# Is the Speed of Light variable?

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1 hour ago, jamesfairclear said:

I am proposing that the standard measurement of speed resulting in c is not accurate where there is relative motion between the emitter and the destination because the light received (red shifted or blue shifted) is qualitatively and quantitatively different from the light that was emitted. In other words apples are being compared with oranges.

If you believe the above matches observations and relativity (SR and GR) and other laws of physics, can you please provide some evidence that can be investigated?

(Your quotation sees off in the last post. I did not state all of those comments)

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james fairclear

My proposition is based on the observations from mainstream physics. is there a specific issue that you are thinking about?

Please separate your text from the quote  when replying to the words of others or you could be accused of changing their words.

Never mind, let us consider your claim that your proposition is based on mainstream Physics.

How do you explain the relativistic Transverse Doppler shift?

To do Doppler you really require at least two spatial dimensions because the relativistic transverse Doppler only appears then.
This clearly distinguishes classical Doppler from relativistic Doppler.

So to make a start, consider a light source moving away from a stationary observer, as you originally posted.
Let there be two spatial axes, I have labelled x and y.
To avoid confusion between v and greek nu I am using u for velocity.

In general the velocity u has a radial component ur and a component at right angles to this called the transverse component ut.
As shown the emitter is receding at the radial velocity and

${u^2} = u_r^2 + u_t^2$

Now consider that the source emits light pulses (it does not matter whether we are talking waves or photons in fact it is better if we talk about pulses) such that
the frequency is f0, as measured in its frame.
So the time between pulses, T0 is given by

${f_0} = \frac{1}{{{T_0}}}$

as measured by the source.

The Observer receives pulses with a frequency

$f = \frac{1}{T}$

as measured by the observer.

We seek a connection between f and f0 ; T and T0.

So in the time between emitting pulses the source moves a distance urT0 before the next pulse.

As a result the observer measures the time between pulses in his system as

$T = {T_0} + \frac{{{u_r}{T_0}}}{c} = {T_0}\left( {1 + \frac{{{u_r}}}{c}} \right)$

This is just classical Doppler.

Now consider what happens when ur is = 0

In this case,  classically

T = T0

Thus there can be no doppler shift ( as expected)

However applying relativistic equations predicts that even if ur is zero, the transverse velocity will still introduce a Doppler shift

And what do you know ?

Such a shift has been experimentally verified

Edited by studiot
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18 minutes ago, Ghideon said:

If you believe the above matches observations and relativity (SR and GR) and other laws of physics, can you please provide some evidence that can be investigated?

(Your quotation sees off in the last post. I did not state all of those comments)

The relevant observational evidence from mainstream Physics is that red shifted light from a receding source is less energetic than non red-shifted light from a relatively stationary source.

What further evidence would you consider to be required to substantiate the principal I have outlined?

Is there a particular relativity issue that has occurred to you?

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1 minute ago, jamesfairclear said:

The relevant observational evidence from mainstream Physics is that red shifted light from a receding source is less energetic than non red-shifted light from a relatively stationary source.

What further evidence would you consider to be required to substantiate the principal I have outlined?

Is there a particular relativity issue that has occurred to you?

When measuring the speed of light in vacuum the speed is found to be invariant. You suggest that those measurements are incorrect?

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Can we agree that light emitted by distant stars is the same as the light we see from our own sun ?
That the same elements and processes that power our sun, and emit light, are the same as those in far-away stars ?
And that this light follows the inverse relationship between frequency and wavelength ?

IOW      F*L=c    where F=fFequency,  L=waveLength and c=SoL

We know this relationship is followed at the moving source, and at our 'stationary' receiver.
We also know that the energy of light is proportional to its frequency

IOW      E=hF     where h=Planck's Constant

So if we can agree that the Energy is less at the receiver, or, we can measure the Frequency and waveLength , and find it to be less and longer ( respectively ) for a common emission process, we can easily multiply the two together, and get the exact same SoL.

Or are you suggesting light/stars/elements are different in different parts of the universe ?

edit;   If that is your suggestion, you have a really high mountain to climb in terms of proof, as you are now attempting to re-interpret a much wider area of Physics.
Good luck.

Edited by MigL
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5 hours ago, studiot said:

Please separate your text from the quote  when replying to the words of others or you could be accused of changing their words.

Never mind, let us consider your claim that your proposition is based on mainstream Physics.

How do you explain the relativistic Transverse Doppler shift?

To do Doppler you really require at least two spatial dimensions because the relativistic transverse Doppler only appears then.
This clearly distinguishes classical Doppler from relativistic Doppler.

