ”
And then there were the words I puzzled over briefly before realizing what it meant. “Their being and meaning will never know the obsolescence of most of that which is taught.”
Frankly, that was a lesson that takes a life-time to understand, for in time we come to know that many things we are taught while young will eventually be found wrong, or at least inaccurate. In other words, so-called truths change.
In 2064, fifty years from now, how will you or your descendants be reminded of things you said, or things your parents and other loved ones thought way back in 2014? How will memories of 2014 be renewed?
Even now, the concept of writing love letters seems sweet but archaic to those in their twenties. So I wonder, will there be such a thing as love letters in the future?
Facebook posts certainly won’t be preserved for fifty years. In fact, both Facebook and Twitter will be long forgotten, replaced by more culturally relevant trends. And let’s face it, have you ever said anything on Facebook that deserves to be preserved for fifty years?
I suppose that as my father saw his time on earth becoming increasingly limited, he realized that time, the time to enjoy life, was a precious commodity, yet one not well appreciated until the sand in the clock is half run out. That is an important lesson that I, with my own sand ebbing away, have at last come to appreciate. But if I did not have my Father’s letter to read now, fifty years later, it would be a lesson long forgotten.
In a tweeting, Facebook society, how will we hold pages and memories in our hands when our parents and other loved ones are gone?
Every night a pilot from Atlanta makes a round-robin cargo flight to Albany GA and Dothan AL, then continues down to the coast to load cargo from Panama City FL, Pensacola, and Mobile AL before returning home. He used to fly a single engine Beech Bonanza, but now pilots a Baron, a twin-engine, 190 kt fast mover.
On really rough weather nights I’ve watched vicariously through FlightAware.com as he scurries away from lethal skies and diverts to any safe harbor. His cargo is your lifeblood, literally, but it’s not worth dying for.
He makes that flight each night because during the day in each of those cities patients had blood drawn at their doctor’s office. The samples that will tell the doctor the life and death stories of the day’s patients are whisked away to a large laboratory near Atlanta for processing overnight.
After taking off from Gwinnett County Airport near Lawrenceville, GA at 6 PM or so, the solitary pilot returns to his home base about midnight.
I was alerted one night that a plane I’d flown to Houston and back, a Cessna Centurion 210, had a gear collapse at the local Panama City Airport. I knew the plane well.
Unfortunately, shortly after the only runway was closed the Quest Diagnostics Baron approached the area, attempting to land. I turned on my aviation radio and heard the “850”, as it’s called, being told to hold, circling, while airfield crews attempted to move the damaged Centurion off the runway.
And that’s where the politicians come in.
Local Panama City politicians felt obliged to close down the Panama City airport with two runways (formerly known as PFN) and relocate to a larger facility, again with two runways. The new two runway airport, KECP, looked great in an artist’s rendition.
But artists don’t build airports. The reason why the second runway was not built is not a subject for this blog posting. What is the subject, is that promises made to the citizens of Panama City were not promises kept. And on that night as “850” circled overhead, there would be real consequences for the political decisions which had been made.
Once construction began on the main 10,000 ft long runway at the donated site, all mention of the second runway was forgotten; not by the local pilots, but by the local politicians and the land company.
Second runways serve important purposes. They are usually called “cross-wind” runways. I’ve landed many times on the cross-wind runway at PFN, and I’ve also been on Delta flights that used that runway when the wind across the main runway was dangerously high.
Cross-wind runways are not only a safety factor for overbearing wind conditions, but also provide an alternate landing site in case the main-runway is closed due to an aircraft being stuck on the runway.
That night as “850” was trying to land to pick up the day’s tissue samples from the Panama City area, the main runway was closed by the broken Centurion, and there was no backup runway. The pilot circled Panama City until his fuel became critical, and then he flew on to his next stop in Pensacola.
So all the blood drawn from patients in the Panama City area that day missed the trip to the Quest Diagnostics laboratory, due to a promise made but not kept.
But I suppose that is hardly news. Rather, it appears to be deeply woven into the very fabric of politics.
Lately I have been puzzled by news reports about fellow scientists who are thinking not just out of the box, but out of the universe.
The first news that had me struggling was the suggestion that a universe might be the projection of a hologram. Not our universe, necessarily, but some artificial, mathematically contrived universe. Of course, the news outlets added a more dramatic flare to that headline, which on further reading was wildly misleading. I don’t think any scientist was claiming that we are actually a hologram, a three-dimensional projection of a lower dimensional us.
Try to translate for the popular press arcane notions of mathematical physics, and you’re bound to come up with some misrepresentation. We are not, I argue, like the projected holograms of Princess Leia asking Obi-Wan Kenobi for help in the Star Wars epics. However, it certainly would be interesting to think about. Who, we might ask, made the hologram, and who is projecting us and our galaxy into what we perceive to be a three-dimensional universe? Speculation could run wild.
Now there is another speculative and down-right mind-assaulting scientific proposition. As the press is representing it, it is proposed that we are “living” in a computer simulation. The actual human race may be long dead and vanished, but some technologically advanced civilization has coded a simulation of the defunct human race.
For what purpose, I have no idea. Unless of course we are not just a simulation, but a computer game wrought for educational purposes.
But perhaps that’s being too charitable. I would put odds on us being simulated for entertainment purposes.
If we be contrived entertainment, then perhaps that relieves us of some moral responsibility. We are not the ones bombing, beheading, and torturing our fellow man. The devil made us do it; with the devil being whoever made the sick part of the human simulation. Like Jessica Rabbit once famously said, “I’m not bad, I’m just drawn that way.”
Or, perhaps the base part of the human simulation is not intentionally evil, but the result of bad coding. Coding “glitches” do occur, from the ObamaCare website to computer games, with sometimes unexpected results. Most computer gamers have experienced, or have heard of, bizarre things happening when the gaming software has a glitch. Game characters may unexpectedly launch into outer space, or disembowel themselves, when all they were supposed to do was take a step forward.
In spite of what this post title says, I’m not suggesting that the published scientific assertions are in fact true. However, as a species we should at least consider the implications if they were true. What if my love affair with a young woman were simulated, or a projected hologram? The way I felt was so palpable, so vibrant that it’s hard not to believe in its reality, and its uniqueness. What if the birth of our children, and their children, was simply part of a gaming script? What if our lives were simply an immersive simulation?
For me that would make life hollow and unsatisfying. However, in my simulated brain I would still have to wonder about the person or persons who created us, the coders of the simulation. They would be, for all practical purposes, our simulation Gods.
Now that is ironic. I do not actually believe the hologram or simulation hypotheses, but I do find it interesting that these brand new scientific propositions seem to force us into considering a creator, a God. And to think, mainstream science has been trying to force us away from the belief in God for most of the last century.
So, I have to wonder, is science changing its mind?
As a professional in underwater diving, and an amateur airman, I’ve been thinking a lot lately about the causes of accidents and “near-misses”. If you’re reading this in early 2014, you are no doubt aware of several recent incidents of commercial and military jets landing at the wrong airport. In the latest case there was a potential for massive casualties, but disaster was averted at the last possible moment.
As they say, to err is human. From my own experience, I know the truth of that adage in science, medicine, diving, and the subject of this posting, aviation. Pilot errors catch everyone’s attention because we, the public, know that such errors could personally inconvenience us, or worse. But lesser known are the sometimes subtle factors that cause human error.
I can honestly tell you exactly what I was doing and thinking that caused errors at the very end of long flights. Those errors, none of which were particularly dangerous or newsworthy, were nonetheless caused by the same elements that have been discovered in numerous fatal accidents. Namely, what I was seeing, was not at all what I thought I was seeing.
