Griffiths Introduction to Elementary Particles · Problem 3.3

Symmetries — David J. Griffiths

Physics — QFT · lorentz-contraction-density

Problem

(a) How do *volumes* transform? Specifically, if a container has volume

V'

in its own rest frame,

S'

, what is its volume as measured by an observer in

S

, with respect to which it is moving at speed

v

? (b) How do *densities* transform? (If a container holds

\rho'

molecules per unit volume in its own rest frame,

S'

, how many molecules per unit volume does it carry in

S