## Photon's puzzle.

Discussions on classical and modern physics, quantum mechanics, particle physics, thermodynamics, general and special relativity, etc.

### Photon's puzzle.

Photon's puzzle.
==============
1) When photon travel  '' with absolute constant velocity its wavelength is infinite.''

https://www.pa.msu.edu/courses/1997spri ... otons.html

2)  Photon can have short  wavelengths  ''as photons with higher energy'' and
photon also can have long wavelengths.

https://www.pa.msu.edu/courses/1997spri ... otons.html

Does somebody can explain: how photon can change its infinite wavelength ( !)
to another wavelengths: short or long ?
Thanks
====================
socrat44
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### Re:   Photon's puzzle.

Sorry, but nowhere in the page you linked can I find the phrase "with absolute constant velocity its wavelength in infinite." nor is there anything even close to that on that page.

I do see where it says that" the factor g may approach infinity as the velocity approaches c."
Here the g stands in for $\gamma$, which is the gamma factor or
$\frac{1}{\sqrt{1- \frac{v^2}{c^2}}}$

I also noted that in another page of this site they give wavelength as lambda or $\lambda$, which looks a little like an inverted gamma. Did you confuse the two?

When you put something in within quote marks and then give a link, people are going to assume that you are giving a direct quote from the link.

JMP1958
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### Re:   Photon's puzzle.

JMP1958 » August 26th, 2017, 10:33 am wrote:Sorry, but nowhere in the page you linked can I find the phrase
"with absolute constant velocity its wavelength in infinite."
nor is there anything even close to that on that page.

I do see where it says that" the factor g may approach infinity as the velocity approaches c."
Here the g stands in for $\gamma$, which is the gamma factor or
$\frac{1}{\sqrt{1- \frac{v^2}{c^2}}}$

I also noted that in another page of this site they give wavelength as
lambda or $\lambda$, which looks a little like an inverted gamma.
Did you confuse the two?

When you put something in within quote marks and then give a link,
people are going to assume that you are giving a direct quote from the link.

a) when quantum of light travel with absolute constant velocity its wavelength is infinite.

b) when the factor g, that stands for . . . which is the gamma factor or . . . .
- then the story is different

c) how can the mathematical factor (g . . . . . that stands for . . . which is
the gamma factor or . . . .) change physical situation?
===========================================
socrat44
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### Re:   Photon's puzzle.

socrat44 » 26 Aug 2017, 19:58 wrote:a) when quantum of light travel with absolute constant velocity its wavelength is infinite.

b) when the factor g, that stands for . . . which is the gamma factor or . . . .
- then the story is different

c) how can the mathematical factor (g . . . . . that stands for . . . which is
the gamma factor or . . . .) change physical situation?
===========================================

Photons always travel at c relative to every inertial frame. And their wavelengths depend on their energies relative to the frame of the emitter - it cannot be infinite, for that will mean zero energy and hence no photon, since $E = hc/\lambda$.

The observed wavelength then further depends on the relative speed between emitter and observer through the relativistic gamma factor, as JMP has pointed out.

BurtJordaan
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### Re:   Photon's puzzle.

BurtJordaan » August 27th, 2017, 3:33 am wrote:
socrat44 » 26 Aug 2017, 19:58 wrote:a) when quantum of light travel with absolute constant velocity its wavelength is infinite.

b) when the factor g, that stands for . . . which is the gamma factor or . . . .
- then the story is different

c) how can the mathematical factor (g . . . . . that stands for . . . which is
the gamma factor or . . . .) change physical situation?
===========================================

Photons always travel at c relative to every inertial frame.
And their wavelengths depend on their energies relative to the frame of the emitter
- it cannot be infinite, for that will mean zero energy
and hence no photon, since $E = hc/\lambda$.

The observed wavelength then further depends on the relative speed
between emitter and observer through the relativistic gamma factor,
as JMP has pointed out.

Light  with constant speed c DOESN'T DEPEND on the emitting body.
The speed of light c is a constant and INDEPENDENT of the relative motion of the source and observer.
Light in vacuum propagates with the speed c , REGARDLESS of the state of motion of the light source.
=============================
socrat44
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### Re: Photon's puzzle.

