Thought experiment with electron and proton

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Discussion Overview

The discussion revolves around a thought experiment involving a universe with only one electron and one proton, exploring the implications of their interactions governed by Coulomb's law and the strong interaction. Participants examine the behavior of these particles, considering both classical and quantum mechanical perspectives, and the potential outcomes of their interactions.

Discussion Character

  • Exploratory
  • Technical explanation
  • Conceptual clarification
  • Debate/contested

Main Points Raised

  • Some participants propose that if the electron and proton start at rest, they would move back and forth indefinitely due to their mutual Coulomb attraction.
  • Others argue that the kinetic energy of the electron plays a crucial role; if it is high enough, the electron could escape to infinity, while lower kinetic energy would lead to the formation of an excited hydrogen atom that emits photons as it transitions to lower energy states.
  • Some participants clarify that electrons do not experience the strong nuclear force and are treated as point particles, suggesting that they would not radiate energy in a universe with only one electron and one proton.
  • Contradictory views emerge regarding the possibility of radiation, with some asserting that energy radiation cannot occur in the specified universe, while others maintain that the system would evolve into a hydrogen atom in a ground state, emitting photons.
  • Participants discuss the implications of quantum mechanics, noting that the hydrogen atom could exist in a superposition of states and might drop to the ground state due to fluctuations in the electromagnetic field.
  • There is mention of the proton's stability, with some suggesting that it might decay under certain theoretical frameworks, such as grand unified theories, though this is contested and remains speculative.
  • Several participants express uncertainty about the initial conditions and the relevance of the thought experiment, questioning the assumptions made in the original post.

Areas of Agreement / Disagreement

Participants do not reach a consensus, as multiple competing views remain regarding the behavior of the electron and proton, the role of radiation, and the implications of quantum mechanics in this scenario.

Contextual Notes

Some limitations include the lack of clarity on initial conditions, such as the distance between the particles and the applicability of Coulomb's law. There is also ambiguity regarding the assumptions about the nature of the forces acting on the particles and the relevance of quantum field theory in this context.

  • #31
yeah, it is kind of silly to talk about 'how would things work if we allowed some of quantum mechanics but not other parts'. For anything to properly make sense, either stay fully classical, or go into the quantum regime. Anything in the middle is not so useful. Well, maybe there are some exceptions, like how semi-classically, the electron in the atom feels a magnetic force from the proton, since from its viewpoint, the proton is moving around it. But really, it is better to do these things the proper (fully-quantum) way.
 
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  • #32
DaleSpam said:
No matter how you look at it it is simply not correct that it winds up "going back and forth forever".

Why not ? Are there observations that rule it out ?
 
  • #33
Yes. Atoms at rest are observed to not emit synchotron radiation.
 
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  • #34
DaleSpam said:
Yes. Atoms at rest are observed to not emit synchotron radiation.

That seems to rule out only curved electron orbits.
 
  • #35
DaleSpam said:
Yes. Atoms at rest are observed to not emit synchotron radiation.

You mean atoms in a stationary state.
 
  • #36
Electrons in a stationary atom are moving, since they have kinetic energy. So in a sense they are eternally moving back and forth.
 
  • #37
DaleSpam said:
It is contrary to observation.

All of it's kinetic and potential energy, yes.

Classically the electron would, by radiating, increase its kinetic energy and decrease its potential energy indefinitely. That is possible because classical point charges have infinite electromagnetic self energy. The total energy would never become negative.
 
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  • #38
my2cts said:
Classically the electron would, by radiating, increase its kinetic energy and decrease its potential energy indefinitely.
Indefinitely? If something is radiating energy away, how can this go on indefinitely?
 
  • #39
forcefield said:
That seems to rule out only curved electron orbits.
Obviously. The Coulomb potential couldn't lead to any others.
 
  • #40
my2cts said:
Electrons in a stationary atom are moving, since they have kinetic energy. So in a sense they are eternally moving back and forth.
They may have KE, but their expected position is not changing. They are not moving back and forth.

my2cts said:
Classically the electron would, by radiating, increase its kinetic energy
You have this exactly backwards. An electron loses KE by radiating.

In any case, atoms are not observed to radiate indefnitely either.
 
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  • #41
This thread is such a mess of classical and quantum concepts and blatant misinformation that it is not useful any more, if it ever was useful.

The question in the OP was clearly and correctly answered back in post 2. If forcefield does not like the answer then he/she is free to consult an actual textbook.
 
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