On Wednesday, April 27, 2022 at 2:55:37 PM UTC+3 johnk...@gmail.com wrote:

> It's not perfect, no analogy is, but classical thermodynamics can provide 
> a pretty good analogy.[...] but that world is *VASTLY* outnumbered by 
> worlds in which other things happen.
>

You mean, statistical mechanics.

Counting worlds, then? I remember as a young student, the "equal 
probabilities" argument based on sheer ignorance of the microstate made me 
depressed. A much better explanation is based on the sort of agument known 
by the name "arbitrary functions", started by Jules Henri Poincaré. Here is 
an example of mine.

Whatever the microstate is (among those compatible with what we know), let 
us focus on the box in which the gas is contained. It has been constructed 
with some procedure, of which we can obtain (with good approximation) 
probability density functions of errors. For example, if we aim to make the 
height to be 4 meters exactly, then we know that the method of construction 
will give us 4 meters plus some error of known distribution. Therefore the 
dimensions of the box are random variables -- even if we assume for the 
time that the surfaces are perfectly flat and it is perfectly orthogonal. 
Every time a gas molecule hits a wall, its future trajectory becomes 
randomised, as well as that of every other molecule it bounces with. Soon a 
probabilistic description of the gas-in-the-box is all we can do, but these 
probabilities are well grounded on the errors in the construction of the 
box.

(If, instead of errors of construction, you prefer to deal with errors of 
measurement, we shall be mired by the controversy in the foundation of 
statistics. Therefore I suggest that we just consider construction.)

George K.

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