Does time cease to exist for a photon?

Invalid question. Photons have a lifetime from our point of view in that they are created and destroyed via interaction with matter.

Okay, but a photon that has been moving through space uninterrupted since the Big Bang has experienced no passage in time, correct?

Originally posted by yayacatfight
Okay, but a photon that has been moving through space uninterrupted since the Big Bang has experienced no passage in time, correct?

well, there are a lot of problems with talking about the rest frame of a photon, or equivalently, time experienced by a photon. but the answer to your question is yes, insofar as you can speak about time experienced by a photon, time stops. a photon has not seen any time pass since the beginning of the universe. the best way to make sense out of this statement, i think, is to assign the photon a very small mass, and take the limit as that mass approaches 0.

lethe,

another problem with imagining photon as timeless entity is, the oscillating EM fields. don't they necessitate time, to oscillate..?

Originally posted by everneo
lethe,

another problem with imagining photon as timeless entity is, the oscillating EM fields. don't they necessitate time, to oscillate..?

yes, all kinds of logistic problems arise when you try to speak about the rest frame of the photon. however, i don t think this one is as big a deal as you think it is. in the "rest frame" of a photon, the energy of the photon is redshifted to 0. thus, the EM waves do not oscillate in that frame. there are a lot of problems with this picture, especially in a quantum treatment (e.g. no such thing as zero oscillation), so if you like, give the photon a small mass, and take the limit as it goes to zero. actually, there are some difficult problems with giving the photon any nonzero mass in the quantum picture as well. so i m just gonna wave my hands now.

*wave wave*

whatever.

lethe,

Originally posted by lethe
so if you like, give the photon a small mass, and take the limit as it goes to zero. actually, there are some difficult problems with giving the photon any nonzero mass in the quantum picture as well. so i m just gonna wave my hands now.


giving photon a small mass, say m0 -->0, makes some sense to me. since from the emittance to its destruction the photon maintains constant velocity so there is no question of increase in m0. also "time dilates to infinity" does not say time freezes absolutely. and photon follows the very axiom it gives rise to, am i right.?.

i understand there are difficult problems in giving a nonzero mass to photon. still you can discuss the pros and cons of this situation. actually this is bothering me for quite sometime. just want to get the mess cleared up in my mind.

Originally posted by everneo
lethe,



giving photon a small mass, say m0 -->0, makes some sense to me. since from the emittance to its destruction the photon maintains constant velocity so there is no question of increase in m0. also "time dilates to infinity" does not say time freezes absolutely. and photon follows the very axiom it gives rise to, am i right.?.

i understand there are difficult problems in giving a nonzero mass to photon. still you can discuss the pros and cons of this situation. actually this is bothering me for quite sometime. just want to get the mess cleared up in my mind.

i m not quite sure what you re asking there. OK, let s give the photon some small mass, and forget about the problems this causes for now.

increase in m0? m0 is rest mass, it is a constant. it doesn t depend on velocity. (don t use the concept of relativistic mass. it is anachronistic and misleading)

time dilates to zero, not infinity, as your speed increases to c. but remember, if the photon has some mass, then it cannot travel at c, so time will not freeze for it. that was the whole point of giving it some mass, remember? so that we can talk about it s rest frame, without time stopping.

"photon follows the axiom it gives rise to". i m not sure what this means. what axiom?

You can't prove an axiom using that axiom. An axiom of relativity is

C is constant for all observers.

Thus put a rest frame on the photon, and the photon must have a speed of c in that rest frame.

Paradox?

:)

lethe,


"If the rest mass of the photon was non-zero, the theory of quantum electrodynamics would be "in trouble" primarily through loss of gauge invariance, which would make it non-renormalizable; also, charge-conservation would no longer be absolutely guaranteed, as it is if photons have vanishing rest-mass. However, whatever theory says, it is still necessary to check theory against experiment.

