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A man who ran out of air at the bottom of the ocean

bbc.com

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Re: A man who ran out of air at the bottom of the ocean

#171

Post by nradov »

dig1 wrote: post #102
jdietrich wrote: post #88

Earlier quoted context omitted.

At sufficiently high partial pressure, it's toxic. https://en.wikipedia.org/wiki/Oxygen_toxicity Nitrogen becomes narcotic at high pressure; breathing normal air at 30m is like being tipsy, but below 90m it can be fatal. https://en.wikipedia.org/wiki/Nitrogen_narcosis

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 thi…

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.

Re: A man who ran out of air at the bottom of the ocean

#172

Post by nradov »

eitally wrote: post #122
folkrav wrote: post #116

Earlier quoted context omitted.

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…

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.

Re: A man who ran out of air at the bottom of the ocean

#173

Post by nradov »

garmaine wrote: post #63
X6S1x6Okd1st wrote: post #40

Earlier quoted context omitted.

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.

Re: A man who ran out of air at the bottom of the ocean

#174

Post by nradov »

peripitea wrote: post #167

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.

Re: A man who ran out of air at the bottom of the ocean

#175

Post by garmaine »

bduerst wrote: post #168
garmaine wrote: post #166

Earlier quoted context omitted.

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.

Re: A man who ran out of air at the bottom of the ocean

#176

Post by [deleted] »

bduerst wrote: post #160
jerf wrote: post #156

Earlier quoted context omitted.

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/res…

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

[deleted]

Re: A man who ran out of air at the bottom of the ocean

#178

Post by m463 »

TheOtherHobbes wrote: post #94
idlewords wrote: post #44

Earlier quoted context omitted.

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.

Lot easier than trying to go downwards with a snorkle.

Re: A man who ran out of air at the bottom of the ocean

#179

Post by thaumasiotes »

jandrese wrote: post #49
omoikane wrote: post #18

Earlier quoted context omitted.

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.

Re: A man who ran out of air at the bottom of the ocean

#180

Post by diveanon »

nradov wrote: post #171
dig1 wrote: post #102

Earlier quoted context omitted.

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 thi…

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…

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?

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