What is the current understanding of the nature of photons?

[lightarrow]

It is easy to say Now send v --> c , but hard to do...
because we can do that, for example, for an electron, since electron EXISTS at v --> c .
Hovewer, photon do not exist at v --> c , photon exist ONLY at v = c
So, I am not sure that we may use LIMIT formalism for photon.

So, if a photon had mass, its momentum and its energy should be infinite, in that case.

 

[Mentz114]

Hi Bright,

But, if we have a choice to forget about QFT, we may think whatever we want about existence of photons between measurements

(my emphasis).
In this case, you are not doing science. You must have experimentally testable hypotheses. How do you propose to find out what's happening between measurements, without making a measurement? It's a logical conundrum.

M

 

[Bright]

How do you propose to find out what's happening between measurements, without making a measurement?

I like this question so much!
Unfortunately, I have no clear answer yet ...

My first idea... if photon does not exist between measurements, its evergy does not exist as well. That means NO conservation of energy.

If we believe in conservation of energy, we MUST admit that energy of photon DOES EXIST between measurements. If energy exists between measurements, in what form it exist? The evident answer is: "In form of vulgar photon"
Thus, it seems to me that right now we just proved that photon DOES EXIST between measutements.



If you do not like this proof, I am redy to prove that Mentz114 exists ONLY when he is online. But when we see OFFLINE after his nick, that means that Mentz114, (AND EVEN THE INDIVIDUAL BEHIND THIS NICK!), is not available on the PhysicsForum, and even is not available on the Earth and is not available in the Universe.

Moral: in addition to measurements, there are another possibilities to verify existence. For example, the CONSERVATION LAWS.

Another idea. Assume on Jan. 2, 2008, at 9:00 am, we proved Pythagorean theorem. Then on Jan 10, 2008, at 9:00, we again proved this theorem. My question is: what about this theorem for period of time from Jan 3 to Jan 9? Was it valid for that period of time? According to YOUR consideration, Pythagorean theorem not only was not verified for that period of time, it even did not existed at all between couple of its actual proofs.

 

[Bright]

So, if a photon had mass, its momentum and its energy should be infinite, in that case.

If a photon had REST mass, its momentum and energy should be infinite at v = c

 

[lightarrow]

My first idea... if photon does not exist between measurements, its evergy does not exist as well. That means NO conservation of energy.
If we believe in conservation of energy, we MUST admit that energy of photon DOES EXIST between measurements. If energy exists between measurements, in what form it exist? The evident answer is: "In form of vulgar photon"
Thus, it seems to me that right now we just proved that photon DOES EXIST between measutements.

You started with "If we believe in conservation of energy..." and you finish with "we just proved that photon DOES EXIST". My question is: "believing" is enough as "prove"?

Moral: in addition to measurements, there are another possibilities to verify existence. For example, the CONSERVATION LAWS.

Faith on conservation laws is not physics. Conservation laws are valid as long as they are experimentally valid.

 

[lightarrow]

If a photon had REST mass, its momentum and energy should be infinite at v = c

Can you please write down the equations defining photon's energy and momentum as functions of your inertial mass?

 

[Bright]

You started with "If we believe in conservation of energy..." and you finish with "we just proved that photon DOES EXIST". My question is: "believing" is enough as "prove"?
Faith on conservation laws is not physics. Conservation laws are valid as long as they are experimentally valid.

OK, forget about "believing in conservation of energy"...

Conservation of energy is a law of physics and all of us never heard about its violations.
So, starting with experimentally established law of conservation energy, we can prove that photon exists between measurements. Otherwise law of conservation of energy is wrong.

 

[Bright]

Can you please write down the equations defining photon's energy and momentum as functions of your inertial mass?

No, I cannot, because photon's energy and momentum ARE NOT functions of inertial mass.
They are functions of frequency only

$$E = h\nu$$

$$p = h\nu / c$$

 

[lightarrow]

No, I cannot, because photon's energy and momentum ARE NOT functions of inertial mass.
They are functions of frequency only

$$E = h\nu$$

$$p = h\nu / c$$

So, where is the physical meaning of your "inertial mass"?

