# Are point particles always points?

jaydnul
Tell me if I am correct:

The wave part of wave-particle duality is a probability wave. An electron, for example, is always a 0 dimensional point (as far as we know), and the wave characteristic of the electron determines the possible locations of the electron and probability of finding it in that location.

Mentor
Well first off the wave particle duality isnt really how its looked from the modern perspectice:

The real answer is that for all quantum objects we know of position is an observable and nothing has revealed any type of spread out structure etc for objects like an electron or photon - neutrons, protons etc - yes - but they are not considered fundamental.

Basically QM is a theory about the results of observations, measurements etc etc and since we can devise experiments that return a position we say they are point like particles - but quantum particles - not how they are visualized classically.

Thanks
Bill

Last edited:
kaplan
Tell me if I am correct:

The wave part of wave-particle duality is a probability wave. An electron, for example, is always a 0 dimensional point (as far as we know), and the wave characteristic of the electron determines the possible locations of the electron and probability of finding it in that location.

Yes, that's correct. But given the inherent and unavoidable uncertainty in its position, the statement "the electron is always a 0 dimensional point" is a bit misleading. What "point particle" really means is that the electron and its wavefunction have no substructure - the more energy you use to probe it the better you will localize it (although never with perfect accuracy), and you will never discover any new level of complexity. You'll just keep squeezing the wavefunction down into a smaller and smaller region.

That's by contrast with for instance a proton, where if you probe with enough energy you discover quarks. And of course electrons may well have substructure too at some small length we haven't reached yet (for example at the Planck length something different has to happen).