Hi socrat44,

What you said is true but what Jorrie said was:
BurtJordaan wrote:Photons always travel at c relative to every inertial frame.

Meaning if you shot a beam of light from the rear of your spaceship to the front of your spaceship and measured the travel time, it would always be c (the speed of light). While it is true that the beam is moving slower in the forward direction of travel.. as you point out.. relative to your moving but inertial spaceship.. your clocks will also be dilated by a specific amount, dependent on your velocity. Thus.. the speed of light will always measure to take the same proper time within the spaceship, regardless of your velocity, in the forward direction.

The catch is that the measured speed of light from front to back will be much faster.. obviously. Speed c is speed c relative to the Universe and doesn't give a frack about the speed of the light source or your ship. But.. again.. there is no way to accurately measure the speed of light in one-direction due to issues of simultaneity.. or actual timing the transit time in either direction. Best you can do is measure the two way speed of light by bouncing the beam off a mirror and measuring the round trip time inside the spaceship.

The issue now is that the round trip time would be a constant, as the Universe would see it, thus with your clocks being Dilated, that round trip time should be shorter the faster you are traveling.. as it's a true Universe Time constant and not a Proper Time constant.

But...

Since we have already done this type of experiment.. and such an observation has not shown a change in round-trip time due to velocity of the experiment.. there must be more to this picture.

So now it gets even more complicated because all the Electronics involved are operating in Dilated Proper Time. Add to that.. that a reflection is not actually a simple reflection. It's absorption and re-transmission in the interaction of the Photon and the Electron shells of the material of the Mirror, dilated to Proper Time.

End results is that the two-way round-trip speed of light Time always measures the same, regardless of the velocity of the experiment.

As Jorrie has said several times on several posts, the Universe operates in such a manner as to hide our Velocity through it. Believe me when I say that I've been searching for a flaw in such for years.. to no avail. I even jumped on the dispersion and falloff of radiant light inside a spaceship.. but discovered that the aberration of light is such as to compensate for velocity. Another dead end.

The only means of checking our Absolute Velocity may be the Red/Blue shift in the CMB relative to our direction of travel. But even that only measures our velocity relative to the CMB and may not be that accurate for an Absolute velocity through the Fabric of Space-Time itself.

Regards,
Dave :^)

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### Re: Photon's puzzle.

Dave_Oblad » August 27th, 2017, 5:54 am wrote:
The only means of checking our Absolute Velocity may be the Red/Blue shift
in the CMB relative to our direction of travel. But even that only measures our
velocity relative to the CMB and may not be that accurate for an Absolute velocity
through the Fabric of Space-Time itself.

Regards,
Dave :^)

Can you explain what physical parameters ''the Fabric of Space-Time itself'' have ?

i ask this question because, . . . from your email it seems , that without
''the Fabric of Space-Time itself'' it will be hard to understand what light is.

Thanks.
=============
socrat44
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### Re: Photon's puzzle.

Hi socrat44,

By "Email", I presume you meant "Post"...? Since I have not addressed you privately yet.

As per your last question, that is a very large answer. Best (if you have the time) to look below my Picture in the upper right corner and see below that.. my "View Blog (3)" link. Click it. My primary blog is a list of posts about various subjects. The answer you want is under the top(?) post called "The Mathematical Universe".

By answer.. my posted thread is just my personal hypothesis in describing the nature of our Reality. I do it this way so I don't have to repeat my position for every new person that passes through.

Note: I am not any sort of authority or expert. By trade.. I'm an Electronics and Software Design Engineer. But I am mostly self taught from the Internet and other more knowledgeable people that frequent this site. Jorrie is at the top of my list for helping me to understand Relativity... but not as deeply as himself. My Math skills pretty much suck...lol.

Best wishes,
Dave :^)

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### Re: Photon's puzzle.

Dave_Oblad » August 27th, 2017, 10:26 pm wrote:
Hi socrat44,

see below that.. my "View Blog (3)" link. Click it.

Best wishes,
Dave :^)

The Mathematical Universe
post by Dave_Oblad on June 15th, 2016, 11:35 pm
=====================

Discovery vs. Invention:
. . . .
This would apply to all Math.
All Math Existed at the very beginning of Time, waiting to be discovered.
And if every Equation existed since time began, then so did all their
respective solutions.
The Equations and Solutions are Mathematical Truths.. and are therefore Timeless.

