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

I Planck length and space expansion/contraction

  1. Jul 28, 2017 #1
    Imagine a cubic volume of space, defined today, with edges of the order of the Planck length.

    As cosmological time goes forward this volume expands so that the edges of the cube expand with the scale factor. This seems ok.

    However, as physics is time-reversible, it should be valid to imagine time going backwards so that the edges contract with the scale factor.

    But then they would be smaller than the Planck length. If the Planck length is the smallest length scale then is there a contradiction here?
  2. jcsd
  3. Jul 28, 2017 #2
Share this great discussion with others via Reddit, Google+, Twitter, or Facebook

Have something to add?
Draft saved Draft deleted