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Empty Space Just a quick thought you might enjoy.

  1. May 12, 2008 #1
    "Empty Space" Just a quick thought you might enjoy.

    I was reading a book on quantum gravity the other day when I found myself having a lot of trouble grasping the idea of empty space. When you really sit back and take it in, it is so weird only because we never really experience it. Another interesting thing that I found with "empty space" is that whenever we dig deeper into smaller particles, it seems we always introduce more space, from this one might think that the smallest thing would indeed be space itself considering i do not think most have a hard time accepting it as the biggest thing also.

    One other thing I thought about was how most people can look into the sky and consider it "empty", obviously we know it is full with countless atoms just too small for the human eye to see. Well taking this into perspective it would seem that the "empty space" in atoms could easily harbor smaller particles just too small to detect.
  2. jcsd
  3. May 13, 2008 #2

    Sometimes I wonder if there is any empty space at all, simply because wherever you look at there is always waves. But waves and particles are the same thing.

    You may then be tempted to define emptyness as "where mass isn't", and therefore argue whether mass-less waves should not count against emptyness, however mass itself is not truly confined/shaped into something, there really isn't a point where mass begins and where mass ends even for a single particle.

    And after all... why should mass define emptyness? Mass is just a property, why should it be used to define "occupied space" rather than for instance charge? What does charge have less than mass? :)

    Finally. Wherever there is something, we can measure it or interact with it. Wherever there is nothing to interact with, no property whatsoever, is there really anything at all? Perhaps not even emptyness.
  4. May 13, 2008 #3


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    It's very difficult to define emptiness, especially once you get down to Planck scales. Then it becomes something more like "maybe empty space?" with no clear definitions for the words empty or space. Also, there is an observational (and therefore very real?) limit to how small particles can be, so in theory if we built a more and more powerful microscope, we should be able to see them all. That's very basic theory and I'm sure it could never be done, but at a very surface level there's no reason not to think that.

    As far as the sky being empty... look a the average matter density and compare it to Earth. It is, indeed, very empty out there!
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