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Tsunami
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In Popper's autobiography, published in his contribution of Library of Philosophers, I read the following, after Popper's presentation of Boltzmann's ideas about entropy:
A bit further this is formulated as such:
Is this all accepted? Any additional comments? (The arrow of time always sounded valid to me.)
p.125-6 said:All this is highly convincing; but in this form it is unfortunately wrong. Boltzmann at first interpreted his H-theorem as proving a one-directional increase of disorder with time. But as Zermelo pointed out, Poincaré had proved previously (and Boltzmann never challenged this proof) that every closed system (gas) returns, after some finite time, to the neighbourhood of any state in which it was before. Thus all states are (approximately) recurring for ever; and if the gas was once in an ordered state, it will after some time return to it. Accordingly there can be no such thing as a preferred direction of time - an "arrow of time" - which is associated with entropy increase.
A bit further this is formulated as such:
p.126 said:The situation looks like this: every closed system (a gas, say) spends almost all its time in disordered states (equilibrium states). There will be fluctuations from the equilibrium, but the frequency of their occurences rapidly decreases with their increasing size. (...) Accordingly, if we want to predicts its future, we can predict (with high probability) an entropy increase, and a precisely analogous retrodiction of its past can also be made. It is strange that it is rarely seen that with Zermelo a revolution occurred in thermodynamics.
Is this all accepted? Any additional comments? (The arrow of time always sounded valid to me.)