What are microstates and macrostates in statistical physics?

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Microstates in statistical physics refer to the specific configurations of a system, such as the outcomes of coin tosses, while macrostates represent broader characteristics defined by variables like the total number of heads. Each macrostate can correspond to multiple microstates, illustrating how different configurations can yield the same overall property. Accessible states are those microstates that a system can occupy without breaking any governing physical laws. Understanding these concepts is crucial for grasping the principles of entropy and statistical mechanics. This foundational knowledge aids in analyzing the behavior of complex systems in physics.
Lizwi
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Please help me, what are micro and macrostates, what are accessible states?
 
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Consider five coin tosses. I would call each of the possible outcomes a microstate (for example, HTTHT, THHHT, HHHTH, TTTTT and so on. H stands for heads and T for tails).

Now suppose I define a variable such as X=Total number of heads. For the microstates I have mentioned above, X will take values 2, 3, 4, 0 and so on. X is a macrostate. It tells you nothing about the specific configuration of the system. For example, X=4 will correspond to five microstates (HHHHT, HHHTH, HHTHH, HTHHH, THHHH), but you have no way of knowing which one.

An accessible state is a microstate the system can take without violating any laws governing the system.

I hope it is clear now.
 

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