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Units time?

  1. Dec 8, 2009 #1
    In a space time with metrics :
    [tex]ds^2=f(t)(-dt^2+dx^2+dy^2+dz^2)[/tex]

    which is the unit that measures time t?

    second?, meter of time?
     
  2. jcsd
  3. Dec 8, 2009 #2

    Dale

    Staff: Mentor

    For dimensional consistency it would have to be the same units that dx, dy, and dz are measured in.
     
  4. Dec 8, 2009 #3
    then , if dx,dy and dz are in meters, then t is in meters of time???
     
  5. Dec 8, 2009 #4

    Dale

    Staff: Mentor

  6. Dec 8, 2009 #5

    DrGreg

    User Avatar
    Science Advisor
    Gold Member

    A "metre of time" is the time it takes for light to travel one metre, i.e. (1/299792458) seconds.

    Or you could measure dx, dy and dz in light-seconds and then dt is in seconds.
     
  7. Dec 10, 2009 #6

    Matterwave

    User Avatar
    Science Advisor
    Gold Member

    to be explicit, a c^2 should appear before dt^2 to explicitly convert time into units of distance. But, in relativistic units c=1 so we just omit the c and it's understood.
     
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