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Author Topic: Might photons have mass and the speed of light not be absolute?  (Read 3376 times)

Offline Qurius

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Is it possible that photons have mass and that the speed of light is not absolute?

“IF” I understand the theory correctly, it was originally assumed that nothing can travel faster than the speed of light, and that since photons just happen to travel at the speed of light they must have no mass.

But, isn't this a circular argument? By definition, the speed at which photons travel is the speed of light.

Since light (photons) can be influenced by gravity, magnetism, and other things, is it possible that photons actually do have mass and that the particles that travel faster than photons (faster than the speed of light) simply have less mass?

I admit my “understanding” of these things is limited and dated, but this is an honest question for me.

Thank you for your help.
« Last Edit: 18/11/2015 09:05:08 by chris »


 

Offline Craig W. Thomson

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Is it possible that photons have mass and that the speed of light is not absolute?

“IF” I understand the theory correctly, it was originally assumed that nothing can travel faster than the speed of light, and that since photons just happen to travel at the speed of light they must have no mass.

But, isn't this a circular argument? By definition, the speed at which photons travel is the speed of light.

Since light (photons) can be influenced by gravity, magnetism, and other things, is it possible that photons actually do have mass and that the particles that travel faster than photons (faster than the speed of light) simply have less mass?

I admit my “understanding” of these things is limited and dated, but this is an honest question for me.

Thank you for your help.
Just for the record, I am not a scientist, just somebody interested in this stuff.

Most people here are familiar with the idea of the photon as a "force carrier." That basically means that it sort of like a piece of information. When an excited atom emits a photon, that photon carries a piece of electromagnetic information with it. It tells another particle it deflects, for instance, "deflect this direction," or if it is absorbed, it says, "oscillate at this frequency." The thing the photon is "carrying" is a message about electromagnetic force. I think it's useful to consider the photon as "carrying" mass, as well, or at least information about how much mass it will have once "bound" to a system.

Less people seem to be familiar with the concept of "binding energy." Without delving into minutiae about relativistic mass, rest mass and a lot of complicated jargon, suffice it to say that mass and energy are equivalent according to the laws of physics. You can get energy from mass, as in combustion or fusion, or you can get mass from energy, as in the case of particle accelerators where kinetic energy is turned into new particles. In short, mass and energy are interchangeable. The interesting thing, though, is that photons, while being massless as a free travelling photon in space, actually contribute a tiny amount of mass when you isolate their oscillation at a location in space and they become "bound" to that system.

My own personal statement of mass/energy equivalence is this: Energy is unbound mass that travels through space, and mass is bound energy that occupies a location in space.

I would also like to point out that photons travel as two oscillations along a straight line:

http://i.stack.imgur.com/xImFr.png

If you throw in an oscillation along the z axis, or the 3rd dimension, travelling in a straight line no longer becomes possible for the photon. It would have to stay at a location in 3 dimensional space in order to oscillate in all 3 directions at the same time, and would then exist as a particle with mass. This is sort of what happens when it becomes "bound" to a system and adds a bit of mass to the system, except that the particle it's interacting with supplies the third oscillation.

Anything with mass should be oscillating in three dimensions, and therefore cannot travel in a straight line at light speed because the z axis is involved. Photons don't oscillate in the z axis, so they set the speed limit.
« Last Edit: 15/11/2015 18:43:34 by Craig W. Thomson »
 

Offline agyejy

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If you throw in an oscillation along the z axis, or the 3rd dimension, travelling in a straight line no longer becomes possible for the photon. It would have to stay at a location in 3 dimensional space in order to oscillate in all 3 directions at the same time, and would then exist as a particle with mass. This is sort of what happens when it becomes "bound" to a system and adds a bit of mass to the system, except that the particle it's interacting with supplies the third oscillation.

Anything with mass should be oscillating in three dimensions, and therefore cannot travel in a straight line at light speed because the z axis is involved. Photons don't oscillate in the z axis, so they set the speed limit.

Any beam of light with a finite diameter has a longitudinal component in addition to the normal transverse components. The longitudinal component being by definition an oscillation in the direction of travel which is by definition perpendicular to all transverse components. There is nothing about wave mechanics in general that prevents a wave with both longitudinal and transverse components from existing and traveling in a straight line at the known propagation speed of the medium through which it is traveling.

