What is a vacuum?

Russell Garber ( (no email) )
Sat, 30 Oct 1999 20:44:08 -0400

Hi all,
This may sound like a dumb question, and I may be just thinking illogically
due to too much thinking, but what is a vacuum? To be clear, I am not
speaking of the ether/Aether/ZPE or anything along those lines, but
strictly a vacuum as the absence of matter. To start, I will explain what
got me thinking about this. I was thinking about density, and balloons
(helium, hot air, or whatever) and how a balloon can lift weight. Again to
be clear, I understand how that works (the total density of the balloon and
the payload it is carrying, is less than the weight of the air it
displaces) This got me thinking of a theoretical vacuum balloon. What I
mean by this, is a hollow object made of a lightweight, rigid material
(strong enough to not collapse under the inside vacuum pressure), but
large enough to displace more air than it's weight (picture a helium
balloon, filled with nothing (a vacuum), instead of helium, weighing the
same (the balloon material itself), but strong enough to maintain the size
and shape it would be when filled with enough helium to float... again
remember this is just imaginary). Would this vacuum balloon float? I
think that it would float for the same reason the helium balloon floats,
but this got me thinking about other strange things. One question it
brought to mind is, what happens to a vacuum when it is filled with air?
Does the vacuum just disappear? or does it rise up into space where it is
at an equal density with it's surroundings? Thinking about that question
led to another question, if atoms are always moving about, what are they
moving in? What is in between the molecules of water, air, etc... If it
is a vacuum, then why do they not sink down (being more dense than a
vacuum) and take up all the space, until they can no longer move about?
Picture oil floating on water, and then imagine air as a liquid, floating
at a higher level because it is less dense, and helium at a higher level,
etc., etc. Anyway, I think you get the idea.... I apologize if I am
talking non-sense, but as I have stated in the past, sometimes when you
spend too much time thinking about one thing, non-sense begins to make more
and more sense. (not to mention that the idea of nothing (a vacuum) being
able to take up space (well not exactly, but you know what I mean), is a
weird concept in itself) :) In any case, I am looking forward to your


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