It is almost certainly impossible to do any experiment which would establish that the photon rest mass is exactly zero. The best we can hope to do is place limits on it. A non-zero rest mass would lead to a change in the inverse square Coulomb law of electrostatic forces. There would be a small damping factor making it weaker over very large distances.

The behavior of static magnetic fields is likewise modified. A limit on the photon mass can be obtained through satellite measurements of planetary magnetic fields. The Charge Composition Explorer spacecraft was used to derive a limit of 6x10-16 eV with high certainty. This was slightly improved in 1998 by Roderic Lakes in a laborartory experiment which looked for anomalous forces on a Cavendish balance. The new limit is 7x10-17 eV. Studies of galactic magnetic fields suggest a much better limit of less than 3x10-27 eV but there is some doubt about the validity of this method."

http://math.ucr.edu/home/baez/physics/ParticleAndNuclear/photon_mass.html


the limit on the photon mass does not reduce its velocity and its constant throughout its existence.


about time dilation :


you are talking about increment in time - that is sure 0.
i meant any unit of time, say 1 sec. - as per gamma correction its goes to infinity.


Please see and comment on the response (where no mass, no time etc) below. thanks

______________________________________________


ryans,


i did not try to prove any thing. i just focus on consistency of the axiom of constant c.

If the axiom includes the rest frame of reference of the photon itself then it is still consistent. because if the time dilation is applicable to photon then its not 'photon' anymore in that frame of reference for there won't be anymore oscillations of EM fields (pl note the time is frozen) that 'photon' need to have as a wave. that frame of reference is as valid as (or atleast not invalidated for variable c) any other frame of reference where c is constant.

This is where theory moves off into fantasy. As per axiom 1

All observers measure the same value for c.

This implies that photons DO NOT HAVE REST FRAMES. You cannot use time dialtion and length contraction formula's in the limit of
m->0 and v->c. Photons form part of the axiom, thus the theory does not apply to them. The arguements are purely mathematical conjectures.

It's stupid to give a photon a relativistic frame of reference as any frame of reference must have photons travelling at the speed of light. Therefore the photon 'at rest' must be travelling at the speed of light compared to itself!!!!

its equally stupid to argue that the photon is at rest in that frame. hmm.. resting photon is not a photon at all ; let alone the question of c, its fixed velocity..:p

everneo,

[ By: icsd:It's stupid to give a photon a relativistic frame of reference as any frame of reference must have photons travelling at the speed of light. Therefore the photon 'at rest' must be travelling at the speed of light compared to itself!!!!


By everneo:its equally stupid to argue that the photon is at rest in that frame. hmm.. resting photon is not a photon at all ; let alone the question of c, its fixed velocity.


Question: Assuming an observer is traveling along side your photon at 99.9999999c. We claim the observer sees the photon still going v =c. By what magic do we all of a sudden believe that at c (the photon velocity considering itself at rest) wouldn't still see itself going c? I know its stupid but that is consistant within Relativity (I believe) to say that. In reality the photon doesn't exist at a rest velocity but I think one could still consider it a photon's rest reference point. I think I am saying that right.

1. Einstein's basic postulate says that in all reference frames c is constant. In other words there is no reference frame where photon can have velocity other than c. This effectively excludes a rest frame for photon.

2. I asked a doubt : If a photon has a rest frame and that frame does not observe that photon as a photon (as a particle or as a wave) then there is no violation of the axiom of "constancy of c at all frames."

This seems rather wierd to me too but who knows what happens at c. Instead of stamping me as fantacy fiction author it would be an interesting discussion to explain why that is not possible (oh, please don't say the axiom says so).

Isn't the search for nutrinos with restmass the same problem we are having here?

Originally posted by milton w monson
Isn't the search for nutrinos with restmass the same problem we are having here?

neutrinos follow a different set of wave equations from photons. the neutrino wave equation (and that of all fermions) allows them to have mass. the photon wave equation does not.

current theory does not allow photon to have mass, and does allow the neutrino.