Further, it is well known that photons that are absorbed by an atom are destroyed and cease to exist. There is no continued interaction after the photon is absorbed. A photon does not become bound to an atom. It is absorbed and destroyed by the interaction.
 

Offline Craig W. Thomson

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blah, blah, blah
Not interested in having this conversation with you a second time. Once at physforum.com was bad enough. I came here to get away from the trolls, not to have you follow me here.

Let's not forget, you forgot about the electroweak interaction in that conversation, so stop trying to pass yourself off as some sort of expert.
« Last Edit: 16/11/2015 07:09:04 by Craig W. Thomson »
 

Offline Craig W. Thomson

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Any beam of light with a finite diameter has a longitudinal component in addition to the normal transverse components.
I will address this nonsense, though. A photon is a wave packet, otherwise known as a quantum of energy. It is not a "beam," nor does that beam have a diameter. This is not a 1950's sci-fi movie. Light doesn't propagate continuously like water from a firehose. It propagates in discrete lumps like baseballs from a pitching machine.
« Last Edit: 16/11/2015 07:16:54 by Craig W. Thomson »
 

Offline Colin2B

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Light doesn't propagate continuously like water from a firehose. It propagates in discrete lumps like baseballs from a pitching machine.
I like the analogy.
I tend to think of a myriad of tiny, brief flashes and also imagine throwing a bucket of marbles down a hill - moving together but totally uncorrelated in phase and polarisation except in very special circumstances.

.. The longitudinal component being by definition an oscillation in the direction of travel which is by definition perpendicular to all transverse components. 
I wouldn't say this is an oscillation by definition. What is oscillating are the transverse components and it is the variation of time along the z axis that allows us to determine the periodicity of those oscillations. An oscillation along the z axis would imply some sort of frequency modulation which I'm not aware of occuring in normal light.

I agree with what you are saying about photon absorption.
« Last Edit: 16/11/2015 11:24:53 by Colin2B »
 

Offline Thebox

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Is it possible that photons have mass and that the speed of light is not absolute?

“IF” I understand the theory correctly, it was originally assumed that nothing can travel faster than the speed of light, and that since photons just happen to travel at the speed of light they must have no mass.

But, isn't this a circular argument? By definition, the speed at which photons travel is the speed of light.

Since light (photons) can be influenced by gravity, magnetism, and other things, is it possible that photons actually do have mass and that the particles that travel faster than photons (faster than the speed of light) simply have less mass?

I admit my “understanding” of these things is limited and dated, but this is an honest question for me.

Thank you for your help.

Hello, Photons travelling through space are neutral, I like to call them a ''convertual particle'',  they have neutral mass until they hit something which by thermodynamics then converts the energy into positive  mass.
Of cause I am not a scientist, and science will tell you I am wrong.
 

Offline lightarrow

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Is it possible that photons have mass and that the speed of light is not absolute?
It' possible but it's not true at the present state of experimental results. If you look in the Particle Data Group site you find a superior limit for photon mass (I don't remember the value in this moment, I think around 10^(-50) grams).
Quote
“IF” I understand the theory correctly, it was originally assumed that nothing can travel faster than the speed of light, and that since photons just happen to travel at the speed of light they must have no mass.
But, isn't this a circular .? By definition, the speed at which photons travel is the speed of light.
It's not circular because there is however a limit speed (maximum speed of signals, which is the one used in relativity and called "c"). If photons had mass, they wouldn't travel at that maximum speed but a little bit less.
Quote
Since light (photons) can be influenced by gravity, magnetism, and other things, is it possible that photons actually do have mass and that the particles that travel faster than photons (faster than the speed of light) simply have less mass?
It's possible but in physics, when at present state something has zero mass because it's lower than the experimental precision, we simply say "it has zero mass" without specifying "for what concerns our present knowledge", because it's always implicit.

