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A man who ran out of air at the bottom of the ocean (bbc.com)
394 points by acdanger on June 3, 2019 | hide | past | favorite | 170 comments

What is really interesting is that at depths below 65m the real danger isn't running out of air, but that air itself becomes toxic due to the higher partial pressure of oxygen and it's effect on the nervous system.

Tech and commercial divers breathe exotic air mixtures which are hypoxic and include helium to mitigate this.

Dive science is pretty fascinating and is still a developing field.

pressurized oxygen has different effects on your breathing/vascular system ?

At sufficiently high partial pressure, it's toxic.


Nitrogen becomes narcotic at high pressure; breathing normal air at 30m is like being tipsy, but below 90m it can be fatal.


Nitrogen narcosis is usually called "drunkenness of depth" (if I translate this correctly), because it produce effect like you are drunk.

I've seen and heard many stories of experienced divers that would do silly things due this effect; that is why you always have to have partner with you and the rest of the crew near by.

This effect is highly dependent of person and I've seen guys goes beyond 40m without getting this at all.

I'm no professional diver, but did a bunch of dives between 60-100ft, and it seems like it can start happening to me around 70-80ft. Experienced divers will be more conscious about when it happens to them, and will plan their actions accordingly.

It's pretty eerie. It's _literally_ like being drunk, but you happen to be strapped to an oxygen tank with 100ft of water over your head, and could get extremely sick if you did something too stupid.

It's actually a pretty safe activity, given you follow safety rules. It's however pretty easy to stray from them.

Yep, especially for inexperienced divers. This is why one of the cert qualification dives is a "deep" dive, usually in the 90-110ft (30ish meters), and why that dive is usually just a really simple descent + a few elementary tasks at the bottom while maintaining neutral buoyancy.

Experience provides no protection against narcosis. There is no adaptive effect. Experienced divers who think they can somehow handle it are just fooling themselves.

I have had it happen as shallow as 10m (33ft).

It really depends on your physical readiness before the dive.

Lack of sleep, being hungover, hunger, dehydration can all contribute to narcosis.

Fortunately it is pretty hard to miss once you have experienced it a few times.

If you ever experience just go up a couple meters and the symptoms should dissipate.

When teaching students about the effects of depth on cognition, one fun trick is to give them a couple of combination locks attached to a slate (with the combinations written on the slate). Time each of them opening the locks on the surface, then time them opening another slate with the same sort of locks at 60 feet -- a depth not normally associated with awareness of cognitive changes.

I usually have my students come up with a couple secret handshakes that we practice on the surface beforehand.

I like the combination lock too, but I've found that a lot of people struggle with the locks regardless of depth and it can throw some false positives.

Much of the differential narcosis effect is actually due to carbon dioxide rather than nitrogen. CO2 will interfere with your ability to think clearly even worse than nitrogen. If you're relaxed and breathing deeply then you generally won't accumulate much CO2, but then if you have to exert yourself it suddenly hits you and can have severe effects.

The solution to both N2 and CO2 narcosis is the same: put more helium in the mix.

Interesting, is there any research to support this?

If CO2 is a major contributor to narcosis wouldn't breathing heavier help alleviate it since you are exhaling more CO2?

I've usually heard nitrogen narcosis referred to as "rapture of the deep"


Calculating your maximum operating depth and the time you can spend there before experiencing oxygen toxicity is an important part of advanced diving training.

For deep dives I really enjoy the planning phase, it requires a high degree of technical expertise and a thorough understand of your bodies physical limits.

Do you use a rebreather at all?

Personally no, I have the training but the cost is prohibitive.

Also the complexity of rebreather equipment is much higher than traditional scuba diving, so the risk of failure while underwater is much greater.

It is amazing tech though, if the price comes down by half it may become realistic for me.

>If you lower the brain temperature down to 30C (86F), it can increase the survival time from 10 to 20 minutes. If you cool the brain to 20C (68F), you can get an hour.

Wow, I actually didn't know this until now. Is this method used anywhere in medical procedures to resuscitate or prolong life?

It absolutely is. There's been considerable research on the use of therapeutic hypothermia during surgery, or after a traumatic injury.



The popularized way to say that is ”Nobody is dead until warm and dead”

See for example https://www.ncbi.nlm.nih.gov/pubmed/24882104, which states ”the longest time from cardiac arrest to return of spontaneous circulation was 6 h and 52 min”

About 30 years ago, my grandma had her entire aortic arch and then some more of the aorta itself replaced in a daring procedure. (I guess one can still call it as such today).

Notably, her body was cooled down significantly to reduce her metabolic rate down to nothing.

She survived several years, although she never quite recovered fully after that...

"You're not dead until you're warm and dead." Is a quote that stuck with me. I was reading an article [1] about a person who froze to death and made a practically complete recovery.

By the way this story is a must read.


About 10 years ago, finishing up High School, I had work practice at a company developing a product that would cool the brain without cooling the rest of the body.