My conclusion:
Math was existed before beginning of the universe, more correct,
Math as Consciousnesses was existed before beginning of the universe.

The Absolute Void:
. . .
Now that I have an absolute Nothing.. can we get a Universe from it?
YES!
Because the one thing we can't exclude is Truth,
because Truth has no Physical Properties.
As stated in my opening..
Mathematical Truths are Timeless and Truths don't occupy any Space.
They simply Exist. And that's all we really need.

My opinion:
You explain what ''absolute void'' is  like a rabbi (or priest ) lecture  in
synagogue (or church).
Why do not to say, that absolute void is cold continuum with temperature T=0K.

Time:
My opinion.
A world without masses, without electrons, without an
electromagnetic field is a void world without time.

But if masses appear, if charged particles appear,
if an electromagnetic field appears then time appears too.
For example:
we live in gravity-time which was created by masses of Earth.
we live in gravity-space which was created by masses of Earth.
everybody lives some period of time until he can produce EM field.

Complexity:
My opinion.
Mathematical Universes is based on a set of rules.
This set of rules is very limited, because if you violate a small rule
you destroy an atom, a cell . . .  . the existence.

Wrap Up:
There is no arbitrary limit on their complexity.
Any intelligent life that forms in such a Universe would notice that
everything is stepped, because it is made of Cells in all directions.

My opinion.
There is limit on our physical complexity, which is made of cells
and there are limits of  the universe' s  creation.
The universe was created from simple to complex, and from simple rule / formulas
to complex equations. The simple rules and formulas can understand everybody,
the complex mathematics and physics is kingdom of very educated professionals.
=================
socrat44
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### Re: Photon's puzzle.

Is a single photon also a Maxwellian wave?
==============

Look into Wave-particle duality.
It is a major part of Quantum Mechanics which answers your question.

A quick summary: light is not just a wave, not just a particle.
In some situations it behaves like a wave; in others it behaves like a particle.
/ Cort Ammon /
https://physics.stackexchange.com/quest ... llian-wave
============================

Yeah, i can understand:
Photon is like a cow, sometime it gives milk and  sometime - beef.
/ socratus /
=======================
socrat44
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### Re: Photon's puzzle.

socrat44 » August 26th, 2017, 5:16 am wrote:  Photon's puzzle.
==============
1) When photon travel  '' with absolute constant velocity its wavelength is infinite.''

The proper time of a photon between a signal and receiver is essentially instant so a photon has no wavelength or, as you said, “Its wavelength is infinite.” All time intervals at c are instant so a wavelength and a velocity of c are mutually exclusive. This is one of many reasons why c is a spacetime dimensional constant and not a speed. You can’t separate time from space in spacetime. The constant c is a ratio giving us the amount of time found in any interval of space and it is independent of all speeds because it is a constant space/time ratio and not a speed.

The formation of light waves has been demonstrated with the Thomas Young double slit experiment. When a laser is fired through the double slit one photon at a time, each photon strikes the detector in a single spot and a single spot is not a wave. The wave pattern develops over a period of time and begins to emerge after many photons have been fired so the wavelike nature of light is not the property of a single photon. It takes many photons and a length of time to form the pattern of a light wave.

I like to think of light waves as similar to the waves we see in sand at the bottom of a stream. The moving water picks up grains of sand and deposits them one at a time in wavelike patters and in patterns differ with size and weight of the grains so moving water lays down sand particles in waves but it is not the sand particles that are waving. Light has waves because the spacetime environment is wavelike and this same environment determines which electron at the source can emit a quantum of energy (photon) and which electron in the receiver can receive a quantum of energy before the exchange takes place.

When two electrons are able to share a common harmonic connection and occupy the same light cone, a “transaction” occurs in which a quantum of energy is exchanged. Light emission and absorption are not random events.
socrat44 » August 26th, 2017, 5:16 am wrote: Photon's puzzle.
2)  Photon can have short  wavelengths  ''as photons with higher energy'' and
photon also can have long wavelengths.

