Why do we need a photon to mediate the electromagnetic force?

[Cane_Toad]

No, it isn't. That's the whole issue behind EPR-type experiments! You are arguing about what Bell identified as "realism".
Zz.

Please explain which issue you are talking about from EPR, and which of his statements this is applying to. I'm getting lost in the referents.

 

[Fra]

I apologize for entering the thread so late, I don't mean to comment on the previous discussions, just comment this line...

I suppose by physical reality I mean the object possesses states separate from and independent of the measurement process.

What would you say is the difference between a measurement process and interaction process in general? Aren't measurements effectively an interaction where the outcome yields new information? Human measurements are specially designed and controlled interactions. But hardly of any other principal "nature" than say two particles interacting? Or, what would the pricipal difference be?

Assuming the idea of symmetry between observation and interaction, the idea of reality beeing independent from measurements seems to suggest that this reality would be in a different universe, since it is also independent of interactions? Which would suggest that this type of reality have no connection to the universe we live in?

IMO, something that lives it's own life, independent of interactions with me(x) lacks justification for me(x). My personal thinking is that the qualifying justifications is the interactions, because what else is there? This is still a little fuzzy, but I'm not sure how much clearer it'll get.

/Fredrik

 

[reilly]

LorentzR --You would do well to study Mandel and Wolf's Optical Coherence and Quantum Optics.Virtually anything you want to know about photons is covered. Photons are old hat because they are an extremely useful and powerful concept; really no different from the concept of time, or force, or... We and our ancestors made all this stuff up; ZapperZ is dead on target about proofs and physics.

How would you design an experiment to determine the reality of a photon?
Regards,
Reilly Atkinson

 

[LorentzR]

No, it isn't.
Zz.

Sorry I can’t agree.

The evidence for the validity of quantum mechanics comes from the comparison between what quantum mechanics predicts and the actual observed outcome of the experiments. Whether or not the quantum objects whose states are described by quantum mechanics actually have an independent physical reality is completely irrelevant to the validation process.

That's the whole issue behind EPR-type experiments! You are arguing about what Bell identified as "realism". It has nothing to do with those particles, but rather with how QM describes those particles. You are also mixing your "personal tastes" into this, which has never been a valid argument against anything in physics. It is why I asked for experimental observations in the very first place. If not, we might as well argue about our favorite colors.

Zz.

I suppose I am bringing my personal taste into my argument. My personal taste is to try not to be seduced by the experimental results into thinking what I’m seeing is evidence of the physical reality of quantum objects. I have to remember we do not have,as yet, a complete logical sequence that links the response of a detector in an experiment to the physical reality of quantum entities that are supposed to be under investigation.

 

[LorentzR]

LorentzR --You would do well to study Mandel and Wolf's Optical Coherence and Quantum Optics.Virtually anything you want to know about photons is covered. Photons are old hat because they are an extremely useful and powerful concept; really no different from the concept of time, or force, or... We and our ancestors made all this stuff up; ZapperZ is dead on target about proofs and physics.

I absolutely agree with ZapperZ's comments on proofs and physics. But his assertion that the Photon has a physical reality is inconsistent with his comments on proofs.

How would you design an experiment to determine the reality of a photon?
Regards,
Reilly Atkinson

I would think with great difficulty.

A reductionistic theory in which the photon is required to have physical reality would throw the balance of probabilities towards realism. As you say its all made up stuff and does not completely hold together.

 

[LorentzR]

I apologize for entering the thread so late, I don't mean to comment on the previous discussions, just comment this line...
What would you say is the difference between a measurement process and interaction process in general? Aren't measurements effectively an interaction where the outcome yields new information? Human measurements are specially designed and controlled interactions. But hardly of any other principal "nature" than say two particles interacting? Or, what would the pricipal difference be?

Assuming the idea of symmetry between observation and interaction, the idea of reality beeing independent from measurements seems to suggest that this reality would be in a different universe, since it is also independent of interactions? Which would suggest that this type of reality have no connection to the universe we live in?