I think they had mixed results, and I haven't seen them or their competitors launch their products.

It works though, but it seems very difficult to cool the brain without chilling the whole body.

I believe that this is a common trope in medical dramas. While I'm unaware of how often it is actually done, I know that I have seen it done in multiple episodes of House, or ER, etc, etc.

At least it's an accurate medical trope :)

So this may be the basis of cryogenics? If you just cool down in specific way, you can turn off metabolism and then turn back on again at later date?

Well not really. Cooling the patient down will give you a few hours at most under ideal conditions. Metabolism isn't turned off, just slowed down. If you freeze the patient the ice crystals damage the cells so much that revival becomes impossible.

Flash freezing (using liquid nitrogen to freeze something really quickly) is used successfully for smaller objects, such as frozen berries and frozen vegetables that you can buy at the grocery store. The Wikipedia page on flash freezing links to this [0] site with some more discussion. The Wiki page also says that flash freezing still can take a few hours, so there are still ice crystals created, but a lot less/smaller than if you just put it in the freezer.

Overall it seems it's just a matter of waiting for technology to advance to the point where we can very move a 150 pound 2-meter-tall 1-foot-deep object from 98 degrees to 30 degrees, and at that point the science fiction will become reality.

[0]: https://web.archive.org/web/20120111233417/http://www.biotec...

The size matters significantly for this. Much larger and it becomes difficult to remove the heat throughout fast enough to do a flash freeze.

This is correct. Flash freezing an entire human body consistently would be incredibly difficult.

Even speaking as a brit, your mixture of metric and imperial and metric fascinates me.

I personally would've written 150lb, 6'6 tall, 1ft deep, 37 to 0 degrees

150lb? That always strikes me as distinctly American, as opposed to 10st 10lb.

I'm so glad America got away before y'all went stone-crazy.

Redefining the hundredweight, seriously?

Hey, for a '1,000 pennyer' I'll advocate for your pound-as-largest-unit madness.

You had options! The London stone for wool was 12.5 lbs, which would give you the same 8 stone to the hundredweight without redefining a hundredweight as 112 lbs.

Or if you wanted to go the other way -- there were plenty of other definitions of the stone in use at the time, after all -- you could have gone with 16 pounds, to maintain parity with the dram and the ounce. Y'all still likely would have screwed up the hundredweight, as 128lb, but you might have at least fixed things by making the ton 16 hundredweight/2048 lb, which would at least have been some lovely binary fractions.

But 14 pounds? That's just madness.

Oops yes, I would actually have said 10 stone 10. I just copied the comment text because I was focusing on the 2 meters

Tell tale sign of a Canadian.

Cryonics involves vitrification, not freezing. Ice crystals do no damage if they never form in the first place.

Now the method of achieving vitrification involves pumping the body full of toxic antifreeze. But in principle it's easier to flush the antifreeze out when warming than to reverse ice crystal damage, though the techniques have not yet been worked out.

Thankfully it's not necessary for the reversal procedure to exist now for cryonics to be successfully used in preservation for the future.

There is zero chance that a human pumped full of antifreeze today will ever be successfully revised. Cryonics is a total scam by hucksters preying on desperate idiots.

And don't bother telling me that it's worth doing if there's even a tiny chance. The chance is exactly 0, and those resources are better spent on the living.

You can basically say that anyone living 500 years ago would say "there is zero chance" that what we take for granted today exists at all. Look at the technological achievements of even the past 50 years, most of it could hardly be predicted.

There's a pretty big difference between the statements:

"We are likely to have life extending and resuscitation technologies in 500 years that are better than what we have today."


"The dead rich people in these particular vats of antifreeze have any more than a snowball's chance in hell at being successfully resuscitated."

I think the parent's analysis is correct. Your statements, while also correct, don't really refute the issues pointed out by the parent.

It didn't point out any issues... it just made the unsubstantiated claim that a cryonics patient has no chance of ever being revived.

It IS physically possible to revive cryonics patients--as in the laws of physics would permit it, even if we don't have anything near the technology required, yet. This isn't a bold claim but rather a statement of fact with respect to information preservation of the vitrification process, and long-term storage at cryogenic temperatures, both of which are well studied in the context of things like organ donor preservation.

So if you're claiming that cryonics has "a snowball's chance in hell" of working, then I presume that either you are (1) ignorant of the science, or (2) making some sort of statement about long-term storage prospects or the credibility of the organizations involved.

But neither you nor the grandparent actually made any specific claims.

> So if you're claiming that cryonics has "a snowball's chance in hell" of working, then I presume that either you are (1) ignorant of the science, or (2) making some sort of statement about long-term storage prospects or the credibility of the organizations involved.

I'm signed up to be a cryonics patient when I die, but yeah, the chances are pretty much nil. Personally, I'll take a slightly diminished bank account and a potentially non-zero percent chance of further life over a zero percent chance, but I won't delude myself into thinking that there's effectively any chance of success here.

