四し元げん速そく度ど

noun

four-velocity

Technical term in relativity; the four-vector analogue of velocity in Minkowski spacetime.

• 特とく殊しゅ相そう対たい性せい理り論ろんでは、四し元げん速そく度どの大おおきさは常つねに光こう速そくに等ひとしい。

  In special relativity, the magnitude of the four-velocity is always equal to the speed of light.