This Demonstration proposes a clarification of contradictory theoretical approaches to relativistic thermodynamics. According to our suggestion, a new concept of internal energy leads to thermodynamic equilibrium conditions that incorporate the existing propositions. You can manipulate spacetime vectors related to the intensive parameter
representing energy-momentum equilibration.
In equilibrium, two moving and interacting thermodynamic bodies obey
. In the coordinate system of the first body this condition can be expressed by the spacetime velocity vectors of body centers and energy currents as
and
, respectively. The snapshots show famous particular cases for the relative speed
.
Snapshot 1: the Planck–Einstein equilibrium, when the energy current is carried by the moving body,
; in this case the moving body appears cooler
Snapshot 2: the Blanusa-Ott equilibrium, when the energy current stays with the observing body,
; in this case the moving body appears hotter
Snapshot 3: the Landsberg equilibrium, when the energy current velocities compensate each other inside the two bodies,
; in this case the temperatures of the two moving bodies are equal
Snapshots 4 and 5: the Doppler blue shift and red shift (
) equilibria, when the energy transfer is due to radiation,
,
; in these cases the temperatures of the two moving bodies are related by a Doppler shift
![[Snapshot]](HTMLImages/index.en/thumbnail_1.gif)
![[Snapshot]](HTMLImages/index.en/thumbnail_2.gif)
![[Snapshot]](HTMLImages/index.en/thumbnail_3.gif)
![[Snapshot]](HTMLImages/index.en/thumbnail_4.gif)
![[Snapshot]](HTMLImages/index.en/thumbnail_5.gif)
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