What I don't understand about this logic is, how do you have any confidence that if by some miracle you were brought back to conscious life again, your life wouldn't be an absolute living hell (organ damage, paralysis, etc.)? Like even if you had infinite money and resources to spend on whatever you wanted, would that risk be sitll worth it to you?

You don't. You can only hope that a) future people won't revive you unless they're somewhat confident it'll leave you better off than you were when frozen, and b) worst comes to worst, they can still euthanize you.

Cryonics is ultimately a bet on future technology and future humanity.

Future people will use the frozen as a resource. I would buy a 2139-October call option on 100-frozen-hopefuls ... that's when I estimate techniques for revival will be viable and when legal hurdles to mass exploitation will be overcome. In 120 years nobody will care about your intentions in being frozen.

...why? How could there possibly be utility in a corpsicle when you could much more easily achieve the same thing with AI?

> I would buy a 2139-October call option on 100-frozen-hopefuls.

Unless you live inordinately long, you'll only be in a position to benefit from that if you are wrong about it being a worthwhile investment. (But right about the technological enablers—just wrong on the socio/legal issues.)

It seems unlikely to me that we'd acquire the ability to revive a brain from death before the state of medical technology advances sufficiently to repair nerve damage or regenerate organs. You could put a kind of guarantee into this by only having your head or brain preserved, so the minimum viable tech level for resurrection would be regrowing a body.

I'd be more concerned with the emotional and mental challenges of being revived centuries hence, which would be considerable to say the least.

There's nothing new about all this...

Tutankhaman will tell you what to expect when you use cutting-edge technology and preservation techniques in the hopes of some future civilization reviving you.... you'll end up under glass in a Museum. Hell, nobody even TRIED to revive King Tut... you think they'll put much effort into a bunch of anti-freeze saturated popsicles? Seriously doubt it.

If you look far enough in the future it is probably feasible to engineer organs in the long run, or who knows maybe full bodies?

> a statement of fact with respect to information preservation of the vitrification process

That's not a statement of fact, it's a statement of belief. Personally, I think it's highly unlikely that any current vitrification process preserves sufficient information for the patient to be revived. We're nowhere near even understanding what "sufficient information" would be, let alone how to preserve it.

The thing is .. it is more about biology than physics.

You can flush water pipes with whatever you want and clean and rewater it. A complex organism like the human body - and the brain, we still dont really understand?

Not likely. Maybe not 0 chance in SciFi future, but still not likely.

Actually it is physically impossible to revive cryonics patients because essential information has been irretrievably lost. I don't think you understand the physics (or biology) here.

What information?

By this logic, we don't even need to freeze the body. Simply opt in to being resimulated later, since the technology will exist "some day".

A lot of "cryonically-frozen" people are only their heads, since it's been well-known for a while that there's no way to unfreeze the bodies. I suspect it may literally be easier to scan their brains than to unfreeze them, even if they were healthier to begin with. That's not a statement of my belief in the ease of scanning a brain; it's a statement of my belief in just how hard it is to "thaw" a body and get anything back. I'd say it's like getting handed a pile of slag and told to turn it back into a working engine, except that task is multiple orders of magnitude easier.

But that's my point, why even bother freezing the brain, if simply waiting a few centuries more of tech progress will mean you don't even need the brain to be consciously brought back?

It's just replacing the faith in one omnipotent's afterlife with another.

How would that work? Future technology, no matter how advanced, would still require the information in your brain to simulate you. The point of cronics is to preserve that information.

But currently we don't know what "information in your brain" would be required, so it's a huge leap of faith to suppose that cryonics is successfully preserving it.

(That's supposing "information in your brain" would even be sufficient by itself. Another leap of faith.)

The connectome. Your identity is encoded in the neural network of your brain, which is preserved in vitrification. I don’t know why this is controversial.

Just simulate the entire universe and pluck the brain structure of the person you're trying to bring back into reality.

You're missing the point though. These solutions entirely rely on future technology development being the omnipotence that gives you afterlife.

That seems more to be an assumption you're bringing in, rather than others. There's a huge gulf between "technology that can read the structure of the brain and recreate it" (which seems to be something merely lacking in know-how and tech, but with no fundamentally-impossible steps), and "simulate the entire universe as-is, in situ, and assume it's 100% accurate, and pluck people out of it" (a la https://qntm.org/responsibility), which seems outright impossible as no system can simulate itself fully. I'm honestly having trouble wrapping my head around how you're both managing to insist on the latter being the only possibility while simultaneously telling people that it's a bad assumption.

That's the point. Whether it's reviving frozen brains or resimulating consciousness, it's an entirely faith-based argument in technological progress.

You’re assuming magic.

"Any sufficiently advanced technology is indistinguishable from magic."

But even the most advanced technology can’t accomplish magic. It still exists in the real world and is subject to physical law, such as the laws of statistical mechanics and information loss.

