Does an electron have a makeup

[ZapperZ]

I agree that there is considerable subtlety to the whole situation, and I have tried to emphasize from the start that the statement "electrons emit photons" is really just part of a working language used by high energy physicists.

But this is exactly the point that I've been trying to make here with regard to "context". The statement was not made by a "high energy physicist", and it isn't meant to be understood within that context. Being around them every single working day, I tend to know that this is not a common question that they would ask on a forum such as this. It is why I hesitate to include such discussion since it is actually not relevant to what that person had in mind, and what he can understand.

Not only that, there's plenty of opportunity for misunderstanding. We see that occurring all the time when we try to give a bit more than what they can comprehend - example: Casimir effects and why many think this is trivial and want to "extract energy" out of the vacuum state.

Again, as I've said when the issue of relativistic mass came up, responding to things like this must include the person asking or making that statement as a large part of the consideration. We simply cannot spew out answers that simply satisfy our knowledge without regards to how it will sound at the other end. If I'm talking to a high energy physicist (and this occurs very often), I'm sure you will know that there will be a different "tone" to the conversation than what I would do on here.

Zz.

 

[CarlB]

This may be true, I don't really know. Physicists do like their Lorentz invariance, and maybe because they've spent so long doggedly defending it against the anti-relativity nutjobs, some can't see the difference between nutjobs and serious researchers. Still, I read about new tests of Lorentz invariance and I hear more and more about Lorentz invariance violation, so I have to hope that most physicists aren't so bad. Either way, I'm young, and I do think it would be great to find a violation.

The question of the substructure of the electron and Lorentz invariance are tied together by a theorem due to Coleman and Mandula which can be stated as:

"The Coleman-Mandula theorem, which states that space-time and internal symmetries cannot be combined in any but a trivial way ..."
http://www.arxiv.org/abs/hep-th/9605147

This theorem, which divides the mysterious internal symmetry of the electron away from the symmetry of space-time which we are more or less familiar with, is a BIG obstacle to attempts to produce geometric theories that unite the particles. What happens is that when you try to write the elementary particles with a geometric interpretation you are forced to either (a) violate the Coleman Mandula theorem by making the relationship between particle symmetries and spacetime symmetries non trivial, or (b) explain away hundreds of particles that your theory predicts but that the experimentalists never see. Of course the argument of the Coleman Mandula theorem relies on perfect Poincare / Lorentz symmetry.

In my own case, I found a very simple theory for the underlying structure of the fermions, one where the particles show up quite naturally with no excess states to explain away. And it is in extreme violation of both the Coleman Mandula theorem and Lorentz invariance. And of course physicists don't want to hear about it.

But when I srcrubbed all the obvious violations of Lorentz invariance from the theory and left it as just a phenomenological comment on the lepton masses and mixing angles it got attention, because now it could be rewritten using the (Lorentz invariant) Higgs mechanism:
http://www.arxiv.org/abs/hep-ph/0605074

Compare the complexity of the above to the original:
http://brannenworks.com/MASSES2.pdf

The complexity is the consequence of requiring that Lorentz symmetry be exact "all the way down", this despite the complete lack of experiments done at infinite energies. So the issue becomes one of dueling simplicities.

Relativity is an elegant and simple theory of spacetime, but it implies an inelegant and complicated theory of elementary particles, one with no particular relationships between the different particles. And yet the elementary particles exhibit remarkable coincidences and their masses are related by very simple functions.

Carl

 

[ZapperZ]

"The Coleman-Mandula theorem, which states that space-time and internal symmetries cannot be combined in any but a trivial way ..."
http://www.arxiv.org/abs/hep-th/9605147



But when I srcrubbed all the obvious violations of Lorentz invariance from the theory and left it as just a phenomenological comment on the lepton masses and mixing angles it got attention, because now it could be rewritten using the (Lorentz invariant) Higgs mechanism:
http://www.arxiv.org/abs/hep-ph/0605074

Compare the complexity of the above to the original:
http://brannenworks.com/MASSES2.pdf

Can you please cite the journals where these papers have been published? Thanks.

Zz.

 

[reilly]

Quote:
Originally Posted by reilly

As a final comment to bolster my case, I say, "If it's good enough for Feynman, it's good enough for me." In his "QED-The Strange Theory of Light and Matter" he says:

"The third basic action is: an electron emits or asorbs a photon ..."

