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

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Discussion Overview

The discussion revolves around whether electrons accelerate when transitioning between energy states, particularly in the context of quantum mechanics. Participants explore the nature of electron motion, the implications of quantum theory, and the interpretations of electron behavior in various frameworks.

Discussion Character

  • Debate/contested
  • Conceptual clarification
  • Exploratory

Main Points Raised

  • Some participants question whether electrons have motion or only accelerate when they gain energy, highlighting the ambiguity in defining electron behavior in quantum mechanics.
  • Others argue that the classical view of electrons as small objects moving around a nucleus does not hold in quantum mechanics, where position and velocity cannot be precisely defined.
  • It is suggested that electrons exhibit continuous motion, but this is framed as a classical approximation rather than a definitive description of quantum behavior.
  • Participants discuss the notion of "transition" between energy states, with some asserting that this does not imply physical movement akin to classical particles.
  • There is a debate about whether electrons can be considered point particles and how this affects the understanding of their motion and trajectories.
  • Some contributions reference Bohmian mechanics, which posits that fundamental particles have motion and acceleration, contrasting with standard quantum mechanics that does not define electron trajectories.
  • Questions arise regarding the implications of quantum mechanics on the concept of movement, particularly in relation to probability and the most probable positions of electrons.

Areas of Agreement / Disagreement

Participants express differing views on the nature of electron motion and the validity of classical versus quantum descriptions. There is no consensus on whether electrons can be said to accelerate or move in a classical sense, and multiple interpretations of quantum mechanics are presented without resolution.

Contextual Notes

Limitations include the reliance on different interpretations of quantum mechanics, the ambiguity in defining motion and acceleration, and the unresolved nature of electron trajectories within standard quantum theory.

  • #31
PeroK said:
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.
 
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  • #32
Delta2 said:
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".
 
  • #33
PeterDonis said:
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.
 
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  • #34
Delta2 said:
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.

Delta2 said:
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.
 
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  • #35
The OP appears to be gone and the thread topic has been thoroughly covered. Thread closed.
 

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