There is no problem here really. The photon doesn't move anywhere. There is no 'wave' from its perspective. It only appears to move and wave from your perspective. From its own perspective, the photon is unconcerned about where it was or where its going, because its not moving, time is still. It IS the measuring stick of the universe afterall -- its length is the 'size' of space for a given time unit. You have to stop viewing time and space as they appear to you in your ordinary experience, and see them as simply dimensions with no 'character' -- hope i'm not confusing you more than you are. The photon is not conscious of its own existence, everything that 'appears' to change is only so from your own perspective -- that is, you superimpose continuity of electromagnetic wave energy traveling across the fabric of the universe to a a fleeting particle-like entity when really there is only a flow of 'information' about the state of the particle that actually moves and sort of 'appears' at each location where you thought a photon had been. That is you can think of it as a movement of the information describing its quantum state to the 'next' successive point in space, rather than the movement of any actual particle-like entity.

The fact that there is no reference frame at which the photon is 'at rest' is meaningless when the photon never really moves... the photon IS the warp and woof of the universe so to speak. Think of a transverse wave, it appears to move forward, when in reality, a bunch of points are moving up and down and not 'forward' per se. In this sense, its wave has no 'mass', but acts (i.e., follows the curvature of space-time) like something that does... see the illusion?

There is no such thing as a 'physical' world... just packets of information that superimpose 'substance' onto something that neither has form, nor color, nor sound, nor touch, nor smell...

:m: :cool:

thanks all.

gundamwing: i would appreciate any suggestions you have regarding a book i should read.

perhaps one that brought you to this comment, "There is no such thing as a 'physical' world... just packets of information that superimpose 'substance' onto something that neither has form, nor color, nor sound, nor touch, nor smell... "

Originally posted by yayacatfight
thanks all.

gundamwing: i would appreciate any suggestions you have regarding a book i should read.

perhaps one that brought you to this comment, "There is no such thing as a 'physical' world... just packets of information that superimpose 'substance' onto something that neither has form, nor color, nor sound, nor touch, nor smell... "

Actually that wasn't from any book i've read... I just put together all that I know about the world, and this is the natural conclusion I came to. Examine perception itself by logical arguments, you'll see that nothing exists except consciousness. The physical world you hold so dear, is nothing but the map that is projected in your consciousness of something "out there" which we can never really know.... because fundamentally.... all the information about "the world we see" is through our sensory organs... which themselves only exist in our mind... everything IS mind.... if you think it through, you'll see this... if you don't -- you'll call me a looney duck.

The ideas aren't too original.... you can find similar thoughts expressed by some of the philosophies of india... e.g., Ramana Maharshi... for starters....

if you want a physics oriented reading... I would suggest David Bohm...definitely gonna keep you up... there's one book i particularly found interesting... "The holographic universe"....

thanks, i'll check those out.

GundamWing

I just started reading the book you recomended "The Holographic Universe", but it is written by Michael Talbot, not David Bohm. Seems a bit crackpot at the moment, but I am going to finish it before I judge it completely.

It has made me come to a conclusion though. There are 2 types of crackpots.
There are those like MacM (not personal Mac, but this is what I know, and indeed you know you are), those who have little or know understanding of current theories and mathematics, and have no intent on understanding, but still persist to push their outrageous ideas. This crackpot has little chance of making his theory become commonly accepted as, even though the idea might be there, they have little understanding of where current theories fail and what needs to be resolved.

Then there is the second kind of crackpot. Those people like Wolfram, Bohm and even Einstein. These people know the current theories like the back of their hand, and even had a hand in formulating them, but come to the conviction that they project either an inconsistent or false sense of physical reality that a major overhaul or reinterpretation is required. Their theories usually explain all of the phenomena predicted by the theory they are replacing, but constitute a major paradigm shift in the way we view or understand physical reality.

I told my father just what you said when he used vanity press to publish his boook "Physics is Constipated".

ryans,

It has made me come to a conclusion though. There are 2 types of crackpots.
There are those like MacM (not personal Mac, but this is what I know, and indeed you know you are), those who have little or know understanding of current theories and mathematics, and have no intent on understanding, but still persist to push their outrageous ideas. This crackpot has little chance of making his theory become commonly accepted as, even though the idea might be there, they have little understanding of where current theories fail and what needs to be resolved.