In John Cramer’s “Transactional Interpretation,” a quantum of energy (photon) does not, and can not, leave an electron at a signal source until it has established a two-way, wave-like connection with an electron at the receiver. Higher energy quanta are able to arrive at closer spaced intervals than lower energy quanta so they lay down a pattern of shorter wavelengths than do lower energy quanta. The wavelength of light is determined by the wavelike nature of the spacetime environment and not by the individual photon. A single photon does not have a wave.

https://en.wikipedia.org/wiki/Transacti ... rpretation
http://www.informationphilosopher.com/s ... ts/cramer/
bangstrom
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### Re: Photon's puzzle.

bangstrom » 29 Aug 2017, 19:56 wrote:The constant c is a ratio giving us the amount of time found in any interval of space and it is independent of all speeds because it is a constant space/time ratio and not a speed.

This is a very questionable definition of 'c', because what you stated is a matter of definition or convention, not physics. The physics of spacetime is defined by events and the spacetime intervals between events. What you described roughly coincides with light-like intervals, but it is not true for time-like or space-like intervals.

The better definition of 'c' is: the maximum local speed at which all conventional matter and hence all known forms of information in the universe can travel through free space. And speed is the locally observed distance of travel divided by the locally observed time of travel over that distance.

E.g. from https://en.wikipedia.org/wiki/Physical_constant#Natural_units:
Physical constants can take many dimensional forms: the speed of light signifies a maximum speed limit of the Universe and is expressed dimensionally as length divided by time...

BurtJordaan
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### Re: Photon's puzzle.

Wow, there are personal theories all over this physics thread. Now there's no question I'm being trolled. My thread gets booted and there wasn't 1 single personal theory expressed in it.
Last edited by ralfcis on August 29th, 2017, 5:41 pm, edited 1 time in total.
ralfcis
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### Re: Photon's puzzle.

ralfcis » 29 Aug 2017, 23:09 wrote:Wow, there are personal theories all over this physics thread. Now I know I'm being trolled. My thread gets booted and there wasn't 1 single personal theory expressed in it.

Ralf, you have also been given considerable leeway before being "booted" to the personal theories section.

If the guys here attack established science, they might go the same route. As I view it presently, they are just somewhat confused...

BurtJordaan
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### Re: Photon's puzzle.

I was given that leeway for a previous thread which I agreed was over the line. It remained in physics nonetheless. There was no personal theory involved in the thread I was booted for. There was a question that went unanswered and an attempt to find the answer mathematically for myself. You did not understand my answer and I was booted summarily for no reason. Also, I got nowhere with complaining to the forum administration. If I was in the wrong they would have said something. Instead I got silence.
ralfcis
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### Re: Photon's puzzle.

And speaking of leeway I'm wondering why so many people on here are allowed to say the one-way speed of light is indeterminable. I know you've written many past threads in support of that until Don Lincoln showed up and said no; you just move 2 atomic clocks slowly apart so the movement introduces negligible relitavistic effect, fire a lazer, compare the clocks and voila, the one-way speed of light. No more anisotropy and 2 clock vs 1 clock arguments. They are clearly wrong and I'm tired of them perpetuating the same misconceptions (and there are many others) through thread after thread without being stopped by a moderator.
ralfcis
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### Re: Photon's puzzle.

ralfcis » 30 Aug 2017, 02:02 wrote:I know you've written many past threads in support of that until Don Lincoln showed up and said no; you just move 2 atomic clocks slowly apart so the movement introduces negligible relitavistic effect, fire a lazer, compare the clocks and voila, the one-way speed of light.

Don and I agreed that that his 'cables method' is "good enough for all practical purposes". Purists say that in principle Don still uses two synchronized clocks. Or more scientifically, he establishes a definition of simultaneity for the 2 points.

The "slow-moving clock" is just an approximation, because the relative movement causes a small error in the measurement. This one can compensate for using SR, but then it means using the constancy of c in the test to measure the value, to there is some circularity in the argument.

Measuring the two-way time delay with one clock and halving the delay to get the one-way delay is the only one without any ifs and buts. Especially after using it in multiple random directions.

BurtJordaan
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### Re: Photon's puzzle.

