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In a way, thinking about it a bit, It takes a vacuum pump a considerable expenditure of energy to completely evacuate a vacuum chamber.

Water, or a very little water vapor inside a 55 gallon drum can "create" a vacuum as a result of condensation.

That may be apples to oranges. I suppose, but maybe not.

How do water vapor molecules floating aimlessly around inside a big spacious 55 gallon drum even "know" there are other water vapor molecules in there to combine with? To me this does not seem like just normal gradual condensation of particles randomly happening to bump into each other. The "implosion" is.very sudden and violent, the energy involved seems quite extreme to me.

What is the "atmospheric pressure" outside the drum but also the result of the attractive force of air molecules, attracted to the earth and to each other.

Another point made in the Vertasium video, perhaps given more significance than it really deserved, (I think it was probably just coincidence), but he points out that when tbey measured, the drum had collapsed in the shape of a perfect equilateral triangle, at least in the central area. I doubt this is consistent through all the steam in a drum demonstrations that have been performed, but I haven't checked and don't really know.

If significant in any way though, what strikes me as potentially significant is that such a triangular shape also parallels water crystals or snowflakes. Well a triangle is three sided and a snowflake is six sided, but still, the basic shape of the snowflake is two triangles.

This certainly could not have much of anything to do with the arrangement of air molecules outside the drum, but if the water vapor inside the drum was building up some kind of tension, it seems logical that the tension would follow the molecular structure of the water molecules similar to crystal formation.

I suppose I'm really letting my imagination run away with me at this point, but who knows?

Vertasium thought it was worth remarking about at some length, giving a different explanation. My explanation may be wrong but it is consistent with my general theory, though, as I said, it's probably just a coincidence and could not be consistently reproduced, but might be worth some additional looking into. Maybe worth mentioning anyway.

Well, that's kind of funny. I just finished watching the video and at the very very end he says, paraphrasing, you may have noticed that the big drum and the smaller drum crumpled into different shapes, the smaller drum formed something that looked like a hexagon...

A hexagon is literally a snowflake shape.

Too weird.

Another point in the video I thought was telling.

He starts out saying that he previously used his high speed camera but the frame rate was still not fast enough, so the can crushing in slow motion was basically photoshopped.

So he had to get a faster high speed camera.

How or why is the "condensation" so incredibly rapid?

I thought initially that the condensation was gradual but the can itself was so strong it resisted being crushed until reaching a certain point of extremely low pressure.

But there is this other version of the experiment using aluminum cans.

Aluminum cans are not so strong.


https://youtu.be/atsgIvOUFhA?si=V_E9TTL_O3V71ZGV


But here again, the soda cans are open, not tightly sealed with a screw top.

Why doesn't the cold water just rise up into the can?

I mean atmospheric pressure is pushing down on the water bath. That is what normally happens when you have a container upside down in water and pull a vacuum. Aluminum is strong enough to hold water. The water should just rise up into the can filling the vacuum.

But no.

There are dozens of examples of such experiments just inverting an aluminum can into a pan full of ice water and the can implodes like a gun shot... BAM! With a loud report. Sounds like a gunshot.

Happens so fast the water has no time to be pulled up into the can. That's what I would expect would happen if the condensation were at all gradual, the water would just rise up into the can.

Anyway, I'm thinking that a heat engine or Stirling engine is not so much running on gradually heated and expanded air as on explosions and implosions.

By compressing the gas and heating it the molecular repulsive forces cause an explosion, then the expansion and cooling cause the molecular forces of attraction to take over and cause an implosion.