ANS: I know many do not like to see me make references to UniKEF and I have been holding back on that as much as possible.

However, as long as there are those that want to assualt me (and I am not taking this personal ryans) then I will continue to defend myself and UniKEF.

First ryans, while anybody would like to be liked generally speaking, that isn't the way the world works. So your not likeing me or having a distorted view of me doesn't have any overwhelming impact upon me.

In regard to this string it did come to my mind of another parallel between this topic and UniKEF and I would like to point it out because I think it actually may mean something.

We see the invarance of light. We accept it and we mathematically model it. While it still makes no sense to us we forge ahead.

Likewise in UniKEF the field is proposed to exist as an energy gradient. That is regardless of your motion you maintain a fixed velocity to the field because (if you will) the field seems to track your motion. That is the U field is your rest frame of reference.

UniKEF energy is also an invarient field. But I see it not as the same energy shifting in bias but as a plurality of energies.

CAN THAT BE THE SAME CASE WITH LIGHT. JUST AS LIGHT CAN BE PROJECTED WITH MULTIPLE FREQUENCIES CAN IT ALSO NOT BE PROJECTED AT MULTIPLE ENERGIES OR VELOCITES FORMING A GRADIENT? DOES THAT NOT MAKE RED/BLUE SHIFT A FORM OF LORENTZ CONTRACTION?

Now I think if I should have raised this issue on this MSB about a field that acted in this fashion, I would have the loudest of objections from many here. CRACKPOT, CRACKPOT.

Yet it is exactly what we see in light and you back that to the hilt.

Think about that for just one moment.

And finally ryan, I don't take your responses to heart for three simple reasons.

1 - They are untrue.

2 - You have not yet come to realize that in fact I do know many things that you think I don't know but that I choose to disregard them as being blocks to envisioning viable alternatives.

3 - As others have pointed out on this MSB, Einstein was a patent clerk when he concieved Relativity.

AND "NO" CHROOT, I AM NOT COMPARING MYSELF TO EINSTEIN BY THIS STATEMENT. ONLY THE FACT THAT SPECIALIZED EDUCATION OR OCCUPATION IS NOT EXCLUSIVE TO HAVING REASONABLE THOUGHTS. (By that I didn't mean to imply Einstein had reasonable thoughts:D )

3 - As others have pointed out on this MSB, Einstein was a patent clerk when he concieved Relativity

Although, wasn't he well educated in physics and mathematics at the time? You know, like having degrees and stuff.

AD1,

I would think so. I was just giving my detractors a bit of heartburn.:D

GundamWing - Right on. Usually those views come from Buddhists but it sounds like you came at it from a different direction. It would be good to discuss your thinking. Usually the discussion quickly gets too mystical but it sounds like you've worked it out from the physical evidence. (I've reached the same conclusion from the same evidence).

Fancy explaining a bit about how you reached your conclusion?

Wow now you guys got me looking forward to learning some physics in university because this stuff seems so interesting. But if you assign a mass to a photon wouldn't that go againist the compton effect which said that photons have no mass.

Also talking about Einstein you guys ever see the family guy when they make fun of him being a patent clerk, HILARIOUS!!

ut if you assign a mass to a photon wouldn't that go againist the compton effect which said that photons have no mass.

PHOTONS HAVE NO MASS
PHOTONS HAVE NO MASS
PHOTONS HAVE NO MASS
PHOTONS HAVE NO MASS
PHOTONS HAVE NO MASS
PHOTONS HAVE NO MASS
PHOTONS HAVE NO MASS
PHOTONS HAVE NO MASS
PHOTONS HAVE NO MASS
PHOTONS HAVE NO MASS

ryans,

Originally posted by ryans
PHOTONS HAVE NO MASS
PHOTONS HAVE NO MASS
PHOTONS HAVE NO MASS
PHOTONS HAVE NO MASS
PHOTONS HAVE NO MASS
PHOTONS HAVE NO MASS
PHOTONS HAVE NO MASS
PHOTONS HAVE NO MASS
PHOTONS HAVE NO MASS
PHOTONS HAVE NO MASS


I do believe you meant "No Inertial Mass??? The photon has energy then it has mass. Lets not discard E = mc^2.