IMO, something that lives it's own life, independent of interactions with me(x) lacks justification for me(x). My personal thinking is that the qualifying justifications is the interactions, because what else is there? This is still a little fuzzy, but I'm not sure how much clearer it'll get.

/Fredrik

I suspect that quantum systems continuously interact with the rest of the universe and are fully connected to the universe we live in.

In order for an observation to be made the effect of an interaction must be amplified into a detectable event. Then there must be somebody there to observer the event.

For a “particle” to have physical reality it must have a universe to interact with and be able to reference the magnitude of its physical states.

 

[LorentzR]

What are you saying about the relationship of physical to quantum? They do have a loose relationship in that one models the other.

We do not have a wholly reductionistic theory modelling one with the other. We depend on the Born rule for quantum mechaics to work.

I don't understand how the quantum object is "separate and independent" from observable results. The quantum object predicts the results, although this doesn't imply unity between object and result.

Quantum mechanics predicts the results.

 

[XVX]

I’m particular interested in the Pseudo-Riemann manifold where the contracted Riemann-Christoffel tensor vanishes. This is the event arena of general relativity where the geometry is locally modeled on the Minkowski metric.

Accepting the validity of relativity then a four-fold Riemann space-time must be rejected as the event arena for the physical world. We are left with the Pseudo-Riemannian Space-time.

My question is how does the photon (and the graviton) fit into such an event arena.

My feeling is, historically, these particles were initially invented to explain action at distance at a time when the geometry world was falsely thought to be Riemannian in nature. Riemannian Geometry being locally modeled on Euclid.

There is no metric for the Universe. And certainly, the perihelion of Mercury was not calculated with the Minkowski metric. And unquestionably, GPS systems do not use the Minkowski metric. The Minkowski metric is GR’s special case in which one has Newton’s Laws and a finite speed limit theory that is commonly known as, SR.


But why photons?

Why does matter choose energy in packets?

When EM waves are incident upon Hydrogen, is there some mechanism in Hydrogen that says, “we will wait a time ‘t’ dependent upon wave amplitude, to collect ‘E’ energy and then decide what to do with it.”?

Or does energy come in packets?

I picture particles like billiard balls surround by a potential barrier. When a photon hits Hydrogen, the photon can either, get over the barrier and be absorbed into the center or there is just a collision with the outer barriers. An EM wave of high energy, but low frequency has a bunch of balls, but individually, they are weak and none can penetrate the absorption barrier. These are photons. These are the packets of energy that bombard a target. The target is not bombarded by some solid piece of energy that the target chooses whether to take a bite out of or not and how big the bite should be. I see no contradictions with the photon, GR and Minkowski space.

QM showed this interaction with matter and quantized energy and QED was just the next step in saying, well, if EM waves are made of photons, then what about the rest of E&M? And QED has been tremendously successful, although, its greatest triumph of the anomalous magnetic dipole moment of the electron is not nearly as good for the muon.

And trying the same strategy to understand gravity in a similar way and make us believe in a graviton has been a failure. While I don’t believe in the graviton, GR reigns supreme here, Einstein was unable to formulate an EM theory with “his” strategy. And QM reigns supreme here.

As of today, IMO, the photon is the explanation for the EM forces and GR is the explanation for the gravitational force.

BTW, one step in disproving the photon would be to give a new model for the photoelectric effect………….just...for starters.

 

[Anonym]

And unquestionably, GPS systems do not use the Minkowski metric.

?

To the best of my knowledge, they do. I have no reference handy, but all algorithms (iterations, Kalmans, etc.) are based on the Minkowski interval.

Regards, Dany.

 

[cristo]

?

To the best of my knowledge, they do. I have no reference handy, but all algorithms (iterations, Kalmans, etc.) are based on the Minkowski interval.

Regards, Dany.

