The expression

\[\frac{1}{\sqrt{1-v^2/c^2}}\]

occurs so often in special relativity that it s given a special lable, \[\gamma\]

.The gamma or Lorentz factor tells us how the Lorentz transformation of special relativity departs from the Galilean Transformation of Newtonian mechanics. For small speeds, there is really not much difference at all, and the Galiean transformation.Newtonian mechanics is a good approximation, but as the speed increase, the

\[\gamma\]

factor approaches infinity.
At high speeds special relativity must be used if calculations are to be accurate.