Physics, Astronomy & Cosmology / Re: QM puzzle: Is a measurement being made in the 2 slit experiement all the time?« on: Yesterday at 16:16:38 »
So the integral we'd be interested in, representing the total probability of finding the electron at the screen from 'then'/ that time to infinity is finite << 1. Specifically we can assume the electron would never be found at the screen, write it off and just fire the next electron.Sounds reasonable
Anyway, we were talking about a lack of detection at the screen as being a lack of measurement:Depends on your definition of measurement. In real life, measurement is epistemological. If the electron hits the lab wall, you're unaware of it and your epistemic wave function isn't altered by the event. In the sim, the sim would know that the wall was hit and the actual wave function would be altered, and the real wave function would collapse. The screen then also measures the collapse because the screen measures the wall; it becomes entangled with the wall state.
Well, that is still some measurement by the screen as far as I can see.Yes, you know it missed, so the epistemic wave function is altered by the knowledge, even if it isn't 100% certain.
It is NOT at the screen at any time, although there are lots of other places it can beUnless you're assuming a counterfactual interpretation, I think it a mistake to talk about where it is in the absence of measurement. But a lot of simulations do exactly that, so I suppose it depends how your sim is implemented. You know it missed, so the new wave function can yield odds of where it likely hit, and that's assuming that the lab is reasonably closed and it doesn't shoot off into space never to interact with anything, as so many photons never do.
Is it possible for a thing to exist despite the fact that it hasn't and will not in the future interact with anything else?A matter of definitions. What does it mean to exist? There's conservation laws, so of course it exists. It merely lacks a location/momentum.
Anyway.... there's always gravity which we don't tend to include in any Quantum Mechanics, the electron is still providing some energy density and thus curving space, i.e. it is interacting with something else in some way (you would think).
For example, the electrons can encounter other particles and potentials en route to the barrier and/or screen.Always wondered about that. Do they regularly do the electron-gun thingy in a vacuum to avoid that sort of thing?