What is the relative speed of photons?

[Hurkyl]

By the way, I don't understand why you made the photons go at a right angle to each other. Why not simplify the problem and have the atom emit them in opposite directions

The simplest version of his argument would go as follows:

"Consider the rest frame of the photon. The photon isn't moving at c in this frame, which is a contradiction!"

However, I would suppose that this doesn't sufficiently obfuscate his conceptual error, so he has to go and complicate the scenario in order for him to ignore the blatantly obvious.

 

[jdavel]

However, I would suppose that this doesn't sufficiently obfuscate his conceptual error, so he has to go and complicate the scenario in order for him to ignore the blatantly obvious.

Sort of like the "Triplet Paradox" used by many of StarThrower's ilk!

This thread has become more about human nature than about physics. Who can hold out longer, a mob of arguers with the certainy based on 99 years of experiments and 99+% of the world's physics community agreeing with us or one anonymous player in cyber space with who knows what motives?

Anyway I give up, he's all yours. I come here to share what I think I know, and to learn from what the rest of you know. StarThrower doesn't want the former, and he hasn't got any of the latter!

 

[MindWarrior]

The simplest version of his argument would go as follows:

"Consider the rest frame of the photon. The photon isn't moving at c in this frame, which is a contradiction!"

However, I would suppose that this doesn't sufficiently obfuscate his conceptual error, so he has to go and complicate the scenario in order for him to ignore the blatantly obvious.

If you look back at post 36, you will see something interesting.

At any moment in spacetime when t>0, the y coordinate of photon A is ct.
At any moment in spactime when t`>0, the y` coordinate of photon gun C is -ct`. Hence the following equations are true:

y = ct & y` = -ct`

From which it follows that

y/t = c & c = -y`/t`

From which it follows that:

y` = -y \frac{\t^\prime}{t}

The above transformation is correct. If we use the Lorentz transformation, we will have division by zero error.

Thus, starthrowers analysis is correct. The theory of special relativity self-contradicts.

If we finish off his analysis, the contradiction becomes clear. Photon B is moving through an inertial reference frame at a speed greater than c=299792458.

His argument begins as follows:

In the rest frame of C, the Pythagorean theorem gives the distance between photon A and photon B as a function of the spacetime coordinate t. We have:

H^2 = (ct)^2 + (ct)^2 = 2 (ct)^2

From which it follows that they hypotenuse (which is the distance between the photons) as a function of spacetime coordinate t is:

H(t) = \sqrt{2} ct

We can thus write H(t`) using the transformation above. H(t`) is the distance that photon B is from photon A, in terms of spacetime coordinate t`. The analysis will show that in the rest frame of photon A, the speed of photon B exceeds the speed of light. The rest frame of photon A is an inertial reference frame, since it is moving in a straight line at a constant speed in the rest frame of C, which is also inertial. Thus, a photon can move in an inertial reference frame at a speed greater than c.

Kind regards,

Star

 

[Hurkyl]

Thus, starthrowers analysis is correct.

...

Kind regards,

Star

You know, if you're going to pretend to be someone else, you should probably change your sig.

 

[russ_watters]

You know, if you're going to pretend to be someone else, you should probably change your sig.

Lol, hang a left and enter the surreal.

 

[Severian596]

ROTFL

I am not Severian, I am his evil twin. And I am here to tell you this discussion has degenerated into people pretending to be someone else so people will listen to...people.

HAHHAA!

 

[outandbeyond2004]

I am reminded of Bill Clinton's asking for a definiton of the verb 'to be,' (or something else?) in a legal deposition somehow.

 

[jdavel]

I am reminded of Bill Clinton's asking for a definiton of the verb 'to be,' (or something else?) in a legal deposition somehow.

outandbeyond,

Oh, it was even better than that! He said, "That depends on what your definition of the word "is" is."


And with that, I suggest that it's time for this thread to be locked!

 

[ramcg1]

?

The paragraph above does not in any way imply the conclusion.

" A photon arriving at an atom can either join that atom or continue on its journey. At each atom there is an interaction. Each time the photon moves on it moves on with the velocity c with respect to the atom it just interacted with. If that atom was traveling at a different velocity to the previous atom then SR is applied to its frequency and wavelength (it may also have to adjust its amplitude).

SR and GR are only descriptions of these interactions not the macro universe."

