## 16 The Transformations of *S* , *k* iand *R*

We assume in the remaining sections that temperature is a key variable which is directly connected to many structural properties of materials, and therefore is independent of the velocity of an observer:

*T' * = *T*

Given the invariance of temperature we get from section **8** for the transformations of *k* and *R *

*k' * j= *k* · √ mmmm and mmm *R'* j= *R* · √

The two gas constants are thus not cut from the same cloth as the speed of light *c* jand the Planck constant *h* . It is therefore not appropriate to set the value of *k* jto 1, as is done in the *system of natural units* **j**with *c* , *h_bar* jand the gravitational constant *G* .

*S* j= *k* · *ln* (Ω) japplies for physical entropies, where Ω is the inverse of an invariant probability. Therefore entropy transforms the same as the Boltzmann constant *k* :

*S'* jj= *S* · √

Entropies of information theory however are relativistically invariant !