Lightspeed is not Constant (to observer) !!

[nakakayama]

From the ceiling of a passenger car, light ray is emitted down. When the moving car is filled with water, diagonal of light ray may be more gentle to an observer who stands on the ground. And the diagonal (depends only on c/n and v) may be simple appearance. It may be the same about air or vacuum too (Galilean transformations may stand up about all).

From the ceiling of passenger car, light ray is emitted down somewhat to the right. One passenger car is moving to the right, another passenger car is moving to the left at the same speed. To an observer who stands on the ground, the length of two light rays is not the same.

http://www.geocities.co.jp/Technopolis/2561/eng.html

[Mulder]

I'd love to see you fill a passenger car with water. The water, of course, slows the light and so refracts it. Where's the problem here?

[Mongrel]

I'd love to see you fill a passenger car with water. The water, of course, slows the light and so refracts it. Where's the problem here?

Didn't they do that (amusingly of course) on Top Gear?

On topic though.
The speed of light in free space is a physical constant defined...When light is traveling in a medium, its speed is less than c and becomes a function of the refractive index of the material.

[nakakayama]

Allow me to repeat to quote, please.

Einstein's theory stands up only on vertical light ray (in a passenger car) ? Einstein's theory does not stand up on diagonal light ray (in a passenger car) ?

[nakakayama]

From the ceiling of a passenger car, a few light rays are emitted to lower right. The angle (of these) is different (one is vertical). How does Einstein's theory explain this (passenger car is moving to the left) ?

Sorry, if it's invalid.

[Mulder]

The whole point of relativity is that there is no unique frame of reference. So the concept of 'diagonal rays' is meaningless in relativity.

The time light takes to arrive at any point depends on the distance travelled (which is rarely a straight line because time space is curved br gravity) and the medium through which it travels - water will both slow light down and change its direction.

So, are you saying there is an experiment that has demonstrated that light takes longer or shorter than it should to reach a point in space, given the distance travelled and the mediums traversed? If so, do you have a link?

[nakakayama]

To Mr.Mulder,

Thank you for relevant reply. As you say, "diagonal light ray" may be meaningless in relativity.

Sorry, i can't understand well the third part of your writing (i am weak in English). All my view and idea is shown in my web site (in English) below (Fortunately, it entered into Google's directory : Physics > Relativity > Alternative)
http://www.geocities.co.jp/Technopolis/2561/eng.html

[Mulder]

I speak English reasonably well and I don't undrrstand this from your link:

"Two stars glitter on the right and on the left. Two mirrors are set at 45 degrees (like letter V), and are reflecting star light down. Speed of two reflected lights is always equal (maybe). Therefore, when two mirrors move together to the right or the left, wave length of two reflected lights is changed. In other words, wave density (number of waves that stay within an unit length of light path) of reflected light is changed by mirror's motion. But how about incident light ? Wave density is not changed by mirror's motion ! In short, wave density of reflected light and incident light is generally not the same. The theory of constancy of light speed may be impossible to explain this situation."

Light changes wavelength when it is reflected by a moving object (red or blue shift) to observers in most frames of reference. The strange bit here is 'wave density', which the writer defines as 'the number of waves that stay within an unit length of light path'. I don't see why anyone would want this concept - it serves to confuse matters.

The simpler way to look at it is that changing wavelength also changes frequency but not speed. In fact, speed = frequency x wavelength. What the wavelength of the photons of light is makes no difference to its speed. Nor does it matter how many times the wave goes up and down in any particular distance or time.

So when the light is reflected, its wavelength is changed but not its speed.

Relativity will be replaced one day by a better theory but only when there is evidence that it is wrong. If the writer of the article can show that reflection changes light speed as well as wavelength then good luck to them!

[nakakayama]

To Mr.Mulder,

This time, i may understand all of your writings. But allow me to limit my reply on two points.

You write, "when the light is reflected, its wavelength is changed but not its speed". i write, "when the light is reflected, incident light's wavelength is not changed but its speed". Look at not reflected light but incident light.

The word "wave number" is in encyclopedia of physics. It's inverse number of wavelength. The concept of this word may be fatal to relativity (the word "extinction" may be also).

[Mulder]

You write, "when the light is reflected, its wavelength is changed but not its speed". i write, "when the light is reflected, incident light's wavelength is not changed but its speed". Look at not reflected light but incident light.

The incident light is not affected by reflection (how could it be?). The reflected light has BOTH wavelength and frequency changed but NOT speed!


The word "wave number" is in encyclopedia of physics. It's inverse number of wavelength. The concept of this word may be fatal to relativity (the word "extinction" may be also).

Using wave number makes a very simple thing look complicated. As you say, 'wave number' is the inverse of wavelength. Why use the inverse?

