洛斯密特悖论
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Loschmidt's paradox, also known as the reversibility paradox, irreversibility paradox or 脚本错误：没有“lang”这个模块。,[1] is the objection that it should not be possible to deduce an irreversible process from time-symmetric dynamics. This puts the time reversal symmetry of (almost) all known low-level fundamental physical processes at odds with any attempt to infer from them the second law of thermodynamics which describes the behaviour 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.
Loschmidt's paradox, also known as the reversibility paradox, irreversibility paradox or ,
的悖论，也被称为可逆性悖论，不可逆性悖论,
Origin
Josef Loschmidt's criticism was provoked by the H-theorem of Boltzmann, which employed kinetic theory to explain the increase of entropy in an ideal gas from a non-equilibrium state, when the molecules of the gas are allowed to collide. In 1876, Loschmidt pointed out that if there is a motion of a system from time t0 to time t1 to time t2 that leads to a steady decrease of H (increase of entropy) with time, then there is another allowed state of motion of the system at t1, found by reversing all the velocities, in which H must increase. This revealed that one of Boltzmann's key assumptions, molecular chaos, or, the Stosszahlansatz, that all particle velocities were completely uncorrelated, did not follow from Newtonian dynamics. One can assert that possible correlations are uninteresting, and therefore decide to ignore them; but if one does so, one has changed the conceptual system, injecting an element of time-asymmetry by that very action.
Reversible laws of motion cannot explain why we experience our world to be in such a comparatively low state of entropy at the moment (compared to the equilibrium entropy of universal heat death); and to have been at even lower entropy in the past.
Before Loschmidt
In 1874, two years before the Loschmidt paper, William Thomson defended the second law against the time reversal objection.[2]
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Arrow of time
< ! ——类别: 热力学—— >
Category:Philosophy of thermal and statistical physics
类别: 热力学和统计物理学哲学
Category:Non-equilibrium thermodynamics
类别: 非平衡态热力学
Any process that happens regularly in the forward direction of time but rarely or never in the opposite direction, such as entropy increasing in an isolated system, defines what physicists call an arrow of time in nature. This term only refers to an observation of an asymmetry in time; it is not meant to suggest an explanation for such asymmetries. Loschmidt's paradox is equivalent to the question of how it is possible that there could be a thermodynamic arrow of time given time-symmetric fundamental laws, since time-symmetry implies that for any process compatible with these fundamental laws, a reversed version that looked exactly like a film of the first process played backwards would be equally compatible with the same fundamental laws, and would even be equally probable if one were to pick the system's initial state randomly from the phase space of all possible states for that system.
Category:Physical paradoxes
类别: 物理悖论
This page was moved from wikipedia:en:Loschmidt's paradox. Its edit history can be viewed at 洛斯密特悖论/edithistory
- ↑ Wu, Ta-You (December 1975). "Boltzmann's H theorem and the Loschmidt and the Zermelo paradoxes". International Journal of Theoretical Physics. 14 (5): 289. doi:10.1007/BF01807856.
- ↑ Thomson, W. (Lord Kelvin) (1874/1875). The kinetic theory of the dissipation of energy, Nature, Vol. IX, 1874-04-09, 441–444.