This on p 91 in Chap 3 in which he discusses the basics of electron-photon interactions, as described by 3-point interactions.

Regards,
Reilly



OK, but to quote from the same guy:

Quote:
Originally Posted by RPF

"A single free electron cannot emit one photon because of conservation
of energy and momentum, but if two electrons are near one another,
one may emit a photon which the other immediately absorbs"

and

"Quantum Mechanics permits the temporary existence of states, which,
if maintained, could not conserve energy"

The Theory of Fundamental Processes, Chapter 6, page 30. Richard. P.Feynman

So, yes, OK, but always differentiate between real and virtual,

Compton scattering: A real electron absorbs a real photon and becomes
a virtual electron until it emits a real photon and becomes a real electron
again.


Regards, Hans

Levels of the game -- different audiences , different takes, different issues.

Regards,
Reilly

 

[ZapperZ]

Levels of the game -- different audiences , different takes, different issues.

Regards,
Reilly

Yeah, but it shows that you pick and choose what to quote, which is why I seldom play that game. So let's stop quoting Feynman (or anyone else for that matter) on this issue just to support some point.

Zz.

 

[samalkhaiat]

It seems to me legitimate to say that electrons do emit photons
And if so, why couldn't electrons also absorb photons if they can emit ones?



Regards

You are right. The emission and the absorption of radiation by the atomic electrons are completely symmetrical processes.

Any way, the emission/absorption of photons by electron does not imply any substructure for the electron.

regargs

sam

 

[samalkhaiat]

When an electron is in a field, be it in electric or magnetic field, it can easily interact with those fields and emits photons

The more accurate and symmetrical statement would be;
when an electron is in em field, it can interact with it and emits/absorbs photons.

I see this almost every week whenever we try to accelerate and decelerate bunches and bunches of "free" electrons in a particle accelerator.

What you see is the radiation from the accelerated electrons. These electrons are NOT free, rather they are interacting with accelerating field.

A FREE electron is an electron that is not in interaction with any field apart from its own field. This FREE electron does not emit/absorb photon.

For the same reason (violating energy, momentum and angular momentum conservation), a single photon can not "emit/absorb" electron-positron pair.

However, in the presence of an extra agent, like the field of the nucleus, the electron is nolonger free and can emit/absorb photon.

The problem here is that when someone talks about an electron absorbing a photon, we are talking about something like the photoelectric effect where an object absorbs a photon, for real, or an atom absorbing a photon, causing an electronic transition. In each of these processes, for conservation laws to be preserved, a bunch of things are required. In a photoelectric effect, the lattice ions are required to provide the recoil momentum. In an atomic transition, it requires the electronic orbit to change by + or - 1 angular momentum dictated by the selection rule. In other words, something simply cannot just swallow a photon that easily.

You seem to have no problem in saying that an intracting electron can emit photon, Yet you think that such electron can not absorb photon! This is absurd. Both these processes are determind by the same physics and math.
Indeed, the "detailed balancing" equation ( the relation between emission and absorption rates in Fermi's golden rule) expresses symmetry between emission and absorption of radiation.

1) When you excite the H-atom by shining light on it:

i) Do the energy and angular momentum of its nucleus (proton) change?
NO.
ii) Do the energy and angular momentum of the coulomb field change?
NO.
iii) Do the energy and angular momentum of the electron change?
YES, they do change by exactly the same amounts carried by the
incident photon.

2) When we calculate the absorption rate by the golden rule, we plug in Hamiltonian which describes the interaction between the electron and the incident photon.
3) It is the electron's charge (not the zero charge of the atom) that appears in the absorption rate.
4) It is the electron's mass that appears in the interaction Hamiltonian.

For these (and some two more) reasons, one can say;

It is the atomic electron (not unspecified ghost in the atom) that absorbs, eats or swallows the incident photon.

regards

sam

 

[reilly]

ZapperZ -- Yes, I'll use one quote for beginners, and quite another for professionals. In some quarters that might be called "teacher's perogative." I defer to thousands of instances of physicists great and ungreat alike defying rigor to talk about "absorption and emission" -- this group includes virtually all of the founders.