Long before the advent of GPS navigation, cell phones and electronic charts, I was flying myself and an Army friend (we had both been in Army ROTC at Georgia Tech) from Aberdeen Proving Ground, MD to Georgia. I was dropping him off in Atlanta at Peachtree-Dekalb Airport, and then I would fly down to Thomasville in Southwest Georgia where my young wife awaited me.
Since it was February most of the planned six hour flight was at night. We couldn’t take-off until we both got off duty on a Friday.
I had planned the flight meticulously, but I had not counted on the fuel pumps being shut down at our first planned refueling spot. After chatting with some local aviators about the closest source of fuel, we took off on a detour to an airport some thirty miles distant. That unplanned detour was stressful, as I was not entirely sure we’d find fuel when we arrived. Fortunately, we were able to tank up, and continue on our slow journey. We were flying in my 2-seat Cessna 150, and traveling no faster than about 120 mph, so the trip to Atlanta was a fatiguing and dark flight.
As we eventually neared Atlanta, I was reading the blue, yellow and green paper sectional charts under the glow of red light from the overhead cabin lamp. Lights of the Peachtree-Dekalb airport were seemingly close at hand, surrounded by a growing multitude of other city lights. Happy that I was finally reaching Atlanta, I called the tower and got no answer. No matter, it was late, and many towers shut down operations fairly early, about 10 PM or so. So I announced my position and intentions, and landed.
The runway was in the orientation I had expected, and my approach to landing was just as I had planned. However, as I taxied off the runway, I realized the runway environment was not as complex as it should have been. We taxied back and forth for awhile trying to sort things out, before I realized I’d landed 18 nautical miles short of my planned destination.
I had so much wanted that airport to be PDK, but in my weariness I had missed the signs that it was not. I had landed at Gwinnett County Airport, not Peachtree-Dekalb.
No harm was done, but my flight to Thomasville was seriously delayed by the two extra airport stops. It was after 1 AM before I was safe at the Thomasville, GA airport, calling my worried wife to pick me up.
She was not a happy young wife.
A few years later, I added an instrument ticket to my aviation credentials, and thought that the folly of my youth was far behind me. Now, advance quite a few decades, to a well-equipped, modern cross-country traveling machine, a Piper Arrow with redundant GPS navigation and on-board weather. I often fly in weather, and confidently descend through clouds to a waiting runway. So what could go wrong?
Wrong no. 2 happened when approaching Baltimore-Washington International airport after flying with passengers from the Florida Panhandle. Air Traffic Control was keeping me pretty far from the field as we circled Baltimore to approach from the west. I had my instrumentation set-up for an approach to the assigned runway, but after I saw a runway, big and bold in the distance, I was cleared to land, and no longer relied on the GPS as I turned final.
As luck would have it, just a minute before that final turn we saw President George W. Bush and his decoy helicopters flying in loose formation off our port side. I might have been a little distracted.
In the city haze it had been hard to see the smaller runway pointing in the same direction as the main runway. So I was lining up with the easy-to-see large runway, almost a mile away from where I should have been. It was the same airport of course, but the wrong parallel runway.
I was no doubt tired, and somewhat hurried by the high traffic flow coming into a major hub for Baltimore and Washington. Having seen what I wanted to see, a large runway pointed in the correct direction, I assumed it was the right one, and stopped referring to the GPS and ILS (Instrument Landing System) navigation which would have revealed my error.
The tower controller had apparently seen that error many times before and gently nudged me verbally back on course. The flight path was easily corrected and no harm done. But I had proven to myself once again that at the end of a long trip, you tend to see what you want to see.
Several years later I had been slogging through lots of cloud en-route to Dayton, Ohio. I had meetings to attend at Wright Patterson Air Force base. It was again a long flight, but I was relaxed and enjoying the scenery as I navigated with confidence via redundant GPS (three systems operating at the same time).
As I was approaching Dayton, Dayton Approach was vectoring me toward the field. They did a great job I thought as they set me up perfectly for the left downwind at the landing airport. But then I became a bit perturbed that they had vectored me almost on top of the airport and then apparently forgotten about me. So I let them know that I had the airport very much in sight. They switched me to tower, and I was given clearance to land.
As I began descending for a more normal pattern altitude, the Dayton Tower called and said I seemed to be maneuvering for the wrong airport. In fact, I was on top of Wright Patterson Airbase, not Dayton International.
Rats! Not again.
Well, the field was certainly large enough, but once again I had locked eyes on what seemed to be the landing destination, and in fact was being directed there by the authority of the airways, Air Traffic Control (ATC). And so I was convinced during a busy phase of flight that I was doing what I should have been doing, flying visually with great care and attention. However, I was so busy that my mind had tunnel vision. I had once again not double checked the GPS navigator to see that I was being vectored to a large landmark which happened to lie on the circuitous path to the landing airport. (I wish they’d told me that, but detailed explanations are rarely given over busy airwaves.)
Oddly enough, if I had been in the clouds making an instrument approach, these mind-bending errors could not have happened. But when flight conditions are visual, the mind can easily pick a target that meets many of the correct criteria like direction and proximity, and then fill in the blanks with what it expects to see. In other words, it is easy in the visual environment to focus with laser beam precision on the wrong target. With all the situational awareness tools at my disposal, they were of no use once my brain made the transition outside the cockpit.
To be fair, distracting your gaze from the outside world to check internal navigation once you’re in a critical visual phase of approach and landing can be dangerous. That’s why it’s good to have more than one pilot in the cockpit. But my cockpit crew that day was me, myself and I; in that respect I was handicapped.
Apparently, even multiple crew members in military and commercial airliners are occasionally lulled into the same trap. At least that’s what the newspaper headlines say.
My failings are in some ways eerily similar to reports from military and commercial incidents. Contributing factors in the above incidents are darkness, fatigue, and distraction. When all three of these factors are combined, the last factor that can cause the entire house of cards, and airplane, to come tumbling down, is the brain’s ability to morph reality into an image which the mind expects to see. Our ability to discern truth from fiction is not all that clear when encountering new and unexpected events and environments.
The saving grace that aviation has going for it is generally reliable communication. ATC saved me from major embarrassment on two of these three occasions.
I only wish that diving had as reliable a means for detecting and avoiding errors.
If you’ve planned a deep dive, to say 100 meters or deeper, you may have wondered just how your rebreather scrubber will handle that depth. Since pressure is equalized across a carbon dioxide (CO2) absorbent canister within a rebreather, it won’t implode. But what about the chemical absorption reactions occurring within the scrubber?
The rebreather scrubber is a vital part of your underwater life support system, so that question is a pretty important one. And the answer is very hard to find.
I recently traveled to Ireland to act as an external examiner for a Ph.D. student’s Doctoral Dissertation defense in the Department of Mechanical, Biomedical and Manufacturing Engineering of the Cork Institute of Technology. The very talented graduate student was Shona Cunningham, and her dissertation was titled, “Carbon Dioxide Absorption and Channeling in Closed Circuit Rebreather Scrubbers”. She’s an athlete, musician, and perhaps most importantly for you readers, an avid diver.
Her work is the first computational fluid dynamic representation of scrubber canister thermokinetics. A portion of her dissertation work has already been published. Apparently it was partially inspired by some of my computer simulation descriptions posted on this blog, which can be found here, here and here.
Dr. Cunningham’s analytical approach (using Ansys CFX) showed that ambient pressure (depth) could reduce the effectiveness of scrubber canisters. In support of that finding were the words from the Dive Gear Express web site regarding the Diverite O2ptima using the ExtendAir scrubber cartridge.
