Trying to make sense of the double slit "experiment"

[Claude]

How did you find PF?: A quick Google search of Physics forum gave me a link to this site.

I have a good background in science (BSC Mathematics), but not specifically in Quantum theory. That happened after I left University.
I have read lots, know a fair bit but wouldn't dare to claim I "understand" too much of it (beyond classical relativity).
I believe the best way to progress (for me) is to question / challenge commonly accepted ideas and theories that one is expected to accept without too much analysis.
Being an outsider and a "newbie", I ask for your understanding and forgiveness in advance. But know that I always appreciate the chance to learn from those who have more knowledge than I. So long as you can justify your position - I don't believe in dogma...
So let's have some fun!

My first question is this:
Shooting electrons through a double slit (refer Dr. Tonomura and Belsazar), electrons are fired individually and detected as individual events on the other side of the slits.
As you know, the electrons appear to land "randomly" until an interference pattern eventually emerges.

My question is this: A particular electron is expected to travel in a straight line unless some force is applied to deflect it.
As is obvious in this particular experiment, electrons ARE deflected. Sometimes quite a lot.
What is the source of the force? Is it accidentally provided by the experiment apparatus?
Doesn't the conservation of energy apply?

Sorry if this is trivial or silly...

 

[PeroK]

My question is this: A particular electron is expected to travel in a straight line unless some force is applied to deflect it.
As is obvious in this particular experiment, electrons ARE deflected. Sometimes quite a lot.
What is the source of the force? Is it accidentally provided by the experiment apparatus?
Doesn't the conservation of energy apply?

In QM, particles do not have a well-defined trajecory. That said, a free electron fired at the slits can be modeled quite well by a classical path. When the electron is confined to two narrow slits, however, its behaviour can no longer be modeled classically. One way to look at the double slit is that the electron, for a short time, is trapped in a double potential well. Then, afterwards, it is free again, but has picked up an uncertain amount of lateral momentum from its time in the potential well.

If you look at it closely, then this lateral momentum must have come from an interaction with the slits. I found this analysis, for example:

https://iopscience.iop.org/article/10.1088/1742-6596/701/1/012007/pdf

 

[BvU]

Hello and

A particular electron is expected to travel in a straight line

To some considerable extent. However, the wave character of electrons makes that you can't have an exact transversal position and zero uncertainty on the transverse momentum. From there on it's all exactly as in the case with photons:optics.

https://www.feynmanlectures.caltech.edu/III_01.html

 

[Vanadium 50]

that one is expected to accept without too much analysis.

I don't believe in dogma...

You are coming into this with a view of what a physics education is that is a) wrong, and b) insulting to those of us who have gone through it. Are you sure this is the path you want to take?

I believe the best way to progress (for me) is to question / challenge commonly accepted ideas and theories

Usually not. Presenting a parade of incorrect statements hoping to be corrected is slow, inefficient and more likely than not to make everyone cross. A better way is for you to do some reading and say something like"in X they say Y, but I don't understand how they got from A to B." You might take a look at https://www.physicsforums.com/insights/little-excuse-ask-question-cold/

As pointed out, you start to go awry here:

A particular electron is expected to travel in a straight line unless some force is applied to deflect it.

That's true for planets and baseballs, where the wave nature is irrelevant. It is not true for electrons where the wave nature is important. Electrons can diffract and interfere, like waves. And they can be counted like particles.

 

[Nugatory]

I believe the best way to progress (for me) is to question / challenge commonly accepted ideas and theories...

That approach requires that you first understand the commonly accepted theories. Otherwise you're challenging a straw man, and all you'll ever get from that is a belated awareness that it was unworthy of your time.

So to the extent that you want to properly understand what quantum physics does say, this forum is the right place to ask questions. Uninformed challenges, not so much.

 

[weirdoguy]

that one is expected to accept without too much analysis

Expected by whom?