## The Gamma Factor

The factor called 'the gamma factor' occurs frequently in special relativity eg and indicates how good a fit Newtonian mechanics fits observations.

Ifis close to 1 becausethe Newtonian mechanics fits observations well, with the goodness of fit improving asdecreases.

The following table shows howdiverges from 1 asincreases. Divergence becomes noticeable as increases above 0.2.

 0.001 1.0000005 0.01 1.00005 0.1 1.005 0.2 1.021 0.3 1.48 0.4 1.091 0.5 1.155 0.9 2.29 0.99 11.26 0.999 22.37

Depending on the accuracy required smaller values ofmay be acceptable, but values ofabove 0.2 are generally unacceptable.

Speeds at which Newtonian mechanics is a good approximation are cal non relativistic speeds and speeds at which Newtonian mechanics is not a good approximation are called relativistic speeds.