“As pressure increases the total number of molecules, the relative concentration of CO2 molecules in the loop is reduced, slowing the chemical absorption process. Thus as depth increases, scrubber efficiency will decrease.”
The U.S. Navy has no experience with the Diverite O2ptima, but they have information on other rebreathers using granular absorbent. That experience shows that there is no reliable depth effect across all rebreathers and all absorbents.
For example, in one rebreather there was indeed a 17% decrease in endurance using large grain absorbent (Sofnolime 408) at 50°F in descending from 190 fsw to 300 fsw (58 to 92 msw) breathing air. However, there was no decrease in durationwhen using fine grain absorbent (Sofnolime 812) under the same conditions. (On an actual dive, air would never be used at 300 fsw, but air was used in this study for scientific reasons.)
In another rebreather using Sofnolime 812, for a change in depth from 99 fsw to 300 fsw (30.3 to 92 msw) there was a 29% increase in duration at 75°F, a 10% increase at 55°F, and a 15% decrease at 40°F. Although air diluent was used at 99 fsw, 88/12 heliox diluent was used at 300 fsw.
From another manufacturer I obtained information on two of their rebreathers. At 4°C, 1.6 L/min CO2 injection rate (corresponding to a fairly heavy work rate), 40 L/min ventilation rate using air diluent, there was a 27% decrease in one rebreather in going from 15 to 40 msw (50 fsw to 132 fsw), and a 11% decrease in another of their rebreathers in dropping from 40 msw to 100 msw.
In another rebreather tested under the same conditions except depth, the canister duration dropped 39% between 15 and 40 msw.
So, there is some support for a drop in duration with depth, but in other cases there is either no effect or an increase in duration with deeper depths. Clearly, if the high number of inert gas molecules coming with a pressure increase makes it more difficult for CO2 to reach absorption sites, then that would be a simple and unavoidable fact of physics. But that cannot be the whole story. What is likely to be going on, a hypothesis, is being developed for a later posting.
Should the effect of depth on your particular rebreather matter to you? Logically it shouldn’t. Even on a deep dive, the majority of the dive time is spent shallow, decompressing.
However, consider the case where you conduct a deep dive with an anticipated short bottom time, but something bad happens on the bottom. You or your dive team becomes fouled, ensnared in lines. Or there is a a partial cave collapse trapping you. The benefit of a rebreather over scuba is that it gives you time to sort out your problem. Gas consumption is not nearly as great a concern as with open circuit breathing apparatus.
However, as the minutes tick by as you work deep to get yourself or a team member free, you might wonder, “How is my scrubber handling this depth?” In the middle of a crisis is no time to be making assumptions about the status of a major part of your life support system.
Ask your manufacturer how your canister performs at depth. You have a right to know, and that information just might prove useful some day.
There is a good reason why God and aliens (of the extraterrestrial variety) use telepathy to communicate. It is the only secure form of information transmission. Everything else is subject to capture, storage, and retrieval.
But governments aren’t alone in information spying — commercial industry is perhaps outpacing governments in their data collection efforts. Their motivations may be different, but the frenetic pace and implications are every bit as invasive. Privacy, as we’ve known it, is dead.
I’ve previously written about Google Noodling , which is a way of catching Google in their data-mining efforts. And like the tone of that article, you have to take a lighthearted view of such efforts. It is not going away. And if we don’t “get over it”, we may, in my estimation, go a little crazy.
But there is a positive side to all this, and a large and growing number of people are finding this side to be personally satisfying. That has to do with family connections, or genealogy. I’ve written about that topic as well.
Last night I solved a very personal family puzzle through the help of Ancestry.com. Both my parents had brown hair and brown eyes. Both their younger children, sons, had blond hair and blue or green eyes.
I’ve spent a lot of time of late with my brother before he passed from a prolonged illness, and I was struck as never before with the purity of the blue color in his almost iridescent eyes. (I’m the one with the green eyes.) When young, both of us had blond hair, which eventually darkened with age. My brother was tall and thin. I was thin, but vertically challenged.
In the next generation, both my children have green eyes, perhaps because I married a green-eyed girl. Our daughter has blonde hair, and even a granddaughter has greenish-brown eyes. And a new grandson baby seems to have blue eyes and blond hair.
I have never ceased wondering, as did my parents no doubt, where those light colors came from. Having believed strongly in my mother’s fidelity, I kept assuming that someday I would discover the source of the blue/green eyes and blond hair.
That happened last night, thanks to the technology of digitization and data mining. I discovered a World War I selective registration document from my Grandfather who died in a hotel fire many years before my birth. At the age of 34 he had blue eyes and “light” hair. He was both tall and “slender”, pretty much a perfect description of my brother.
The next morning I was able to go through unidentified family photos, and there he was, identified at last, the Grandfather I never knew. So apparently it wasn’t the mailman after all!
Obviously this discovery is of interest to no one except my cousins and other relatives. However, it does point out the value of computers, computer databases, and the sharing of information that large databases make possible. There is a tangible reward, for both the company providing the product (the database) and the customers who benefit from the data shared.
I’m sure that when my Grandfather filled out his draft card in 1918, he had no idea that the digital image of that card would end up in the hands of his unborn grandchildren and great grandchildren 95 years later.
Which makes me wonder, what will the world know about each of us 100 years from now? We’ll be long gone, but the record of our existence will survive somewhere in the depths of a digital storage facility. Without a doubt our descendants will enjoy reading about the inane things which pleased or troubled us in 2013, and which we so freely posted thinking that no one was listening, and no one really cared.
Believe me, some people will care. And apparently, everybody’s listening.
My fig tree is a diabolical, horticultural menace sprouted from a demon seed. I’ve tried to kill it, but it won’t die.
In general, I love trees, and figs, but this particular fig tree (Ficus carica for the Latin purists out there) has sorely offended me. It has attacked me, causing, as they say, bodily harm.
And to top that, it doesn’t even produce edible figs. Some people call them goat figs, because only goats are undiscriminating enough to eat them. I’m guessing any goats eating my figs will be cursed — for eternity.
The conflict began like most conflicts, with an innocent encounter. I was using a water hose to tunnel under a concrete slab to install a 3-inch diameter drainage pipe. I then inserted a five-foot long piece of pipe. So far, so good.
But I decided I needed to replace that pipe with a longer, more flexible pipe, which promptly got stuck in the hole. Looking into the tunnel I’d made I saw that some relatively small roots were now in the way. I cut them with a lopper and then blindly inserted my left hand into the hole to help pull the pipe through.
It was a tight fit, and the back of my hand was grinding into the sand and the cut ends of the roots as I tussled with the pipe and finally pulled it through the hole. There was no pain associated with the sandpapering of my hand. But, as I later realized, I was grinding something toxic into the skin.
The next morning I looked at an irregular shaped red blotching on the hand. I assumed that the sandpapering from grinding against the sand grains had irritated the skin. But as time went on, the discoloration got worse, not better. A physician friend recommended a combined antibiotic and topical steroidal ointment, and bandages to protect the irritated skin. Dutifully applied for several days, that treatment resulted in absolutely no improvement. In fact, the discoloration seemed to worsen.
I continued to work on the drainage project outside, and, as it turned out, sun light seemed to make the discoloration worse.
A week later when irregular shaped blisters erupted, I realized that my skin had reacted to something in the sand, and the most likely candidate was fig tree sap from the roots I’d cut moments before inserting my hand.
The Internet revealed that fig tree sap was highly irritating to human skin. In fact, it appears to be an effective chemical weapon.
