Given U^k_i, the components of U is a delta function i.e for i=k U^i_k =1,(adsbygoogle = window.adsbygoogle || []).push({});

to prove it is invariant under Lorentz transformation~~

I don't know how to express it in Einstein summation notation, I am very confused with the upper-lower index, is it right to write the transformation in this?

U'^k_i = T^i_m T^n_k U^k_i ? where T is the Lorentz transformation~~

yukyuk

**Physics Forums - The Fusion of Science and Community**

Join Physics Forums Today!

The friendliest, high quality science and math community on the planet! Everyone who loves science is here!

The friendliest, high quality science and math community on the planet! Everyone who loves science is here!

# How to deal with the index in Einstein summation?

Loading...

Similar Threads - deal index Einstein | Date |
---|---|

I Contravariant first index, covariant on second, Vice versa? | Feb 16, 2018 |

I Index gymnastics, matrix representations | Oct 6, 2017 |

A GR index gymnastics -- Have I misunderstood something or typo? | Jun 5, 2017 |

B How relativity deals with simultaneity as requirement | Feb 23, 2016 |

What does the general theory of relativity deal with? | Nov 3, 2015 |

**Physics Forums - The Fusion of Science and Community**