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Offline lightarrow

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Just for the record, I am not a scientist, just somebody interested in this stuff.
Same for me.
Quote
Most people here are familiar with the idea of the photon as a "force carrier." That basically means that it sort of like a piece of information. When an excited atom emits a photon, that photon carries a piece of electromagnetic information with it. It tells another particle it deflects, for instance, "deflect this direction," or if it is absorbed, it says, "oscillate at this frequency." The thing the photon is "carrying" is a message about electromagnetic force. I think it's useful to consider the photon as "carrying" mass, as well, or at least information about how much mass it will have once "bound" to a system.
No, mass is a different thing which has nothing to do with the concept you are expressing here.
Quote
Less people seem to be familiar with the concept of "binding energy." Without delving into minutiae about relativistic mass,
Better you don't talk of "relativistic mass", in fact.
Quote
rest mass and a lot of complicated jargon, suffice it to say that mass and energy are equivalent according to the laws of physics.
They are not, in fact photons have non-zero energy but zero mass.
Quote
You can get energy from mass,
Actually it's not true, but I admit I grew up with this idea too.
Quote
as in combustion or fusion, or you can get mass from energy
It's incorrect the same: the system mass doesn't change (as well as its energy).
Quote
as in the case of particle accelerators where kinetic energy is turned into new particles. In short, mass and energy are interchangeable.
It's not so simple.
Quote
The interesting thing, though, is that photons, while being massless as a free travelling photon in space, actually contribute a tiny amount of mass when you isolate their oscillation at a location in space and they become "bound" to that system.
Please let's not talk of "oscillation" in the case of photons. About "mass contribution", it's the same for every form of energy acquired by a system *which is still* in the frame of reference considered. If a photon is absorbed by an atom which then recoils, the energy acquired by the atom doesn't result in its mass increase only, but in its kinetic energy too. For this reason mass and energy are two different things.
Quote
My own personal statement of mass/energy equivalence is this: Energy is unbound mass that travels through space, and mass is bound energy that occupies a location in space.
Maybe, depending on what you mean with "unbound" and with "location in space". The central concept is that the system is *still*, that is stationary, that is its total momentum is zero. Then its mass is simply its total energy (a part a factor c^2). So a system's mass is "the system's energy in a frame of reference where the system is still" (where "still" means total momentum = 0, in the case of a system of more than a single mass point or more than a single rigid body). The fact the system must be still means that mass and energy are totally different concepts: mass requires state of motion (= 0) in its definition, energy doesn't !

No comment for the rest of what you write, because it's quite nonsense to me.
Regards.

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« Last Edit: 16/11/2015 14:31:43 by lightarrow »
 

Offline agyejy

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blah, blah, blah
Not interested in having this conversation with you a second time. Once at physforum.com was bad enough. I came here to get away from the trolls, not to have you follow me here.

Let's not forget, you forgot about the electroweak interaction in that conversation, so stop trying to pass yourself off as some sort of expert.

1) When someone tries to correct your misconceptions and teach you some valid science that is not trolling.

2) Please do not bring the drama from the other forum here it is likely to get us banned.

Any beam of light with a finite diameter has a longitudinal component in addition to the normal transverse components.
I will address this nonsense, though. A photon is a wave packet, otherwise known as a quantum of energy. It is not a "beam," nor does that beam have a diameter. This is not a 1950's sci-fi movie. Light doesn't propagate continuously like water from a firehose. It propagates in discrete lumps like baseballs from a pitching machine.

The term beam is often used to describe large numbers of coherent particles. Nothing about the word beam requires a continuous propagation.

.. The longitudinal component being by definition an oscillation in the direction of travel which is by definition perpendicular to all transverse components. 
I wouldn't say this is an oscillation by definition. What is oscillating are the transverse components and it is the variation of time along the z axis that allows us to determine the periodicity of those oscillations. An oscillation along the z axis would imply some sort of frequency modulation which I'm not aware of occuring in normal light.

I agree with what you are saying about photon absorption.

For any finite beam of photons there is a longitudinal oscillation of the electric field in addition to the transverse oscillations. This is a relatively complicated thing so it isn't really taught even in college. I'd provide a link but it would be deactivated. Instead a cursory google search for longitudinal and light should be enlightening.
 