Splitting hairs on physics just means you're missing the point of Arthur C. Clarke's quote - https://en.wikipedia.org/wiki/Clarke%27s_three_laws#Origins

I don't think I'm splitting hairs. The quote, in context, is applied in the other direction: a sufficiently advanced technology which exists has mechanisms which seem indistinguishable from magic to a primitive mind. But you can't apply it in the other direction and say anything which seems like magic could exist with sufficiently advanced technology. This is because there are physical limits which constrain what any future technology could do.

To a pre-industrial mind, a cell phone would be magic. Other things that would seem like magic are faster than light travel, perpetual motion machines, or exact quantum state duplicators. However baring radically new and highly unlikely physics (which would be the hugest cop-out to assume), there will never ever be faster-than-light travel, perpetual motion machines, or quantum replicators. Such technology is simply impossible. Not "we don't know how to do it" but "we know that it cannot be done."

Likewise, once your brain is cremated or reduced to worm food, there is absolutely no way to recover that connectome information which defines who you are. The laws of physics disallow it.

I have only the slightest idea of what technology that is able to revive a cryo preserved brain would look like, and it would certainly seem like magic to someone today. But to revive a cremated brain would require actual magic. There's an important difference there.

However, this won't bring you back, it will just bring back a clone that is exactly like you.

Suppose we get solid evidence that reincarnation is real. Or even just imagine that it is.

Being held in stasis for an unknown length of times seems like utter hell compared to moving on to your next life.

In that sense, a clone is preferable, but maybe not for the new consciousness inhabiting it.

Of course it will bring me back. It's my consciousness, just sans the biological CPU.

If it were true then it means being you can be duplicated ad infinitum and therefore you have no personality on your own. I done think we have a good answer to that.

A zero chance is your opinion. I'd estimate there is a high change some of them will come back in some form. I'm more a believer in extracting information to an AI simulation than reanimating the old bodies.

You have perfect knowledge of future technologies?

Doesn't it sound similar to "Prove that I cannot win a billion!" from someone who spends money in casino?

There's a big difference between telling someone they aren't going to win in the casino and telling them they have "zero chance" of winning. The later is false and is probably an ineffective argument because it's obviously false.

Yes, they should have said "roughly zero chance", which is true. They were just rounding down.

Also, frozen oblivion is better than being brought back by those who will not honor your motivations for being frozen. If it's possible to be brought back, organ-harvesting, post-cryo-slavery, medical-experiment-subject are the likely outcomes.

Not for cryogenics, unfortunately, but yes for hibernation. NASA has funded the study of medically induced torpor for hibernating humans for deep space exploration: https://ntrs.nasa.gov/archive/nasa/casi.ntrs.nasa.gov/201800...

If we ever do crewed interstellar travel, even if we can get the trip time down to 50 years or so, we’ll probably want something like this. But it’s useful even for Mars trips since you can fit a LOT more people in the same space.

Interesting. That PDF doesn't seem to include increased radiation exposure while having a slowed ability to repair the damage.

Wonder if that's just because it's not viewed as important?

There may be less oxidative stress as well, so it’s tough to say what wins out. Anyway, there are methods of providing radiation shielding to occupants as well.

Would you need to feed nutrients people during hibernation or is that a state of extrenely low metabolism?

It’s answered in the PDF. There’s nutrient delivery, but metabolic rate is halved so there’s less required.

I think you mean cryonics, not cryogenics.

Sure, there is research in applying this to premature babies in some cases

The documentary is on Netflix, it's worth a watch: https://www.netflix.com/watch/80215139

Thank you. Just watched it. Good one.

The thing that bothered me that they resumed to do the same dive 3 weeks after the accident - it doesn't sound like enough time to setup protocols to prevent the same accident from occurring again. Also it was very weird to hear that they don't have checklist to follow when they ships's dynamic position system fails...They were essentially trying to control the ship by whatever they can think of for over 20 min while somebody is suffocating on the ocean floor.

Not really suprising that there wasn't a checklist, a DP3(GPS, backup and failsafe)ship shouldn't ever suffer DP run off. Then it did. So now I suspect there are actually checklists.

Netflix just gives me a "Netflix Site Error – Page Not Found".

What's the documentary called, so I can find it by other means please?

It's called "Last Breath".

It's from Netflix Canada, not sure if available outside of US / CA.

Saw it appear on Netflix a while ago and ignored it.

Now I'm watching it :)

Reminds me of the fantastic movie The Abyss (1)...vaguely recall a similar scene where there's N tanks of oxygen for N+1 people, so they submerge 1 of the crew to lower her (i think) metabolic rate.

Curious why they don't have emergency unmanned drones with the crew or why they don't have emergency tanks at their work site (which he was able to get back to)

(1) - Not sure how well it has aged (https://en.wikipedia.org/wiki/The_Abyss)

Commercial divers do have extra breathing gas in the bell, which is positioned at their work site. The problem in this case was the bell was dragged out of position.