So to make a start, consider a light source moving away from a stationary observer, as you originally posted.
Let there be two spatial axes, I have labelled x and y.
To avoid confusion between v and greek nu I am using u for velocity.

In general the velocity u has a radial component ur and a component at right angles to this called the transverse component ut.
As shown the emitter is receding at the radial velocity and

${u^2} = u_r^2 + u_t^2$

Now consider that the source emits light pulses (it does not matter whether we are talking waves or photons in fact it is better if we talk about pulses) such that
the frequency is f0, as measured in its frame.
So the time between pulses, T0 is given by

${f_0} = \frac{1}{{{T_0}}}$

as measured by the source.

The Observer receives pulses with a frequency

$f = \frac{1}{T}$

as measured by the observer.

We seek a connection between f and f0 ; T and T0.

So in the time between emitting pulses the source moves a distance urT0 before the next pulse.

As a result the observer measures the time between pulses in his system as

$T = {T_0} + \frac{{{u_r}{T_0}}}{c} = {T_0}\left( {1 + \frac{{{u_r}}}{c}} \right)$

This is just classical Doppler.

Now consider what happens when ur is = 0

In this case,  classically

T = T0

Thus there can be no doppler shift ( as expected)

However applying relativistic equations predicts that even if ur is zero, the transverse velocity will still introduce a Doppler shift

And what do you know ?

Such a shift has been experimentally verified

Apologies for any mixup in responses (I have only just started using this Forum).

Both the classical Doppler shift and the relativistic Transverse Doppler can be causal factors in the Red shifting of light from a receding light source according to the distance.

However this has no bearing on my proposition that Red shifted light can be characterised as travelling at a speed less than c in terms of the difference between rates of energy transfer at the source and destination.

Unless of course you are inferring that the rate of energy transfer at the source is by virtue of the relativistic Transverse Doppler effect the same as that of the destination.

4 hours ago, MigL said:

Can we agree that light emitted by distant stars is the same as the light we see from our own sun ?
That the same elements and processes that power our sun, and emit light, are the same as those in far-away stars ?
And that this light follows the inverse relationship between frequency and wavelength ?

IOW      F*L=c    where F=fFequency,  L=waveLength and c=SoL

We know this relationship is followed at the moving source, and at our 'stationary' receiver.
We also know that the energy of light is proportional to its frequency

IOW      E=hF     where h=Planck's Constant

So if we can agree that the Energy is less at the receiver, or, we can measure the Frequency and waveLength , and find it to be less and longer ( respectively ) for a common emission process, we can easily multiply the two together, and get the exact same SoL.

Or are you suggesting light/stars/elements are different in different parts of the universe ?

edit;   If that is your suggestion, you have a really high mountain to climb in terms of proof, as you are now attempting to re-interpret a much wider area of Physics.
Good luck.

I am proposing that any light received from any source that is measured to be red shifted (and thus inferred to be from a receding source) can be characterised as travelling at less than c in terms of the difference in energy transfer rates between source and destination.

Clearly in the absence of any supporting evidence it would be entirely speculative to suggest that light/stars/elements are different in different parts of the universe. So no I am not suggesting that.

Edited by jamesfairclear
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25 minutes ago, jamesfairclear said:

Apologies for any mixup in responses (I have only just started using this Forum).

Both the classical Doppler shift and the relativistic Transverse Doppler can be causal factors in the Red shifting of light from a receding light source according to the distance.

However this has no bearing on my proposition that Red shifted light can be characterised as travelling at a speed less than c in terms of the difference between rates of energy transfer at the source and destination.

Unless of course you are inferring that the rate of energy transfer at the source is by virtue of the relativistic Transverse Doppler effect the same as that of the destination.

No I am not addressing the rate of energy transfer just yet.

Since you did not (and have not yet) reply to my first post, I did not want to put too much into the subsequent post.
The post was the begining of a development, the next stage of which would be the introduction of Einstinian relativity.
However both my posts concentrate on something more fundamental than energy flows.
That is the measurement of time (which you need to measure energy flow).

Your treatment still mixes up time measurements by source and observer, which are necessarily different unless reduced to a single frame by some pre-agreed frame transformation.

MigL was correct in saying that the energy you speak of is not frame invariant.
This is because it is a three dimensional viewpoint.
Both energy and momentum are invariant when reduced to a single frame or when considered as four dimensional quantities in four dimensional spacetime.

So would you like to proceed to the next (relativistic) stage ?

I would expect to see some mathematics supporting the hand waving in the discussion.

