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

[Martyn Arthur]

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

 

[Hyperfine]

If a wave propagates through vacuum, is it transverse or longitudinal?

Will your electron propagate through a vacuum?

 

[PeroK]

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.

 

[Vanadium 50]

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."

 

[renormalize]

But a photon is also a quantum particle, not a classical wave, and is only longitudinal.

Did you mean to say "is only transverse"?

 

[Vanadium 50]

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.

 

[jtbell]

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?

 

[renormalize]

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"?

 

[vanhees71]

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.

 

[vanhees71]

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 $s \in \{1/2,1,3/2,\ldots \}$).

 

[Vanadium 50]

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.

 

[vanhees71]

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!

 

[BillyDoster]

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)))

 

[PeroK]

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!