## 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.