The heat death is a possible final state of the universe, in which it has reached maximum entropy. The belief of a heat death is derived from the second law of thermodynamics, which claims that entropy tends to increase in an isolated system. If the universe lasts for an infinite time, then it will asymptotically approach a state where all energy is evenly distributed. Interestingly, when Helmholtz proposed the idea of heat death in 1854, it was 11 years before Clausius's final formulation of the Second law of thermodynamics based on entropy (1865) (the first formulation: 1850).

Despite the term "heat death", the temperature of the entire universe would be very close to absolute zero in this scenario. Heat death is however not quite the same as "cold death" or the "Big Freeze " in which the universe simply becomes too cold to sustain life due to continued expansion, though the result is quite similar (see: [1] for a more detailed explanation).

Interestingly, recent work in inflationary cosmology has inverted the heat death notion, suggesting that the early universe was in a thermal equilibrium and thus heat death–like state prior to cosmic expansion. Meanwhile, in an expanding universe, some believe the maximum possible entropy increases far more quickly than the actual entropy with each time increment, pushing the universe continually further away from an equilibrium state despite increasing entropy. Furthermore, the very notion of thermodynamic modeling of the universe has been called into question, since the effects of such factors as gravity and quantum phenomena are very difficult to reconcile with simple thermodynamic models, rendering the utility of such models as predictive systems highly doubtful according to some.

Nonetheless, the scientific evidence overwhelmingly points to an eventual heat death if the second law of thermodynamics is correct and if the Universe is in fact a closed system.

However, see Final anthropic principle for a discussion of the fact that the second law does not imply life's eventual extinction.

See also

• Second law of thermodynamics
• Big Rip
• Big Crunch
• Big Bang
• Dyson's eternal intelligence
• Ultimate fate of the Universe
• Isaac Asimov's "The Last Question"

External links

• Entropy and the second law (includes a brief mention regarding heat death)
• Heat death vs. cold death