# Speed of Entropy change

If time in systems moving with different speed goes differently, does speed of entropy change differ in these systems? (is "speed of entropy change" a valid term? can we compare them?)

-

Entropy is an invariant $S \rightarrow S' = S$, whereas time is not, in general. Therefore the rate of change of entropy (this is the correct term) is a frame dependant quantity.
$$\frac{\mathrm{d} S}{\mathrm{d} t} = \gamma \frac{\mathrm{d} S'}{\mathrm{d} t'} = \gamma \frac{\mathrm{d} S}{\mathrm{d} t'}$$
with $\gamma$ the time-dilation factor.