# Expansion of elementary particle

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?

• Hi, I have never read that an elementary particle contains forces holding it together. If may well be true, but I don't think we have any experimental evidence for another type of force affecting experimental results. The size of an electron ( or rather the lack of it), makes it very difficult to examine.
– user108787
Sep 22, 2016 at 6:06
• Related: physics.stackexchange.com/q/2110/2451 and links therein. Sep 22, 2016 at 6:46
• @CountTo10 Thank you for the response. That makes sense. I was assuming there was some intrinsic internal structure but cannot of course yet prove that for electron. So if something is a point particle and lacks any internal forces, would not expansion influence the very definition of that point's spatial width (i.e. $x = 0$ itself)? If it was found that point particles have a minimum spatial width, wouldn't the "point particle" expand as well in such a case? Sep 22, 2016 at 13:28