The Universe is a Giant Heat Engine ✎ express
The idea of a expanding universe, proposed by Georges Lemaître, finds an unexpected analogy. Space behaves like a piston in a cylinder: dark energy pushes it, much like steam. The relationship between pressure and volume in this 'engine' is strikingly similar to that of a steam boiler.
Most surprising: the cosmic horizon isn't just a boundary; it radiates heat like a warm object.
Scientists tested two models for this cosmic engine: one idealized, setting an unreachable upper limit, and a simpler, more realistic one. Calculations show efficiency always falls below the theoretical ceiling and never exceeds one. Not even the universe can create energy out of nothing.
The cosmic horizon isn't just a geometric edge: it has a temperature, like a heated body. This makes gravity a part of thermodynamics.