 Four-vector

A four-vector transforms as $U^{\prime \mu }={\Lambda }^{\mu }{}_{\nu }{U}^{\nu }$ under every Lorentz transformation.

A four-vector is a mathematical object used in the theory of relativity, which combines space and time into a single entity. In the context of physics, four-vectors help simplify the description of physical phenomena in a way that respects the principles of special relativity. A four-vector has four components, typically denoted as \( V^\mu \), where \( \mu = 0, 1, 2, 3 \).