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8 hours ago, jamesfairclear said:

It follows that it will take longer for a given quantity of light energy (E) emitted by A to arrive at the receding destination than it does for the same given quantity of light energy (E) to arrive at the relatively stationary destination.

The measured time from the start of light emission (throwing the switch) to the first moment when light is detected (arrival of the first photon) at either destination results in a calculated speed of c.

That’s not how we measure speed. We care how fast the photon moves. Not anything that depends on a different photon.

8 hours ago, jamesfairclear said:

I am proposing that the standard measurement of speed resulting in c is not accurate where there is relative motion between the emitter and the destination because the light received (red shifted or blue shifted) is qualitatively and quantitatively different from the light that was emitted. In other words apples are being compared with oranges.

Imagine a 100 metre race where a competitor leaves the start line with an average chest to back measurement of 40cm which then increases to 40 metres by the time the front of his chest trips the photoelectric cell at a measured time of 11 elapsed seconds. If his back crosses the line 5 seconds later than his chest it raises considerable doubt as to whether he has run the race in 11 seconds or 16 seconds or indeed if he is really the same competitor that started the race.

Does a photon swell its chest while en route?

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49 minutes ago, jamesfairclear said:

Clearly in the absence of any supporting evidence it would be entirely speculative to suggest that light/stars/elements are different in different parts of the universe. So no I am not suggesting that.

So you look for the 6 main Carbon absorption lines in the spectrum of the light from a far-away receding galaxy, and instead of finding one in the blue, two in the green, one in yellow, one in orange and one in the deep red, you find one in the orange, two in the red and three in the infra-red region of the spectrum.

You can measure the frequency and wavelength of he incoming light, and it follows the relationship F*L=c .

So, either Carbon absorbs different wavelengths/frequencies of light in that far-away galaxy, or, the spectrum is red-shifted.
Those are your only two choices; The choice of c being variable is not even a consideration.

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1 hour ago, MigL said:

So you look for the 6 main Carbon absorption lines in the spectrum of the light from a far-away receding galaxy, and instead of finding one in the blue, two in the green, one in yellow, one in orange and one in the deep red, you find one in the orange, two in the red and three in the infra-red region of the spectrum.

You can measure the frequency and wavelength of he incoming light, and it follows the relationship F*L=c .

So, either Carbon absorbs different wavelengths/frequencies of light in that far-away galaxy, or, the spectrum is red-shifted.
Those are your only two choices; The choice of c being variable is not even a consideration.

I don't think you have understood my proposition.

1 hour ago, swansont said:

That’s not how we measure speed. We care how fast the photon moves. Not anything that depends on a different photon.

Does a photon swell its chest while en route?

Figuratively speaking yes.

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2 hours ago, studiot said:

No I am not addressing the rate of energy transfer just yet.

Since you did not (and have not yet) reply to my first post, I did not want to put too much into the subsequent post.
The post was the begining of a development, the next stage of which would be the introduction of Einstinian relativity.
However both my posts concentrate on something more fundamental than energy flows.
That is the measurement of time (which you need to measure energy flow).

Your treatment still mixes up time measurements by source and observer, which are necessarily different unless reduced to a single frame by some pre-agreed frame transformation.

MigL was correct in saying that the energy you speak of is not frame invariant.
This is because it is a three dimensional viewpoint.
Both energy and momentum are invariant when reduced to a single frame or when considered as four dimensional quantities in four dimensional spacetime.

So would you like to proceed to the next (relativistic) stage ?

I would expect to see some mathematics supporting the hand waving in the discussion.

As far as I can see I did respond to your post on the topic of the relativistic Transverse Doppler shift but perhaps you anticipated a more detailed response?

Current theory explains Red shift through classical Doppler shift and relativistic Transverse Doppler shift.  In the latter case the calculations take account of time dilation in one of the 2 inertial frames of reference. For the purposes of relativistic calculations the speed of light is considered to be constant in all inertial frames of reference. From this it would be expected to follow that the rate of energy transfer from any light source (receding or not) will also be a constant as measured within a given inertial frame of reference.

My proposition is based on the observational evidence that Red shifted light from a receding light source is less energetic at the destination than when emitted at the source. Whatever the cause/s of this though the widely accepted and well evidenced scientific fact remains that the light received is less energetic.

I am more than happy to hear your Relativistic viewpoints on this topic.

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1 hour ago, jamesfairclear said:

Figuratively speaking yes.

So it takes longer for an atom to absorb a photon from a receding source, than from a stationary one, with the photons at the same frequency in the absorber’s frame?

