Wierd science question re: Death

I have read that the only cause of death is lack of oxygen to the brain.

The cause of this lack of oxygen is mere window dressing.

According to wikipedia:

Drowning is death caused by the filling of the lungs by a liquid, usually water, rendering breathing ineffective and leading to death due to asphyxia.

From NASA

On December 16, 1994, a lad from Key Largo nicknamed "Pipin" (his real name is Francisco Ferreras), rode a lead sled 417 feet down, then shot back to the surface 2 minutes, 24.45 seconds later to break his own world record for deep-diving on a lungful of air. Afterward, Pipin was pretty nonchalant about the whole thing, telling reporters, "It's just one more step on the way to 500 feet."

Had he been wearing standard scuba gear, Pipin could descend to about 350 feet before suffering "rapture of the deep," a narcotic like stupor caused by compressed nitrogen. If Pipin worked for a commercial diving outfit that serviced oil rigs, he'd spend weeks in pressurized nodules so he could work at a depth of 1,000 feet. Some test dives using oxygen mixed with various exotic gases have enabled people to survive at 2,400 feet, but that seems about the limit for unprotected humans.


In this case we can ignore decompression. Terminal velocity in water is about 55.4 feet/second using specially designed equipment (see http://intuitor.com/moviephysics/abyss.html).

By my calculations you would hit 2,400 feet after 43 seconds - fairly easy to hold your breath until then - except for the massive pressure differential between your lungs and the surrounding water.

So now I have to figure out what what pressure your chest can withstand at which point you cannot hold your breath, but I reckon, either way you drown. The question is whether your lungs fill with water because you loose consciousness because the oxygen content of your lungs has dropped to a certain point, or because the pressure pushes the air out of your lungs....

Interesting question. On average, in ocean water, about the maximum sink rate an unstreamlined mass will achieve is going to be in the vicinity of around 25 feet per second, maybe 30; the sink rate for a WWII 600 pound depth charge was 30 feet per second. A typically weighted free diver can, with swimming, barely manage 8 or 10 feet per second, a weighted hardhat diver will achieve a sink rate of around 15 to 20 feet per second. While the record for unassisted, breath-hold diving is around 165 feet (down and back in just over 2 minutes, the up leg taking a little over 95 seconds), the record for SCUBA diving is just over 1000 feet, for tethered, hardhat/pressure suit diving about twice that.

OK - now, without special training and conditioning, most folks won't be able to hold their breath much longer than a minute, and with oxygen deprivation taking on average somewhere around 4 to 6 minutes to shut down brain function, we can assume you'll be dead of drowning in something under 7 minutes, if you live that long.

2 minutes, 120 seconds, at a constant (if probably unrealistic) 20 feet per second, theoretically woud put you at 2400 feet, or roughly 75 atmospheres, well over 1000 pounds per square inch. At half that sink rate, 10 feet per second, you'd be at 600 feet, under a pressure of around 560 pounds per square inch. Either way, I figure pressure effect on an unprotected human body likely would be a major contributor to, if not the primary cause of death.

If you were holding your breath, wouldn't you die from having your lungs explode?

It'd be more like implode, bunny, as the pressure gradient increased with depth ... I think. I dunno, haven't tried it, myself. Not partioularly inclined to, either - my interest doesn't really equal my curiosity in this case. Now, if someone else wants to give it a shot, I'd be glad to read their results.

Cool, thanks for the info, guys!

Best bet so far is that the person would die of drowning, and if that wasn't bad enough, it would be a pretty painful way to go due to the force of the pressure increase.

I initially had thought the pressue would do it from the few times I've gone diving. I clearly remember feeling how "compacted" I felt at depths of as low as 20-30 feet and thinking, "damn! I'm still fairly close to the surface and it feels like this?"