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I read the claim that the total weight of the air above my (or rather: the average adult human's) body equals that of two elephants.

Now I am pretty sure that if two elephants would stand atop of me, I would get crushed. But does the above mean that this crushing is due to the combined weight of air and elephants (net 4 elephants) and that if two elephants would stand on me in a vacuum I would be perfectly fine?

Just to be on the safe side I thought I check it with the users of this site before trying it out.

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    $\begingroup$ +1 because you made me laugh an an embarrassing amount. $\endgroup$
    – Philip
    Jun 9 '20 at 17:58
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    $\begingroup$ Does this answer your question? Why the pressure of atmosphere doesn't crush you when you e.g. walk outside? $\endgroup$
    – user258881
    Jun 9 '20 at 19:02
  • $\begingroup$ Partially, it explains why the air won't crush me, but it doesn't explain why two elephants in a vacuum would. (I mean they would, wouldn't they?) What is the difference? $\endgroup$
    – Vincent
    Jun 9 '20 at 19:45
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You don't get crushed because there is typically as much air pressure inside your body acting outward as there is air pressure outside your body acting inward, so that the typically cancel each other out. So there is no net force acting on you to crush you.

Right, I understand now that the pressure coming from the inside (that balances out the pressure from the air) need not to come just from air, but the entire body is helping. So far so good. Still the question in the original post remains: if I would replace the air above me by two elephants, would my body still be able to withstand it?

In order to compare apples to apples, you would need to (1) remove the atmospheric air (create a vacuum about the body) and (2) somehow apply a force equivalent total amount of weight associated with the elephants uniformly over the entire surface of your body, so that you essentially create the same uniform exterior pressure over your body with the elephants that the atmosphere alone would have created.

Hope this helps.

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  • $\begingroup$ Yes I have heard this before but I find it hard to believe. The air column above me is much taller than I am and also fully filled with air while in my body the air needs to compete with blood, bones etc. How can there be as much air pushing upward as there is air above me acting downward? Also why would it be acting upward in the first place? There is no negative gravity in my body, right? $\endgroup$
    – Vincent
    Jun 9 '20 at 18:23
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    $\begingroup$ Pressure is transmitted in all directions. Air doesn't 'compete' with blood and bones because they are basically incompressible. The answer is correct. +1 from me. $\endgroup$
    – Gert
    Jun 9 '20 at 18:41
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    $\begingroup$ @Vincent Here is some more background: wtamu.edu/~cbaird/sq/2015/09/14/… $\endgroup$
    – Bob D
    Jun 9 '20 at 18:54
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    $\begingroup$ Well @Vincent , technically the body does get crushed until the internal and atmospheric pressure balances out. And lucky for us that isn’t much! $\endgroup$ Jun 9 '20 at 19:05
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    $\begingroup$ @Vincent I can think of better things to wrap around my body- but have fun! $\endgroup$
    – Bob D
    Jun 9 '20 at 20:36
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The air pressure is coming at you from all sides. If you were standing in a vacuum and there was just a tiny opening in the top, you would not be able to block the opening with your head. The air pressure would cause air to rush in through the hole. If you managed to stick your head in the hole, you would indeed feel a tremendous amount of weight. When air pressure is coming at you from all sides, however, there is a lot of cancellation, and the pressure inside your body is enough to keep you from imploding.

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  • $\begingroup$ Human bodies exposed to vacuum do not explode. en.wikipedia.org/wiki/Soyuz_11 $\endgroup$ Jun 9 '20 at 20:30
  • $\begingroup$ @SolomonSlow Thank you for the clarification. I thought I read once that your lungs would burst if exposed to low pressure, but I can't find any verification of that, so maybe it's not true. $\endgroup$
    – Yachsut
    Jun 9 '20 at 21:11
  • $\begingroup$ You can be seriously injured, and possibly rupture a lung, if you try to hold your breath when the pressure around you is dropping fast. It happens sometimes to novice SCUBA divers who swim to the surface in a panic. But, I don't think your throat can hold back enough pressure to actually explode your chest. $\endgroup$ Jun 9 '20 at 21:41
  • $\begingroup$ Yes, that makes sense, now that I think about it. Thank you! $\endgroup$
    – Yachsut
    Jun 9 '20 at 22:24

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