What is statistical mechanics ?

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What is statistical mechanics ? Has it got something to do with probability ? Why are they different statistical mechanics like Bose-Eistein, Fermi mechanics ? And is the Kinetic Theory of gases related to this mechanics ?

I know, I have many question , I just can't find any good material on this online.

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What is statistical mechanics ?

I doubt anyone here could give a spontaneous explanation to such a wide question that is better than the Wikipedia article on the topic.

Has it got something to do with probability?

Yes. Think of it as "statistical physics".

Why are they different statistical mechanics like Bose-Eistein, Fermi mechanics ?

Because different physical systems have different behaviors. Also, it's not considered as different statistical physics, but really just as different classes of systems/behaviors/statistics. As a not-100% fitting analogy: Normal probability theory has different probability distributions, too: Gaussian distributions, Poissonian distributions, binominial distributions, ...

And is the Kinetic Theory of gases related to this mechanics ?

Probably "yes", if you stretch your understanding of "related" sufficiently.

Edited by timo
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What is statistical mechanics ?

Statistical mechanics deals with the collective behavior of many objects, far too many to treat each one individually. Loosely, the idea is that the average microscopic properties of a collection of particles is directly related to the bulk macroscopic properties of the collection that we can directly measure. This framework provides an understanding of thermodynamics in terms of the physics at the microscopic level.

A good example here is that the temperature of an ideal gas is a measure of the average velocity or kinetic energy of the individual molecules of the gas.

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What is statistical mechanics ?

It is an extension of mechanics that considers statistical effects (deviations on the evolution and behaviour of systems prepared initially in the same state) in mechanical systems.

Has it got something to do with probability?

Yes, the deviations are not deterministic and thus have to be described in probabilistic terms; i.e. which is the probability that the system will do "this".

Why are they different statistical mechanics like Bose-Eistein, Fermi mechanics ?

Are not different statistical mechanics but different statistics or more correctly different distributions. Fermions and bosons have different requirements regarding their quantum mechanical state and thus their quantum statistical mechanics states are also different: Fermi-Dirac distribution describes fermions and the Bose-Einstein distribution describes bosons.

And is the Kinetic Theory of gases related to this mechanics ?

I know, I have many question , I just can't find any good material on this online.

Yes. kinetic theory of gases is a subset of statistical mechanics. One often speak of the kinetic regime or kinetic branch of statistical mechanics.

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"The theory in which the properties of macroscopic systems are predicted by the statistical behaviour of their constituent particles." The Penguin dictionary of Physics.

I just recall how many years ago I and most of my fellow students looked a bit gloomy before a statistical mechanics lecture.

Edited by Griffon

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