The slower you move the clocks apart, the smaller the error which means one-way c measured in this way tends to a limiting value that matches the 2-way c within acceptable experimental error. It doesn't mean it blows up into a completely unknown value. Purists use this to block any further discussion about relativity, "Well you can't make a judgement on this or that because there's no way to measure the 1-way speed of light". I say enough of that false, nit-picky, discussion-ending argument.

Did you ever see the movie, "The Paper Chase"? In it there was this annoying elitist student that kept calling his team mates "robot pimps". I never understood what that meant until this forum. It means guys who pimp ideas they don't understand to make themselves look smarter but they're really nothing but robot pimps. Now I'm that guy.
ralfcis
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### Re: Photon's puzzle.

BurtJordaan » August 29th, 2017, 3:56 pm wrote:
bangstrom » 29 Aug 2017, 19:56 wrote:The constant c is a ratio giving us the amount of time found in any interval of space and it is independent of all speeds because it is a constant space/time ratio and not a speed.

This is a very questionable definition of 'c', because what you stated is a matter of definition or convention, not physics. The physics of spacetime is defined by events and the spacetime intervals between events. What you described roughly coincides with light-like intervals, but it is not true for time-like or space-like intervals.

The better definition of 'c' is: the maximum local speed at which all conventional matter and hence all known forms of information in the universe can travel through free space. And speed is the locally observed distance of travel divided by the locally observed time of travel over that distance.

E.g. from https://en.wikipedia.org/wiki/Physical_constant#Natural_units:
Physical constants can take many dimensional forms: the speed of light signifies a maximum speed limit of the Universe and is expressed dimensionally as length divided by time...

The “speed” I described is for light-like intervals and it is not for time-like or space-like intervals. The only thing all three have in common is that they are all considered as involving ‘speed’ but one of these is not like the others. Two are variables and one is not etc., etc.. The value of c is much more like the ‘speed’ of a computer than ‘speed’ as it applies to horses or bullets where an observable object is moving through space.

The constant c functions as a true spacetime dimensional constant in relativity and nothing like a speed in the classical sense as having a velocity. Velocities can be added or subtracted from space-like or time-like intervals but not to c which suggests that c is not a speed despite being called ‘the speed of light.’ And the speed of an object is never measured by its departure and arrival times unless its speed can be observed to be constant over the distance. Light can’t be observed between signal and receiver so even the notion that light ‘travels through space’ is conjecture not supported by observation.

Space-like and time-like intervals both have an element of duration but light-like intervals do not. For light, emission and absorption are simultaneous events happening on the same light cone with no duration in between. The view that I find questionable is notion that the ‘speed’ of c is in any way similar to a ballistic speed or the the speed of a photon particle traveling through space. This equating of the two ‘speeds’ as similar is the source of much confusion and paradoxical "puzzling" onclusions.
bangstrom
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### Re: Photon's puzzle.

ralfcis » August 30th, 2017, 1:29 am wrote:The slower you move the clocks apart, the smaller the error which means one-way c measured in this way tends to a limiting value that matches the 2-way c within acceptable experimental error. It doesn't mean it blows up into a completely unknown value.

In SR, the observed time delay between two otherwise simultaneous events is one second for every 300,000 km of separation, without exception, so I don’t buy the idea that moving both clocks slower or faster or one slow and the other fast will make any difference.

The relative distances (amount of spacetime) between observers and events is the only thing that matters to the observed timing.

Our standard units of length, time, and the value of c are all mutually defined so there is circularity in all our measurements of the ‘speed’ of light. A second is a fraction of a year and a meter is a fraction of a light year so table top measurements are small scale attempts to measure the speed of light over the distance of a light year. This is an impossibility since the measurements can only return the value for c that was used in the original determinations for length and time.
bangstrom
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### Re: Photon's puzzle.

bangstrom » August 29th, 2017, 1:56 pm wrote:
socrat44 » August 26th, 2017, 5:16 am wrote:  Photon's puzzle.
==============
1) When photon travel  '' with absolute constant velocity its wavelength is infinite.''

The proper time of a photon between a signal and receiver is essentially instant
so a photon has no wavelength or, as you said, “Its wavelength is infinite.”