>Curious why they don't have emergency unmanned drones with the crew or why they don't have emergency tanks at their work site (which he was able to get back to)

There was a UUV in the water, which helped to locate the casualty but wasn't capable of performing a rescue.

Bailing out to open-circuit SCUBA doesn't help for very long, because of the immense pressures involved. As you go deeper, you need more pressure to inflate your lungs. A cylinder that lasts for an hour near the surface will only last for a couple of minutes at 100m. Tethered divers do carry bailout gas cylinders, but they're very much a temporary fix for brief losses of gas supply.

There are major logistical problems with portering dozens of gas cylinders to a job site that may actually increase the overall risk, because of the far greater time spent in the water. That pile of cylinders won't help you a jot if you lose the job site or you're incapacitated. Saturation divers are increasingly switching to closed-circuit rebreather bailout systems, which recirculate the breathing gas and so are far less affected by depth.

Even that is only a partial help because of the effects of hypothermia - if you lose your umbilical, you lose the warm water supply that stops you from freezing to death. You also lose your lighting and communications, which substantially impedes your ability to self-rescue.


> A cylinder that lasts for an hour near the surface will only last for a couple of minutes at 100m

And unfortunately for saturation divers, you can't pressurize cylinders on-site to make up for the difference.

Pressurizing your tank to 210 bar (which puts the same stress on the cylinder walls as 200 bar at the surface) doesn't change the factor-of-10 increase on the other side of your P1V1=P2V2 balance.

Not to mention that you need even more air for decompression time...

She chooses to drown with the idea that she can be revived quickly enough to survive. They aren't trying to share oxygen or anything.

IIRC the rig was moved out of place. they were already having massive problems at that point in the film.

fun facts about the abysss.

1. it's a version of the divine comedy, particularly the inferno.

2. the set still exists as of a several years ago


Yeah even if the unmanned drones are too hard, having spare tanks at the work site sounds like an easy way to at least supply oxygen... however without the umbilical cord he loses the heat supply. Maybe its more pleasant to pass out while your body freezes.

Getting cold probably saved his life by reducing the metabolic burden. This is done intentionally during certain surgeries, such as aortic aneurysm repairs. It also informs the ER standard: you're not dead until you're warm and dead.

Also, it's staggering how much oxygen can be dissolved into your system at depth. The Navy did some experiments where they put pigs in a chamber, pressurized them to something obscene, like 300 feet, and replaced their blood with water. The oxygen diffused so well the pigs were still conscious and walking around. Source: I work with a lot of Navy dive medicine officers.

That's also why hyperbaric oxygen therapy is an effective treatment for carbon monoxide poisoning. Even when all the hemoglobin receptors are bound to carbon monoxide, enough oxygen will diffuse into the blood to keep the patient alive.

That’s fascinating.

Yeah that's amazing isn't it. Replacing blood with water sounds like magic though. The blood does more than just carry oxygen doesn't it?

I was just saying though, if he did have more oxygen down there he would have had to be awake for that freezing experience...

Or with blood plasma, maybe.

At least for recreational diving each diver has two regulators attached to their tank, so if you have N tanks you can provide breathing gas to 2N people.

The movie involves hard dive suits, not SCUBA regulators. But you'd think there'd be an extra emergency regulator hanging off the tank...

Commercial diving rigs don't have extra "octopus" regulators attached to the bailout tank. The divers wear hard hats with integrated regs plus free flow valves so an extra reg would be pointless.

What an incredible tale. Ironically, this story at the moment shows up directly beneath one titled "Hacking the Casio F-91W to Handle 1000+ PSI"

Main article aside, I have to take the article to task for the section where they talk about an airplane and the oxygen masks that deploy when the aircraft depressurises and the passengers find it "hard to breathe".

Having gone through a depressurisation chamber as part of my flight training, at 35,000 feet (the normal cruising altitude for most passenger aircraft), it isn't actually hard to breathe. In fact, it feels quite normal. Your body just doesn't get enough oxygen into the bloodstream because the density of O2 in the stuff you are breathing in is so low, which causes onset of hypoxia.

The very reason why we do the sessions in the chamber - so that we can detect the symptoms of hypoxia particular to our own bodies, because there is normally no way to tell that you are no longer in an O2 rich atmosphere until you notice your fingernails turning blue and flashes of lights on your retina as well as feeling slightly tipsy (my own symptoms).

At higher altitudes (50,000 feet and up), then yes, there are issues because your diaphragm cannot create enough pressure differential against the outside air pressure to make you inhale and fill your lungs. My flight instructor was a test pilot in the 50's and 60's and he said when they were at that altitude, they were literally force fed liquid oxygen through their masks. They couldn't breathe it in, so they just had to open their mouths every few seconds and LOX would be shoved in (at freezing temperatures too, which used to dry out their nose, mouth and throats according to him).