Photons have momentum, not mass, 2 different things. This just outlines your complete and utter lack of understanding of basic physical principles.

And yes, let's discard E=mc^2, it doesn't apply to photons. Photons have no inertial mass, gravitational mass, or any other mass you care to mention.

ryans,

Originally posted by ryans
Photons have momentum, not mass, 2 different things. This just outlines your complete and utter lack of understanding of basic physical principles.

And yes, let's discard E=mc^2, it doesn't apply to photons. Photons have no inertial mass, gravitational mass, or any other mass you care to mention.

ANS: You know better than that. And you know I know it.

I used the term inertial mass for if I had said rest mass the string would have spiraled off into the fact that photons don't exist at rest.

E = mc^2 applies to photon as well. If you recall my first night on this MSB when chroot and I became introduced, I pointed out that he had used the currently accepted format of referring to momentum rather than relavistic mass but they are infact twins.

You do not develope momentum without mass. A photons mass is directly related to its energy. Absorb its energy and it ceases to exist. So there is no inertial mass but mass due to its energy.

Or are you claiming photons have no energy? I think not.

Photons have relativistic mass, however that term isn't much used in physics anymore.

icsd,


Originally posted by jcsd
Photons have relativistic mass, however that term isn't much used in physics anymore.




ANS: Agreed but used here because of the claim photons have no mass by a fellow that otherwise likes to be very correct in detail.

I cannot believe we are at this point again.

No Mass, No Mass, No Mass.

Photons have no mass by definition. How hard is it to see this. Sure, go ahead and apply E=mc^2 to photons, but this is just ignorance. The energy of a photon is perfectly given by E=hf.

It's just like me saying that I am going to apply Einsteins theory of general relativity to the viscous flow of a liquid in a pipe. I'll rename all the components of the equation and go from there.

When yopur talking about just "mass" you never mean relativistic mass and few people even use the term relativistic mass anymore but for a while (were talking about just after Special Relativity)it was the accepted definition of mass.

Actually that wasn't from any book i've read... I just put together all that I know about the world, and this is the natural conclusion I came to. Examine perception itself by logical arguments, you'll see that nothing exists except consciousness. The physical world you hold so dear, is nothing but the map that is projected in your consciousness of something "out there" which we can never really know.... because fundamentally.... all the information about "the world we see" is through our sensory organs... which themselves only exist in our mind... everything IS mind.... if you think it through, you'll see this... if you don't -- you'll call me a looney duck.

The ideas aren't too original.... you can find similar thoughts expressed by some of the philosophies of india... e.g., Ramana Maharshi... for starters....

Or you might want to try Rene Descartes, Cogito Ergo Sum. What you say here is nothing but regurgitated Cartesian Dualism, except in your case it isn't dualistic but singular. You posit that nothing exists outside of consciousness. So I ask, how does consciousness account for the material world?

if you want a physics oriented reading... I would suggest David Bohm...definitely gonna keep you up... there's one book i particularly found interesting... "The holographic universe"....

The holographic principle is interesting, but really has little philosophical bearing as you seem to imply here. It is merely a geometrical construct used to explain certain entropic principles of horizons.

ryans,

I have no problem with symantics and generally speaking one should try to use current definition to avoid confusion but you deliberately distort the facts of the case and your propaganda misleads those that come here and don't understand the truth of the subject and for that you need to be horse whipped.

You have attacked me and others and have attempted to make us look ignorant when in fact you are hiding the truth behind symantics.

