Time-reversal symmetry

Common card · No. 277636

T-symmetry or time reversal symmetry is the theoretical symmetry of physical laws under the transformation of time reversal, T : t ↦ − t . {\displaystyle T:t\mapsto -t.} Since the second law of thermodynamics states that entropy increases as time flows toward the future, in general, the macroscopic universe does not show symmetry under time reversal. In other words, time is said to be non-symmetric, or asymmetric, except for special equilibrium states when the second law of thermodynamics predicts the time symmetry to hold. However, quantum noninvasive measurements are predicted to violate time symmetry even in equilibrium, contrary to their classical counterparts, although this has not yet been experimentally confirmed. Time asymmetries are said to give rise to an "arrow of time" distinguishing the past of any given moment from its future. They generally fall into one of three categories: those...

Read on Wikipedia · Image Isabelle Grosjean ZA, CC BY-SA 3.0