You are right.
Photon at speed  c   has no wavelength.
i used wrong term.
So, photon travels with constant speed  c  without wavelength as a pure particle.
Question: '' When does wavelength of photon appear ?''

Another aspect of photon.
===
One postulate of SRT says: the speed of quantum of light in a Vacuum
is a constant ( c= 299,792,458 km/ sec)  /  Michelson-Morley experiment  /
In this movement quantum of light  DOESN'T  have TIME
The time is stopped for him / it.
But this is possible only if his reference frame - vacuum -  also doesn't have time.
It means that the reference frame - VACUUM  is a TIMELESS  continuum.
==================================.
socrat44
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### Re: Photon's puzzle.

There are 3 things that can cause clocks that were perfectly sync'd together to read differently when apart. Relativistic age difference occurs as a result of the speed of separation between the clocks. It is the twin paradox effect. Then there's the relativity of simultaneity or sync offset difference strictly due to the distance between them. And finally the speed of light delay time difference. All 3 must be accounted for to get a true measure of the one way speed of light between 2 separated clocks.

I don't really care that relativity says they must be accounted for in order for the findings to agree with relativity. Relativity needs to grow a spine and stick by what it states and not always give the namby-pamby response that we don't really know for sure. How can anything be built on such a soft foundation.

I also don't care that over a light year distance these effects begin to take on significantly measurable effects to our reference frame because once you account for relativity, their effects are nullified just as they're nullified at the small scale/atomic clock reference frame. If you fear there are monsters lurking then you have no faith that atomic clocks are like a time microscope that brings relativistic effects into our reference frame at everyday speeds. Do you discount bacteria exist because you have to use (and follow the rules of use) a (space) microscope to see them?
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### Re: Photon's puzzle.

bangstrom » 30 Aug 2017, 10:53 wrote:Space-like and time-like intervals both have an element of duration but light-like intervals do not. For light, emission and absorption are simultaneous events happening on the same light cone with no duration in between.

Bang, you are making little sense in most of your reply. I have singled out the above, because from a relativistic p.o.v., the underlined part is the most blatantly false. In every inertial frame, a light-like spacetime interval has definite and measurable spatial (dx) and temporal (dt) components. The only thing that is special for light-like intervals is that dx=cdt. And two events separated by a a light-like interval cannot be simultaneous in any inertial frame!

I reiterate, the 'c' that we are talking about in relativity is the observable local propagation speed of light in free space. Since there are no "photons" (single or multiple) in relativity, we do know that light propagates between points in spacetime and is not only there when detected. Our choice of units does not influence the fact that space and time are separate entities with separate definitions - we would not have a useful concept like 'spacetime' if there were no difference.

Finally, if you want to make up your own definitions of what 'c' is, you are in the private theory territory that Ralf complained about for this thread. Or perhaps it is just a philosophical view, but it does not go in standard physics.

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### Re: Photon's puzzle.

ralfcis » 30 Aug 2017, 12:35 wrote:I don't really care that relativity says they must be accounted for in order for the findings to agree with relativity. Relativity needs to grow a spine and stick by what it states and not always give the namby-pamby response that we don't really know for sure. How can anything be built on such a soft foundation.

A good example of the sort of grumbling that causes Ralf's posts to be removed from scientific discussions. In the five+ years that I have tried, he seems to be no closer to understanding the theory that he grumbles about. Mea culpa! :)

BurtJordaan
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### Re: Photon's puzzle.

BurtJordaan » August 30th, 2017, 7:21 am wrote:
bangstrom » 30 Aug 2017, 10:53 wrote:Space-like and time-like intervals both have an element of duration but light-like intervals do not. For light, emission and absorption are simultaneous events happening on the same light cone with no duration in between.

Bang, you are making little sense in most of your reply. I have singled out the above, because from a relativistic p.o.v., the underlined part is the most blatantly false. In every inertial frame, a light-like spacetime interval has definite and measurable spatial (dx) and temporal (dt) components. The only thing that is special for light-like intervals is that dx=cdt. And two events separated by a a light-like interval cannot be simultaneous in any inertial frame!