 

[Bright]

So, where is the physical meaning of your "inertial mass"?

The couple of expressions for E and p do not describe ALL PROPERTIES of photons. There are many other properties of photon not included in these expressions, for example interference, difraction etc.

We may 'feel' physical meaning of "inertial mass" when we are trying to change absolute speed of photon. But photon is RESISTING so much. We cannot change its absolute speed even a little bit. That means its inertial mass (tangential component of it) is very large, or even infinity.

 

[lightarrow]

The couple of expressions for E and p do not describe ALL PROPERTIES of photons. There are many other properties of photon not included in these expressions, for example interference, difraction etc.

We may 'feel' physical meaning of "inertial mass" when we are trying to change absolute speed of photon. But photon is RESISTING so much. We cannot change its absolute speed even a little bit. That means its inertial mass (tangential component of it) is very large, or even infinity.

So, your "infinite inertial mass of a photon" is just another name for "light's speed doesn't change"? Why the need of another name, then?

 

[Mentz114]

We may 'feel' physical meaning of "inertial mass" when we are trying to change absolute speed of photon. But photon is RESISTING so much. We cannot change its absolute speed even a little bit. That means its inertial mass (tangential component of it) is very large, or even infinity.

Wrong logic. You can't apply a force to a photon, so discussing it's inertial mass is a waste of time. It is wrong to apply calssical mechanics, eg F=ma, to photons, as you've been told a dozen times.

Classical reasoning applied to the bending of light around the sun does not agree with experiment. I think that demonstrates the futility of doing it.

 

[Bright]

So, your "infinite inertial mass of a photon" is just another name for "light's speed doesn't change"?

Yes. it is! At last, lightarrow was the first who understood what I am saying...

Why the need of another name, then?

Because if we use the PREVIOUS name, we must think why we cannot change light speed.
But if we use the NEW name, we must not think why we cannot change light speed.

This just a way of unification of physical concepts... We just MINIMIZED number of concepts, which are necessary to explain everything we can observe in nature.

 

[Bright]

Wrong logic. You can't apply a force to a photon, so discussing it's inertial mass is a waste of time.

Wrong statement. In my post about reflection photons from MOVING MIRROR (my post #82 in this topic), I EXPLAINED HOW TO APPLY A FORCE TO PHHOTON. When we move mirror, we must apply ADDITIONAL FORCE. In result, energy of photons becomes larger after reflection from moving mirror.

It is wrong to apply calssical mechanics, eg F=ma, to photons, as you've been told a dozen times.

I never applied classical mechaniks, eg F=ma, to photon. I just used F=ma TO EXPLAIN WHAT IS INERTIAL MASS IN NONRELATIVISTIC CASE. Then I suggested that anybody give relativistic generalization.

Classical reasoning applied to the bending of light around the sun does not agree with experiment. I think that demonstrates the futility of doing it.

Yes, I know, the difference from GR is two times, if I am not mistaken... Again, I did not use classical reasoning for photon, it was jast NONRELATIVISTIC explanation of the tern INERTIAL MASS.

 

[Mentz114]

Bright,
energy is not a relativistic invariant, so it is measured differently from different frames. This includes the frequency of light. This accounts for your 'force', so in my opinion your first premise is wrong.

Can you explain how light is lensed by gravity if it has 'infinite inertial mass' ?

M

 

[Bright]

Can you explain how light is lensed by gravity if it has 'infinite inertial mass' ?

I already explained that.
There ate TWO component of Inertial mass of photon.

Tangential component of inertial mass, which is infinity, that means absolute speed of photon cannot be incresed.

Normal (to velocity) component of inertial mass, which is NOT infinity, that means directin of photon can be changed. This means light may be lensed in gravitational field.

 

[Mentz114]

How many masses do you need ? Is there a different mass for every value of the impact parameter ? This is imaginative but it doesn't clarify anything.

Predict the experimentally determined deflections, and I'll grant you have achieved something.

M

 

[ZapperZ]

In your response to Mentz114 query, please also include exact, peer-reviewed references to support your claim of the two component masses, keeping in mind the PF Guidelines on speculative, personal theory.