Quoting from AllAllergy.net, “Phytophotodermatitis is an acute skin reaction that may be easily confused with other causes of contact dermatitis. It is characterized by sunburn, blisters, and/or hyperpigmentation. The reaction takes place when certain plant substances known as psoralens, after being activated by ultraviolet light from the sun, come in contact with the skin. This report describes phytodermatitis due to contact with figs. (Watemberg 1991)”
Amazingly, the discoloration of my hand is still visible 6 weeks after the insult. But, I’m happy to report, that fig tree is not; visible that is. It was cut low to the ground. Eerily, it’s toxic sticky sap continuously coats the stump, so apparently that bedeviled fig tree is not entirely finished with its mayhem.
That sappy stump will, no doubt, be plotting a comeback this winter, out of pure botanical meanness. But I am firmly set on a plan of containment. Only time will tell whose chemical weapons are the more effective, the tree’s or mine.
Strangely, my war with the fig tree got me to thinking about art censorship. It’s true.
Most art devotees are aware of the stylistic device of placing a sculpted fig leaf in a strategic location to disguise the anatomical humanness of otherwise manly looking gods or athletes. Apparently, this form of censorship was foisted upon the art world by powerful religious prudes of the Enlightenment.
Well, as I sulked about my long-lasting dermatological insult, I got to wondering; why would anybody even think of putting a fig leaf anywhere near what is arguably a sensitive part of the human body?
I strongly suspect that the artisans would not have deliberately incorporated fig leaves as part of their design, because they probably knew all too well just how irritating fig leaves can be.
I imagine Adam and Eve were both made rather uncomfortable by their leaves. Perhaps that was part of God’s revenge for their disobedience. Makes me wince to think of it.
But I digress. This current horror story ends like most horror stories; the foe fig is vanquished at the end. But just before the ending credits role, you catch a glimpse of the fig tree stump, still pulsing its hellish chemical weapons, and not at all fully dead. For all I know, it may already be planning its sequel, where it turns really nasty.
Lesson learned: I’ll be waiting for it, with gloved hands next time.
It seems ironic that at the same time that equality of the sexes in marriage is being heavily promoted, there is a scientific announcement that the male of the human species is anything but equal; we are genetically weak. According to at least one female scientist, human males are destined to die out due to the fragility of our single Y chromosome.
This grave announcement comes from none other than the aptly named Professor Graves, of Australia.
Her forecast got me to thinking; what if I was the last human male on Earth. What would life be like?
My first naive, and probably delusional impression was that I would inevitably become a hot item. It really wouldn’t matter what I looked like; I would be desirable simply because of my rarity.
Which, if true in a fantasy sort of way, could actually be a nightmare. I would surely not be attracted to ALL females. I mean, that covers a pretty wide territory. The human population is pretty diverse.
However, once you become that unique of an entity, perhaps your free will may go out the window. It may not matter what I want. For instance, becoming or remaining paired with a single lady, remaining monogamous, might itself become a fantasy.
But as I delved a little deeper into this musing, another possibility presented itself. A world without men could only exist if scientists figured out a way to keep the population going without men. I suppose it’s possible, in an artificial sort of way. So what would I be then?
Well, perhaps nothing more than a freak, a rare oddity with a bizarre anatomical abnormality. Is it reasonable to expect genetic deviants to be in great demand by the ladies? I think not.
So, I hope that the scientist who claims that men may die out due to their chromosomal vulnerabilities is wrong. If not, the psychological outlook of that declining population of manly men would probably be bleak. And certainly, if by accident of birth I were the last man standing, my life experience might be every bit as challenging as it is for those with rare congenital handicaps.
Knowing that, I feel sure that if the scales of male/female birth ratios begin tipping away from the current normality, some male-dominated government will fund extensive research aimed towards preserving the status quo. Ironically, the answer to whether that research would be fruitful or not, might already be written in our genetic code.
As they say, only time (five million years by Professor Graves’ estimate) will tell.
So, how do you think that makes me feel, the only Neanderthal on Earth? No one bothered asking my opinion.
Morality, I think, is based on the profit motive; on hidden agendas. It is arguably immoral to create a solitary herd animal when there is no financial reward for creating an entire herd. A herd animal is lonely without a herd. I know; I am a herd animal too, in the strictest sense. If there was financial gain involved, I can guarantee you a herd would reappear, like magic.
Other than a tourist attraction, what could the incentive be for creating a herd of mammoths? The novelty would quickly wear off, I’m sure.
At least it did for me. The curiosity and wonder I invoked in the public as a child began to wane as I grew ever more body hair, and began to assert my independence, and hormones. Quickly I became yet another difficult, and apparently not very attractive, adolescent. I was seen as boring; old news.
But curiously, at the same time the morality of creating a single previously extinct herd animal was being discussed, the Russians uncovered liquid blood from the underbelly of an ice-bound Mammoth. Almost immediately, that miraculously preserved blood became a siren of inescapable beauty to geneticists. The most pious of them wondered, so I read, why God would reveal this magic pool of genetic mystery after so many millennia if in fact humans were not fated to recreate the Mammoth.
And almost in the same breath, Neanderthal. After all, Mammoths and Neanderthal are forever linked through folklore, originating in the cave art of my ancestors.
Which brings me to a dream I had. It is true that supposedly primitive people put stock in dreams; but I digress.
I dreamed that Armageddon came suddenly, with nuclear weapons unleashed from Iran, Israel, North Korea, Russia, China, and the United States. It was horrifying, and true to prediction a nuclear winter ensued. Virtually no humans survived.
But there were survivors who actually thrived in the dark and cold. They were a large band of us Neanderthals who had been bred in secret locations in Siberia. After the holocaust, we Neanderthals were able to escape and pillage the remains of a devastated Earth.
And once again, herds of recreated Woolly Mammoths were also released in Siberia and fell prey to our kind, once again providing us sustenance.
Unwittingly, geneticists had secretly and unwittingly ensured the survival of a race of hominids, not exactly human, but close.
When the surviving humans and Neanderthals met, there was once again romance in the air. Beggars can’t be choosers when genetic survival is at stake.
But like I said, it was only a dream. I’m sure it could never really happen.
I suppose it was inevitable that I would be different; the ultimate “n” of one, the rarest species in the universe, the only Neanderthal on Earth.
By human standards I am very spiritual; I can remember my time before incarnation. I was told that I would be given a unique opportunity to excel in this lifetime. Of course, I had no idea what that truly meant. But there are no “do-overs” in life. I’m stuck for as long as I am here; so I might as well make the best of it.
Since no one knows how long Neanderthals live, I’m starting my memoirs now, at age 25. This way, if some violence or illness claims me, I’ll leave behind a record of what some would call a curious life. But it’s the only life I’ve known.
It all began in March 2013 when my ancestral genome was completely identified. Far as I can tell, that work was only a matter of curiosity. Actually, I would classify it not as curiosity but as mischief.
They tell me I was born in 2018. My earliest memories are of being tested and prodded. My body’s supply of blood has been withdrawn at least 10-times over, finding a home in just about every laboratory in the world.
I never signed a consent form for that testing, but apparently I have no more rights of consent than any other non-Homo sapiens. I am, apparently, guinea pig.
IQ tests seem to be of particular interest to academic scientists. There is a never-ending line of psychologists trying their particular flavor of IQ test on me. But the truth is, I am Neanderthal, not Homo sapiens. As someone once said, “A cat is a genius at being a cat.” I am a genius at being Neanderthal. I am the smartest one there is.