I reiterate, the 'c' that we are talking about in relativity is the observable local propagation speed of light in free space. Since there are no "photons" (single or multiple) in relativity, we do know that light propagates between points in spacetime and is not only there when detected. Our choice of units does not influence the fact that space and time are separate entities with separate definitions - we would not have a useful concept like 'spacetime' if there were no difference.

Finally, if you want to make up your own definitions of what 'c' is, you are in the private theory territory that Ralf complained about for this thread. Or perhaps it is just a philosophical view, but it does not go in standard physics.

Could you clarify some of your statements. You said,”And two events separated by a a light-like interval cannot be simultaneous in any inertial frame!” That is true but I don’t see how it applies to the light cone itself. Are you saying that, in theory, an object traveling at the speed of light experiences space and time?

And what you mean by “local propagation speed?” I have two understandings of “local.”
One is ‘local’ from the perspective of a specific but remote observer and the other ‘local’ is from the perspective of a light emission itself. That is, the proper time of light or the view from the imagined perspective of a photon. Is (at the speed of light) not a local perspective where all ‘speeds’ become simultaneous in theory?

You say “there are no "photons" (single or multiple) in relativity” but you also say “we do know that light propagates between points in spacetime and is not only there when detected.” I find both the photon and the existence of light between signal and receiver (the traveling through part) to be conjecture lacking in physical evidence. What confidence do you have that light exists between signal and sink? And, if light has a speed, what is speeding?

I consider c to be a dimensional constant but not a speed and you claim it is a speed because it is expressed in units of distance over time. Do you consider c to be both a dimensional constant and a speed or just a speed? Also, a ratio of distance over time can be two kinds of speed. One is the familiar analog speed with an object traveling through space and the other is digital speed like the speed we see on a computer monitor where motion is from pixel to pixel with no ‘traveling through’ the space between. In the case of light, this motion would be from electron to electron. So do you consider the speed of light to be analog or digital and how can we tell the difference?
bangstrom
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### Re: Photon's puzzle.

bangstrom » 31 Aug 2017, 07:42 wrote:Are you saying that, in theory, an object traveling at the speed of light experiences space and time?

No, because no object can travel at the speed of light relative to any frame of reference. You can have muons traveling at very, very close to the speed of light in some frame, but one can still set up another inertial frame in which they are stationary - and in such frame any observer experiences space and time. And in that frame, light still propagates at c. But one cannot set up an inertial frame for light...

And what you mean by “local propagation speed?”

The relativistic understanding is local to the observer, meaning in his immediate vicinity where he can set up an experiment to measure the propagation speed of light (or anything else) locally.

You say “there are no "photons" (single or multiple) in relativity” but you also say “we do know that light propagates between points in spacetime and is not only there when detected.”

In relativity, light is a propagating electromagnetic wave and one can easily detect the progress of any wave, because you do not destroy the wave by observing its passing through whatever suitable instruments.

One is the familiar analog speed with an object traveling through space and the other is digital speed like the speed we see on a computer monitor where motion is from pixel to pixel with no ‘traveling through’ the space between.

The context is fairly obviously the former, because we measure the speed of a wave propagating through (local) space, meaning the distance it travels along your frame's spatial axis in a time interval on your clock.

In the case of light, this motion would be from electron to electron. So do you consider the speed of light to be analog or digital and how can we tell the difference?

In relativity it is from source to detector, or from one detector to the next, whatever they are made of. And it is not 'digital', whatever that may mean in the context of SR, because distance is infinitely divisible in free space.

If you go to light propagation inside a physical medium, you may need quantum field theory (QFT) to understand what is going on, but the common understanding is that the light still propagates at 'c' from atom to atom (not electron to electron, AFAIK). But, my knowledge of QFT is limited, so I do not want to go deeper into that.

BurtJordaan
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### Re: Photon's puzzle.

BurtJordaan » August 30th, 2017, 7:21 am wrote:
bangstrom » 30 Aug 2017, 10:53 wrote:Space-like and time-like intervals both have an element of duration but light-like intervals do not. For light, emission and absorption are simultaneous events happening on the same light cone with no duration in between.

