3 ms·

Not a physics guy, so my understanding is probably wrong. Aren't all particles infinite in size and are just blips in the fields behind our universe?

• antonvs 7y ago
  The "wave function" that we use to model a particle's state has indefinite extent, but when the particle actually interacts with something else, it does so in a single, small location (from our perspective.) When they talk about the proton radius, they're talking about the radius of that interacting object, not its wave function. The wave function can be thought of as describing the probability of an interaction finding the particle in a particular location.
  • bufferoverflow 7y ago
    Isn't there a contradiction in your answer? Since the probability of interaction far away is not zero, why is it not included in the "radius of that interacting object".
    • antonvs 7y ago
      "Radius of the interacting object" was poorly worded. I was referring to the radius of the interaction itself, which is much smaller than the extent of the corresponding wave. For example in the double slit experiment, the interaction occurs on a detector screen in a single, small location with a radius on the order of 10^-15 meters (subatomic), whereas before it interacts with the screen, the wave extends throughout the experimental apparatus.