As I said, I guess I should retract my dissertation and inform my professors that I and they were wrong to treat the photon-electron interaction with such a mistaken and cavelier attitude. This attitude has been in place, at least, since Bloch and Nordsieck did their seminal paper on the InfraRed Divergence, back in 1937 -- to make matters worse, their work shows that there is no elastic scattering of charged particles -- there is always radiation -- and that to make sense of this, the perturbation series must be summed in the low-photon-energy limit

All of Feynman's key papers use the concepts of emission and absorption; as does Dirac's book, as does ... They are talking figuratively, and, I'm sure, assume that people knowledgeable about physics will naturally understand the limitations of English when applied to mathematics, and know that the pros will not be greatly disturbed by a missing dot over an i or two.

I invite you to accept my Virtual Challenge(new thread.) Then we can have a far more informed discussion by looking at a specific problem in great detail.

Regards,
Reilly

 

[ZapperZ]

What you see is the radiation from the accelerated electrons. These electrons are NOT free, rather they are interacting with accelerating field.
A FREE electron is an electron that is not in interaction with any field apart from its own field. This FREE electron does not emit/absorb photon. For the same reason (violating energy, momentum and angular momentum conservation), a single photon can not "emit/absorb" electron-positron pair.
However, in the presence of an extra agent, like the field of the nucleus, the electron is nolonger free and can emit/absorb photon.

At what point do you consider an electron interacting with photons to not be "free particles". Note that I put the word "free" in quotes in the statement that you are responding. Would you consider an RF radiation of 1.3 GHz to be a "EM field" while UV radiation of 5 eV to be "photons"? If that's the case, then would you like to google on laser accelerators, because I can tell you that the basic physics of this, and RF accelerating structure is almost identical.

In the beam-loading experiment, there isn't ONE electron, nor is there ONE photon. A "absorption" is entirely due to electron bunches that are being accelerated, meaning it because the kinetic energy. The accelerating charges also radiate, and this, along with the original RF, causes the resulting field that we measure to be slightly modified, giving the tell-tale sign of "beam loading". This signal is different when no electron bunches are present.

But it would be utterly silly for me to say "Ah ha! I have proof that electrons can absorb photons in this observation!". This was my point in bringing up this particular example that I have seen myself.

Zz.

 

[reilly]

.

1) When you excite the H-atom by shining light on it:

i) Do the energy and angular momentum of its nucleus (proton) change?
NO.
ii) Do the energy and angular momentum of the coulomb field change?
NO.
iii) Do the energy and angular momentum of the electron change?
YES, they do change by exactly the same amounts carried by the
incident photon.

2) When we calculate the absorption rate by the golden rule, we plug in Hamiltonian which describes the interaction between the electron and the incident photon.
3) It is the electron's charge (not the zero charge of the atom) that appears in the absorption rate.
4) It is the electron's mass that appears in the interaction Hamiltonian.

For these (and some two more) reasons, one can say;

It is the atomic electron (not unspecified ghost in the atom) that absorbs, eats or swallows the incident photon.

regards

sam

Of course the proton in the hydrogen atom can absorb a photon, as can any nucleus in general. That's required by gauge invariance, and is reflected in the electromagnetic interaction term in field theory. However, the probability for such absorption is small, at least for photons within the frequency range of the hydrogen spectra.

Given as I am to homework: show that the nuclear photon absorption amplitude is generally much smaller than the electronic photon absorption amplitude for hydrogen. (Hint: recoil is important. And, to keep things as simple as possible, consider both absorption and emission. Why? And then, go back and evaluate the correctness of all samalkhaiat's points in light of your calculations.)

Regards,
Reilly

 

[samalkhaiat]

At what point do you consider an electron interacting with photons to not be "free particles".

At NO point. Since it is interacting. Therefore it is NOT FREE.
Free electron is a solution of the free Dirac's equation (with zero on the right hand side)

Note that I put the word "free" in quotes in the statement that you are responding.

Why do you call it "free". Is "Free" for experimental physicists means "not free" for theoretical physicists?

Would you consider an RF radiation of 1.3 GHz to be a "EM field" while UV radiation of 5 eV to be "photons"? If that's the case, then would you like to google on laser accelerators, because I can tell you that the basic physics of this, and RF accelerating structure is almost identical.

