What is the fabric of the universe?

  1. I just wanted to know what people think of the question "What is the fabric of the universe?" I only see two choices either time or space. I know that gravity is something that warps space, which means it must warp the fabric of space, or our second choice time, and I would think that any theory of gravity must at the very least contain a quantum theory of time, because imho gravity is a function of time not space. What do you think?
     
  2. jcsd
  3. A.T.

    A.T. 6,164
    Gold Member

    Why not both?
    ... and time!

    See links in this post.
     
  4. The fabric of the universe is indeed BOTH space and time.

    We call it space-time.

    And then gravity warps space-time.
     
  5. I started this thread thinking that the fabric was either time, space, or space-time. Maybe I should have started it as a poll and listed "other" as a choice, because after thinking of my own question I would have to change my answer to light as being the fabric, with the photon as the thread and matter the ball of yarn. That would make space the loom, time the the room, and you can believe in any weaver that you want. Sorry if this seems to simple but it made me smile when I thought of it.
     
    Last edited: Feb 17, 2008
  6. marcus

    marcus 24,893
    Science Advisor
    Gold Member
    2014 Award

    The best discussion of this issue----where we are at present on it-----that I know of is in the survey paper by Renate Loll called
    Quantum Gravity on your Desktop


    time and space are largescale perceptions that emerge from some more fundamental processes at microscopic level. Because of Heisenberg Uncertainty, the smaller scale you look the more chaotic spacetime geometry is likely to be. It may not even have a well defined dimensionality down near or below planck scale. Concepts like length area volume angle may be infected with indeterminacy just as in ordinary quantum mechanics the position and momentum of a particle are not completely determined.

    Smooth space and regular time may be illusions which appear at a macroscopic scale, emerging from a microscopic reality which is not so smooth and regular.

    Quantum gravity teaches us to expect this. Wheeler (a great physicist of the last century) used to refer to the "spacetime foam".

    Among presentday researchers, I think Loll's group is as advanced as any. They are not saying what is there but they are running some pretty good simulations of small universes. have some pretty reasonable conjectures.

    Google "renate loll" and see if you can find that recent article at her website.
     
  7. gravity is an extra dimension, above time and the three dimensions of space
     
  8. No time is an extra dimension, not gravity. Gravity is a force or field, and is not a dimension.
     
  9. If gravity were to be a dimension then wouldn't we experience fluctuation of gravity in different reference frames?!
    -ibysaiyan
     
  10. Yes. We could go on and on on why gravity is not a dimension.
     
  11. Gravity makes a good fabric for the universe without it we would never have found evidence of black holes, you've got to love general relativity.
     
  12. Drakkith

    Staff: Mentor

    I don't think gravity can be considered the "fabric" of the universe. More like the fat lady sitting on the fabric having a picnic.
     
  13. Hah, that made me laugh quite hard. Well, it doesn't have to be a fat lady, basically its anything sitting on the fabric, of any size. But I understand what you meant by that post.
     
  14. Chronos

    Chronos 10,117
    Science Advisor
    Gold Member

    Cite some references. I totally disagree.
     
  15. Gravity is much better described as a force upon said "fabric" rather than a constituent of the "fabric" itself. Gravity has an effect upon space-time which would explain why gravity has been shown to travel in excess of light-speed. just as a pull on a non-stretchable object wrapped around the equator would show instantaneous movement on both ends. Gravitational propagation would occur as a dependency of the amount of "Stretch" present in space-time itself.
     
  16. Drakkith

    Staff: Mentor

    Gravity does not travel FTL. It propagates at c. An object wrapped around the equator, when pulled, would react at the speed that sound propagates through the material.
     
  17. Interesting this Chronos. Gravity must have propogated through all of spacetime. Could geometry or curvature be the fabric of reality, that seems reasonable to me, everything is anchored geometrically to the Universe. Curvature is king! :)

    Not a personal theory just an idea.

    Has made me think though, geometry and therefore gravity and curvature are present everywhere, even if curvature is 0 it can still be explained mathematically.

    All really interesting. :smile:
     
  18. phinds

    phinds 9,136
    Gold Member

    Both of the bolded statements are nonsense, as Drakkith has already pointed out (although more politely than me). You really should read up on basic physics before you make such pronouncements on a physics forum.
     
  19. Drakkith

    Staff: Mentor

    Depends on what you mean by "Fabric of reality".
     
  20. phinds

    phinds 9,136
    Gold Member

    Is it just my concept of semantics, or would we, as I believe, all be better off if no one EVERY used the term "fabric" in conjunction with spacetime, but rather used "structure" or some similar concept. "Fabric" carries over unfortunate connotations from standard English.
     
    Jenorah likes this.
  21. Drakkith

    Staff: Mentor

    Agreed phinds.
     
Know someone interested in this topic? Share a link to this question via email, Google+, Twitter, or Facebook

Have something to add?