It does if you step out of relativistic thinking and allow the velocity of the photon to change so that it has a new velocity with repect to the previous interaction.

 

[Severian596]

It does if you step out of relativistic thinking and allow the velocity of the photon to change so that it has a new velocity with repect to the previous interaction.

Okay I'm having trouble with a couple points about this theory but I'll put them in your thread here: https://www.physicsforums.com/showthread.php?t=17809

see you there...

 

[russ_watters]

ROTFL

I am not Severian...

Ehh, it doesn't matter anyway: this board is just a text-based video game and all of you are just simulations generated by the PF server for my amusement.

Prove me wrong.

 

[dgorman]

Nonsense

StarThrower,

You are a fool. And for the record, ten years at a community college don't qualify for "[studying] at a fine northeastern university."

You've attempted to apply philosophy to physics. And you've (no surprise here) done this incorrectly. Much as it bores me to respond to crackpots, I shall (for the benefit of the poor unfortunates who might possibly be persuaded by your drivel) debunk your logic.

In order to prove a system internally inconsistent, one must assume its postulates and arrive, preferably through formal logic, at a contradictory conclusion. You, however, must begin by asserting a proposition not defined by Special Relativity--meaning that you are attempting to prove SR inconsistent outside the system. That doesn't work.

For instance:

Given that (a), "God does not exist," (b) "Only God can create humans," and (c) "Humans exist," prove that the system is internally inconsistent.

One might begin thus:

1. a (given)
2. c & b
3. c -> ~a
QED.

The point is, ST, you must begin from the rules of the system. You haven't done so, and it appears that you cannot do so. Case in point:

You propose to illustrate that SR is internally inconsistent. However, you begin by supposing an intertial frame of reference in which a photon is at rest. You can't do that--the system of SR has no concept of such a reference frame.

You haven't "proven" anything.

Therefore you are a crackpot. QED.

 

[Eyesaw]

If the speed of light is source independent then it is c relative to any observer moving at any velocity as long as the observers all referred to the vacuum frame to measure the flight path of the light. If inertial coordinates not at rest with respect to the vacuum
are used however, the speed of the light must be c + v and c-v with respect to the origin of the inertial observer because the space between the inertial observer and the photon becomes "mixed". This results in anisotropic effects inside different inertial frames because the detector of light from one direction inside an inertial frame would receive it with less energy than light from the opposite direction. So there should be different Doppler shifts of single photons inside an inertial frame, if their speeds are source independent. I.e., Einstein's two postulates contradict each other.

Only if light speed is source dependent can physics be the same inside different inertial frames. And I really think this is the case because waitresses in cafes, servers inside train cabins
moving at 52 miles per hour, and stewardesses on a 747 flying at
534 miles per hour can pour a cup of coffee right into a cup without
spilling a drop so it can't be all that difficult for light to move with a velocity dependent of its source.

Inertial coordinates are a system of coordinates, which can be represented by particles moving at a constant velocity through space, that are at rest with respect to each other. Physical interactions between these particles then should reveal the fact that they are at rest with respect to each other, else Nature's definition of the state of rest between particles would become more complicated. E.g., imagine a source and detector both moving at constant velocity represented by V or J or M or N or S or C or G or L or P or Q or any other letter of the alphabet. If light is independent of source velocity, the detector would think the source is moving relative to it even though they are at rest with respect to one another in the same inertial frame moving relative to a stationary vacuum, leading to an infinite number of definitions for rest. This would be unsatisfying on a philosophical level at least. And as mentioned previously, every day observations (events inside a car, a plane, or on an Earth moving at 30 km/sec through space - we should fall of the Earth when we take a step
if we did not have the same motion as the Earth already) verify source dependence of events for particles, and since waves are the collective motion of particles in space- if they are source dependent then so are the waves they produce. So whether depicted as a wave or as a particle, the speed of photons should depend on the velocity of the source frame, i.e., it should be c+v and c-v in the two directions with respect to the vacuum.

 

[Hurkyl]

as long as the observers all referred to the vacuum frame

How, pray tell, does one tell if they are in "the" vacuum frame? And why must there only be one?

I.e., Einstein's two postulates contradict each other.

I don't see how doppler shift causes a contradiction between the two postulates...

Only if light speed is source dependent can physics be the same inside different inertial frames.

You have it backwards. The only theory of light we have says that light speed is not source dependant. Thus, physics can only be the same inside different inertial frames if the speed of light is not source dependant.

