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cheeze_whiz_shampoo OP t1_j0zziel wrote

Reply to comment by Jagid3 in Could being submersed in a sealed tank of fluid help humans survive heavy G acceleration in outer space? by cheeze_whiz_shampoo

I was imagining filling the lungs with an oxygenated fluid. My brain was just hopping around and I realized I couldnt even imagine what would happen to someone suspended in liquid and undergoing acceleration.

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Origin_of_Mind t1_j117dk8 wrote

Suspending an organism in a density matched fluid could be used to increase the survivable acceleration, but the gain is limited, because different constituents of the body have different density. For example, fat is 0.9 g/cm^(3), while cortical bone is 1.9 g/cm^(3). If the average density were matched by the fluid, the internal stresses due to differences in density of individual parts will remain unchanged, and these differences are of the same order of magnitude as the difference between air and body density.

So, yes, it would work, but the payoff is not too great.

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Game_Minds t1_j12pvb7 wrote

To paraphrase something someone said elsewhere in here, it would allow humans to achieve ludicrous relative accelerations compared to normal human expectations, but that would still be extremely negligible acceleration compared with trying to achieve relativistic speeds

And as a third person said, the cost of transporting and manufacturing this fluid would probably significantly outweigh any gains

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Origin_of_Mind t1_j12yeoh wrote

Human ability to withstand acceleration is not a limiting factor in long range space travel.

With the astronauts experiencing just the ordinary 1g of acceleration all the time they would be able to get to anywhere in the visible universe and get back to Earth in just 100 years (from the point of view of the astronauts themselves.)

But even accelerating the rocket at 1g for more than a few tens of minutes is already beyond our present technology.

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Game_Minds t1_j14d8b6 wrote

I think the idea of the extreme accelerations is that you could use something like a nuclear bomb to clear the first few stages of accelerating and then your onboard fuel supply doesn't have to work as hard, but I think there are more reasons than the G forces why that wouldn't work either. We don't have the tech for much more than 1g of sustained thrust anyway, like you said. These kinds of thought experiments are the very definition of speculative lol

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zyiadem t1_j118dq9 wrote

Our diaphragms are not made to move liquids, and such experiments that have explored this required a Specalized ventilator to avoid permanent damage to the body.

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Game_Minds t1_j12py78 wrote

And we all know being hooked up to a specialized ventilator for extremely long periods is perfectly healthy and fine

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