microstate
(noun)
The specific detailed microscopic configuration of a system.
Examples of microstate in the following topics:
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Microstates and Entropy
- Energy can be shared between microstates of a system.
- With more available microstates, the entropy of a system increases.
- For a given set of macroscopic variables, the entropy measures the degree to which the probability of the system is spread out over different possible microstates.
- With more available microstates, the entropy of a system increases.
- The more such microstates, the greater is the probability of the system being in the corresponding macrostate.
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Stastical Interpretation of Entropy
- The following table shows all possibilities along with numbers of possible configurations (or microstate; a detailed description of every element of a system).
- Note that all of these conclusions are based on the crucial assumption that each microstate is equally probable.
- There is only 1 way (1 microstate) to get the most orderly arrangement of 100 heads.
- There are very few ways to accomplish this (very few microstates corresponding to it), and so it is exceedingly unlikely ever to occur.
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The Third Law
- Entropy is related to the number of possible microstates, and with only one microstate available at zero kelvin the entropy is exactly zero.
- where kB is the Bolzmann constant and W is the number of microstates.
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The Third Law of Thermodynamics and Absolute Energy
- Entropy is related to the number of possible microstates according to $S = k_Bln(\Omega)$, where S is the entropy of the system, kB is Boltzmann's constant, and Ω is the number of microstates (e.g. possible configurations of atoms).
- At absolute zero there is only 1 microstate possible (Ω=1) and ln(1) = 0.
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Changes in Energy
- In a thermodynamic system, pressure, density, and temperature tend to become uniform over time because this equilibrium state has a higher probability (more possible combinations of microstates) than any other.
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Common Bases of Logarithms
- The entropy (S) of a system can be calculated from the natural logarithm of the number of possible microstates (W) the system can adopt: