deletions | additions       diff --git a/When_such_observer_measures_the__.tex b/When_such_observer_measures_the__.tex  index 91fb385..09dfd4f 100644  --- a/When_such_observer_measures_the__.tex  +++ b/When_such_observer_measures_the__.tex 
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When such observer measures the energy of the radial lightray, it is equivalent to   $$  h\nu = \dot{t_i} \frac{dt_\gamma^\mu}{dr} = \left(1-\frac{2M}{R_i}\right)^{-1/2} h\nu_0  $$