Can the Transverse Nature of a Wave from an Electron Gun be Observed?

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Discussion Overview

The discussion centers around the nature of waves emitted from an electron gun, specifically whether these waves can be classified as transverse. Participants explore the implications of quantum mechanics on the wave-particle duality of electrons and the definitions of transverse and longitudinal waves.

Discussion Character

  • Exploratory
  • Debate/contested
  • Conceptual clarification

Main Points Raised

  • Some participants question the classification of waves from an electron gun as transverse, suggesting that electrons are quantum particles and do not fit classical definitions of waves.
  • There is a discussion about whether photons, as quantum particles, can be classified as transverse or longitudinal, with conflicting views on their nature.
  • Some participants argue that the description of a wave's nature depends on definitions and context, particularly regarding polarization and spin.
  • One participant highlights the distinction between classical and quantum descriptions, noting that the terminology used may not accurately reflect the underlying physics.
  • Another participant introduces the concept of electron polarization, suggesting that it may relate to the discussion of transverse properties.
  • There are references to the wave-particle duality of electrons, with some participants expressing a sense of wonder about the complexities of quantum mechanics.

Areas of Agreement / Disagreement

Participants express multiple competing views on the nature of waves from an electron gun, with no consensus reached regarding whether these waves can be classified as transverse. The discussion remains unresolved with varying interpretations of quantum mechanics and wave behavior.

Contextual Notes

Participants note that definitions of terms like "transverse," "longitudinal," and "spin" can vary, which complicates the discussion. There is also mention of the challenges in separating spin and orbital angular momentum in a gauge-invariant manner.

Martyn Arthur
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TL;DR
How do we know that a wave fired from an electron gun is transverse in transit?
Hi.
What equipment /mechanism / experimental procedure is used to determine that the nature of a wave fired from an electron gun is transverse in transit?
Thanks
Martyn
 
Physics news on Phys.org
If a wave propagates through vacuum, is it transverse or longitudinal?

Will your electron propagate through a vacuum?
 
Martyn Arthur said:
TL;DR Summary: How do we know that a wave fired from an electron gun is transverse in transit?

Hi.
What equipment /mechanism / experimental procedure is used to determine that the nature of a wave fired from an electron gun is transverse in transit?
Thanks
Martyn
An electron is a quantum particle. It's not a classical wave, and neither transverse nor longitudinal.
 
PeroK said:
An electron is a quantum particle. It's not a classical wave, and neither transverse nor longitufinal
But a photon is also a quantum particle, not a classical wave, and is only longitudinal.

That said, I don't understand what the OP means and I suspect he doesn't either. If he can express this thought in terms of observables, it might be discussable, but as it is it's words words words. Like "a weath of pretty little flowers which smell bad."
 
Vanadium 50 said:
But a photon is also a quantum particle, not a classical wave, and is only longitudinal.
Did you mean to say "is only transverse"?
 
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Either. Depends on if you are talking spin or electric field direction. Which emphasizes the OPs confusion the description of a thing is not the same as the thing.
 
Martyn Arthur said:
the nature of a wave fired from an electron gun is transverse in transit
Where did you read this? Can you give us a link or reference so we can see where you're "coming from" on this?
 
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Vanadium 50 said:
Either. Depends on if you are talking spin or electric field direction.
That's a good point, I was thinking only classically. Massless photons or gravitons do indeed always have longitudinal spin with transverse polarization. For massive electrons it seems polarization must refer to spin-up or spin-down with respect to some external magnetic field B. A e-beam is then "polarized" to the extent it consists of unequal numbers of electrons with up vs. down spins. If the B-field happens to be perpendicular to the beam propagation direction, might this then constitute "transverse electron polarization"?
 
PeroK said:
An electron is a quantum particle. It's not a classical wave, and neither transverse nor longitudinal.
Of course you can have polarized electrons, i.e., electrons with their spin in a given direction.
 
  • #10
Vanadium 50 said:
Either. Depends on if you are talking spin or electric field direction. Which emphasizes the OPs confusion the description of a thing is not the same as the thing.
A photon can only be "transverse". A photon as a massless spin-1 particle, has only two polarization-degrees of freedom. The natural choice is helicity, i.e., the projection of total angular momentum to the direction of the momentum, and the helicity can only take the values ##\pm 1##. That's a subtlety of massless particles with spin. It has always only two helicity states ##\pm s## (with ##s \in \{1/2,1,3/2,\ldots \}##).
 
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  • #11
vanhees71 said:
A photon can only be "transverse".
A photon's electric field can only be "transverse". A photon's spin can only be "longitudunal."

(Convention is to talk about fields, trhough). What I tried to bring up, and obviously failed to do well, is that this is a description that depends on definition. You tell me the definition you use, and I'll tell you what names the physics requires.

When making a physical prediction, of course we get the same answer no matter which words we use. This is why I think the OP's question "which words do we use?" is ill=posed.
 
  • #12
Define what you mean by spin then. It's not possible to split the total angular momentum into spin and orbit parts in a gauge-invariant way!
 
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  • #13
As I recall, the electron has corpuscular-wave dualism! It behaves both like a wave and like a particle! There are many interesting things in the world))) So many discoveries are yet to come)))
 
  • #14
BillyDoster said:
As I recall, the electron has corpuscular-wave dualism! It behaves both like a wave and like a particle! There are many interesting things in the world))) So many discoveries are yet to come)))
QM explained that one!
 

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