GPS systems involve satellites orbitting a massive body (the earth) and thus must use general relativity somewhere. In fact, GPS uses both special and general relativity. Check out this paper for more info: http://relativity.livingreviews.org/Articles/lrr-2003-1/

 

[LorentzR]

There is no metric for the Universe. And certainly, the perihelion of Mercury was not calculated with the Minkowski metric. And unquestionably, GPS systems do not use the Minkowski metric. The Minkowski metric is GR’s special case in which one has Newton’s Laws and a finite speed limit theory that is commonly known as, SR.

.

I was trying to make the distinction between Riemann space and Pseudo Riemann space.

The former is locally modeled on Euclid and the latter, as used in GR, locally modeled on Minkowski.

The metric in a gravitaional field is Schwarzschild's

 

[Anonym]

In fact, GPS uses both special and general relativity.

Thank you. Your statement is obviously correct:

“Hence, the principle of the constancy of c finds application as the fundamental concept on which the GPS is based.

Therefore, to implement Eqs. (1 ), the receiver must generally perform a different rotation for each measurement made, into some common inertial frame, so that Eqs. (1 ) apply.

For the GPS it means that synchronization of the entire system of ground-based and orbiting atomic clocks is performed in the local inertial frame, or ECI coordinate system [6].” Etc.

I refer to XVX:” There is no metric for the Universe. And certainly, the perihelion of Mercury was not calculated with the Minkowski metric. And unquestionably, GPS systems do not use the Minkowski metric. The Minkowski metric is GR’s special case in which one has Newton’s Laws and a finite speed limit theory that is commonly known as, SR.”

I am at holydays now and can’t check about Mercury. I am sure that he is wrong about it too. His statements I consider absurd.

Regards, Dany.

 

[cristo]

I am at holydays now and can’t check about Mercury. I am sure that he is wrong about it too. His statements I consider absurd.

What, particularly, about his statements are absurd? There is no "metric for the universe," since GR is a local theory.

The solution to the precission of the perehilion of Mercury was one of the great successes of GR. This certainly does not use the flat spacetime metric, but instead uses the Schwarzschild metric. You can see this derivation is many GR textbooks if you are not convinced!

 

[Mentz114]

There is a metric for the universe. It's called the Friedman-Lemaitre-Robertson-Walker metric. See any book on cosmology.

 

[Anonym]

There is no "metric for the universe," since GR is a local theory.

Perhaps I did not understand him properly. Tomorrow I will prepare the answer as needed.

Regards, Dany.

 

[lightarrow]

I picture particles like billiard balls surround by a potential barrier. When a photon hits Hydrogen, the photon can either, get over the barrier and be absorbed into the center or there is just a collision with the outer barriers. An EM wave of high energy, but low frequency has a bunch of balls, but individually, they are weak and none can penetrate the absorption barrier. These are photons. These are the packets of energy that bombard a target. The target is not bombarded by some solid piece of energy that the target chooses whether to take a bite out of or not and how big the bite should be. I see no contradictions with the photon, GR and Minkowski space...

So, which are photon's dimensions? If they existed, would they be independent of its energy? If a photon is a particle, how is its wavefunction related with the existence of that particle in a specific point of space? Is the wavefunction THE particle?

I sincerely cannot understand how you can so easily give real existence to mathematical objects.

Yes, QED has been proved up to a very high degree. Does it mean we should believe in the existence of "energy packets" flying from source to detector? Maybe; but maybe someone could, one day, describe the same results with a different theory.

Certainly, it's not the case to reject a theory that works so well! But I'm not saying this. What I mean is that I can't understand how can low energy photons exist from source A to detector B if you cannot detect them (because you destroy them in doing it).

 

[cristo]

There is a metric for the universe. It's called the Friedman-Lemaitre-Robertson-Walker metric. See any book on cosmology.

Of course, the FRW metric is as close to a model of the visible universe that we have. However, my point was that GR is a local theory, with local curvature. For example, the FRW metric would not describe the metric outside, say, a massive star. In retrospect, my point didn't really answetr the question!

Anyway, this has gotten rather off topic-- I've just noticed that this is a thread in the QP forum!

