I'm trying to understand the stress-energy tensor and I keep seeing the phrase, "momentum in the time direction is energy". I don't understand this. In the definitions of the momentum four-vector that I've found, the time component is the object's rest mass times the speed of light times gamma.(adsbygoogle = window.adsbygoogle || []).push({});

Here's an example:

http://scienceworld.wolfram.com/physics/MomentumFour-Vector.html

This gives units of momentum, not of energy. What am I missing?

**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!

# Momentum in the time direction

Loading...

Similar Threads - Momentum direction | Date |
---|---|

B What speed and direction are we actually traveling? | Wednesday at 11:14 AM |

A Dark Matter and the Energy-Momentum Tensor | Mar 12, 2018 |

I Energy-momentum formula and deBroglie wavelength | Jan 19, 2018 |

I 4-momentum of a massless particle | Jan 15, 2018 |

I How do we get invariant curvature from momentum and energy? | Dec 9, 2017 |

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