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If you have a particle that is indivisible (e.g. electron), we assume the forces holding it together would prevent it from expanding. If the forces holding the indivisible particle together were weaker than that due to cosmic expansion, wouldn't the particle itself also expand in volume as well? Also, if there was a particle that lacked any internal forces, what exactly happens? (I realize this may violate the definition for a particle, but I'm trying to understand how everything [since "things" occupy space] should expand as long as they don't have internal forces preventing this expansion.)

Now, by wave-particle duality, there is an associated wave function in the position space denoting probabilities of detecting a particle somewhere. Due to expansion, would not cosmic expansion affect (however minimally) the probability associated with detecting a wave at a particular position?

Qmechanic
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Mathews24
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1 Answers1

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The reason for a particle being indivisible, may (or does) not have anything to do with the strength of any forces holding it together. In the case of the electron, our current understanding is that it is a point particle. In other words, it does not have any size (or volume) associated with it. In this sense it is literally a mathematical point. Therefore, there are no internal forces necessary to hold it together. Moreover, a point does not expand, even if the space in which it is embedded expands. Such an expansion would indeed expand the wave function of that particle. As a result, the length scales, such as the wavelengths, of the particle would become longer. This is what happened to the cosmic background radiation, for instance.

flippiefanus
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