Offline lightarrow

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Any beam of light with a finite diameter has a longitudinal component in addition to the normal transverse components.
Longitudinal "component" of what?
Quote
The longitudinal component being by definition an oscillation in the direction of travel which is by definition perpendicular to all transverse components.
An "oscillation" of what?
Quote
There is nothing about wave mechanics in general that prevents a wave with both longitudinal and transverse components from existing and traveling in a straight line at the known propagation speed of the medium through which it is traveling.
Are you talking of a light beam in the void or else?

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Offline lightarrow

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A photon is a wave packet,
Not proved.
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otherwise known as a quantum of energy.
"Wave packet" and "quantum of energy" are two different things.
Quote
Light doesn't propagate continuously like water from a firehose. It propagates in discrete lumps like baseballs from a pitching machine.
Actually you can only say that light behaves as lumps of energy in interactions but you cannot say it does it "in propagation". You can find the "lumps" when photons interact with a photographic plate, for example, but you cannot say the same is true from source to detector (photons are really mysterious things).

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« Last Edit: 16/11/2015 14:50:13 by lightarrow »
 

Offline lightarrow

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Hello, Photons travelling through space are neutral, I like to call them a ''convertual particle'',  they have neutral mass until they hit something which by thermodynamics then converts the energy into positive  mass.
Of cause I am not a scientist, and science will tell you I am wrong.
more than anything, I would say it's nonsense.

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Offline agyejy

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Any beam of light with a finite diameter has a longitudinal component in addition to the normal transverse components.
Longitudinal "component" of what?
Quote
The longitudinal component being by definition an oscillation in the direction of travel which is by definition perpendicular to all transverse components.
An "oscillation" of what?
Quote
There is nothing about wave mechanics in general that prevents a wave with both longitudinal and transverse components from existing and traveling in a straight line at the known propagation speed of the medium through which it is traveling.
Are you talking of a light beam in the void or else?

--
lightarrow

Here is a paper on the transverse component of the light. It is an oscillation of the electric field and can occur in any medium.

diposit.ub.edu/dspace/bitstream/2445/43553/1/602108.pdf
 

Offline lightarrow

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Any beam of light with a finite diameter has a longitudinal component in addition to the normal transverse components.
Longitudinal "component" of what?
Quote
The longitudinal component being by definition an oscillation in the direction of travel which is by definition perpendicular to all transverse components.
An "oscillation" of what?
Quote
There is nothing about wave mechanics in general that prevents a wave with both longitudinal and transverse components from existing and traveling in a straight line at the known propagation speed of the medium through which it is traveling.
Are you talking of a light beam in the void or else?

--
lightarrow

Here is a paper on the transverse component of the light. It is an oscillation of the electric field and can occur in any medium.

diposit.ub.edu/dspace/bitstream/2445/43553/1/602108.pdf
No, I was asking you about the "longitudinal" component.

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lightarrow
 

Offline agyejy

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Any beam of light with a finite diameter has a longitudinal component in addition to the normal transverse components.
Longitudinal "component" of what?
Quote
The longitudinal component being by definition an oscillation in the direction of travel which is by definition perpendicular to all transverse components.
An "oscillation" of what?
Quote
There is nothing about wave mechanics in general that prevents a wave with both longitudinal and transverse components from existing and traveling in a straight line at the known propagation speed of the medium through which it is traveling.
Are you talking of a light beam in the void or else?

--
lightarrow

Here is a paper on the transverse component of the light. It is an oscillation of the electric field and can occur in any medium.

diposit.ub.edu/dspace/bitstream/2445/43553/1/602108.pdf
No, I was asking you about the "longitudinal" component.

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lightarrow

Sorry that link is about the longitudinal component not the transverse component. Sorry for the miscommunication.
 