You'll have a point once you can put forth a source dependant theory of electromagnetism that is consistent with experiment.

If light is independent of source velocity, the detector would think the source is moving relative to it

How so?

 

[quantumdude]

" A photon arriving at an atom can either join that atom or continue on its journey. At each atom there is an interaction. Each time the photon moves on it moves on with the velocity c with respect to the atom it just interacted with. If that atom was traveling at a different velocity to the previous atom then SR is applied to its frequency and wavelength (it may also have to adjust its amplitude).

SR and GR are only descriptions of these interactions not the macro universe."

Tom: ?

The paragraph above does not in any way imply the conclusion.

ramcg1: It does if you step out of relativistic thinking and allow the velocity of the photon to change so that it has a new velocity with repect to the previous interaction.

No, it doesn't follow. I'm not talking relativity, I'm talking logic. The paragraph does not contain a single premise regarding "the macro universe", and yet somehow it appears in your conclusion.

 

[OneEye]

Prove that the relative speed of the two photons is c if you can.

Regards,

StarThrower

P.S.

By Euclidean geometry, if the relative speed of the photons is c, then the two photons form an equilateral triangle with the atom, whose area is increasing in time. The interior angles of an equilateral triangle are 60 degrees. However, the emission angle was stipulated to be 90 degrees. This is a contradiction.

How can someone have such a math education and be so confused at the same time?

If two dogs leave the igloo at the same time, and travel at the same speed at right angles to each other then (according to the above logic), the dogs will form an equilateral triangle with the igloo, and thus will not be at right angles to each other!

Gadzooks! Geometry is broken! Pythagoras is busted! I and my anti-twin will immediately converge and annihilate each other, generating dark energy and forcing the galaxies apart!

The figure described by the igloo-and-dogs (or the atom and photons) is an isosceles triangle (not an equilateral) with sides ct, ct, and \sqrt { 2 } ct.

Let's make it a point to check this guy's math in the future, okay?

P.S. Someone else may already have made this comment. I confess to having been impatient enough not to read the entire thread.

 

[outandbeyond2004]

1. StarThrower is diddling us.
2. He is very careless in thinking.
3. He is congenitally unable/averse to think logically.
4. His prejudicies would take enormous effort to eradicate.
5. Some other explanation may be possible.

I don't know which of these explanations are true. However I am now going to guess that this thread is not worth perusing any more. I did gain some insights, but they came at some cost, and I feel that any more, if any, insights would not be worthwhile.
The thread did provoke some thinking (maybe good mental exercise), also, but . . .

I will lurk a little while to see what response, if any, comes to this post.

 

[geistkiesel]

An atom is at rest in an inertial reference frame. Suddenly, two photons are emitted from it, at right angles to one another.

What is the relative speed of the photons?

P.S. Assume they depart from the atom at 299792458 meters per second in the atomic frame, as has been found true by experiment.

The obvious 2c.

SR theory predicts that the relative velocity will be c. The reason for this prediciton is derived from the postulates of SR. AS you have described the experiment, a pure observation, so to speak, you have related the unambiguous experimental result that the photons are moving at the relative velocity of 2c. Any measuement of the velocity of anyone photon must show an escape velocity of c with respect to the immobile atom of the photon's birth. To mesure otherwise would contradict the experimental results.
Whatever is measured of the moving photons, The elative velocity of the photons is determined by adding the absolute value of their respective speeds (we let c = 1) to get 1^2 + 1^2 = 2. The relative part we take from the vector directions.

The SR theorists must also respond that the photons were not emitted simultaneously as measured from any moving frame. So a frame very near the emitting atom moving perpendicular (or any other angle) to the subsequently emitted photons calculates the emited photons were not simultaneously emitted, and this even if the observer on the faster frame also measures the velocity of each photon as c with respect to the host emitting atom.
SR says to revise the experimental results to conform with theory. Obedience, faith and professional security considerations sum to determine the 'real to postulated transition scenario' equates to the most expedient, the wisest option among a host of options, "shucks, its even obvious", certainly the best of all possible worlds...

We are here now where all experimental results measures a non-SR value. Alongs come SR to demonstrate that the measured experimental value, unambiguously determined, or measured, axiomatically demonstrates the relative velocity of 2c, must now be revised to be c. A demonstrated real 2c is equated to a theoretical postulated value of c. 2c = c. 2 =1. Real unergoes a transformation to a theoretically postulated variant value, where "postulated" means "formed in someone's mind".

