1 pc    =  3.1 x 10^(16) m



  50 kpc  =   50 * 1000 * 3.1 x 10^(16) m

          =   1.55 x 10^(21) m


A ray of light should travel this distance in a time

               1.55 x 10^(21) m
    t0    =  -----------------------
             2.99792458 x 10^(8) m/s


          =    5.17 x 10^(12) seconds

 
          =    roughly 164,000 years