Can you explain the concept of entropy?

Answer 1

Entropy is disorder, scientifically analysed. It can actually be measured in calories, the same unit that is used for measuring heat, and there is a logical connection between heat and disorder, because heat is a type of random (hence disorderly) motion that takes place on an atomic or molecular level.

If you have a glass of water, in which there is some salt at the bottom, that salt will gradually spread evenly throughout the water, which is a process driven by entropy. Random changes lead to certain kinds of statistical results. Even though the movement of any given salt ion is not predictable, the movement of all the salt ions is collectively very predictable, and it is a movement toward a more disorderly state. If you have an orderly arrangement of any kind, such as an alphabetical arrangement of books, and you introduce energy into the system which works at random - let us say that the library is hit with a hurricane - the arrangement will become more disorderly, or in other words more entropic. The books will not remain in alphabetical order if they are blown around randomly by the wind. We also would not expect that a collection of books that are not in any kind of order would accidentally be put into alphabetical order by the wind. It is not impossible, but it is ridiculously unlikely. That is entropy, in a nutshell.