Zz.

 

[jostpuur]

In your response to Mentz114 query, please also include exact, peer-reviewed references to support your claim of the two component masses, keeping in mind the PF Guidelines on speculative, personal theory.

Zz.

To me it looks like he is doing something like this:

$$m := \frac{|F|}{|a|}$$

In relativistic case this quantity will depend on the direction of the force, so he is getting different values for his mass for different directions.

 

[ZapperZ]

To me it looks like he is doing something like this:

$$m := \frac{|F|}{|a|}$$

In relativistic case this quantity will depend on the direction of the force, so he is getting different values for his mass for different directions.

If so, then that would be rather absurd, don't you think? He's already arguing that a is identically zero. So how would m be any different for different direction of force? And since when is there a definition for the "transverse" component of a mass anyway?

Still, this is all rather moot since F=ma just doesn't apply to photons. If this is what is being applied here, this line of discussion is all wrong because it is based on a faulty premise.

Zz.

 

[jostpuur]

If so, then that would be rather absurd, don't you think? He's already arguing that a is identically zero. So how would m be any different for different direction of force?

$$m := \frac{|F|}{|a(F)|}$$

a=0 only when the force is in the same direction as the velocity of the photon. a depends on the force, and gets non-zero values for other directions, since it is possible to change the direction of the photon.

Still, this is all rather moot since F=ma just doesn't apply to photons. If this is what is being applied here, this line of discussion is all wrong because it is based on a faulty premise.

This is why I used := sign to emphasize, that m merely became a new number with a new definition.

My opinion on the matter: Bright is underestimating the mainstream physics, and insists figuring stuff out his own way and using his own terminology. Not really the same as proposing a speculative personal theory, yet, though.

 

[Bright]

To me it looks like he is doing something like this:
...

I am not doing something like that...

My opinion on the matter: Bright is underestimating the mainstream physics

Wrong! I know what mainstream physics is.

... and insists figuring stuff out his own way and using his own terminology.

I have many published papers with figuring stuff out my own way and using my own terminology. One of them have more than hundred citation by other authors... Maybe half of my own terminology had been in 2 or 3 years after publication accepted by other authors... :zzz:

 

[Mentz114]

I have many published papers with figuring stuff out my own way and using my own terminology. One of them have more than hundred citation by other authors... Maybe half of my own terminology had been in 2 or 3 years after publication accepted by other authors...

So why on Earth have you not cited them, and the papers that cite your papers ? Your theories, expressed in this thread ( which you seem to have hijacked ) are not even wrong.

I suspect you lack the confidence to reveal yourself and cite your own work, because you know this.

 

[Bright]

Your theories, expressed in this thread are not even wrong.

Peter Woit said exactly the same words about String Theory and even published a book with that title. Thank you so much...

which you seem to have hijacked

What do you mean?

 

[Mentz114]

This thread was started by 'mephisto' with the question ' What is a photon ?' and you have turned it into a 'discussion' about mass vectors and other weird theories. That is what is meant by 'hijack'.

From an earlier post you say -

Ok! Below is a better proof. It is well established, that black holes has only mass (and sometimes momentun).

Instead of the box we have black hole. We drop proton and antiproton toward black hole. These proton and antiproton ADD mass to the original mass of black hole. Now, assume that inside black hole two our particles annihilate. This process CANNOT reduce mass of resulting (original black hole plus two our particles) mass of black hole. So, this is a proof that photons have gravitational mass.

P.S. Inertia mass of photon is more evident. Inertia is an ability of an object to RESIST to its acceleration (or deacceleration). Now, if speed of photon is v = c, there is NO WAY to make it faster or slower. That means that inertia mass of photon is INFINITY.

If this is what you call a 'proof' or even believable you are way off.

It is well established, that black holes has only mass (and sometimes momentun).
That's wrong for starters although not relevant to your 'argument'.

"Now, assume that inside black hole two our particles annihilate."
Why ? How do you claim to know what goes on beyond the event horizon ?

So, this is a proof that photons have gravitational mass.
Sheer nonsense. Energy gravitates as energy! There's no need to have any mass around at all.