EM-Field, when quantized, is equivalen to photon field. Your numbers does not change this fact.

The accelerating charges also radiate,

The accelerated charge is an interacting charge. Yes it does radiate.This is a classical fact proved by Maxwell's.


Without offering any reason, You said that the atomic electrons do not absorb photons.
I (like few thausands of physicits) say they do and I gave you my reasons in my last post.

So tell us, when you excite an atom by shining light on it, What are your reasons for saying that the atomic electrons do not absorb the incident photon?

regards

sam

 

[ZapperZ]

Without offering any reason, You said that the atomic electrons do not absorb photons.
I (like few thausands of physicits) say they do and I gave you my reasons in my last post.

So tell us, when you excite an atom by shining light on it, What are your reasons for saying that the atomic electrons do not absorb the incident photon?

regards

sam

Er... where did I say that??!

Zz.

 

[CarlB]

Can you please cite the journals where these papers have been published? Thanks.

The articles by Yoshio Koide and me (Carl Brannen) were only completed in late April or May of this year so it's too early to say "have been published". As of now, I believe that the only article scheduled to be published that uses my neutrino mass predictions is that by Mohapatra and Smirnov in the November 2006 Annual Review of Nuclear and and Particle Science, Vol. 56. The present version of this paper is here (look for an update in a month or so):
http://www.arxiv.org/abs/hep-ph/0603118

That this article will include the new neutrino mass predictions is from private communication from Alexei Smirnov; maybe he will change his mind. Dr. Smirnov mentions my name, presumably with regard to the neutrino masses, at his recent seminar talk in Munich [see page 10]:
http://users.physik.tu-muenchen.de/lsoft/seminar-talks/AlexeiSmirnov06.pdf

The above link is from here:
http://users.physik.tu-muenchen.de/lsoft/seminars.html

Uh, I should mention that the acrobat file takes such a long time to download that you are better off saving it to your computer rather than trying to open it up with your browser.

Carl

 

[samalkhaiat]

Er... where did I say that??!

1) In post#13 you said;
"But an electron does NOT absorb photon! You're confusing an atom absorbing photon via electronic transition..."

In post #20, I corrected the first part of your statement by saying;

"Free electron does not absorb or emit photon."

Then, I asked you the following question about the second part;
" So what is it in the atom, other than electron, that absorbs and emits photons? "

2) Post#24, You said;
"...they are confusing an atomic transition to mean an electron absorbing that photon."
That photon? You clearly meant that the atomic electron does not absorb the transition-causing photon. Does it not?

3) In post#25 you said;

"Correct." to somebody who claimed;

"it's not the electron itself that absorbs the photon,"

4) You also made similar statements in post #32 & 35.


regards

sam

 

[ZapperZ]

1) In post#13 you said;
"But an electron does NOT absorb photon! You're confusing an atom absorbing photon via electronic transition..."

Then you've read MORE than what I wrote. I was emphasizing that someone who says that an electron can absorb a photon is often thinking of an atomic absorption, and confusing THAT phenomenon with an electron absorbing a photon, when in fact it is the whole atom that is responsible.

I believe I've made more than enough assertion on this in this and other threads that I have never ever claim that an atom cannot absorb or emit a photon. This would be silly.

I hate to think you wasted all your effort directing this at me.

Zz.

 

[marlon]

In Compton scattering there is only one electron, right? I mean, Compton shot x-rays into some material, but the theoretical description makes no mention of the material. The essential part of Compton scattering is just some free electron which at lowest order absorbs a photon and then emits another.

Indeed, the associating Feynman diagram just needs one electron. But, what i meant to say is this : Compton scattering is a , err, "dangerous" example because people who refer to electrons absorbing photons really refer to atoms aborbing photons and thereby boosting up an electron to a higher discrete energy level. I am sure you will agree on the fact that these processes are quite different in nature (for example if you compare the discrete electronic energy levels to the energylevel of a free electron).

marlon

 

[jtbell]

Indeed, the associating Feynman diagram [for Compton scattering] just needs one electron.

In addition to your accompanying remarks, one might note that the electron in the middle portion of the diagram (after absorbing the incoming photon and before emitting the scattered photon) is virtual. That's a different sort of thing from a real electron absorbing a photon and recoiling as a real electron, which is impossible.

