What is the definition of correlation and coupling?

[lsloneil]

When dealing with system containing millions of particles( for example, charged particles or magnetic particles) with statistical mechanics, I may often see the description or explanation that the certain effect is due to the coupling or correlation of particles. So can anybody give me a specific definition of coupling and correlation? Does coupling or correlation simply mean the interaction between particles?

Thanks a lot!

 

[pam]

Coupling means interaction.
Correlation can occur because of symmetries without explicit interaction.

 

[charng]

Correlation and coupling are two important concepts in statistical mechanics that help explain the behavior of systems containing a large number of particles. Correlation refers to the degree to which the movement or behavior of one particle is related to the movement or behavior of another particle. In other words, it measures the extent to which the particles are influencing each other. This can be positive, meaning that the particles move in a similar or coordinated manner, or negative, meaning that the particles move in opposite or opposing directions.

Coupling, on the other hand, refers to the strength of the interaction between particles. It describes how strongly the particles are connected or linked to each other. In statistical mechanics, coupling can refer to various types of interactions, such as electromagnetic or gravitational forces, that influence the behavior of the particles.

In general, correlation and coupling are closely related concepts. The strength of the coupling between particles can affect the degree of correlation between them. For example, strong coupling between particles can lead to high levels of correlation, whereas weak coupling may result in lower levels of correlation.

Overall, correlation and coupling are important factors to consider when studying systems containing a large number of particles. They help us understand how the particles interact and influence each other, and how this ultimately affects the behavior of the system as a whole.