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

Question about distance units in relativity

  1. May 1, 2012 #1
    When one considers (proper time) ΔΤ2 = Δt2 - Δx2 - Δy2 - Δz2, with c = 1, if t is in seconds, are the units of x,y and z necessarily 3x108 meters?
    Last edited: May 1, 2012
  2. jcsd
  3. May 1, 2012 #2


    User Avatar
    Gold Member

    Yes. The unit of length is 1 light-second which makes c = 1.
  4. May 1, 2012 #3


    User Avatar

    Yes. You may find http://en.wikipedia.org/wiki/Natural_units interesting - there are several alternative systems of "natural units", but setting c=1 is most common. (There are also semi-joke "supernatural" units where pi=1, useful for interpretive dance physics, a.k.a "hand-waving".)
Share this great discussion with others via Reddit, Google+, Twitter, or Facebook