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Energy of empty space

  1. Sep 25, 2014 #1
    If we were to take a region of space which had nothing in it, no particles, no light, just empty space, would this space contain energy of some sort?

    Also if space can warp, change, bend etc then can space be made of something? Like a material? If empty space is nothing then how can it bend or warp under the presence of mass?

    If we took all the energy out of the universe and then placed a planet in the universe, would there be gravity? If so does this not show that gravity is the result of a physical material being warped under the mass of an object?

    I just don't see how space can have characteristics if it isn't made of something. A number doesn't have any physical characteristics so why does space, which is nothing, which means it doesn't actually exist?
  2. jcsd
  3. Sep 25, 2014 #2
    Empty space has potential energy. We know it can produce pairs of particles spontaneously. We've also seen some odd effects like the Casimir Effect which can pull plates of metal together when they are separated by very small distances. The effect is theorized to be caused the negative pressure of the small waves that can fill the gap being unbalanced by the large waves on the outside that can not. However, it is a huge leap to go from the infinitesimal energies that empty space is theorized to have to the astronomical energies needed to move galaxies.

    You see the bending of space every day. The moon doesn't circle the earth because there's an invisible rope of force holding it to the Earth. The moon orbits the Earth because it is following a straight line in space-time. There is no 'Force' of gravity, that is a simplification they teach in High School. There is only curved and not-so-curved space-time. The problem is our minds have evolved to naturally think in lines and grids and nature really doesn't care about the way our brains are wired.

    Yes, if you took all the energy out of the universe, you are still leaving the Earth, which has mass. Mass bends space-time, so there would be gravity.

    Space is not nothing, it is a dimension. It can have a shape and you can put things into it and then measure the separation between those objects. I hope that's been helpful.
  4. Sep 26, 2014 #3


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    Sten Odenwald is among those who assert space is a consequence of gravity. I like that idea because it renders a sense of meaning to the concept of vacuum energy. See http://www.astronomycafe.net/gravity/gravity.html for discussion.
    Last edited: Sep 26, 2014
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