 

[ZapperZ]

So, which are photon's dimensions? If they existed, would they be independent of its energy? If a photon is a particle, how is its wavefunction related with the existence of that particle in a specific point of space? Is the wavefunction THE particle?

I sincerely cannot understand how you can so easily give real existence to mathematical objects.

Can you show me evidence in history where we actually give in THAT easily? May I remind you how much resistance the Einstein's photoelectric effect model had when it was first introduced? Should I point out to you Millikan's highly skeptical paper on it when he set out to literally falsify it? Where is this "easy" part? I want to know!

So you also have issues with the whole of classical E&M? After all, it IS nothing more than a set of "mathematical objects"? I don't see you complaining about this in the classical physics section whenever classical E&M is discussed. The energy band gap in your semiconductor is also a relic of some mathematical objects. Yet, you freely use it in your electronics.

If such a picture doesn't exist, then show me an alternative explanation to the experimental observations that I have mentioned, which, btw, NO ONE has attempted to tackle. Show me a non-photon formulation of the anti-bunching phenomenon and we'll talk. Yet, all we get are nothing more than objections due to a matter of TASTES! This is not physics and this has never been a valid argument against anything in physics.

Zz.

 

[George Jones]

?

To the best of my knowledge, they do. I have no reference handy, but all algorithms (iterations, Kalmans, etc.) are based on the Minkowski interval.

Regards, Dany.

Like cristo, I don't see how GPS calculations can be done solely with the Minkowski metric. Here's a simplified (but still quite accurate) https://www.physicsforums.com/showpost.php?p=731738&postcount=5" that uses the Schwarzschild metric and some Newtonian approximations.

 

[Anonym]

Like cristo, I don't see how GPS calculations can be done solely with the Minkowski metric.

Come on, guys! The original statement was:

And unquestionably, GPS systems do not use the Minkowski metric.

“A man ought to read just as inclination leads him; for what he reads as a task will do him little good." I find it strange that I know to read English better than you!

Thanks for the refs. Few years ago I was involved in the engineering projects connected with GPS.

Regards, Dany.

 

[George Jones]

Come on, guys! The original statement was:

Yes, and you responded

all algorithms (iterations, Kalmans, etc.) are based on the Minkowski interval.

To me, this seems to say that no other spacetime intervals are needed. Apparently, this is not what what you meant. Phrases like "all are based on" and "all are based soley on" are sometimes used interchangeably.

“A man ought to read just as inclination leads him; for what he reads as a task will do him little good." I find it strange that I know to read English better than you!

A bit of a cheap shot. Too easy.

 

[vanesch]

I absolutely agree with ZapperZ's comments on proofs and physics. But his assertion that the Photon has a physical reality is inconsistent with his comments on proofs.

I guess this comes about because when a useful theoretical concept becomes so familiar that we use it all the time, we give it some kind of "physical reality" status. Like you give "physical reality" status to the earth, the moon, your sister etc... Nevertheless, all these are nothing else but "theoretical concepts" which you use in your (intuitive) way of explaining your perceptions. "your sister" is nothing else but a theoretical concept you have that explains a lot of your perceptions (for instance, when you think that you "see your sister"). You cannot even set up "an experiment which would prove the physical reality of your sister" if you think deeply about it.
It's true that some concepts are closer to our intuition than others, so we are less eager to put its status of "physical reality" to doubt. The further away are those concepts from things that look like our "daily reality" (whatever that may mean for a relativist :-), the easier we put them in doubt.

I'm fully with ZapperZ when he says that science is just a way of putting together conceptual (theoretical) frameworks which "explain observations". Some of these frameworks are more suggestive of "physical reality" than others, simply because some are closer to the intuitive grasp we have of what we always assumed to be "part of physical reality" than others.

So what doesn't matter is the ontological question ("is it part of physical reality"), but rather the epistemological part, which determines what we can ultimately know about our perceptions - measurements - observations.