I have been asked what I think about the “Caveman” videos. Well, my ancestors, like yours, lived in caves; that’s true I suppose. However, the caricatures I see are as repugnant to me as blackface is to an African-American. Enough said.
As an adolescent I was constantly pitted physically against older boys. I’m proud to say I whipped their butts; every single one of them.
Starting at age 14, the U.S. Army began running me through endurance and strength tests. They found my limit, for sure, but never told me how I compared. But I did overhear someone in a grey suit once say, “We need lots more like him.”
I guess that means someone likes Neanderthals.
Speaking of liking, I’ve often wondered if I’ll ever find a girl. They tell me that humans and Neanderthals once interbred, but based on my experience, that seems highly unlikely now. Besides, who would fall in love with a guinea pig, even a well-endowed guinea pig. I am, after all, not human.
Even a child can appreciate the strangeness of watching the broad, glistening side of a dinosaur lumbering past the bedroom window. Fortunately the creature paid me no heed; it didn’t pause to look in the window, just kept moving on, quickly disappearing from view.
I lay there, frightened I suppose, but all I remember in detail very many years later is the remarkable sight of that moving mass of ponderous flesh. I didn’t see its head or its tail, just its massive hulk of a body sliding along the side of the house as close as could be without touching the house wall, or ripping off the roof. I sensed somehow that the dinosaur was not carnivorous; likely a plant eater, perhaps a brontosaurus, and thus no immediate threat to me.
I frankly cannot tell if that image was a flash of a dream, or a waking hallucination.
I was maybe seven and much more interested in cowboys and Indians than dinosaurs. I was not a toy dinosaur collector, and neither were my friends. In fact, I think this was long before kids, or adults, knew enough about dinosaurs to be fascinated with them. And yet there it was, gliding quietly and smoothly past my bedroom window.
That image lasted maybe four seconds, and yet those four seconds have lasted a lifetime — literally.
If my brain is at all typical, then it seems to me that visual images occurring spontaneously and transiently in six and seven year olds are perhaps associated with a growing and rewiring brain. However, as an adult my most remarkable memories are of similar dreamlets, extremely vivid dreams lasting but a few seconds, just as did the imagery of the dinosaur walking past the window.
Due to my being an adult I can’t explain them by remodeling of my brain. So perhaps there is something unique about them that has nothing at all to do with age.
They are certainly varied, and seem to have nothing whatsoever in common with my actual life. For instance, one dreamlet was of launching off a tall spire in a crystal city, and gliding on wings in an obviously nonhuman form, in a non-Earthlike place. That was probably the strangest, and yet most interesting five seconds of my life.
Another dreamlet, hypnagogic in that I was falling asleep, lasted maybe only a second. In it I clearly saw a white car veer directly into the path of my car, and what had to be an unavoidable head-on collision.
For some time I was on the lookout for white cars (Do you have any idea how many white cars there are?), but years have passed since then and I am still very much alive.
I’m well aware that no one wants to hear about someone else’s dreams, unless they’re being paid to do so. But that is not what this writing is about. Instead it’s about the strange events called dreamlets, moving images that pop into our heads when we are not concentrating on anything in particular.
I suspect we all have them, but due to their brevity few people talk about them. They really aren’t open to interpretation, at least in the same manner as more prolonged dreams which have been interpreted by psychoanalysts like Jung and Freud, and a host of modern day analysts.
Arguably, the most modern discussion of these dreamlets is by Professor Charles Tart who has built a world-wide reputation on such matters. And yet he, like me, is reduced to only asking questions. In a recent blog posting he mentions a few potential explanations for dreamlets, some of which would be considered bizarre by most readers, but admits that none of them seem to match his experiences completely.
What interests me about his writing, however, is the fact that what he experiences during meditation and what I’ve experienced spontaneously share points in common. That leads me to believe these events are generalized throughout the human population. In other words, you may remember events similar to the dinosaur passing by your window, and may wonder what that was about. This posting, then, is to tell you that you are not alone. Unfortunately no one has authoritative answers for you.
If you have an interest in learning more about these brief events, then you may find Dr. Tart’s blog stimulating.
I was recently reminded that almost everyone who is literate and has access to a computer and Internet connection has used Google to find something of interest to them.
The way I was reminded of that was from Google Analytics which gives me feedback on this blog. Over a period of a few days I witnessed a curious rise in the number of hits on a tongue-in-cheek description of a faux energy company (Cosmic Capacity Corporation) that purportedly sells personal black holes.
Typically, the draw of a sample of my dry humor is low. So why should there be a rapid uptick in interest?
Well, I’m just as mindful of national security as the next person, so as I witnessed the first wave of unexpected interest my thoughts were that bad people were trying to expand their knowledge of potentially dangerous devices. After all, anything that could make most anything disappear, and if detected, evaporate itself beyond all trace of detectability must be of interest to criminals.
But whoever they were, they weren’t stupid: they caught on quickly that the posting was a ruse. Stay time was approximately 30 sec.
However, over the period of a week, the numbers continued rising, and then fell just as quickly back to their normal near-dormancy levels. Something strange was going on.
The limited data I have points to a total of 333 hits occurring with an approximately Gaussian (normal, Bell-shaped curve) frequency between January 21 and 27.
With that realization, I may have now solved the mystery. When I looked at the timing and shape of the rise and fall, a memory was triggered of college student life.
I have no way of knowing if this is true, but let’s assume that on Monday the 21st, over 300 students attended the first of the week’s Monday, Wednesday, Friday classes on introductory science in a large University. The lecture hall was packed when the professor announced that a paper on Personal Black Holes was due on Monday week.
On that day (Monday) ten students hit Google and immediately found my blog posting on Personal Black Holes. The next day 25 students hit the site followed on Wednesday (perhaps encouraged by a reminder in class) and Thursday by a much larger group of students. On Friday, 35 procrastinators did the same thing.
I don’t think I would be wrong to suggest that after a Friday night spent in college recreation, Saturday was a day of hangovers and recovery. (Yes, I am speaking from personal experience.) No one hit my site on Saturday, and I imagine the majority were resting, or perhaps writing.
On Sunday, it appears that three late-bloomers hit the site, and the rest were preparing their paper for Monday.
Early Monday morning, one desperate procrastinator hit the site. I can just imagine the student screaming, “You have got to be kidding! This is a joke?”
Yes, it was a joke, a fact the average student figured out in 39 seconds before moving on.
Government and industry is constantly pressing for metrics, ways to measure business success other than from sales. The problem with metrics is that figuring out what to do with the numbers is not always obvious . What do they represent?
Since my site is not a business, and does not earn me a cent, I normally pay no attention to its metrics. However, this time, after moving beyond my initial alarm, I felt that I might be gaining insight into the hidden “research” trends of young college students. As a scientist, that intrigues me.
It would be more intriguing if someone discovered that A students were the first to turn to Google for answers. I’m sure Google would find that satisfying.
It could of course be just the opposite. Perhaps top students hit the library first and then follow up with Google search as a last check. Actually, that result would surprise me, but arguably it cannot be ruled out.
Lastly, it could be that my college class hypothesis is completely wrong. It could be that Chechen rebels were exploring ways to solve their political/military problem, but somehow I doubt it.
As we scientists are trained to say, more research is needed.
Have you ever watched a local sailboat race from the shore?
It’s not exactly an adrenaline-pumping spectator sport. On the boats of course there is plenty of excitement — shouting, sometimes cursing. But from shore all the on-boat drama is missing.
GoPro cameras have ushered in a new era of taking the viewer into the action. And based on the action that I commonly see on the Internet, that action is not of local sail boat races. It is instead full of speed and thrills. The penultimate example of the testosterone driven thrill seeking, in my opinion, is the dangerous sport of wingsuit flying, always perilously close to terrain.
