Dismiss Notice
Join Physics Forums Today!
The friendliest, high quality science and math community on the planet! Everyone who loves science is here!

Noob time-space thought problem

  1. Apr 17, 2012 #1
    this one bothers me - pls point out the flaw in my reasoning:

    Time-space may be called a 'fabric', and may be depicted as a 2D 'sheet'. An object with mass deforms the sheet.

    If i were to grab one edge of this 'inelastic sheet' and pull it 1 cm, would the movement would be instantaneous across the sheet .. i.e... any one point of the sheet moves just 1 cm, but the distant edge, many light-years away, also *immediately* moves towards me 1 cm. too?

    Or, would the tension I create warp the 'elastic sheet', and so cause my immediately surrounding fabric to move ~1 cm, but stretching the fabric so that the distant part only responded to the tug over some much longer time period, analogous to pulling a rubber sheet of the same size.

    Would the transfer of this pull across the sheet be faster/slower/the same speed of light?
  2. jcsd
  3. Apr 17, 2012 #2


    User Avatar
    Gold Member

    Don't take the rubber sheet analogy too literally.

    The very quick answer to your question is that curvature of space-time is what gravity is, so gravitational waves, and thus changes in the curvature, are presumed to travel at c.
  4. Apr 19, 2012 #3
    ok thanks!
Share this great discussion with others via Reddit, Google+, Twitter, or Facebook