We all know that today physicists have changed the definition and only use "mass" as a word for "rest mass" or "inertial mass"

Einstein himself recognized that the old term "Relavistic Mass" was a problem. It is hard to justify "Infinite Mass". He stated "It is better not to refer to the mass of a moving body but to its momentum instead. He did not say "Relavistic Mass" was incorrect, for surely it isn't as it was used for years but physicists today like to avoid the discussion but the facts of Relativity haven't changed, they have merely been disguised by referring to a moving body's momentum.

Of course any highschool student would know that momentum can be translated to mass just as energy can be translated to mass. And no E=mc^2 is not the correct form to describe "mass of motion or energy". The correct formula is in the article below.

************** RYANS BS COVERUP ****************
quotes:
--------------------------------------------------------------------------------
Originally posted by ryans
PHOTONS HAVE NO MASS
PHOTONS HAVE NO MASS
PHOTONS HAVE NO MASS
PHOTONS HAVE NO MASS
PHOTONS HAVE NO MASS
PHOTONS HAVE NO MASS
PHOTONS HAVE NO MASS
PHOTONS HAVE NO MASS
PHOTONS HAVE NO MASS
PHOTONS HAVE NO MASS

*******************
Photons have momentum, not mass, 2 different things. This just outlines your complete and utter lack of understanding of basic physical principles.

And yes, let's discard E=mc^2, it doesn't apply to photons. Photons have no inertial mass, gravitational mass, or any other mass you care to mention.

*******************
I cannot believe we are at this point again.

No Mass, No Mass, No Mass.

Photons have no mass by definition. How hard is it to see this. Sure, go ahead and apply E=mc^2 to photons, but this is just ignorance. The energy of a photon is perfectly given by E=hf.

It's just like me saying that I am going to apply Einsteins theory of general relativity to the viscous flow of a liquid in a pipe. I'll rename all the components of the equation and go from there.
---------------------------------------------------------------------------

From one of numerous papers avail on the subject. Link provided upon request. Posted here in full to insure nothing has been taken out of context:

Photons have mass damnit, you just no longer call it mass by current definition. Energy and mass are equivelent, momentum and mass are proportional. Anything with energy or momentum must have mass."


********** Article( Bold added by me)******************

What is the Mass of a Photon?
This question falls into two parts:

Does the photon have mass, after all it has energy and energy is equivalent to mass?

This question comes up in the context of wondering whether photons are really "massless," since, after all, they have nonzero energy and energy is equivalent to mass according to Einstein's equation E=mc2.

The problem is simply that people are using two different definitions of mass. The overwhelming consensus among physicists today is to say that photons are massless.

However, it is possible to assign a "relativistic mass" to a photon which depends upon its wavelength. This is based upon an old usage of the word "mass" which, though not strictly wrong, is not used much today. See also the Faq article Does mass change with velocity?.

The old definition of mass, called "relativistic mass," assigns a mass to a particle proportional to its total energy E, and involved the speed of light, c, in the proportionality constant:

m = E / c2. (1)

This definition gives every object a velocity-dependent mass.

The modern definition assigns every object just one mass, an invariant quantity that does not depend on velocity. This is given by

m = E0 / c2, (2)

where E0 is the total energy of that object at rest.

The first definition is often used in popularizations, and in some elementary textbooks. It was once used by practicing physicists, but for the last few decades, the vast majority of physicists have instead used the second definition.

Sometimes people will use the phrase "rest mass," or "invariant mass," but this is just for emphasis: mass is mass.

The "relativistic mass" is never used at all. (If you see "relativistic mass" in your first-year physics textbook, complain! There is no reason for books to teach obsolete terminology.)

Note, by the way, that using the standard definition of mass, the one given by eqn (2), the equation "E = m c2" is not correct.

Using the standard definition, the relation between the mass and energy of an object can be written as

E = m c2 / sqrt(1 - v2/c2), (3)

or as
E2 = m2 c4 + p2 c2, (4)

where v is the object's velocity, and p is its momentum.