The visual rush is not subtle. You are left with the impression that any second you’ll witness a fatal crash. You leave the video thinking that the flyer is one very brave, very skilled, and very lucky person. Or else you just think they’re CRAZY!
But honestly, I’d love to be that crazy— just once anyway.
[youtube id=”GASFa7rkLtM” w=”600″ h=”500″]
When I watch such videos on YouTube I get the sense that I am a spectator at a blood sport event. There is beauty and grace which I admire, but ultimately I know there is risk to the participant, as evidenced occasionally by the literally rib-splitting, pink mist endings to some of those flights. We enter into the action, but comfortably in front of our TV or computer screens with no personal risk to ourselves.
Arguably we are really not so different from the crowds at the Gladiator games, or for a more modern though fictional example, the Hunger Games.
What I like about the new class of miniature, high-definition video cameras is that they allow us to video what we love doing and then share it with the world. That’s nice, but unless what you do is high speed, endearingly cute, or down-right funny, it may be difficult to attract viewers.
I’ve uploaded flying videos, including the high definition video below, but they are not exciting. Instead, they appeal, I think, to those who simply love flight: the visual sensations of landing, of entering clouds, or skimming cloud tops. That type of flight is the way the FAA expects pilots to fly — safely. Yet safe flight is also capable of generating visual sensations that secretly thrill even highly experienced pilots, and keep them in love with their profession.
[youtube id=”wjtOycH0bQc” w=”600″ h=”500″]
On the other hand, the adrenalin-packed videos that high definition cameras provide can entice some pilots to fly unsafely, simply to titillate the cameraman and the viewer. I suspect the pilot in the following video got a high viewer count but I also suspect his wings are about to be clipped by the FAA.
[youtube id=”2OL4FdIQrV4″ w=”600″ h=”500″]
I am very unlikely to engage in risky flying simply because it looks thrilling when posted on the Internet. I want to keep my license; it is a treasured privilege to be able to fly. But also because I’ve lived long enough to know it is quite a different thing to watch a Miss Universe pageant, and quite another to entertain a pageant contestant when she shows up unexpectedly at your door. The thrill may be more intense in the latter case, but the personal risk may be far greater; especially if your significant other meets her at the door.
“Respiratory embarrassment” is an uncommon phrase most likely spoken by physicians and physiologists.
This week I found myself telling an engineer that “respiratory embarrassment can lead to an untoward event”. It quickly became apparent from the puzzled stare I received that I was not communicating.
Scientists and some medical personnel tend to do that; fail to communicate. In fact, they do it a lot.
What I was really saying is that in the right circumstances a person could have difficulty breathing, and that difficulty could cause something bad to happen; an “untoward” event. That bad thing would not necessarily be an aircraft crash, or in the case of a diver, a drowning, but it would mean that the pilot’s or diver’s performance would be impaired.
Why didn’t I just say so?
Laziness I suppose. I was using the language clinicians and physiologists are taught in graduate or medical school, and it flows out of our mouths naturally, without effort. Translating those same words into laymen’s terms takes time and effort.
I next started talking about respiratory impedance, a term understood by some but not all engineers, and rarely if ever by laymen. So once again I was not communicating well with all of my audience which was composed mostly of engineers, but not entirely.
That was the case until I used pictures to explain the otherwise difficult concepts of respiratory impedance and physiological embarrassment. The images below seemed to work, so I thought it worthwhile to share those images with you.
For you engineers, respiratory impedance is proportional to the sum of respiratory flow resistance and pulmonary and chest wall elastance.
So what is that?
Well, for elastance, at least chest wall elastance, think of being buried to your neck in sand. Breathing difficulty comes from the difficulty of moving your chest wall in and out with the weight of sand pressing in on all sides. The pressure of sand impedes your breathing, hence elasticity (the inverse of compliance) is a major component of respiratory impedance.
Based on the photo of the young man pictured on the right, being partly buried for supposedly therapeutic reasons is not a pleasant experience.
Some might disagree. The man on the left is an actor in the 2008 French short film Le Tonneau des Danaïdes by David Guiraud, who seems quite at ease impeding his breathing for the sake of art. I’m guessing he’s either very dedicated, or very well paid.
In diving, respiratory elastance can be elevated by tight fitting wet suits; in aviators by tight fitting chest pressure garments, and in patients, by pulmonary fibrosis brought about by, for example, asbestos exposure.
Another key component of respiratory impedance, that thing that causes respiratory embarrassment, is flow resistance. Sticking your head in the sand would certainly be one way of generating
severe respiratory resistance, with its attendant embarrassment.
Clinically, there are far more common sources of respiratory resistance, for example the narrowing of air passages in the lung caused by asthma. (Sticking your head in sand is probably a reasonable analogy to the sensations experienced during an asthma attack.) Chronic obstructive pulmonary disease (COPD) can also lead to a significant increase in respiratory resistance.
When you focus on the human respiratory system, the body parts shown in pink below, keep in mind that breathing can be impaired by things occurring inside the body (like asthma, COPD, fibrosis) or outside the body. Any life support system used for aviation, diving, mining, or firefighting imposes an impedance on breathing. That impedance in turn can lead to breathing difficulty, which can result in a failure to complete assigned duties.
Perhaps that’s where the “embarrassment” part comes in.
In Greek mythology irresistibly seductive female creatures were believed to use enchanted singing to beckon sailors to a watery grave.
Why this myth endured through the centuries is difficult to say. However, my theory is that it helped explain to grieving widows and mothers why ships sometimes inexplicably disappeared, taking their crew with them, never to be seen again. By the reasoning of the time, there must have been some sort of feminine magic involved.
The oxygen sensors in closed-circuit, electronically or computer-controlled rebreathers are a magic device of sorts. They enable a diver to stay underwater for hours, consuming the bare minimum of oxygen required. The only thing better than a rebreather using oxygen sensors would be gills. And in case you wondered, gills for humans are quite impractical, at least for the foreseeable future.
I have written, or helped write three diving accident reports where the final causal event in a rebreather accident chain proved to be faulty oxygen sensors. So for me, the Siren call of this almost magical sensor can, and has, lured divers to their seemingly blissful and quite unexpected death.
Those who use oxygen sensors know that if the sensor fails leading to a hypoxic (low oxygen) state, loss of consciousness comes without warning. If sensor failure results in a hyperoxic state (too high oxygen), seizures can occur, again leading to loss of consciousness, usually without warning. Unless a diver is using a full facemask, loss of consciousness for either reason quickly leads to drowning.
Due to the life-critical nature of oxygen control with sensors, three sensors are typically used, and various “voting” algorithms are used to determine if all the sensors are reliable, or not. Unfortunately, this voting approach is not fail-proof, and the presence of three sensors does not guarantee “triple” redundancy.
In one rebreather accident occurring during the dawn of computer-controlled rebreathers, a Navy developed rebreather cut off the oxygen supply to a diver at the Navy Experimental Diving Unit, and all rebreather alarms failed. The diver went into full cardiopulmonary arrest caused by hypoxia. Fortunately, the NEDU medical staff saved the diver’s life, aided in part by the fact that he was in only 15 feet of water, in a pool.
In two more recent accidents the rebreathers kept feeding oxygen to the diver without his knowledge. One case was fatal, and the other should have been but was not. Why it did not prove fatal can only be explained by the Grace of God.
The two cases were quite different. In one the diver broke a number of safety rules and began a dive with known defective equipment. He chose to assume that his oxygen sensors were in better shape than the rest of his rebreather. If he had been honest with himself, he would have realized they weren’t. If he had been honest with himself, he would still be alive.
