Loschmidt's paradox

Loschmidt's paradox, also known as the reversibility paradox, states that if there is a motion of a system that leads to a steady decrease of H (increase of entropy) with time, then there is certainly another allowed state of motion of the system, found by time reversal, in which H must increase. The problem was first discussed in 1876 by the Austrian physicist Johann Loschmidt.

Related Topics:
Entropy - 1876 - Johann Loschmidt

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This puts the time reversal symmetry of (almost) all known low-level fundamental physical processes at odds with the second law of thermodynamics which describes the behavior of macroscopic systems. Both of these are well-accepted principles in physics, with sound observational and theoretical support, yet they seem to be in conflict; hence the paradox.

Related Topics:
Time reversal symmetry - Second law of thermodynamics - Paradox

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