Real is transformed to the postualtes of a dead man, Albert Einstein, graduate advisor to the host of current Special Relativity Theorists.

Does this forum have a "surrender at" window? It should.
Or is the surrender window built into the thread?

 

[quantumdude]

The obvious 2c.

Silly wabbit, it wouldn't be 2c even if Galileo's relativity were correct. They're traveling at right angles to each other, not in antiparallel paths.

SR theory predicts that the relative velocity will be c.

No, it doesn't. StarThrower's whole point was that you could make predictions from the vantage point of the rest frame of the photon. In SR, such a frame is undefined. When he goes ahead and tries to transform to a frame moving at v=c to show a contradiction in SR, he uses the LT at a point outside its domain of definition.

The reason for this prediciton is derived from the postulates of SR.

No, it's derived from your misunderstanding of those postulates.

AS you have described the experiment, a pure observation, so to speak, you have related the unambiguous experimental result that the photons are moving at the relative velocity of 2c.

Any measuement of the velocity of anyone photon must show an escape velocity of c with respect to the immobile atom of the photon's birth. To mesure otherwise would contradict the experimental results.

Does any relativity crackpot know the difference between a thought experiment and a real experiment?

Whatever is measured of the moving photons, The elative velocity of the photons is determined by adding the absolute value of their respective speeds (we let c = 1) to get 1^2 + 1^2 = 2. The relative part we take from the vector directions.

No, it isn't. Even in Galilean relativity, the relative speed is sqrt(2)c, not 2c.

The SR theorists must also respond that the photons were not emitted simultaneously as measured from any moving frame. So a frame very near the emitting atom moving perpendicular (or any other angle) to the subsequently emitted photons calculates the emited photons were not simultaneously emitted, and this even if the observer on the faster frame also measures the velocity of each photon as c with respect to the host emitting atom.

Yes, so what?

SR says to revise the experimental results to conform with theory. Obedience, faith and professional security considerations sum to determine the 'real to postulated transition scenario' equates to the most expedient, the wisest option among a host of options, "shucks, its even obvious", certainly the best of all possible worlds...

We are here now where all experimental results measures a non-SR value. Alongs come SR to demonstrate that the measured experimental value, unambiguously determined, or measured, axiomatically demonstrates the relative velocity of 2c, must now be revised to be c. A demonstrated real 2c is equated to a theoretical postulated value of c. 2c = c. 2 =1. Real unergoes a transformation to a theoretically postulated variant value, where "postulated" means "formed in someone's mind".

Real is transformed to the postualtes of a dead man, Albert Einstein, graduate advisor to the host of current Special Relativity Theorists.

Sorry, I missed the part where real data was taken in a real experiment. Could you give me the reference please?

Does this forum have a "surrender at" window? It should.
Or is the surrender window built into the thread?

No, we don't have that, but we'll have one made, just so you can wave your white flag.

 

[geistkiesel]

Undefined, since, as we've pointed out to you before, photons don't have rest frames.




Allow me to remind you that the difference of two velocity vectors in a given reference frame is not, in general, give you the relative velocity of the said objects in SR.




According to GR, the photon is traveling in a straight line, period. And, of course, photons never have inertial rest frames.

Whatever you say about rest frames is to drag SR thepry into a description of a physical event. The photons are moving from their host atom at the velocity as measured from the immobile, unambiguously located atom. The experimental results told you that the photons were moving the velocity c with respect to the host atom. Or pick some other point in the uncerse, what would you determine he velocity of c to be? I bet you will always determine c. This is fundamental to SR, tis the basic postulate. Don't forget he invariance of physical law in all inertial frames.

All you SR theorists, yopu grab this and that from here and thee and say "See, reality isn't real! Re;lity is whja is lurking around in the minds of SR therists". If "postuilate" is a mere mental construct, then the mind of the SRists takes pecedence over the noncurrupted reality of direct and unamiguous observation. Wow, thisnk of the concept.

Think also of the conscious and unconscious considerations of 'professional security matters of SRists iintuiting the inevitable collapse of their precious theory' . . . .

 

[quantumdude]

Whatever you say about rest frames is to drag SR thepry into a description of a physical event. The photons are moving from their host atom at the velocity as measured from the immobile, unambiguously located atom.