The other dive was being run by an organization with a reputation for being extremely safety conscious. Nevertheless, errors of omission were made regarding oxygen sensors which almost cost the experienced diver his life.
In the well-documented Navy case, water from condensation formed over the oxygen sensors, causing them to malfunction. The water barrier shielded the sensors from oxygen in the breathing loop, and as the trapped oxygen on the sensor face was consumed electrochemically the sensor would indicate a declining oxygen level in the rig, regardless of what was actually happening. Depending on how the sensor voting logic operated, and the number of sensors failing, various bad things could happen.
During its accident investigation, when NEDU used a computer simulation to analyze the alarm and sensor logic, it found that if two of the three sensors were to be blocked (locked) by condensed water, the rig could lose oxygen control in either a hypoxic or hyperoxic condition. Based on a random (Monte Carlo) sensor failure simulation, low diver work loads were more often associated with hypoxia than higher work rates, even with one sensor working normally.
We deduce from this result that “triple redundancy” really isn’t.
When the accident rig was tested in the prone (swimming) position at shallow depth, after 2 to 3 hours sensors started locking out, and the rig began adding oxygen continuously. The computer simulation showed that the odds of an alarm being signaled to the diver was only 50%. The diver therefore could not count on being alerted to a sensor problem.
Unfortunately in this near fatal case the rig stopped adding oxygen, the diver became hypoxic and the diver received no alarms at all.
After NEDU’s investigation, the alarm logic was rewritten with a vast improvement in reliability. The orientation of the sensors was also changed to minimize problems with condensation.
Today what is being seen are divers who extend the use of their sensors beyond the recommended replacement date. Like batteries, oxygen sensors have a shelf-life, but they also have a life dependent on use. Heavily used sensors may well be expended long before their shelf-life has expired.
Presumably, the birthing pains of the relatively new underwater technology based on oxygen sensors have now passed. Nevertheless, those who use rebreathers should be intimately familiar with the many ways sensors, and their electronic circuitry, can lead divers ever so gently to their grave.
Like sailors of old, there are ways for divers to resist being lulled to their death by oxygen sensors. First among them is suspicion. When you expect to have a great day of diving, you should be suspicious that your rebreather may have different plans for you. Your responsibility to yourself, your dive buddies and your family is to make sure that the rebreather, like a Siren, does not succeed in ruining your day.
The best way to ward off sensor trouble is through education. To that end, Internet sites like the following are useful. Check with your rebreather manufacturer or instructor for additional reading material.
Recently my inner child took notice of a circle of light racing across the cloud tops as I cruised at 7000 feet and 180 mph with the prevailing westerlies at my back. I was headed east above the Gulf Coast between New Orleans and the Florida Panhandle, and the late afternoon sun crept ever lower behind my right wing. Like a fighter in loose formation, the ring of colored light was keeping pace with the aircraft, just in front of my left wing.
My adult self realized that the spot contained a shadow of the airplane, but the bright halos around the dark shadow puzzled me. When my inner child asked me what it was, I had no ready answer.
I’d seen those halos before without really understanding them, but now I had a chance to photograph them. I grabbed cameras and recorded the beautiful phenomenon while the autopilot kept the aircraft on course.
One of the advantages of general aviation aircraft is that we often fly at the altitudes of the DC3s, the early airliners. Which meant that at 7000 feet I could open a small window beside me without depressurizing the cabin and give the camera a clear view of what I was experiencing.
An understanding of what I was seeing would have to wait.
[youtube id=”sV90o44sCE8″ w=”700″ h=”600″]
With few exceptions, Glories remain in the realm of pilots and Angels. By association, many pilots feel privileged to see a glory. I know I do.
Without knowing the science behind glories, pilots may even interpret them as signs of the divine. After all, they do look suspiciously like halos seen in medieval religious art. Indeed, “glory” is another name for those iconic halos.
Science is only able to partly demystify the subject of glories. The best technical explanation is that glories are the result of reflections (back-scattering) of sunlight coming from directly behind the observer. The tiny spherical water drops in clouds are the objects that scatter the sun light. Oddly enough, the size of the water droplets determines the size of the glory, which by the way may contain multiple rings as seen on the videos in this posting.
This process of ring formation from water droplets is called Mie Scattering, and is described mathematically by Mie Theory. Phillip Laven’s website, http://www.philiplaven.com/index1.html, provides an ample resource for the curious.
Glories have proven to be such an elusive quarry, that I, like many pilots, have developed a fascination with them. Therefore I could not resist making a brief video, with music, of the glories encountered on that one eastward flight. In it you see a classical glory, followed by a fleeting and hard to photograph glory on the side of a cloud, followed by apparent flight into an ever moving cloudbow.
Suppose you find yourself on an alien planet, battling with indigenous species. On your side, you have smarts, both natural and technological. The alien defenders have nothing; no technology. Well, they do have slime, but that’s all.
Brains against the brainless: Who do you think will win?
I spent a summer weekend with my family in a cabin in the Virginia mountains a few years ago. It was nature at its finest, until we discovered after a short walk in the woods that ticks seemingly rained down upon us and were invading our bodies as fast as their little legs could move. We were food, and they were hungry. Human-sized meals didn’t come around those woods very often, apparently.
The entire family, adults and children, stripped down to our underwear on the porch of the cabin, trying to rid ourselves of the invaders. Modesty took second place to the fear of miniature arachnids.
Once the imagined itching had abated and the baby was asleep, we soothed our nerves with puzzles and games, or reading from a well-stocked bookshelf. I picked a book with an interesting cover; it was John Scalzi’s Old Man’s War.
I cannot say enough good things about Scalzi’s debut novel, a futuristic science fiction, other worlds story. Suffice it to say, it features combat between Earthling soldiers and all sorts of bizarre and ruthless alien life forms. Although Scalzi didn’t write about invading armies of ticks, per se, I could easily envision such a terrifying encounter.
I also think and write about extraterrestrial aliens. Like most writers, I assume ETs are sentient, and calculating. Depending upon the writer, those ETs may have either high morals, or no morals at all, but they always have a brain.
Lately, I’ve had to rethink potential plot elements dealing with intelligent life forms. The reason is, scientists now claim that a single celled animal, a slime mold, acts with a shocking degree of intelligence. The kicker is, being a single celled organism, slime mold does not have a brain.
Intelligence without a brain?
Compared to slime mold, ticks are geniuses if we count the gray matter cells contained in their single-minded heads. However, according to a Japanese researcher the brainless slime mold can solve problems even scores of engineers could not easily solve.
Sounds like science fiction to me.
So now imagine the following storyline. Your spaceship lands on a verdant planet that has no higher, brain-possessing life forms, at all. However, what it does have in abundance is slime mold. And of course the threat from slime mold is easy to ignore — until it is too late. The mindless protoplasm senses all sources of food, and fans out in all directions, following the scent.
The ship’s science officer tries to warn the mission commander, but the arrogant and miscalculating commander responds with a volley of lead rounds into the nearest slime; which of course is not in the least bit deterred from its food-finding task.
And when the crew sleeps, as of course they must, the brainless mold finds the food sources, one by one, absorbing the human nutrients.
Human-sized meals don’t come around those woods very often, apparently.
Being brainless, slime mold cannot be considered cunning. But, one could argue, it’s not stupid either: it can’t be tricked. It is, if anything, relentless.
From a cinematic perspective this is not an entirely new theme. The 1958 movie The Blob starring Steve McQueen popularized the idea of mindless organisms devouring humans. But at that time there was no real science behind it. Now there is.