In one sense, any definition is just a matter of convention. In practice, though, physicists now use this definition because it is much more convenient. {{{{{The old isn't wrong but the new is just more convienient. That does not make those that still refer to it for specific discussion egg heads. It makes those that try to deny the existance of the reality of "Relavisitic mass an egg head}}}}


The "relativistic mass" of an object is really just the same as its energy, and there isn't any reason to have another word for energy: "energy" is a perfectly good word. The mass of an object, though, is a fundamental and invariant property, and one for which we do need a word.

The "relativistic mass" is also sometimes confusing because it mistakenly leads people to think that they can just use it in the Newtonian relations

F = m a (5)

and
F = G m1 m2 / r2. (6)

In fact, though, there is no definition of mass for which these equations are true relativistically: they must be generalized. The generalizations are more straightforward using the standard definition of mass than using "relativistic mass."

Oh, and back to photons: people sometimes wonder whether it makes sense to talk about the "rest mass" of a particle that can never be at rest. The answer, again, is that "rest mass" is really a misnomer, and it is not necessary for a particle to be at rest for the concept of mass to make sense. Technically, it is the invariant length of the particle's four-momentum. (You can see this from eqn (4).)

For all photons this is zero. On the other hand, the "relativistic mass" of photons is frequency dependent. UV photons are more energetic than visible photons, and so are more "massive" in this sense, a statement which obscures more than it elucidates. {{{{But that doesn't make it incorrect}}}}

Reference: Lev Okun wrote a nice article on this subject in the June 1989 issue of Physics Today, which includes a historical discussion of the concept of mass in relativistic physics.

Is there any experimental evidence that the photon has zero rest mass?

If the rest mass of the photon was non-zero, the theory of quantum electrodynamics would be "in trouble" primarily through loss of gauge invariance, which would make it non-renormalizable; also, charge-conservation would no longer be absolutely guaranteed, as it is if photons have vanishing rest-mass. However, whatever theory says, it is still necessary to check theory against experiment.

It is almost certainly impossible to do any experiment which would establish that the photon rest mass is exactly zero. The best we can hope to do is place limits on it. A non-zero rest mass would lead to a change in the inverse square Coulomb law of electrostatic forces. There would be a small damping factor making it weaker over very large distances.

The behavior of static magnetic fields is likewise modified. A limit on the photon mass can be obtained through satellite measurements of planetary magnetic fields. The Charge Composition Explorer spacecraft was used to derive a limit of 6x10-16 eV with high certainty. This was slightly improved in 1998 by Roderic Lakes in a laborartory experiment which looked for anomalous forces on a Cavendish balance. The new limit is 7x10-17 eV. Studies of galactic magnetic fields suggest a much better limit of less than 3x10-27 eV but there is some doubt about the validity of this method.



OBTW: Even the concept of "Rest Mass" for a photon is not dead". According to Gauge Theory a photon "may" have mass upwards of 1E-68 Kg and indicates that Relativity has a problem with its view of the space vacuum.


So maybe we should just try and keep things above board and, tell it like it is, and stop trying to score points on the Crackpot Board.

Originally posted by MacM
OBTW: Even the concept of "Rest Mass" for a photon is not dead". According to Gauge Theory a photon "may" have mass upwards of 1E-68 Kg and indicates that Relativity has a problem with its view of the space vacuum.

huh? i don t know where you pulled this statement from, gauge theory requires zero mass.

lethe,

Originally posted by lethe
huh? i don t know where you pulled this statement from, gauge theory requires zero mass.


ANS: Not claiming photons have mass but stating they MAY have mass upto 1E-68Kg. I'll post a link if you feel it is necessary.

Off Topic

Deja Vu - I think you missed the point. To say that "What you say here is nothing but regurgitated Cartesian Dualism, except in your case it isn't dualistic but singular" is like saying 'there's an elephant, except in this case it's a giraffe'. There's nothing necessarily dualistic (in a Cartesian sense) about idealism.

lethe,


Re: Symantics

quote:
--------------------------------------------------------------------------------
Originally posted by MacM
OBTW: Even the concept of "Rest Mass" for a photon is not dead". According to Gauge Theory a photon "may" have mass upwards of 1E-68 Kg and indicates that Relativity has a problem with its view of the space vacuum.
--------------------------------------------------------------------------------


lethe:

huh? i don t know where you pulled this statement from, gauge theory requires zero mass.