But if you want to use wave number, here it is:

Reflection changes wave number AND frequency (and therefore inverse of frequency) but not speed. The incident light is not changed AT ALL.

So the wave equation becomes (wave number) times (inverse of frequency) equals (inverse of light speed)

Wave number is not fatal to relativity, it is fatal to the simple understanding of an easy concept. Science is easier if you simplify things. Making them more complicated just makes it hard for no reason.

[nakakayama]

To Mr.Mulder,

About incident light : Image rail road and look at ahead of train (moving forward). Wavelength (sleepers) is unchangeable. Frequency and speed both are changeable (When incident light hits a moving (at changing speed) black body, it has changeable frequency also).

About the latter part : i don't agree to you. In addition, the paragraph "Reflection changes wave number AND frequency" is wrong (terribly). Yes, wave number of incident light and reflected light (in other word, before and after reflection) is not the same (reflection changes). But frequency of incident light and reflected light is the same (reflection doesn't change). Look at not light source but incident light. About further more, if you want, see the first part of my web-site.

[Mulder]

About incident light : Image rail road and look at ahead of train (moving forward). Wavelength (sleepers) is unchangeable. Frequency and speed both are changeable (When incident light hits a moving (at changing speed) black body, it has changeable frequency also).

In your analogy, you are talking about a object moving directly towards the source of the incident light. Therefore the light, in this example, is being reflected directly back towards its source. However, the case we were talking about above was starlight at 45 degrees! Maybe that is why there is confusion.

In the example you give here, you use railway sleepers as an analogy for light waves. Obviously, the sleepers are always the same distance apart physically. However, what we are concerned with is how the APPEAR to the train driver. They will arrive more quickly, as the train moves, so their APPARENT frequency will increase (ie. more sleepers will pass by per second as speed increases). However, they will also LOOK closer together, eventually blurring together at high speed, ie. their APPARENT wavelength will shorten too. This is the Doppler Effect. (http://en.wikipedia.org/wiki/Doppler_effect)

If the train is approaching a source of sound directly ahead, which is a source of real waves (not just an analogy) of constant wavelength and frequency, its frequency will sound higher than if the train was stationery. This is, again, the Doppler Effect which applies as much to classical physics as relativity. Sound is a much better analogy here as railway sleepers don't really behave like waves.


About the latter part : i don't agree to you. In addition, the paragraph "Reflection changes wave number AND frequency" is wrong (terribly). Yes, wave number of incident light and reflected light (in other word, before and after reflection) is not the same (reflection changes). But frequency of incident light and reflected light is the same (reflection doesn't change). Look at not light source but incident light. About further more, if you want, see the first part of my web-site.

I think you misunderstand. I said the incident light was NOT changed by reflection - its wavelength and frequency stay the same. The reflected light has both its wavelength AND frequency changed according to the wave equation, so that the speed is the same as in the incident light. If you think this is wrong, please explain why.

[nakakayama]

To Mr.Mulder,

About the first part : In this analogy (rail way and train), i am talking about incident light only. 45 degrees, 30 degrees or black body all has not any effect on incident light.

About the second part : In this analogy, rail way is moving (to train at high speed) and train is at a stand-still (or is moving at low speed). You write in the previous post, "The incident light is not changed AT ALL". Yes, wavelength is not changed AT ALL.

About the third part : Sorry, i may not understand your writing well (i'm not good in English). About Doppler effect, i write my view in my web-site. It's contrary to view of main stream. The view of main stream says, "By the motion of observer, wavelength of the incident light (for example, from an observer to a star or a galaxy) changes". Recall, wavelength, in other ward, is wave number !! Can you imagine change of wave number ? It's quite pseudo !!

About the last part : Sorry, i may not understand your writing well also. Any way, light speed isn't constant (to observer). In my web-site, 6 proofs are (all is simple at all).

Sorry, because of private affair, i must stop to post to this forum for the time being. Sorry, my English was bad.

[nakakayama]

Allow me to add, please.

Two light paths are coming from a star. When two observers move along each light path at different speed, wave length of the two light paths (lead to the star) differ (If Einstein's theory is right). Note : Light speed = frequency x wavelength

[Mulder]

About the third part : Sorry, i may not understand your writing well (i'm not good in English). About Doppler effect, i write my view in my web-site. It's contrary to view of main stream. The view of main stream says, "By the motion of observer, wavelength of the incident light (for example, from an observer to a star or a galaxy) changes". Recall, wavelength, in other ward, is wave number !! Can you imagine change of wave number ? It's quite pseudo !!

So you don't agree with Doppler Effect? Do you have any evidence that it is wrong.


About the last part : Sorry, i may not understand your writing well also. Any way, light speed isn't constant (to observer). In my web-site, 6 proofs are (all is simple at all).