That is no problem at all.

The experimental results told you that the photons were moving the velocity c with respect to the host atom. Or pick some other point in the uncerse, what would you determine he velocity of c to be? I bet you will always determine c. This is fundamental to SR, tis the basic postulate. Don't forget he invariance of physical law in all inertial frames.

Don't worry, we won't forget it.

All you SR theorists, yopu grab this and that from here and thee and say "See, reality isn't real! Re;lity is whja is lurking around in the minds of SR therists". If "postuilate" is a mere mental construct, then the mind of the SRists takes pecedence over the noncurrupted reality of direct and unamiguous observation. Wow, thisnk of the concept.

Think also of the conscious and unconscious considerations of 'professional security matters of SRists iintuiting the inevitable collapse of their precious theory' . . . .

You are seriously disturbed, if you think that.

You think we say, "Reality isn't real"?

We are the ones who refer to real experiments, while your crackpot kind refers to imagined experiments.

If that nonsensical rant is what you think, then you are hopeless.

edit: fixed bold font bracket

 

[russ_watters]

All you SR theorists, yopu grab this and that from here and thee and say "See, reality isn't real! Re;lity is whja is lurking around in the minds of SR therists". If "postuilate" is a mere mental construct, then the mind of the SRists takes pecedence over the noncurrupted reality of direct and unamiguous observation.

The trouble is quite simply that you can't accept reality at face value, probably because you just don't like it. "What is lurking around in the minds of SR theorists" has been proven beyond reasonable (even some unreasonable) doubt. It is reality.

 

[geistkiesel]

That is no problem at all.



Don't worry, we won't forget it.




You are seriously disturbed, if you think that.

You think we say, "Reality isn't real"?

We are the ones who refer to real experiments, while your crackpot kind refers to imagined experiments.


If that nonsensical rant is what you think, then you are hopeless.

edit: fixed bold font bracket

What imagined experiments are you refering, Tom, to the imagined experiment described by Einstein in his book, "Relativity" page 25-27? The one he used to justify discarding the concept of simultaneity? This is the same one you memorized, how long ago was it anyway?

Yes, indeed, you say reality is not real, it must be mediated by the insanity of relativity theory. For isntance, in David's hypothetical of photon moving opposite each other from the host atom at the speed of c, that because the photons are moving at the speed of c, because that is what we measured the velocities to be, then the photons are moving away from each other, also at the speed of c.

You invoke a theory to corrupt reality, a memorized reality in the case of most SR theorists. You might say something about light not having a frame of reference, very well.

At what velocity, Tom does the radius of an expanding electromagnetic sphere travel in a stationary frame? It wouldn't do damage to the physics to have a photon pulse length giving say 10^6 photon thick as the thickness of the sphere would it?

The expanding sphere would still be a sphere, all the photons faithfully moving outward from the center of the sphere not all that unlike David's two photons moving outward from the central atom at the speed c, correct? Of course it is correct.

Our expanding sphere reaches the diameter of 2tc after t seconds, correct?
If we measure the diameter of the sphere in the stationary frame after 1 unit of time we can draw a circle on the floor of the stationary platform the exact diameter of our expanding sphere projected on to the floor of the stationary platform.

We do this a million time for the value of t = 1.

Next all the scientists gather together and ponder the question: If the radius is expanding at the rate of c and after 1 time unit the sphere diameter is 2c then how fast have we measured the relative velocities of photons on opposite sides of the expanding sphere to be?

After a few experimental runs we place clocks at a number of points around the circumference of the projected sphere, all at equal diameters, of course. Everytime we measure the diameter of the sphere we get the same number for a unit time t =1. When we compare the arrival times of points along the sphere directly opposite each other we get an expansion rate of 2c, correct? Is there any ambuguity here? I mean a measured expansion rate of oppositiely moving photons being 2c, a measured 2c, that is. No ambiguity, correct?

When we compare clock time of photons along a 1/2 circumference line of the sphere we measure the expansion rate of adjacent photons to be proportional to the angle theta between radius segments connecting the photons, correct? The expansion rate goes from 0 to 2c as the angle theta goes from 0 to pi, correct? All measured relative velocities, correct? Both Measured and calculated, correct?. At an angle of pi/2 the expansion rate would be what? I guess c, or half the rate of photons moving directly opposite each other.

But you say, David's photons don't behave in this way. Why was that again, just one more time?