ANS: Here is the full link:

http://www.aias.us-pub-mattersagnac.pdf


Here are some extracts to look for:


Page (4) "..................... However, standard special relativity in the Einstein vacuum runs into difficulties {3} when dealing with the Sagnac effect in the massless photon, whereas..."


Page (5): ".................... The rest mass mo can be the photon rest mass, which is estimated {13} to be less than 10-68kgm."


Page (8) "........... This prediction has recently been verified experimentally by Hasselbach et al. {1} for electrons, and in a calculation by vigier {13} for photons with mass. It allows for the fact that photons may have mass".

Page (10): ".......... The topological explanation in section 2 is therefore more generally applicable and is a powerful result of gauge theory in the O(3) vacuum rather than the Einstein vacuum."


Page (10 & 11): "......... The result is the same for all matter waves, and agrees with the same calculation in special relativity that the rest mass mo is not zero in the latter calculation. When the rest mass is zero, the latter method is not applicable, but the topological result always holds to extremely high precision. It is possible that the vacuum structure is that of the Poincare' group, whose little group for finite mo is O(3)."

************************************************** *


All I was saying to ryans is that my post was more accurate than his:

PHOTONS HAVE NO MASS
PHOTONS HAVE NO MASS
PHOTONS HAVE NO MASS
PHOTONS HAVE NO MASS
PHOTONS HAVE NO MASS
PHOTONS HAVE NO MASS
PHOTONS HAVE NO MASS
PHOTONS HAVE NO MASS
PHOTONS HAVE NO MASS
PHOTONS HAVE NO MASS

I guess he feels if he says it enough times and in bold, then he will have some enfluence on his "Holographic Reality" and make it so.

Originally posted by MacM
lethe,




ANS: Not claiming photons have mass but stating they MAY have mass upto 1E-68Kg. I'll post a link if you feel it is necessary.

well, if you are telling me that 1E-68kg is the experimental upper bound for the photon mass, then OK. you may conclude that they may have mass since experiment hasn t ruled it out.

by why did you say: "according to gauge theory"? according to gauge theory, they must have 0 mass. according to experiment they might have slightly nonzero.

if you have a link that has a gauge theory with a massive boson, i d like to see it.

lethe,


Page (10): ".......... The topological explanation in section 2 is therefore more generally applicable and is a powerful result of gauge theory in the O(3) vacuum rather than the Einstein vacuum."


ANS: It is not that gauge theory predicts it but that this work suggests that it may have mass in gauge theory vacuum rather than Einstien vacuum.

Originally posted by MacM
lethe,


Page (10): ".......... The topological explanation in section 2 is therefore more generally applicable and is a powerful result of gauge theory in the O(3) vacuum rather than the Einstein vacuum."


ANS: It is not that gauge theory predicts it but that this work suggests that it may have mass in gauge theory vacuum rather than Einstien vacuum.

buh? einstein vacuum? i don t know what you re talking about.

lethe,

I can't answer that either but they seem to think there is a difference. Did you look at the full link. They don't describe it they just mention it in contrast to the gauge O(3) vacuum; which I have no knowledge of either..

The topological explanation in section 2 is therefore more generally applicable and is a powerful result of gauge theory in the O(3) vacuum rather than the Einstein vacuum."

Do you know what O(3) vacuum is Mac. It is simply cartesian topology, i.e. flat space. I suppose then the Einstein vacuum may be O(4) Minkowski space. You are both talking about different gauge theories.

FYI: In surfing the web I realized the link I provided above deals with the Sagnac Effect. It is the process used in optical gyroscopic equipment.

A rotating optical system simular to the MMX that produces some interesting consequences. (c+v & c-v).