You've got 6 'proofs' but do you have any evidence to support any of them? A theory is no good unless it is tested.


Two light paths are coming from a star. When two observers move along each light path at different speed, wave length of the two light paths (lead to the star) differ (If Einstein's theory is right). Note : Light speed = frequency x wavelength

I've quoted that formula several times but you appeared to be disputing it! If two observers are moving at different speeds relative to a star then, yes, they will see it at a different frequency AND wavelength. The speed of light, however, will appear the same to both.

All this sort of stuff has been looked at and tested years ago. Relativity has survived all its tests. It will be replaced by a better theory one day but not because of stuff like wave numbers!

[nakakayama]

It's improved version. Any refutation may be impossible.

Three light paths (A, B and C) are coming from a star and reach three observers (A, B and C). Observer A is at a stand-still. Observer B and C are moving (one moves toward the star, another moves toward opposite direction). From view point of observer A, wave length of the light path B and C must be different (if Einstein's theory is right).

[Mulder]

Three light paths (A, B and C) are coming from a star and reach three observers (A, B and C). Observer A is at a stand-still. Observer B and C are moving (one moves toward the star, another moves toward opposite direction). From view point of observer A, wave length of the light path B and C must be different (if Einstein's theory is right).

I assume you mean at a stand still relative to the star! Remember there is no real 'still' anywhere. That's the point of relativity - everyone has their own frame of reference.

I don't fully understand your new thought experiment. Are you saying that A can see the star and also the light from the star reflected off B and C? You don't say where A and B and C are relative to each other.

In any case, the reflected light from the star will be red or blue shifted (both wavelength AND frequency change but not the speed of light) as far as A is concerned. It will depend on the positions and speeds of B and C relative to A and the star how big these frequency and wavelength shifts are. Also, light will obviously take longer to arrive from the furthest object from A, which ever that one is.

I think the only way you can really demonstrate this problem is if you draw a diagram and also show what equations you are using and how they contradict relativity.

[nakakayama]

To Mr.Mulder, : About your latest post. Allow me to rewrite the thought experiment as follows. Imagine incident light only.

Two light paths (close to each other) are coming from a star and reach two observers (A and B) each. A is moving toward the star, B is moving toward opposite direction (in an uniform motion). At the half way between A and B, there is observer C. Moving speed of A and B relative to C is the same. So, from view point of observer C, wave length (wave number also) of the two light paths must be different (if Einstein's theory is right). Note : light speed = frequency x wavelength

[Mulder]

To Mr.Mulder, : About your latest post. Allow me to rewrite the thought experiment as follows. Imagine incident light only.

Two light paths (close to each other) are coming from a star and reach two observers (A and B) each. A is moving toward the star, B is moving toward opposite direction (in an uniform motion). At the half way between A and B, there is observer C. Moving speed of A and B relative to C is the same. So, from view point of observer C, wave length (wave number also) of the two light paths must be different (if Einstein's theory is right). Note : light speed = frequency x wavelength

I still cannot understand your experiment. You say the light paths are close to each other. Assuming the light paths are straight (which they won't be if they are bent by a strong gravity field between the star and A, B and C) they will be diverging. So the light paths are getting further apart from each other all the time as they travel away from the star. They are only close to each other when they leave the star.

Which light path can C see? Are you talking about light paths reflecting from A and B from the star to reach C? If so, the light from both will be red-shifted by the same amount, because A and B are moving away from C at the same speed.

It would be a lot easier if you drew a diagram and put it up on Flickr or somewhere similar and gave a link from here. Otherwise I don't think I'll ever understand what you are saying.

[Cuddles]

I still cannot understand your experiment. You say the light paths are close to each other. Assuming the light paths are straight (which they won't be if they are bent by a strong gravity field between the star and A, B and C) they will be diverging. So the light paths are getting further apart from each other all the time as they travel away from the star. They are only close to each other when they leave the star.

Which light path can C see? Are you talking about light paths reflecting from A and B from the star to reach C? If so, the light from both will be red-shifted by the same amount, because A and B are moving away from C at the same speed.

It would be a lot easier if you drew a diagram and put it up on Flickr or somewhere similar and gave a link from here. Otherwise I don't think I'll ever understand what you are saying.

I think what he's trying to say is that there are three observers at the same point in space, one moving towards the source (A), one moving away (B) and one stationary (C), all observering the same ray from the source. The confusion is that he realises that they can't all look at exactly the same photon, so he is trying to say that there are three identical rays all following the same path, so that there is one for each of them.

I think he is then concluding that since observers A and B observe the light to be different wavelengths, observer C must observe it to be different from either A or B. Which is entirely correct. A sees a shorter wavelength than B and C, B see a longer wavelength than A or C.