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2 hours ago, jamesfairclear said:

I don't think you have understood my proposition.

Then please correct me where I'm wrong...

You assert correctly that, the energy of the light received from a distant, receding star, is less than the emitted energy by the distant, receding star. And you offer a reduced speed of light as a possible explanation, with various amounts of hand waving as the explanation.

You have been told that relativity tells us the energy measured in different frames, WILL be different, and we can predict mathematically by how much.
And you have been told why a changing speed of light is non-sensical, and can be proven to lead to non-sensical results/conclusions.

I think the mis-understanding might be on your part.

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11 hours ago, jamesfairclear said:

I am proposing that any light received from any source that is measured to be red shifted (and thus inferred to be from a receding source) can be characterised as travelling at less than c in terms of the difference in energy transfer rates between source and destination.

This directly violates a number of basic principles in physics, most notably:
1. Photons are massless, so they cannot propagate at anything other than exactly c.
2. Under the laws of relativity, light traces out null geodesics in spacetime. This is possible only if their propagation velocity is exactly c
3. The propagation of light is described by Maxwell’s equations - these equations are generally covariant in nature, they take the same form regardless of what the state of relative motion is, or where (in relation to gravitational sources) the experiment takes place. Therefore the propagation velocity cannot depend on the observer.
4. The numerical value of c is a direct function of vacuum permittivity and permeability; both of these are fundamental constants, and do not vary with the state of motion of the observer. Thus the value of c cannot vary either.

In a small enough local region, your proposal furthermore amounts to a violation of Lorentz invariance; all available experimental data indicate that no such violations exist.

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2 hours ago, Markus Hanke said:

This directly violates a number of basic principles in physics, most notably:
1. Photons are massless, so they cannot propagate at anything other than exactly c.
2. Under the laws of relativity, light traces out null geodesics in spacetime. This is possible only if their propagation velocity is exactly c
3. The propagation of light is described by Maxwell’s equations - these equations are generally covariant in nature, they take the same form regardless of what the state of relative motion is, or where (in relation to gravitational sources) the experiment takes place. Therefore the propagation velocity cannot depend on the observer.
4. The numerical value of c is a direct function of vacuum permittivity and permeability; both of these are fundamental constants, and do not vary with the state of motion of the observer. Thus the value of c cannot vary either.

In a small enough local region, your proposal furthermore amounts to a violation of Lorentz invariance; all available experimental data indicate that no such violations exist.

If you read the full details of my proposition which is an alternative approach to measuring the speed of light in terms of Energy transfer rates you will see that there are no such violations.

Light received from a relatively stationary emitter A is more energetic than light received at a receding destination from the same emitter A.

It follows that it will take longer for a given quantity of light energy (E) emitted by A to arrive at the receding destination than it does for the same given quantity of light energy (E) to arrive at the relatively stationary destination.

The measured time from the start of light emission (throwing the switch) to the first moment when light is detected (arrival of the first photon) at either destination results in a calculated speed of c regardless of there being any relative motion between the source and destination. This standard method of measuring the speed of light does not take account of any discrepancies between the rates of transfer of Energy at the source and destination respectively.

I am proposing that the standard measurement of speed resulting in c is not an objectively accurate representation of speed where there is relative motion between the emitter and the destination because the light received (red shifted or blue shifted) is qualitatively and quantitatively different from the light that was emitted. One thing is emitted and another different thing arrives at the destination. In other words apples are being compared with oranges.

Imagine a 100 metre race where a competitor leaves the start line with an average chest to back measurement of 40cm which then increases to 40 metres by the time the front of his chest trips the photoelectric cell at a measured time of 11 elapsed seconds. If his back crosses the line 5 seconds later than his chest it raises considerable doubt as to whether he has run the race in 11 seconds or 16 seconds or indeed if he is really the same competitor that started the race.

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4 minutes ago, jamesfairclear said:

I am proposing

Your answers so far do not explain how your proposal could be correct.

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9 minutes ago, jamesfairclear said:

If you read the full details of my proposition which is an alternative approach to measuring the speed of light in terms of Energy transfer rates

But that isn't a measurement of the speed of light. It is a measurement of ... well, energy transfer rate. That is observer dependent (dependent on frequency or wavelength) while the speed of light isn't. We know this from basic theoretical considerations, confirmed by experiment.

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It seems OP just wants to redefine the term 'speed', as Strange (and others) have pointed out, OP is changing the common definition of speed to his own definition, then saying that the 'speed*' is variable.
@James What exactly is the point of that... why would we want to do this, why not just call it energy transfer rate, what great insights do we get from this?