Offline Craig W. Thomson

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Just for the record, I am not a scientist, just somebody interested in this stuff.
Same for me.
Quote
Most people here are familiar with the idea of the photon as a "force carrier." That basically means that it sort of like a piece of information. When an excited atom emits a photon, that photon carries a piece of electromagnetic information with it. It tells another particle it deflects, for instance, "deflect this direction," or if it is absorbed, it says, "oscillate at this frequency." The thing the photon is "carrying" is a message about electromagnetic force. I think it's useful to consider the photon as "carrying" mass, as well, or at least information about how much mass it will have once "bound" to a system.
No, mass is a different thing which has nothing to do with the concept you are expressing here.
Quote
Less people seem to be familiar with the concept of "binding energy." Without delving into minutiae about relativistic mass,
Better you don't talk of "relativistic mass", in fact.
Quote
rest mass and a lot of complicated jargon, suffice it to say that mass and energy are equivalent according to the laws of physics.
They are not, in fact photons have non-zero energy but zero mass.
Quote
You can get energy from mass,
Actually it's not true, but I admit I grew up with this idea too.
Quote
as in combustion or fusion, or you can get mass from energy
It's incorrect the same: the system mass doesn't change (as well as its energy).
Quote
as in the case of particle accelerators where kinetic energy is turned into new particles. In short, mass and energy are interchangeable.
It's not so simple.
Quote
The interesting thing, though, is that photons, while being massless as a free travelling photon in space, actually contribute a tiny amount of mass when you isolate their oscillation at a location in space and they become "bound" to that system.
Please let's not talk of "oscillation" in the case of photons. About "mass contribution", it's the same for every form of energy acquired by a system *which is still* in the frame of reference considered. If a photon is absorbed by an atom which then recoils, the energy acquired by the atom doesn't result in its mass increase only, but in its kinetic energy too. For this reason mass and energy are two different things.
Quote
My own personal statement of mass/energy equivalence is this: Energy is unbound mass that travels through space, and mass is bound energy that occupies a location in space.
Maybe, depending on what you mean with "unbound" and with "location in space". The central concept is that the system is *still*, that is stationary, that is its total momentum is zero. Then its mass is simply its total energy (a part a factor c^2). So a system's mass is "the system's energy in a frame of reference where the system is still" (where "still" means total momentum = 0, in the case of a system of more than a single mass point or more than a single rigid body). The fact the system must be still means that mass and energy are totally different concepts: mass requires state of motion (= 0) in its definition, energy doesn't !

No comment for the rest of what you write, because it's quite nonsense to me.
Regards.

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lightarrow
Holy crap! Let's start here:

http://plato.stanford.edu/entries/equivME/

In other words, yes, mass and energy are equivalent. This is the basis of Relativity and most of modern physics.
 

Offline lightarrow

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Sorry that link is about the longitudinal component not the transverse component. Sorry for the miscommunication.
I can't open it, don't know why. Is there a copy in Arxiv.org? Which is the title of the paper?

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Offline agyejy

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Sorry that link is about the longitudinal component not the transverse component. Sorry for the miscommunication.
I can't open it, don't know why. Is there a copy in Arxiv.org? Which is the title of the paper?

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lightarrow

Transverse and longitudinal components of the propagating and evanescent waves associated to radially-polarized nonparaxial fields
 

Offline lightarrow

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In other words, yes, mass and energy are equivalent.
And if you write "mass and energy are equivalent" anyone understands what I've written?
Or maybe understands something that he/she would use in wrong equations, as almost everyday happens in forums and at school?   :)

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Offline lightarrow

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Transverse and longitudinal components of the propagating and evanescent waves associated to radially-polarized nonparaxial fields
Found, thanks. I'll have a look but don't know if I'm able to understand anything.

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Offline Craig W. Thomson

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(criag)
thanks to the Internet, now regular people think they know more than scientists.
physforum. com/index. php?showtop...=0&#entry785209
I'm 46 years old, so I knew more than some scientists before the Internet was even invented.

I've been studying science since before you became a troll, junior.

The thread topic is mass/photons/the speed of light. If you're not going to talk about that, why don't you hop back on over to physforum.com with the rest of the trolls where you belong?

By the way, please note the number of comments I have posted here, and I've already been thanked for being helpful. Agyejy got thanked even faster. Let's see you do that, LOL
« Last Edit: 17/11/2015 16:00:49 by Craig W. Thomson »
 

Offline Craig W. Thomson

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diposit.ub.edu/dspace/bitstream/2445/43553/1/602108.pdf
Did you even read that?

4.1 Introduction

"As is well known, the longitudinal component (along the propagation direction z) of a
light beam is negligible in the paraxial approximation. Consequently, the electric field
vector is assumed to be transverse to the z-axis, and represented by means of two
components."

