Not so sure about that, just dive a few meters under water, and the pressure gets up very quickly, roughly, every 10m you dive, you get an additional atmosphere of pressure, and people are known to be able to dive below 100m with training but without special apparatus. The problems arise mostly when the pressure changes quickly (or when it gets very high), but a pressure of 10 atmosphere, with sufficient preparation and adjusting time, doesn’t kill a human being.
Yeah; you notice pressure changes easily when you skin dive, but you notice them mostly because of the compressive load on your lungs and the various air spaces in your head, which are full of air at surface pressure. If you go scuba diving instead, you won’t notice the load on your lungs anymore—the regulator delivers air at ambient pressure, not at surface pressure. You do need to equalize the pressure in your ears and facemask frequently as you go up and down the water column, since they’re set to ambient pressure every time you do so and that changes as your depth does, but breathing itself doesn’t get much harder as you go deeper.
(There are various other pressure-related problems that can crop up, though—nitrogen narcosis is the most important one at recreational diving depths.)
Depends on the gas mix and the application. The gas mixes used at depth in technical diving are usually hypoxic, since oxygen toxicity becomes an issue with ordinary air at an ambient pressure of about six and a half bar or depths of around fifty meters; heliox, for example, is usually around ten percent oxygen. On the other hand, it’s fairly common for the gas mixes used during the decompression phase of a technical dive to be richer in oxygen than air is, since that helps flush nitrogen out of your tissues.
This isn’t usually an issue for recreational divers, though, who generally don’t dive below forty meters and use pressurized air or, more rarely, enriched nitrox mixtures. At those shallower depths, you compensate for the richer breathing gas by breathing in a slower, more controlled fashion than you would on the surface, though this has more to do with conserving gas and controlling buoyancy than it does with oxygen issues.
I don’t see how this squares with Silas’ claim that a 15-lb dumbbell hurts your hand when you rest it on it.
OK, I just tested this by balancing the end of a ~21 pound dumbbell on my palm while my palm rested on a counter (surface area of dumbbell end looks to be about 0.60 square inches, making the pressure around 35 psi, or about 2.3 atmospheres?) It was a little painful, but I didn’t cry out or feel the need to get the thing off immediately. So in conclusion, I think Silas might have been exaggerating.
Resting my palm on a pillow instead of a counter, I don’t really experience pain anymore, just discomfort. Maybe that has something to do with the fact that deep diving doesn’t cause pain?
But shouldn’t you rather take into account the tolerances of pregnant women and people younger than the age when one can be trained? If they can’t live on the planet, it can’t be colonized.
I’m not an expert in diving (I only dived once about 10m deep during holidays), but AFAIK the training (and the trouble) is mostly to handle the change in pressure, much more than the high pressure itself. Going from 1Am to 10Am is dangerous if done without respecting many safety measures, but once you’re adjusted at 10Am, it’s not so much a problem. So a child born on higher pressure wouldn’t have too much troubles. Maybe 10Am is too much, but I don’t think 1.5Am or 2Am would cause any serious trouble, if the composition of the atmosphere is good enough.
Not so sure about that, just dive a few meters under water, and the pressure gets up very quickly, roughly, every 10m you dive, you get an additional atmosphere of pressure, and people are known to be able to dive below 100m with training but without special apparatus. The problems arise mostly when the pressure changes quickly (or when it gets very high), but a pressure of 10 atmosphere, with sufficient preparation and adjusting time, doesn’t kill a human being.
Yeah; you notice pressure changes easily when you skin dive, but you notice them mostly because of the compressive load on your lungs and the various air spaces in your head, which are full of air at surface pressure. If you go scuba diving instead, you won’t notice the load on your lungs anymore—the regulator delivers air at ambient pressure, not at surface pressure. You do need to equalize the pressure in your ears and facemask frequently as you go up and down the water column, since they’re set to ambient pressure every time you do so and that changes as your depth does, but breathing itself doesn’t get much harder as you go deeper.
(There are various other pressure-related problems that can crop up, though—nitrogen narcosis is the most important one at recreational diving depths.)
One also needs a lower amount of oxygen in the breathable air.
Depends on the gas mix and the application. The gas mixes used at depth in technical diving are usually hypoxic, since oxygen toxicity becomes an issue with ordinary air at an ambient pressure of about six and a half bar or depths of around fifty meters; heliox, for example, is usually around ten percent oxygen. On the other hand, it’s fairly common for the gas mixes used during the decompression phase of a technical dive to be richer in oxygen than air is, since that helps flush nitrogen out of your tissues.
This isn’t usually an issue for recreational divers, though, who generally don’t dive below forty meters and use pressurized air or, more rarely, enriched nitrox mixtures. At those shallower depths, you compensate for the richer breathing gas by breathing in a slower, more controlled fashion than you would on the surface, though this has more to do with conserving gas and controlling buoyancy than it does with oxygen issues.
I don’t see how this squares with Silas’ claim that a 15-lb dumbbell hurts your hand when you rest it on it.
OK, I just tested this by balancing the end of a ~21 pound dumbbell on my palm while my palm rested on a counter (surface area of dumbbell end looks to be about 0.60 square inches, making the pressure around 35 psi, or about 2.3 atmospheres?) It was a little painful, but I didn’t cry out or feel the need to get the thing off immediately. So in conclusion, I think Silas might have been exaggerating.
Resting my palm on a pillow instead of a counter, I don’t really experience pain anymore, just discomfort. Maybe that has something to do with the fact that deep diving doesn’t cause pain?
People’s pain tolerances vary a lot.
But shouldn’t you rather take into account the tolerances of pregnant women and people younger than the age when one can be trained? If they can’t live on the planet, it can’t be colonized.
I’m not an expert in diving (I only dived once about 10m deep during holidays), but AFAIK the training (and the trouble) is mostly to handle the change in pressure, much more than the high pressure itself. Going from 1Am to 10Am is dangerous if done without respecting many safety measures, but once you’re adjusted at 10Am, it’s not so much a problem. So a child born on higher pressure wouldn’t have too much troubles. Maybe 10Am is too much, but I don’t think 1.5Am or 2Am would cause any serious trouble, if the composition of the atmosphere is good enough.
That is quite interesting. I’ll ask my friends in human physiology department what they think about it and get back to you.