*OP's speed

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1 hour ago, jamesfairclear said:

Light received from a relatively stationary emitter A is more energetic than light received at a receding destination from the same emitter A.

It follows that it will take longer for a given quantity of light energy (E) emitted by A to arrive at the receding destination than it does for the same given quantity of light energy (E) to arrive at the relatively stationary destination.

This is irrelevant. The source is further away when it emits the second photon. It has to travel a greater distance. That in no way means it’s traveling at a lower speed.

I will reiterate what others have said: you are redefining “speed” to mean something new. You aren’t allowed to do that. It already has a definition

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Well I always thought that we already had a perfectly good word for the time rate of flow of energy dE/dt           i.e. power.

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2 hours ago, Strange said:

But that isn't a measurement of the speed of light. It is a measurement of ... well, energy transfer rate. That is observer dependent (dependent on frequency or wavelength) while the speed of light isn't. We know this from basic theoretical considerations, confirmed by experiment.

Interestingly if we look at your statement  as to what you think is not a measurement of the speed of light "But that isn't a measurement of the speed of light. It is a measurement of ... well, energy transfer rate" and then write down what we think is a measurement of the speed of light we can arrive at one and the same definition.

"We arrive at the the speed of light by measuring how long it takes a beam of light to travel a distance d in time t.

A beam of light is a transfer of light energy from one location to another.

Therefore the speed of light can be equally (and arguably more meaningfully) characterised  as the rate at which light energy is transferred from one location to another."

My proposal is an ALTERNATIVE method for measuring the speed of light in the special case where there is relative motion between the source and destination. If you read my proposal carefully you will see that it is not a measurement of energy transfer rate. It is an adjustment to the measured speed of light (which is nominally c using the standard approach) to take into account the discrepancy in energy transfer rates between source and destination.

I repeat my analogy for further clarification:

Imagine a 100 metre race where a competitor leaves the start line with an average chest to back measurement of 40cm which then increases to 40 metres by the time the front of his chest trips the photoelectric cell at a measured time of 11 elapsed seconds. If his back crosses the line 5 seconds later than his chest it raises considerable doubt as to whether he has run the race in 11 seconds or 16 seconds or some averaged time (say 13.5 seconds) between the 2 or indeed if he is really the same competitor that started the race.

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3 hours ago, jamesfairclear said:

If you read the full details of my proposition which is an alternative approach to measuring the speed of light in terms of Energy transfer rates you will see that there are no such violations.

!

Moderator Note

You need to stop telling people to read your proposition. They have, and now they have questions that need answering, and only you can do that.

The membership are giving you VERY specific objections, telling you exactly where your arguments fail, and you're just telling them they don't understand how you're redefining the terms. If this is the extent of your "discussion", we're going to have to rule this preaching, or soapboxing. You need to address the questions the members have, or I'll need to shut this down.

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Bold by me:

46 minutes ago, jamesfairclear said:

Therefore the speed of light can be equally (and arguably more meaningfully) characterised  as the rate at which light energy is transferred from one location to another."

How is it more meaningful? A detailed answer may bring this discussion forward.  I claim that it is not meaningful to characterize the speed of light as something that is invalid, as other members have already stated.

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1 hour ago, jamesfairclear said:

"We arrive at the the speed of light by measuring how long it takes a beam of light to travel a distance d in time t.

A beam of light is a transfer of light energy from one location to another.

Therefore the speed of light can be equally (and arguably more meaningfully) characterised  as the rate at which light energy is transferred from one location to another."

Obviously not.

Say I have a blue LED and a red LED, both 1 metre away from me. Are the photons from the blue LED travelling faster because they carry more energy? (Spoiler alert: no.)

If the blue LED is 1mW and the red LED is 10mW, is the red light travelling faster because it is carrying more energy than the blue light? (Hint: also no.)

1 hour ago, jamesfairclear said:

My proposal is an ALTERNATIVE method for measuring the speed of light

But it doesn't measure speed. It measures power.

That is like saying: my car is faster than yours because it makes more noise.

1 hour ago, jamesfairclear said:

in the special case where there is relative motion between the source and destination.

You could use the Doppler shift to calculate the relative speed between source and destination. But it doesn't change the speed of light.

1 hour ago, jamesfairclear said:

I repeat my analogy for further clarification:

Your analogy is silly and irrelevant to the physics.

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One major point is that it doesn't matter how the OP believes concerning the speed of light.

experimental evidence trumps any argument the OP can present

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