> so that we can detect the symptoms of hypoxia particular to our own bodies

Destin of SmarterEveryDay (with astronaut Don Pettit) recorded his experience with that training, which included a demonstration of the effects of hypoxia on his decision making ability. He doesn't notice the rapidly increasing symptoms:

>> [Destin fails child's shape toy test, saying the cross was a square] "Alright you're starting to have a little shake there, you know from your lack of oxygen. You need to start thinking about getting back on oxygen now Destin."

>> "How would you correct for that? Can you correct for hypoxia for me?" [Destin just sits looking confused] "Alright sir if you don't get on oxygen, you're going to die. Go to your regulator, get all three switches on your regulator..." [Destin looking even more confused: "I don't want to die"]

>> [they get him back on O2, fixing everything in seconds]


Ah, that brings back memories. That was the exact stuff we did, except that my exercises was to count backwards from 1000 by 13's.

We were told that we could possibly make it 3 to 4 minutes at FL250 before having to go back onto oxygen. I managed to get to 5 minutes, but was was pretty much useless after the 3rd minute. I started to feel a real out of body experience, and it was like I was watching my own body do stuff but I couldn't really control it. I managed to get my own mask on and gangload the 3 switches, but I remember watching my colleagues in the chamber struggle and they had to be assisted by the RAAF team. The guys outside the chamber kept a hawk eye watch on all of us, and the guy in the chamber were quick to assist those of us who were in trouble.

What amazed me was as soon as we 'gangloaded' the switches to go back on full O2 with the masks on, recovery to full lucidity was super quick - within 1 or 2 seconds. It wasn't gradual, it was as if someone just whipped a heavy blanket off your brain!

Side story - before we went into the chamber, we had to be fitted for our helmets and masks, and I was seated in the 'fitting chair' in the crew room as 3 RAAF specialists slapped a bone dome and mask on me. Unbeknownst to them, that mask had just come back from a test facility, and thus it still had the wax seal on the end of the O2 hose to the mask.

Normally, there is no seal, so when the mask is clipped on during a test, you can still breathe normally as the valve at the open end just opens and shuts with your lung pressure. With the wax seal on it though, NO air gets through.

It was a few seconds of odd feeling when they snapped the mask on and I tried to breathe in but nothing happened. I remember feeling really freaked out at the sensation of wanting to breathe, but feeling and experiencing absolutely nothing. I started to grapple with the mask release, but they thought I was just uncomfortable with the fit and they kept slapping my hands away and adjusting the side straps.

I went into panic mode, and I am not sure what prompted me, but I started reeling in the trailing hose from my mask and lifted it up to see the seal on the end. One of the crew saw it and exclaimed before grabbing the hose and ripping the seal off. I gulped down lungfuls of air. Not the best start to my first chamber session!

I watched this a few months ago for the first time - it blew my mind. Made it completely clear why you're instructed to put your mask on first before helping others.

Wow that was an interesting read!

This quote got me. All because of compression & decompression.

> “It is quicker to get back from the Moon than it is from the depths of the sea in some ways.”

The polar station in Antartica is also quite inaccessible during winter. Winter-overs are proud of the fact that they are more remote than the ISS. There you can get in a Soyuz and be back in 90 minutes. In Antartica it might be a month before they can airdrop supplies, maybe four month until they can airlift you out.

See also: https://en.wikipedia.org/wiki/A_Place_Further_than_the_Unive...

It's a great series about exploring Antartica, where the title came from the fact that it takes longer to reach Antartica than to reach space.

It makes sense. Antarctica is further away from almost every place on Earth than Space is. Sea level to space is closer than Manhattan to Trenton.

> Sea level to space is closer than Manhattan to Trenton.

"Closer" is a fuzzy concept. I've seen the same point made another way, that you can be closer to space than you are to the sea... even if you're in Japan, a long, narrow island.

But then again, imagine if whenever you tried to drive to Trenton from Manhattan, a tornado picked up your car and threw it back to Manhattan.

Oh my god, I just got that title. Thank you so much!

Futurama kind of made this point:

> How many atmospheres of pressure can the ship take?

> Well, it's a space ship, so I'd say anywhere between zero and one.

This article is quite fascinating, but the title is a bit misleading. The diver was about 100m deep. He was on the sea floor but arguably not "on the bottom of the ocean" (though maybe, by some interpretation)

what is the sea floor if not the bottom of the ocean?

Well, in a way yes, but then so is wading next to the seashore. Think of the converse “at the top of the mountain.” At least I’m thinking some peak and not just on a slope up the mountain.

in that case I too have run out of air at the "bottom of the ocean"

To be more of a smartass than a pedant, but... the bottom of the sea?


Related - David Blaine's world record of holding breath for 17 minutes:


Which is probably already broken:


I think this is the current record. 24 minutes and 3 seconds. It's hard to comprehend.


