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(x1, ct1) = (25m, 25m) - What do the 'm' represent? (SR)

  1. Aug 11, 2012 #1
    I'm currently completing a special relativity assignment, and whenever coordinates are referred to they're represented as (x1, ct1) = (25m, 25m) or (6m, 2m). There are no units given (other than the 'm', and I highly doubt they're using minutes for ct). If someone could clear this up for me I'd be very grateful.

    Cheers!
     
  2. jcsd
  3. Aug 11, 2012 #2

    arildno

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    "m" as in Minkowski coordinates, perhaps?

    ct has dimensions of length, btw.

    Note that unless you work with the full 4-vector, it would be extremely easy for students to misunderstand the notation without the "m", falsely believing the time coordinate was a regular space coordinate.
     
    Last edited: Aug 11, 2012
  4. Aug 11, 2012 #3
    M for meter perhaps, since these have the dimension of length.
     
  5. Aug 11, 2012 #4
    Just to clarify, it is for "meters."

    Spatial units are typically denoted in m, and I'm sure you've seen x represent a spatial coordinate.

    ct is also meters, because c is the speed of light and c=3*108 meters/second [m/s] except it is multiplied by time. So you have a velocity (c) times time.
    (meters/seconds)*seconds=meters because the seconds cancel.
     
  6. Aug 12, 2012 #5
    Ha, it didn't occur to me ct was in meters (very new to SR). Thanks!
     
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