That seems to support what I said:

"I would also like to point out that photons travel as two oscillations along a straight line....If you throw in an oscillation along the z axis, or the 3rd dimension, travelling in a straight line no longer becomes possible for the photon."

More than it supports what you said:

"Any beam of light with a finite diameter has a longitudinal component in addition to the normal transverse components. The longitudinal component being by definition an oscillation in the direction of travel which is by definition perpendicular to all transverse components."

Light speed is constant. It doesn't oscillate between two values in the direction of its travel. This statement sounds to me like you're saying light travels as a compression wave. Ha ha, that's a good one.
« Last Edit: 17/11/2015 17:54:08 by Craig W. Thomson »
 

Offline agyejy

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diposit.ub.edu/dspace/bitstream/2445/43553/1/602108.pdf
Did you even read that?

4.1 Introduction

"As is well known, the longitudinal component (along the propagation direction z) of a
light beam is negligible in the paraxial approximation. Consequently, the electric field
vector is assumed to be transverse to the z-axis, and represented by means of two
components."

That seems to support what I said:

"I would also like to point out that photons travel as two oscillations along a straight line....If you throw in an oscillation along the z axis, or the 3rd dimension, travelling in a straight line no longer becomes possible for the photon."

More than it supports what you said:

"Any beam of light with a finite diameter has a longitudinal component in addition to the normal transverse components. The longitudinal component being by definition an oscillation in the direction of travel which is by definition perpendicular to all transverse components."

For starters your statement requires absolutely no longitudinal component. It strictly forbids any longitudinal component. Secondly the paragraph is discussing the "paraxial approximation" which means that some of the physics that is happening is being ignored for simplicity. Specifically the physics that leads to the transverse component. Furthermore, you've quoted only a small section of that paragraph to make it seem like it supports your point. The entire paragraph is as follows:

Quote
As is well known, the longitudinal component (along the propagation direction z) of a
light beam is negligible in the paraxial approximation. Consequently, the electric field
vector is assumed to be transverse to the z-axis, and represented by means of two
components. This provides a considerable simplification in the calculations. However,
in a number of applications (for instance, particle trapping, high-density recording and
high-resolution microscopy, to mention only some of them), the light beam is strongly
focused and raises spot sizes smaller than the wavelength. In such cases, the paraxial
approach is no longer valid, and a nonparaxial treatment is required. This is a topic of
active research, which has been extensively studied in the last years [1-9].

Note the bolded section which discusses at length the failures of the paraxial approximation and the need for a more complete nonparaxial approach. The next paragraph elaborates:

Quote
So far, different vectorial formulations of nonparaxial electromagnetic fields have been
investigated in the literature (see, for example, [10-13]). Among them, several types of
representations based on the plane-wave angular spectrum have been reported in the last
years [5,14,15]. Such kind of decomposition has revealed to be useful because it allows
separate the contribution of the propagating and evanescent waves. In particular, the
propagating electric-field solution has been written as the sum of two terms [16]: one of
them is transverse to the propagation direction; another one exhibits a non-zero
longitudinal component and its associated magnetic field is also transverse.
Such
analytical description differs from alternative proposals appeared in the literature, also
based on the plane-wave spectrum (see [5] and references therein).

Noting a non-zero longitudinal component of the propagating electric-field solution.

Quote
Light speed is constant. It doesn't oscillate between two values in the direction of its travel. This statement sounds to me like you're saying light travels as a compression wave. Ha ha, that's a good one.

No one said the speed of light oscillates between two values in the direction of travel. Simply that the oscillation of the electric field strength has a non-zero longitudinal component. The two statements are not equivalent.
 

Offline Craig W. Thomson

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blah blah blah
Again, if a photon oscillated in the z axis, it WOULD NOT BE ABLE TO TRAVEL AT THE SPEED OF LIGHT.

Again, a photon consists of two components, one magnetic, the other electric, and these oscillate along two perpendicular planes, the intersection of which is the geodesic followed by that photon.

Again, if a particle oscillates along the x, y AND the z axis, it will have mass, and cannot travel at the speed of light.

All the technical jargon in the world will not change this simple fact.
 

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