Question for the medical readers: a person dies when brain dies from lack of blood flow, right? So all those injuries, say a car crash where heart will stop soon. 1) Disconnect the head from body 2) plug it into a machine that supplies blood, etc 3) the body is repaired 4) reattach head to body. Overlooking the obvious trauma, is this possible?

While extreme/traumatic, I think it could be more reliable as other factors below neck are taken out if equation to dramatically increase chance to survive. Other methods rely on hoping the body isn't too broken to recover. Ie restarting heart, etc then literally giving up as the brain dies from lack of blood flow.

A lite version of above is cutting the veins in neck and attaching a dialysis. Would this lite method work?

Source: Hearsay reports of moving lips from beheaded woman was literally inspiration for this idea, not futurama heads.

Edit: https://theconversation.com/did-anne-boleyn-really-try-to-sp...

We still cannot repair a spinal cord injury. A complete decapitation is a total spinal cord transection and more.

Head transplants have been carried out on mammals successfully in the past. The success criteria isn't in restoring limb function, but rather in keeping the brain alive on a host body.

One problem at a time.

source? I read on this subject about monkey experiments and it seems the results were far from 'successful'.

An Injury is not a clean cut. So when you use a scalpel to sever it its much easier

That's what an ECMO is... a last-ditch effort to perfuse the brain and vital organs to see if the body can recover. It rarely does.

Head transplantation is still too "out there."

One problem with head transplantation that comes to me, is that of resources such as hormones and neurotransmitters produced by the body (i.e. intestines produce neurotransmitters).

Thence it is not only a problem of oxygenation of brain tissue.

It bothers me that it's called a head transplant and not a body transplant.

If I needed to, I would definitely choose a new body over a new head.


an extracorporeal technique of providing prolonged cardiac and respiratory support to persons whose heart and lungs are unable to provide an adequate amount of gas exchange or perfusion to sustain life. The technology for ECMO is largely derived from cardiopulmonary bypass, which provides shorter-term support with arrested native circulation.

It's not just the brain. All the body's organs require perfusion. The heart will also quickly die without perfusion. Other organs will survive a little longer.

Better than cutting the head (or the body) is to reduce the temperature and induce an hypothermal effect like in the article. It is used in some surgeries https://en.wikipedia.org/wiki/Deep_hypothermic_circulatory_a... (Don't try this at home.)

step 4 is pretty hard.

Just do step 1 in reverse.

> They now use emergency tanks that carry 40 minutes of air rather than five.

Glad to see the change, but why even carry a tank with 5 minutes of reserve? Might as well just plan on holding your breath in that case.

The idea is that if there's a problem with the umbilical, 5 minutes should be enough time for a diver to get back to the bell where they have plenty of gas. But in this case the bell was dragged out of position.

This is just idle observation, but when you ascend the air in your lungs expands and you are supposed to continuously exhale to prevent lung rupture. Supposedly if you start with a full pair of lungs, you can ascend pretty much from the bottom of the ocean on just one breath because of this.

Also somewhat related, the deeper you go the less time your tank lasts. From what I remember, at 100m, a "5 minute tank" is probably similar in size to a standard scuba tank.

This is correct; scuba divers are trained to do a controlled emergency ascent while continuously exhaling, because your lungful of air at depth will last the whole way up, and the real risk is not running out of air, but embolism from overexpansion.

The limiting factor in ascent (and therefore the reason for the recreational dive limit of 60 feet) is the risk of decompression sickness. If it weren't for that, a diver at arbitrary depth could ascend on a single breath.

This is not entirely true, not all agencies teach a Controlled Emergency Swimming Ascent (CESA). From memory the only one that teaches this is PADI.

Most don't as this is not a very effective or safe way of getting up once you get bellow a few M of water.

Most agency's will teach you to do an Alternate Source assent where you come up breathing of your buddy's air source, as this allows you to come up at a safer and more controlled rate.

Everybody trains you to not hold your breath while ascending, because this is the easiest way to die doing scuba.

As I remember the PADI training the CESA is the absolute last resort when your buddy is not available. I imagine all authorities would agree that it's less bad than remaining at depth without gas.

No novice diver is going to remain at depth in an out-of-air situation, under any circumstances. The point of training the CESA is to teach people not to hold their breath and hurt themselves when they panic and bolt for the surface. This panic reflex is so strong that it takes dozens of hours of training and practice to be able to signal a buddy and breathe off their air supply in a real emergency situation.

You can see this reality reflected in the rescue diver certification (a fairly advanced level of training), which revolves around how to stop people bolting for the surface when they have trouble getting air. Rescue divers are taught some fairly extreme measures—you pull the person's regulator, yank their fins off, pull off their mask, and hold them down by the tank valve, anything you can do to prevent them surfacing at high speed. Better a briefly unconscious diver than one with an air embolism.

Recreational dive limits are usually set at about 100 - 130ft (30 - 40m) depending on the training standards in use.