It could be that Davids's photons just weren't "up to speed" so to speak. I would check those photons out if I were him, this would be really big news, if you know what I mean, his photons moving at different speeds than your photons and all?

It would be 2c, wouldn't it Tom. I mean 2c as measured in the stationary frame, but only c as modified by SR theory, right?

You might go over tht reality thing again Tom. You had a lot of "!", excuse me, I stand corrected, a lot of "?" to ponder.

By the way, I browzed through the relativity forum and noticed there wasn't the energy and intensity of discussions as we have here, as a result many of the discussions were trivial echoes of dogma, with few, if any spirirted challenges. No one wants to be exiled to the theory development forum, for shame, should that occur. A lot of pomposity and smugness down there though, an awful lot.

 

[quantumdude]

What imagined experiments are you refering, Tom, to the imagined experiment described by Einstein in his book, "Relativity" page 25-27? The one he used to justify discarding the concept of simultaneity? This is the same one you memorized, how long ago was it anyway?

I was referring to the same imagined experiment that you were referring to: StarThrower's.

Yes, indeed, you say reality is not real, it must be mediated by the insanity of relativity theory. For isntance, in David's hypothetical of photon moving opposite each other from the host atom at the speed of c, that because the photons are moving at the speed of c, because that is what we measured the velocities to be, then the photons are moving away from each other, also at the speed of c.

Where did I say, "reality isn't real?"

You invoke a theory to corrupt reality, a memorized reality in the case of most SR theorists. You might say something about light not having a frame of reference, very well.

There's nothing corrupt about it: SR makes no predictions from the vantage point of a frame moving at c.

At what velocity, Tom does the radius of an expanding electromagnetic sphere travel in a stationary frame?

It travels at the speed of light.

It wouldn't do damage to the physics to have a photon pulse length giving say 10^6 photon thick as the thickness of the sphere would it?

The expanding sphere would still be a sphere, all the photons faithfully moving outward from the center of the sphere not all that unlike David's two photons moving outward from the central atom at the speed c, correct? Of course it is correct.

Our expanding sphere reaches the diameter of 2tc after t seconds, correct?
If we measure the diameter of the sphere in the stationary frame after 1 unit of time we can draw a circle on the floor of the stationary platform the exact diameter of our expanding sphere projected on to the floor of the stationary platform.

We do this a million time for the value of t = 1.

Next all the scientists gather together and ponder the question: If the radius is expanding at the rate of c and after 1 time unit the sphere diameter is 2c then how fast have we measured the relative velocities of photons on opposite sides of the expanding sphere to be?

After a few experimental runs we place clocks at a number of points around the circumference of the projected sphere, all at equal diameters, of course. Everytime we measure the diameter of the sphere we get the same number for a unit time t =1. When we compare the arrival times of points along the sphere directly opposite each other we get an expansion rate of 2c, correct? Is there any ambuguity here? I mean a measured expansion rate of oppositiely moving photons being 2c, a measured 2c, that is. No ambiguity, correct?

Small correction: The rate of separation between the two points is sqrt(2)c, not 2c. I said that before.

When we compare clock time of photons along a 1/2 circumference line of the sphere we measure the expansion rate of adjacent photons to be proportional to the angle theta between radius segments connecting the photons, correct? The expansion rate goes from 0 to 2c as the angle theta goes from 0 to pi, correct? All measured relative velocities, correct? Both Measured and calculated, correct?. At an angle of pi/2 the expansion rate would be what? I guess c, or half the rate of photons moving directly opposite each other.

OK

But you say, David's photons don't behave in this way. Why was that again, just one more time?

No, I did not say that. Your confusion arises from the fact that you think that the rate of separation of two photons in one frame is the speed of one photon relative to another. It isn't.

It could be that Davids's photons just weren't "up to speed" so to speak. I would check those photons out if I were him, this would be really big news, if you know what I mean, his photons moving at different speeds than your photons and all?

Since David doesn't have any real photons, it's all pretty academic, now isn't it?

edit: The imaginary photons are StarThrower's, not David's.

It would be 2c, wouldn't it Tom. I mean 2c as measured in the stationary frame, but only c as modified by SR theory, right?

I already told you that it would be sqrt(2)c. That is the prediction of both Galilean and Special Relativity. Relativistic effects don't occur until you start comparing data from different frames.