Bang, you are making little sense in most of your reply. I have singled out the above, because from a relativistic p.o.v., the underlined part is the most blatantly false. In every inertial frame, a light-like spacetime interval has definite and measurable spatial (dx) and temporal (dt) components. The only thing that is special for light-like intervals is that dx=cdt. And two events separated by a a light-like interval cannot be simultaneous in any inertial frame!

How can my statement, “For light, emission and absorption are simultaneous events happening on the same light cone with no duration in between.” be false in light of your statement that, “But one cannot set up an inertial frame for light…” I agree that light is not in an inertial frame and then you demonstrate my statement as false by placing light in an inertial frame. I don’t follow.

The world has changed since 1905 so I am not necessarily trying to be consistent with SR.
bangstrom
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### Re: Photon's puzzle.

BurtJordaan » August 31st, 2017, 2:37 am wrote:No, because no object can travel at the speed of light relative to any frame of reference. You can have muons traveling at very, very close to the speed of light in some frame, but one can still set up another inertial frame in which they are stationary - and in such frame any observer experiences space and time. And in that frame, light still propagates at c. But one cannot set up an inertial frame for light...

I was including light itself as an “object” so, to narrow the question, does light experience space and time?

BurtJordaan » August 31st, 2017, 2:37 am wrote:In relativity, light is a propagating electromagnetic wave and one can easily detect the progress of any wave, because you do not destroy the wave by observing its passing through whatever suitable instruments.

This is one point where I disagree so could you explain how to observe the passing of a light wave without destroying it.

BurtJordaan » August 31st, 2017, 2:37 am wrote:The context is fairly obviously the former, because we measure the speed of a wave propagating through (local) space, meaning the distance it travels along your frame's spatial axis in a time interval on your clock.

How is measuring motion as d/t for analog motion not also true for digital motion like the speed of the moving letters on an electric signboard where there is no ‘motion through space’ but there is d/t? What observation could distinguish analog from digital motion?
BurtJordaan » August 31st, 2017, 2:37 am wrote:
In relativity it is from source to detector, or from one detector to the next, whatever they are made of. And it is not 'digital', whatever that may mean in the context of SR, because distance is infinitely divisible in free space.

Outside of SR, would you consider space to be more likely quantized or a continuum?
bangstrom
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### Re: Photon's puzzle.

bangstrom » 01 Sep 2017, 07:52 wrote:How can my statement, “For light, emission and absorption are simultaneous events happening on the same light cone with no duration in between.” be false in light of your statement that, “But one cannot set up an inertial frame for light…” I agree that light is not in an inertial frame and then you demonstrate my statement as false by placing light in an inertial frame.

I think you misunderstand the meaning of "one cannot set up an inertial frame for light". If such a frame could exist, light must be stationary in it, but also propagate at c in it - an obvious contradiction. Light is always observed (and propagating) in some inertial frame, just not in its own frame, because such does not exist. In every frame, there are always both spatial and time intervals observed between emission and absorption events of light, and they are equal.

I would be interested to hear why you think it unwise to follow SR after 2005...

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### Re: Photon's puzzle.

bangstrom » 01 Sep 2017, 08:23 wrote:
This is one point where I disagree so could you explain how to observe the passing of a light wave without destroying it.

Well, one way is to put any number of partially silvered mirrors along the path of a light flash's propagation and so detect the passing of the light from the flash. There are many more ways of detecting electromagnetic waves passing.

How is measuring motion as d/t for analog motion not also true for digital motion like the speed of the moving letters on an electric signboard where there is no ‘motion through space’ but there is d/t?

Objects and light propagate through space at a speed of delta_d/delta_ t <= c. In the case of your digital letters, nothing propagates, so it can have a speed delta_d/delta_ t > c, in fact anything to infinite. But it is comparing apples and bananas.

Outside of SR, would you consider space to be more likely quantized or a continuum?

Continuum. We have neither a theory nor any observation that says space is quantized. We think energy and and time are quantized, but not space. Because of the time-part, I think it is fair to think that spacetime is quantized.

Planck length is how far light can propagate in one Plank time, but that's not a lower limit, because particles propagate less then a Planck length in one Planck time. But, as I said before, it is outside of my field of expertise, so do not take this too seriously. The uncertainty principle probably makes the view questionably anyway.

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