Why do particles show interference in the double slit experiment?

[PeterDonis]

That you need to justify though

The justification is the many, many experiments that the quantum model makes accurate predictions about, and the classical models don't.

You say you've studied quantum mechanics; if so, you should already know this.

 

[PeterDonis]

I was assuming that space is not empty.

Which, as you have now been told multiple times now, is not a good model in practice--"empty" is not exactly true, but it's a good enough approximation to make accurate predictions for the experiments we're talking about.

You really need to stop repeating things that we've already responded to. It's making this discussion less and less useful.

So the particles would bounce off the medium

Here again your understanding of classical physics is wrong. If you model what's in the chamber as a "medium", particles don't "bounce off" it. A medium is a continuous thing. If you want your particles in your model to "bounce" off something in the chamber, when there is no barrier with slits in it, then you need to have other particles in the chamber, which can collide with the particles you're shooting in.

Again, if you want to improve your understanding of classical physics, you need to start a new thread in the classical physics forum.

 

[PeterDonis]

That is also what a Brownian motion particle would do.

The correct model of Brownian motion is not to consider the particle of interest as being suspended in a "medium". It is to consider a model in which the particle of interest is being bombarded with other particles that are colliding with it, and to do statistics on what behavior that produces when the number of such collisions per unit time is very large. That's how Einstein used Brownian motion to argue for the existence of atoms.

 

[Nugatory]

So you talk about a particle and possible paths going through the slits. Can it go through both slits and is some sort of superposition, or is this all just a mistake of measurement?

Neither. “Going through both slits and is some form of superposition” is a misrepresentation of what QM actually says, just the best we can do without the math. (To get a sense of how misleading it is, it would be just as accurate to say that it goes through neither slit).

Prove a particle is in a superposition. Or can you not?

Of course I can’t because it’s not accurate …. It’s how we talk about what the math says when we’re using natural language. An accurate statement would be something like “after the particle has interacted with the barrier, the state of the quantum particle is described by a vector in an abstract mathematical vector space with infinite complex dimensions; this vector is a sum of other vectors in that vector space; and I can accurately calculate the interference pattern from that vector”.
(and now you understand the tendency to use the simple inaccurate language)

And of course I can’t prove the truth of that statement either, but then again I can’t prove the truth of Newton’s laws either. In both cases all I have is that I can use them to accurately calculate how the universe behaves.

 

[PeterDonis]

Thread closed for moderation.

 

[PeterDonis]

After moderator review, the thread will remain closed, as the quantum mechanical predictions about the double slit experiment have now been described thoroughly enough. Thanks to all who participated.