Some interesting science facts about slime mold are found in this link and the following Scientific American – NOVA video.
In technical or recreational rebreather diving, safety is a matter of personal choice. Wrong choices can turn deadly.
Some poor choices are made for expediency, while others are made with the best of intentions but based on faulty or incomplete information. As a diving professional, it is those latter choices that concern me the most.
A poignant and well documented diving fatality involved a record setting Australian diver, David Shaw. David was an Air Bus pilot for Cathay Pacific.
Professional pilots are immersed in a culture of safety, a culture that makes airline travel the surest means of long distance transport. David applied that same sort of attention to his diving, recording on his personal web site his detailed plans for a record setting dive to recover the body of a diver who died in the 890 feet (271 meter) deep Boemansgat Cave of South Africa 10-years prior to David’s ill-fated dive.
Despite his extensive preparations, David Shaw made a fatal mistake. Like those who fail to appreciate the threat of an approaching hurricane, David failed to recognize the risk of really deep diving with a rebreather.
Unlike other types of underwater breathing equipment, a rebreather is entirely breath powered. That means you must force gas entirely through the “breathing loop” with the power of your respiratory muscles. On a dive to 890 feet, you are exposed to 28 times normal pressure, and breathing gas more than five times denser than normal. The effort involved is enough to dismay some U.S. Navy divers at depths far less than David Shaw intended to dive. Yet in David’s own words, he had previously never had a problem with the effort of breathing.
“The Mk15.5 (rebreather) breathes beautifully at any depth. WOB (work of breathing) has never been an issue for me. Remember that when at extreme depth I am breathing a very high helium mixture though, which will reduce the gas density problem to a certain extent.”
He goes on to say, “I always use the best quality, fine-grained absorbent on major dives. The extra expense is worth it.”
“I have had 9:40 (9 hrs, 40 min duration) out of the canister and felt it still had more time available, but one needs to qualify that statement with a few other facts. Most of the time on a big dive I am laying quietly on deco (decompression), producing minimal CO2 (carbon dioxide).
In those words lie a prescription for disaster.
David wanted to use a single rebreather that would accomplish two tasks — provide a long duration gas supply and CO2 absorbing capability for a dive lasting over nine hours, and provide a low work of breathing so he could ventilate adequately at the deepest depth. To ensure the “scrubber canister” would last as long as possible, he chose the finest grain size, most expensive sodalime available. His thought was, that was the best available.
Arguably, the two aims are incompatible. He could not have both a long duration sodalime fill and low breathing resistance.
As illustrated in a previous blog posting, the smaller the size of granules you’re breathing through, the harder it is to breathe. Think of breathing through a child’s ball pit versus breathing through sand.
Perhaps if David had maintained a resting work rate throughout the deepest portion of his fatal dive, he might have had a chance of survival. After all, he had done it before.
But the unexpected happens. He became fouled and was working far harder to maintain control of the situation than he had anticipated. That meant his need to ventilate, to blow off carbon dioxide from his body, increased precipitously.
A sure sign of high breathing effort is that you cannot ventilate as much as is necessary to keep a safe level of carbon dioxide in your blood stream. CO2, which is highly toxic, can build rapidly in your blood, soon leading to unconsciousness. From the videotaped record, that is exactly what happened.
Had David been fully aware of the insidious nature of carbon dioxide intoxication from under breathing (hypoventilating), he probably would have chosen an alternative method to conduct the dive.
One alternative would be to use a larger granule size absorbent in a rebreather at considerable depth (say, 100 meters and deeper), and reserve the fine-grain absorbent for use in a separate rebreather shallower than 100 meters.
David chose the fine-grain absorbent because of the longer dive duration it made possible. Although fine grains are more difficult to breathe through than large grain absorbent, fine grain absorbent lasts longer than large grain absorbent.
But that long duration is only needed during decompression which is accomplished far shallower than the deep portions of the dive. The time spent deep where work of breathing is a threat is quite short. He did not need the capabilities of a long duration, fine grain absorbent.
From the U.S. Navy experience, there are other problems with this dive which might have hastened the end result. A rapid and deep descent causes the oxygen pressure within the rebreather to climb to potentially dangerous levels; a phenomenon called oxygen overshoot. Thus he might have been affected somewhat by oxygen toxicity. A rapid descent might also have induced the High Pressure Nervous Syndrome which would affect manual dexterity.
While those contributing factors are speculative and not evident on the tape, the certainty of the physics of dense gas flow through granular chemical absorbent beds is an unavoidable fact.
No doubt, many have offered opinions on what caused David’s accident. I certainly do not claim to be intimately involved in all the details, nor familiar with all the theories offered to date. Nevertheless, David’s mistaken belief that using the “best absorbent” was the best thing for his dive, is a mistake that needs to be explained and communicated before this accident is repeated with a different diver in some other deep and dark place.
I sat on the edge of a ball pit at Chuck E. Cheeses, calipers in hand, measuring the diameters of a random sampling of plastic balls within the pit.
I suppose I stood out, an officious looking adult wielding a precision instrument in a place designed for fun. So much so that a father attending his child asked me what I was doing.
I was measuring the ball sizes. I explained that if the balls were too small, and a child became covered with them, then the void space around the balls, the contorted empty volumes that represented places where air can be exchanged, would be too small, making breathing difficult. That made sense to the father, and he seemed pleased that I was looking after his child’s safety.
Contrary to the way it seemed, I was not a corporate inspector for Chuck E. Cheeses. I was also not a government inspector. But I was curious, gaining information for ideas I was developing about the breathing resistance imposed by particles of various sizes. I was acting, as it were, as a free lance scientist investigating flow through porous beds.
Consider the circumstance where a person is forced to breathe through a mass of balls, as in the illustration below. You can see, better than in the case of the ball pit, that if the balls become too small, or smaller balls fill in the void spaces between larger balls, then the person would be at risk for suffocation.
Advertisements for balls sold for ball pits point out the safety advantage of larger balls for children under age 3. The smaller children are obviously more susceptible to tunneling deeper into a pit of balls, some which may piled to two feet or deeper depths.
Balls of 3.1 in. diameter are touted as being ideal for three-year olds, whereas other popular sizes [2.5 in. (65 mm), 2.75 in. (70 mm)] are not. The 3.1 in. ball is almost twice as large, in terms of actual volume, as the 2.5 in. ball.
A problem awaits a child if the ball pit has poorly sorted ball sizes, especially a mixture of larger and small balls. As shown in the figure to the right, well sorted balls provide a porosity (airspace for breathing) of over 32%, whereas a mixture with balls fitting into the void spaces between larger balls can reduce void space down to about 12%. That would not be a good plan for a ball pit.
It also is not a good plan for the Namib mole.
The Namib Golden Mole is found in one region of Namibia because of the peculiar characteristics of the sand in that area. The sand grains are surprisingly homogeneous in size, and as the illustration to the right shows, similarly sized particles have a relatively large porosity. For the mole that means that when they burrow deep into the sand to escape blistering noon day heat, they will not suffocate. They can breathe through the sand.
If the sand were of mixed grain sizes, which is more typical of sand dunes, then porosity would be low and the mole would not be able to burrow deep enough to avoid the African heat without suffocating.
So, quite unexpectedly there is a connection between the uniform size of plastic balls in a ball pit and the survival of a mole in a far away African desert.
You never know where scientific curiosity will lead you.
As will be shown in an upcoming blog post, the topic of breathing through porosities in packed beds is relevant to diving with rebreathers, or breathing through chemical absorbent cartridges in gas masks.