Do electrons accelerate when transitioning from one energy state to another?

[Delta2]

If you take an electron in the ground state of the Hydrogen atom and measure its total angular momentum you get 0 with 100% probability.

The expected value of its kinetic energy is, however, non zero.

What sort of orbit is that, you might ask? Well, it's a quantum mechanical "orbit", which cannot be reasonably explained in classical terms. In particular, in this system it makes little sense to think of the electron "moving" at all.

Some things don't seem to make sense in quantum mechanics. I am sure you ll tell me that they don't make "classical" sense but they make "quantum mechanical" sense. Seems to me one has to redefine fundamental concepts such as the concept of movement in order for QM to make sense.

 

[PeterDonis]

Seems to me one has to redefine fundamental concepts such as the concept of movement in order for QM to make sense.

And if you can point to something in the math that you think deserves to be called "movement" and give a good argument, you might get such a redefinition accepted. But you're not going to do it by just saying "seems to me".

 

[Delta2]

And if you can point to something in the math that you think deserves to be called "movement" and give a good argument, you might get such a redefinition accepted. But you're not going to do it by just saying "seems to me".

No there isn't anything in the math about movement, but somethings just don't make sense. Like we talk about position and momentum in HUP, but a particle doesn't have definite position and velocity and it is like we are forbidden to talk about its "movement". How does this makes sense to you I don't know but it doesn't seem to make sense to me. Maybe you understand it as the particle being simultaneously in many places with a different probability in each place. But this understanding certainly doesn't make classical sense, might make quantum mechanical sense though.

 

[PeterDonis]

we talk about position and momentum in HUP

That's one pair of non-commuting observables to which the HUP applies, but it's by no means the only such pair.

this understanding certainly doesn't make classical sense

You're right, it doesn't. Welcome to quantum mechanics, where the first lesson is: the world is not classical. Classical physics is an approximation that works well in some domains, but that's all it is. You should not expect everything to make sense in classical terms.

 

[PeterDonis]

The OP appears to be gone and the thread topic has been thoroughly covered. Thread closed.