teleportation

[blacbird]

Actually, one of the possible effects on the human body of too rapid a change in pressure regime, at least from high pressure to low pressure, is the bends, a great and sometimes fatal fear of deep divers. High pressure causes nitrogen to be absorbed in the blood, and sudden release of that pressure causes the nitrogen to be released from solution likewise. Horribly painful, and can kill.

caw

[benbradley]

Originally Posted by Anaximander

I don't think there's enough pressure differential in the Earth's atmosphere to cause the bends. As previously mentioned, underwater you can experience many atmospheres of pressure. In air, you have just the one (obviously). That shouldn't be enough to affect blood-gas levels hugely. Take a look at the Stratos jump - Felix Baumgartner jumped from 128,000 feet, at which point the ambient pressure is about a third of one percent of what it is on the ground. Baumgartner went from that to full atmospheric pressure in nine minutes - not instantaneous, but definitely not gradually enough to count as the rest stops that deep-sea divers do to avoid the bends.

I saw the video and heard the commentary, he was in a SEALED suit like a diver's suit or spacesuit when capsule depressurized and he walked out and jumped. I don't know what point he took off the helmet, but he obviously did before he landed.

The problem here isn't the bends, but I find it hard to believe you could survive long in 1/3 of 1 percent of sea level air pressure, even if breathing pure oxygen. With pressure that low, there's not much oxygen entering the lungs.

In summary, I reckon you could teleport anywhere without worrying too much about altitude - equalise your ears when you arrive, take a few deep breaths if you've gone up, breathe gently and slowly if you've gone down, and take it easy for a few minutes.

You could transport into a sealed container with the air pressure matched to where you came from, and it then slowly decrease or increase pressure (over seconds or minutes, depending on how great the distance is) to match the location.

Other than that, the biggest danger you have from extreme altitude changes is finding out that you've teleported somewhere with no ground beneath you. Interesting side issue there: if you find yourself in mid-air, and teleport away, do you keep your speed?

This is similar to the discussion of Larry Niven's transporters - If you're transporting more than a few miles, the transporter needs to compensate for the different direction of motion of different points on Earth. If it knows how fast you're going, it can compensate for that too so that you're standing still at the end of the transport.

[Anaximander]

Originally Posted by benbradley

I saw the video and heard the commentary, he was in a SEALED suit like a diver's suit or spacesuit when capsule depressurized and he walked out and jumped. I don't know what point he took off the helmet, but he obviously did before he landed.

Ah yes, I'd forgotten that detail. Still, regular skydivers aren't in pressure suits, and they have no trouble. They tend to go from 12-14 thousand feet, if I remember correctly (EDIT: a quick Google search confirms this), which is high enough for me to be confident that the Earth's surface doesn't give enough of a pressure differential to not cause the bends.

[Canotila]

Maybe not the bends, but elevation sickness is still very real and affects plenty of people. Some friends flew with their children from sea level to Lima, Peru in one day. Once they arrived their 5 year old became extremely ill and had to be hospitalized. They and their other child were fine, so it doesn't affect everyone equally. She had symptoms like a really bad case of the flu.

It happens when going from a low elevation to a high one, and some people are naturally more susceptible. Try looking up hypobaropathy.

In some cases it can be fatal if it develops into high altitude pulmonary edema (fluid in the lungs, mountaineers die of it every year), or high altitude cerebral oedema (brain swelling).

[blacbird]

Originally Posted by benbradley

I find it hard to believe you could survive long in 1/3 of 1 percent of sea level air pressure, even if breathing pure oxygen. With pressure that low, there's not much oxygen entering the lungs.

The oxygen isn't the problem in this situation. The atmospheric pressure is. 1/3 of 1 percent of sea level pressure is pretty much a vacuum. Your bodily fluids would begin to boil and kill you very quickly.

Three Soviet cosmonauts died in just this fashion back in the 1970s when their re-entry capsule lost its pressure seal. It landed just fine. But they were all dead inside.

caw

[Anaximander]

Originally Posted by blacbird

The oxygen isn't the problem in this situation. The atmospheric pressure is. 1/3 of 1 percent of sea level pressure is pretty much a vacuum. Your bodily fluids would begin to boil and kill you very quickly.

Three Soviet cosmonauts died in just this fashion back in the 1970s when their re-entry capsule lost its pressure seal. It landed just fine. But they were all dead inside.

caw

It's worth noting that this can be averted. NASA has had cases (in 1965 and 1966) in which astronauts have been inadvertently exposed to hard vacuum. Human skin is gas-tight, so while the fluid in your ears, nose, throat, lungs and on the surface of your eyeballs would boil, your blood would not, so you wouldn't explode (contrary to popular belief). There's some debate over what would happen if you were cut and bleeding; I don't know enough about vacuum physics or medicine to comment with much authority. You'd swell to roughly twice your size though, ending with something roughly analogous to Bibendum the Michelin mascot. Reports conflict as to how painful this is.

Anyways, you'd have about 10 seconds of consciousness - about the length of time it takes for your brain to use up the oxygen it's getting. Don't bother trying to hold your breath because the pressure differential would rip the air from your lungs and damage something in the process; even if you managed to not exhale you'd rupture something important somewhere. The estimate is that you'd have around a minute, maybe a minute and a half after passing out before death.

Somewhere I have an excerpt from the Cooke and Bancroft paper from 1966 that I picked up in a lecture on orbital mechanics and spaceflight; I'll see if i can find it, but have a google about for it.

[blacbird]

At Dachau, among the many ghoulish experiments were subjecting Jewish prisoners to pressure chambers in which the atmosphere was essentially pumped out, to see the effects and at what pressure a human would die.

http://www.jewishvirtuallibrary.org/...5_0_14634.html

caw