 

[lightarrow]

Can you show me evidence in history where we actually give in THAT easily? May I remind you how much resistance the Einstein's photoelectric effect model had when it was first introduced? Should I point out to you Millikan's highly skeptical paper on it when he set out to literally falsify it? Where is this "easy" part? I want to know!

So you also have issues with the whole of classical E&M? After all, it IS nothing more than a set of "mathematical objects"? I don't see you complaining about this in the classical physics section whenever classical E&M is discussed. The energy band gap in your semiconductor is also a relic of some mathematical objects. Yet, you freely use it in your electronics.

If such a picture doesn't exist, then show me an alternative explanation to the experimental observations that I have mentioned, which, btw, NO ONE has attempted to tackle. Show me a non-photon formulation of the anti-bunching phenomenon and we'll talk. Yet, all we get are nothing more than objections due to a matter of TASTES! This is not physics and this has never been a valid argument against anything in physics

Ok, but after those times (debates between Millikan and Einstein ecc.), the existence of photons was quite well established. I have never found teachers at university or physics books where someone had any doubt in it.
Certainly there has always been someone who had, but I didn't have knowledge of it.

One day, about 20 years ago, reading an article on Scientific American, I started asking myself about what a photon could actually be. At university, they couldn't say much more than "quantum of EM field". I felt as being the only one to have confused ideas, everyone else didn't seem to bother at all, students and teachers.

And now, after more than 20 years, for the first time, I know, from you, about the existence of another effect, the "antibunching effect", and (from a short search on internet) about how this "established incontrovertibly, and for the first time with visible light, that Einstein's particle picture of light could predict and explain something that a pure wave picture never could".

Incredible! This is the demonstration of the fact that I have always been totally right in having doubts about photons, despite the fact Everyone (and books) had always told me I was Completelly Wrong, mostly because of Blackbody Radiation, Photoelectric Effect, Compton Effect and everything it's written about it in every physics book!

Thank you very much, ZapperZ, you made me happy today!

Regards.

 

[Anonym]

A bit of a cheap shot. Too easy.

Believe me, even my mother tongue Russian I don’t know as required. But phrases like "all are based on" and "all are based solely on" are almost orthogonal for me since here my math background speaking.

Regards, Dany.

 

[Anonym]

"A man ought to read just as inclination leads him”.

Indeed, I present my own inclination only. The story began with:

I’m particular interested in the Pseudo-Riemann manifold where the contracted Riemann-Christoffel tensor vanishes. This is the event arena of general relativity where the geometry is locally modeled on the Minkowski metric.

Accepting the validity of relativity then a four-fold Riemann space-time must be rejected as the event arena for the physical world. We are left with the Pseudo-Riemannian Space-time.

I consider that as obviously correct statement. The second paragraph is perhaps only matter of experience. The physicists use to treat math not as a lady, but as a prostitute (for the very substantial reasons). They call Pseudo-Riemannian (Lobachevski) Space-time the Riemann space-time since to everybody clear that underlined event arena is 4-dim Minkowski. Those that seriously consider otherwise are not physicists.

Now come:

There is no metric for the Universe. And certainly, the perihelion of Mercury was not calculated with the Minkowski metric. And unquestionably, GPS systems do not use the Minkowski metric. The Minkowski metric is GR’s special case in which one has Newton’s Laws and a finite speed limit theory that is commonly known as, SR.

And now I have problem with English. What he mean “special”? If he mean “special” =“unique” than I misinterpreted him, but than it does not fit the spirit of the text above. If he mean particular among the others, nothing really special, than it is not even wrong:

L.D. Landau, E.M. Lif****z, Field Theory:”Theory of gravitation fields, founded on the SR, is called General Theory of Relativity.”

My question is how does the photon (and the graviton) fit into such an event arena.

My feeling is, historically, these particles were initially invented to explain action at distance at a time when the geometry world was falsely thought to be Riemannian in nature. Riemannian Geometry being locally modeled on Euclid.

Clearly, LorentzR is familiar neither relativistic QM nor QED nor with the history of QT.

Regards, Dany.

