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The reason why i don't believe ambient pressure is a possibility has to do with the question of what gases you would use and their effects on the nervous system or other parts of the human body in the long run.
So let me ask: what gases would you use at 101 bar (1km uw) of ambient pressure?
---------- Post added April 17th, 2013 at 02:59 PM ----------
Hpns and either types of O2 toxicity are not acceptable...
O2 is not really an issue. A mix with .21% oxygen would get you around a PPO2 of .21. You could probably use more. HPNS? Hard to say using some nitrogen and hydrogen in the mix could help. Or, just search for people that aren't susceptible.
Given the idea of the story is the people can't directly ascend, keeping pressure to 1 or 2 ATM doesn't fit. Since it is science fiction, the problems of being at ambient are easily dealt with.
Don't think I did. Unless you think he was joking. He said you can't have O2 toxicity problems, I pointed out O2 would not be the problem. I think it is much more likely that you misread my post.
Nitrogen is likely out since the END of anything over 3% would be bad. I agree with HPNS could be an issue. That is why I suggested adding in Hydrogen or finding people not susceptible to HPNS.
---------- Post added May 5th, 2013 at 01:43 AM ----------
I am confused...perhaps that's because people are using ".21%" instead of "21%". LOL
Breathing air at 101ata (1km depth) equates to a PPO2 of 21.21 That's a 'little' beyond the safe max level of PPO2 1.6 Breathing a normoxic mixture at these depths is likely to be unsafe (an understatement)... but who knows? Nitrogen (sedative) has been theoretically proposed to suppress oxygen toxicity to some degree....
A hypoxic mixture (.21%) might solve the toxicity issue, but the need for a replacement gas remains the insurmountable obstacle.
Gasses to discount:
Helium is proven troublesome. HPNS (High Pressure Nervous Syndrome) aka "Helium tremors" is, based on current science, primarily linked with helium use. Inclusion of nitrogen is known to suppress presentation. How that'd play out at 101ata is beyond current science.
Argon, Xenon and Krypton are excessively narcotic.
Radon is radioactive (hence not tested on humans). Very dense gas.
Methane, Halothane and Cyclopropane etc are narcotic also.
Tetrafluoromethane and Sulfur Hexafluoride (SF6) are, I believe, is narcotic, but some small addition helps resolve 'squeeky voice' from helium. Better for a comedy, than sci-fi
Possible gasses:
Hydrogen has deep diving applications - Hydreliox and Hydrox have been used down to ~500m though. O2 must be kept below 3% to avoid explosive risk - that wouldn't be a problem at the author's theoretical depths though.
Neon (Ne), Neox (Ne + O2) and Neoquad (Trimix + Ne) have also been used. It's proven non-narcotic down to ~380m. Neon is very dense though - causing extreme decompression requirements and difficulty breathing at pressure... but that's potentially easy to work-around in 'sci-fi' than reality.
The author could just 'make up' a complex gas mixture that would pass muster with all but the most knowledgeable. Make a theoretical cocktail based on known principles and then use creativity to 'explain' how it'd work.. (one gas cancels negative properties of others etc..)
Like making a cocktail:
8 parts Hydrogen + Neon - the 'mixer'.
A dash of Oxygen - to sustain metabolism (life!) a fraction of 1%.
A tiny sprinkle of Sulfur Hexafluoride to allow them to talk normally.
Some Krypton to sedate (counter-act HPNS).
Name the gas according to systematic elements:
4 gasses quad
5 gasses pent
6 gasses hex
7 gasses sept
8 gasses oct
9 gasses en
i.e. "Pentmix" - a mixture of 5 gasses. Neokryptoxyhydrosulflouride
Alternatively... go with some potentially realistic brew i.e. 'Neohydreliox' and then invent some medication that overcomes issues like HPNS and narcosis. A 'magic pill' that the divers take to stimulate versus narcosis and/or sedate versus HPNS...
The big blue extended version also has a scene where Jean Reno and Jean-Marc Barr are drinking whiskey in a bell with squeaky voices... This is just before they go dancing drunk on the bottom at 100m. Their umbilicals don't even get entangled!
Hey guys,
Thanks for all of your answers. We've been in a hole lately trying to get out of our science-fiction basis, which we finally managed to do, but it means that we'll be trying to make our story as realistic as possible now, and we can't really do anything "magical" anymore. We can stretch reality a bit, but nothing crazy. We have a question you might be able to answer, though: if a dead human body were to slowly sink at the bottom of the ocean, at a depth of, say half a mile, the fish would eat the skin, the ligaments, all that good stuff, but would the bones remain? After 20 years, would you say it's possible you'd still find some of the bones, disseminated everywhere? Would the pressure have any effect on them?
That is not deep enough for the pressure to crush the bones so they could still be there but to some degree buried depending on the type of bottom they were on.
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To be clear, .21% is equal to .0021.