The beginning certification level is 60 feet. You unlock the deeper limit after additional training, and it includes performing a three-minute "safety stop" at 5 meters. 60 feet is about as deep as you want to shoot to the surface from (and if memory serves the limit they give in training is 30 feet, or 2 atmospheres).

I've always been fascinated by how hard diving is. 60 ft seems like a completely trivial depth - about the length of four cars - but already there are non-trivial risks. And from there it rapidly becomes more dangerous and complicated and just plain hard to stay alive.

It's not that hard. If you're interested then go ahead and sign up for a basic open water class. Most people can pass.

Lot easier than trying to go downwards with a snorkle.

Well, it's better than nothing. That's enough to hold your breath 2-3 times, IIRC. That time means a lot.

I feel like you could make 6 minutes of air last an hour or more if you breathed really slowly (like one breath every 30-60+ seconds). Maybe I'm misunderstanding the device he had, or maybe it already has that assumption built in, or maybe he just wasn't quite that efficient but that is part of why he was blacked out but not dead when his friends pulled him up.

It's tough to relax and slow down your breathing when you're scared and about to die. And after a few minutes of forcing yourself to breathe slowly the CO2 accumulation starts to mess with your head.

"But his survival is not unheard of either. Tipton has examined 43 separate cases in the medical literature of people who have been submerged in water for long periods. Four of these recovered, including a two-and-a-half-year-old girl who survived being under water for at least 66 minutes."

Wow, 66 minutes! Amazing.

There is a documentary about this, which I recently watched. https://www.imdb.com/title/tt9056818/?ref_=nm_knf_t1

You're not dead until you're warm and dead, as the saying goes.

Not reading this. I don't want spoilers for the documentary.

Medically there are policies in various countries that differ on the term 'dead' or 'clinically dead'. Various places have different standards of dead.

This has a huge effect on organ donation rates. For my medical emergency thank god I live in the US or my organs would have been donated already.

some places may have a policy for either 'respiratory arrest or cardiac arrest after x period' to be considered clinically dead. If I had been in one of those countries my organs would be in many different people's bodies.

I thank god every day that I was born in the US.

More info please. What happened?

someone tried to kill me for exposing them raping my girlfriend and the doctors used experimental oxygenated blood to save my life. I got really drunk the night i was assaulted because of a related incident. During the incident with my gf, her ex and i were trying to locate her after a party (we were in another dorm and she called us on a cell, not hers) and she recollected she didn't know where she was, she was naked, and that some males were holding her close not letting her go. They would only give her clothes after a sexual act was performed. We tried locating her but we were too late. Afterword, I and the girlfriends ex tried pulling the call 'metadata' but it was deleted or i was not allowed to access it.

I have a higher likelihood of suffering a stroke in my 30s due to the fake blood injections.

My roommate was paid to keep watch while the offender tried to suffocate me. While transported to the hospital i lost consciousness for a long time. The hospital pretended like they had consent to inject me with the fake blood. The hospital covered up the rohypnol in my system. The nurse there assumed i tried to slip a gril a roofied drink and failed. The college buried the report, blaming it all on me. My parents were shamed. My girlfriend ended up dating the offender for 2 years due to violent threats on family. The offender got away with sexual assault against me (buck breaking). The offender stuck his dick up my ass so I wouldn't tell anyone of the event (i am male and it almost worked). The only reason I survived is that I pretended to die (thanks burn notice) only for the offender to realize he didn't want to kill anyone. I had a brown-out of the events for about 1.5 weeks after. This will be my greatest shame for the rest of my life not trying harder to prosecute the incident.

Oh my god that sounds absolutely horrific.

It's worse because the offender was politically connected and there was nothing I could do about the situation at the time i regained recollection. The offender also had large resources to pay ex spooks to keep the situation normal (for him), and digging up dirt on me and my family.

Great, an ad for a documentary. Fascinating story but still an ad.

I got rid of my TV entirely in large part because of the ads. I run an ad blocker. I’m not a fan of most advertising. But man, when something is actually useful and unobtrusive I don’t complain! Imagine if every ad was a captivating story that made you think and introduced interesting concepts (like death being less something to fear and more about what you leave behind). That’s not going to happen, so even if this is an ‘ad’ I for one am quite happy with it.

Fair point. Sometimes I just have angry moments when I realize I’m being sold to. I don’t stop to think that maybe perhaps it’s okay to do this if you are sharing something interesting.

I completely agree! So much of the advertising industry seems to be comprised of people who have an enormous amount of distain for their target demographics. People don't like being taken advantage of or manipulated, and it's depressing that it's gotten to this point.

I just think that in this case, while they (ostensibly) want to promote a documentary, they're presenting it in an honestly compelling way. That's about as much as I could ask for, I think, and I wish others would reimagine how they sell products to align more with this strategy.

This is a fine article in its own right, quite independent of the documentary.

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