P.S. Sorry, our software have funny problem with E.M.

 

[LorentzR]

"A man ought to read just as inclination leads him”.

Indeed, I present my own inclination only. The story began with:
I consider that as obviously correct statement. The second paragraph is perhaps only matter of experience. The physicists use to treat math not as a lady, but as a prostitute (for the very substantial reasons). They call Pseudo-Riemannian (Lobachevski) Space-time the Riemann space-time since to everybody clear that underlined event arena is 4-dim Minkowski. Those that seriously consider otherwise are not physicists.

The Riemann metric signature is positive definite, Schwarzschild and Minkowski metrics are (p,1), hence they are not Riemannian.

Clearly, LorentzR is familiar neither relativistic QM nor QED nor with the history of QT.

Then you must have the answer to my question please enlighten me.

 

[Anonym]

The Riemann metric signature is positive definite, Schwarzschild and Minkowski metrics are (p,1), hence they are not Riemannian.

Apparently, you do not read what I wrote. In addition, Schwarzschild and Minkowski space-time are 4-dim with the signature {+,-,-,-} which is the consequence that the underlined algebraic structure is defined by 4-dim quadratic normal division algebra of the Hamilton quaternions.

Then you must have the answer to my question please enlighten me.

I already together with Zz gave you the answer: If you intend to do physics, study it.

Regards, Dany.

P.S. And try to justify your pseudonym.

 

[pmb_phy]

Because mediating it with pasta would seem awkward?

- Warren

Comments like this sever more to distract the reader rather than help solve the actual problem.

Pmb

 

[XVX]

I meant to come out swinging and show that the Minkowski metric is one “event arena” for GR, not the sole one. Thus, him claiming GR is irrelevant and therefore the photon doesn’t exist.

?

I didn’t think I was making bold statements with my examples and I didn’t mean to imply the Minkowski metric has no use, just that it is……clearly…..not the only one used.

That was the GR statements goal. Perhaps some better statements would have been:

“There is no one metric for the GR events in the Universe.”

"And unquestionably, GPS systems do not use JUST the Minkowski metric."

And I have no comment on Mercury.

Reimann manifold, pseudo-Reimann manifold, non-Euclidian geometry, Minkowski space. Why do we choose what we do?

http://en.wikipedia.org/wiki/Tests_of_general_relativity



Why the photon?

Ya know, there are people to this day that still resist QM. I can only imagine the nuttyness that people must have thought when it was first being introduced as “reality.” But what changed? The idea of “calling something” an electron, a photon? The particle picture of light came before the wave picture. QM is what made physicists say, whoa, this light particle stuff is serious business, we better call it something.

And the photon will always be. Just like Newtonian physics will always be, but not like how the Thompson Model turned out. As time progress’s, we learn more about, “what we call a photon” and our picture of it may change, but that thing called a photon will still remain. Hey, someday the photon may be a vibrating string and we will then say, that string with that mode corresponds to……….a photon.


In type II superconductors, some call the penetration of flux lines, fluxons and treat them as particles. There is a quanta of flux. While I admit that calling these flux tubes particles is a stretch of the definition, it doesn't change the fact that this quanta of flux exists. Whether it's a particle can be debated.
In general,
Doubting what people call "fluxons" means you doubt that there is a quanta of flux.

Doubting what people call "photons" means you doubt that there is a quanta of EM energy.

If QM is just some lucky model that does so well in predicting our Universe, but its explanation of reality is totally wrong, then what a colossal misfortune.

I’m not a betting man, but I’m gunna have to go with…….QM has a lot of explanations that exist in reality. The negative seems to implausible.

With all the electronics surrounding me right now as I type on this incredible device called a computer, I cannot accept this all as luck or coincidence. If I did, then I would be a physicist that believes in absolutely nothing. My only belief being, coincidence dominates.

But at some point, we have to use inductive reasoning.

 

[cristo]

“There is no one metric for the GR events in the Universe.”

Hey, I'm glad it's not just me, then. That's the point I thought you were trying to make!