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Space what is it?

  1. Mar 4, 2009 #1
    I read that mass curves space/time. But what is space that it can be curved? Is it some kind of substance? When it is explained that place a sphere on a sheet that is warped... But in reality what would it look like inn 3dimensions (4 including time) ?

  2. jcsd
  3. Mar 5, 2009 #2
    One of the problems I have with accepting GR & SR is that they require (as I understand it) that time and space are things that have autonomous existence. As far as I understand them time describes the rate of relative movement of things and space describes distance between the relative position of things. I can’t see how either are actual things that can be curved or dilated. If I’m wrong I would be happy if someone can explain how time and space are actual things.
  4. Mar 5, 2009 #3
    All the statements in GR about spacetime can be translated into mundane sounding measurement-language, where observers who have been in various states of motion observe relativistic differences in the durations and lengths they measure. Since the relativity of measurements of length and duration is fundamentally part of the universe, it is convenient and elegant to ascribe the relativity to spacetime itself.
  5. Mar 5, 2009 #4


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    Science Advisor

    Curved spacetime is an abstract mathematical model, that describes the observations we make. Just like forces represented by vectors, which are also not "actual things".
    Check out the links in https://www.physicsforums.com/showpost.php?p=2046692&postcount=4" for visualizations of curved space time which include the crucial time dimension.
    Last edited by a moderator: Apr 24, 2017
  6. Mar 5, 2009 #5
    Hello earamsey

    There was a recent thread regarding this subject you might find interesting-

  7. Mar 6, 2009 #6
    The way I came to conclude that space was a something was by thinking about it one day.
    I thought that if there was "nothing" between earth and the moon, then they would be touching. If I asked someone what lyed between the earth and the moon, a likely response would be "nothing but space". So, therefore, I thought, space must be something if it can seperate objects.
  8. Mar 6, 2009 #7


    Staff: Mentor

    Spacetime is simply the geometry of physics, i.e. the distance and direction between things in physics. If there is a large stress-energy tensor then the geometry is measurably curved, i.e. two straight lines may intersect twice.
  9. Mar 7, 2009 #8
    It is possible that our "physical" space is a N-dimensional brane, curving in a more dimensional "fundamental", "coordinate", "mathematical" space.
    So i is posisble that there are 2 different answers...
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