This paper offers a marriage of concepts from both classsical thermodynamics and special relativity, thus forming a new part of modern thermodynamics. The
main concepts taken from themodynamics and special relativity are those of a heat engine and E=mc2 respectively. Central to understanding the operation of this relativistic heat engine is the fact that upon heating a mass, its rest mass increases! This concept is nonexistent in classical thermodynamics. An increase in rest mass means that both the internal energy of a mass and its macroscopic kinetic energy increase!!!Thus, it is seen that special relativity provides a way to upgrade immediately part of a low form of energy, heat, into a high quality energy, macroscopic kinetic energy. This was the genesis of this engine.Here is the engine's operation: Accelerate a mass to a high speed. At that speed add heat from a comoving heat reservoir, thus increasing the kinetic energy of the mass. After heating, slow the “heavier” mass down to its initial speed. More work is seen to be produced during the last process than was absorbed during acceleration. Next, cool the mass to complete the cycle.The efficiency of this engine is derived, and seen to be analogous to the corresponding Carnot equation.