 

[CarlB]

Can you please cite the journals where these papers have been published? Thanks.
Zz.

Apparently, my neutrino mass formula is now officially mentioned "in the peer reviewed literature" here:

http://staging.arjournals.annualreviews.org/doi/full/10.1146/annurev.nucl.56.080805.140534

I guess I should admit that I haven't actually read the above article. But I fairly sure I'm referenced in it because I just got my first DNS hit from someone clicking through the article to my web page. I'll drive over to the local university and see what it looks like.

By the way, I've been enjoying watching DNS hits enough that I've decided to not publish other than on my own web pages. After all, it's not like it's going to hurt my career or anything.

Carl

 

[arivero]

Apparently, my neutrino mass formula is now officially mentioned "in the peer reviewed literature" here:

http://staging.arjournals.annualreviews.org/doi/full/10.1146/annurev.nucl.56.080805.140534

I guess I should admit that I haven't actually read the above article.

Very expensive journal, but the article is the one of Mohapatra & Smirnov, of course:

Neutrino Mass and New Physics
R.N. Mohapatra, A.Y. Smirnov
Annual Review of Nuclear and Particle Science. Volume 56, Page 569-628, Nov 2006

We review the present state and future outlook of our understanding of neutrino masses and mixings. We discuss what we think are the most important perspectives on the plausible and natural scenarios for neutrinos and attempt to throw light onto the flavor...Did you got time http://www.dpf2006.org/DPF06%20Participants.pdf to go pub crawling with Yoshio?

 

[Qubix]

Ok, this might sound strange, but the electron is not neutral (like the atom for example), so if the entire electron has negative charge and no internal structure, how does it maintain it's existence as an entity. I'm imagining a sphere created out of magnets...they would repel each other and the whole particle would disintegrate. This obviously does not happen to the electron, so where am I wrong? :)

 

[mmix]

electron has no internal structure, until we prove that it isn't.
"negative charges" and "no internal structure" seems to be connected each other.
what is negative charges? don't answer to me. I knew it from what we have experimented from it.

 

[enotstrebor]

The Standard Model is the best theory that we have up till now when it comes to describing the properties of elementary particles (of which the electron is one);

The SM is a wave particle duality model. Thus in effect the wave nature (double slit expiriment-wavyness) is explained via one mathematical model the particle collisional nature via another mathematical model.

It is the best theory to date but some consider the duality of the model is a weakness and some hope for a wave particle unity model, since the electron is only itself (singular) and not a split personality (duality).

The electron does not have an internal structure for several reasons in this model. No experimental verification,

From coulombic collisional analysis, using a particular mathematical model, the electrons collision appears mathematically point like. Interestingly, Compton's himself analysed non-coulombic scattering using different mathematical assumptions and resulted in an electron with a radius (I am not validating Comptons assumptions as true, just noting).

What is true is that any proposed sub-structure to the electron must explain how it can interact point like. Note that non-point spinning objects can have point like behavior. It is known as a gyroscopic reaction (about the center point of spin)

no other elementary particles to decay into,

This is not relevant to sub-structure possibilities, for example a string type substructure theory.

Also, no theory proves this possibility, in stead it is ruled out by the theory used to construct the standard model (eg field theories and group theory to govern the symmetries)...

Not true. The Standard Model does not rule out substructure. It just does not need it. but then it is a wave particle duality theory, not a wave particle unity theory so it doesn't need to have substructure to produce both the wave nature and the particle nature from a single model.

The Standard Model is not the end all and be all. Far from it. In addition to the wave particle duality nature of the SM and the singularity nature of the actuall particle, Nature is also signular, but the Standard Model has five different mathematical views (Copenhagen, Many Worlds, Transactional, etc.) of what nature is, and most of these views make nature look absurd.

Finally, the SM can not even say what the photon is. It only says how it interacts! There is no model of the photon and model of matter which when the two models are "interacted'", they produce the observed behaviors. But this is what happens in Nature (at least if you believe in a reality outside onself, etc. etc.)

 

[ZapperZ]

Er.. I'm going to lock this thread because people are replying to VERY OLD posts (pay attention to the date these are posted, people!), and also to people who are ... er ... no longer with us.

Zz.