 

[geistkiesel]

Silly wabbit, it wouldn't be 2c even if Galileo's relativity were correct. They're traveling at right angles to each other, not in antiparallel paths.



No, it doesn't. StarThrower's whole point was that you could make predictions from the vantage point of the rest frame of the photon. In SR, such a frame is undefined. When he goes ahead and tries to transform to a frame moving at v=c to show a contradiction in SR, he uses the LT at a point outside its domain of definition.



No, it's derived from your misunderstanding of those postulates.



Does any relativity crackpot know the difference between a thought experiment and a real experiment?



No, it isn't. Even in Galilean relativity, the relative speed is sqrt(2)c, not 2c.



Yes, so what?



Sorry, I missed the part where real data was taken in a real experiment. Could you give me the reference please?



No, we don't have that, but we'll have one made, just so you can wave your white flag.

M<y mistake. I saw something elose. I retract th post that is the subject of this post.

So sorry.

 

[geistkiesel]

You're in the wrong profession, mate. You should have become a comedian.

How come light, which travels at straight lines, can and does bend around the sun, allowing us to see objects which are actually behind it? Or are you going to suggest that light does not travel at a straight line now?

What bending around the sun experiments ae you discussing?

 

[geistkiesel]

Tom, In my expanding EM sphere with a radius expanding at c then we must have a diameter of 2c after 1 unit of time would we not? Or, say just measure ona radius leg and draw in the projected circle, it is all so simple. Show me how the sphere gets from a 2c diameter sphere with the radius expanding at C, to less than 2c, I think you said the (2)^1/2c. If ever there was a contradcition in terms does not it sound like a contradiction in terms? A c radius sphere after 1 second turns into a (2)^1/2c diameter sphere.

Where is there to look to get a straight answer on this? I apologize, I just don't believe it. Convince me or something. I am pliable, in my new found humilty after my carelessness in that post to you.
Show me., I'll listen.

 

[quantumdude]

Tom, In my expanding EM sphere with a radius expanding at c then we must have a diameter of 2c after 1 unit of time would we not?

Looks like I've made a mistake, too. I thought you were still talking about points moving in perpendicular directions, in which case the separation (in both Galileo's and Einstein's relativity) would be sqrt(2)c. Yes, points on opposite sides of the sphere would have a separation of 2c, in either theory.

But, as has been pointed out, the rate of change the separation between the two photons is not the same as the speed of one photon relative to the other. In Galileo's relativity, one photon sees the other moving away at 2c. SR makes no rigorous prediction, because v=c is outside the domain of definition of the Lorentz transformation.

 

[geistkiesel]

Looks like I've made a mistake, too. I thought you were still talking about points moving in perpendicular directions, in which case the separation (in both Galileo's and Einstein's relativity) would be sqrt(2)c. Yes, points on opposite sides of the sphere would have a separation of 2c, in either theory.

But, as has been pointed out, the rate of change the separation between the two photons is not the same as the speed of one photon relative to the other. In Galileo's relativity, one photon sees the other moving away at 2c. SR makes no rigorous prediction, because v=c is outside the domain of definition of the Lorentz transformation.

OK plot a circle in front of you with a diameter with arrows pointing outward, in the direction of expansion, just like we discussed. Now draw a radius rotated say 4 degrees from one of the radii already drawn. Connect this rotated radius tip to the radius tip farthest back (should look like a shortened diameter). What is the expansion rate of these radii?

If oppositely directed radii are expanding at a 2c rate then slightly off "direclty opposite" radii should conform to the same logic should it not? Aren't all radii expanding with the same logic even though the velocity of expansion, v(e) < c for nonparallel radii? Are we still outside the Lorentz transformaion tho v(e) < c? If so when, if ever , does SR enter this scenario?

Sorry about that other "expansion" sitiuation in the previous posts. I simply misread and was talking about oppositely expanding photons while everyone else in the room was talking about photons leaving the source 90 degrees apart. My apologies and for all my dissing that accompanied my mistake .

 

[geistkiesel]

The trouble is quite simply that you can't accept reality at face value, probably because you just don't like it. "What is lurking around in the minds of SR theorists" has been proven beyond reasonable (even some unreasonable) doubt. It is reality.

OK. Focus on one photon of a short photon burst located at M. What is the rate of expansion of the radius of the expanding sphere as measured by the photon selected for scruiny? The answer is c is it not?