I suspect that the main confusion is from the equation, which he has given, of c = f*l
I think what he is trying to say is that since the frequency and wavelength are both seen to change, the speed must have changed as well.
Nakakayama, is that correct? If so, it's an easy question to answer. Quite simply, the speed of light, c, remains constant. In fact, it is that constant nature of c that results in wavelength varying when frequency does. If c were not fixed, when you changed l, for example, c and f could take on any values at all. As it is, if l changes then since c is constant, f only has one possible value and everything works out very neatly.

[Croydon Bob]

Cuddles! Welcome back.

[Mulder]

I think what he's trying to say is that there are three observers at the same point in space, one moving towards the source (A), one moving away (B) and one stationary (C), all observering the same ray from the source. The confusion is that he realises that they can't all look at exactly the same photon, so he is trying to say that there are three identical rays all following the same path, so that there is one for each of them.

Drawing a diagram not only clarifies but even sometimes solves these kind of problems. If you can't draw it then it probably couldn't happen anyway.

[nakakayama]

To Mr.Mulder,

About the first part : Two light paths are parallel (practically). The star is very far. Rail-way looks diverging.

About the second part : From view point of C, frequency of A and B must be differ. It's important (the core of the main point). The ways that clarify this fact may not be important (to clarify may be easy). To compare two papers (Data is printed at A and B) is one of ways. P.S. Is wave-length and wave number of the light path (from observer to the star) changeable (by observer's motion) ?? View of main stream says, "changeable". Mad !!

This and next post may be my last post. Thank you.

[nakakayama]

Light speed may be various as follows.

[Relative to light source] : constant c, in vacuum only, may continue for a few second (it's emission theory).
[Relative to aether] : constant, slower somewhat than c.
[Relative to medium] : constant c/n, equalized by extinction.
[Relative to observer] : variable (As formula : light speed = frequency x wavelength shows).

[nakakayama]

To Mr.Cuddles,

You seem not to grasp what i'm trying to say. Problem is only in the formula : light speed = frequency x wavelength. Too simple, therefore, difficult to grasp ??

You write, "c that results in wavelength varying when frequency does". It's right about reflected light. But about incident light, i believe, it's mad !!

Why mad ?? This varying (change of wavelength caused by mirror's motion) moves at the speed of c or c/n on the reflected light path. But how about on the incident light path ? None can explain, i think (Only frequency and light speed of incident light are changeable).

[Mulder]

Why mad ?? This varying (change of wavelength caused by mirror's motion) moves at the speed of c or c/n on the reflected light path. But how about on the incident light path ? None can explain, i think (Only frequency and light speed of incident light are changeable).

Are you saying incident and reflected light are different? Both obey the c = frequency x wavelenth formula. But the incident light is not changed by reflection. A photon will take longer and move further to reach a mirror that is moving away. But that won't change the frequency and wavelength BEFORE it reaches the mirror. How can it?

[nakakayama]

To Mr.Mulder,

Change of incident light (by change of mirror's motion)
Lightspeed & frequency : Change, Wavelength : Unchangeable.

Change of reflected light (by change of mirror's motion)
Wavelength & frequency : Change, Lightspeed : Unchangeable.

Both obey the c = frequency x wavelength formula, as you wrote.

[Mulder]

Change of incident light (by change of mirror's motion)

How? How is light changed BEFORE it is reflected?

Would it help if you thought of an individual photon as a wave with a defined length and frequency? When it is reflected by a stationary object, it changes direction only. When it is reflected by a moving object, frequency and wavelength also change.

[Mulder]

Nakakayama

Is this (http://www.anti-relativity.com/dopplerparadox.htm)what you are talking about?

If so, the answer is here (http://en.wikipedia.org/wiki/Relativistic_Doppler_effect). The 'trick' is taking into account time dilation.

[nakakayama]

Correction (On my yesterday's post). For "c" read "lightspeed". The last sentence is corrected as follows.

"Both obey the lightspeed = frequency x wavelength formula."

To Mr.Mulder,

Light is not changed BEFORE it is reflected.

[Mulder]

Correction (On my yesterday's post). For "c" read "lightspeed". The last sentence is corrected as follows.

"Both obey the lightspeed = frequency x wavelength formula."

To Mr.Mulder,

Light is not changed BEFORE it is reflected.

If light isn't changed BEFORE it is reflected, and its frequebcy and wavelength are changed AFTER reflection (by the moving 'mirror'), according to the formula you give above, then what is the problem? That is what the relativistic doppler effect SAYS will happen.

[nakakayama]

To Mr.Mulder,

The problem is that the light speed must be changeable (according to the formula).

[Mulder]

The problem is that the light speed must be changeable (according to the formula).

No, because the wavelength AND frequency change so that c remains the same. Unless you have some evidence that it is not so.

[nakakayama]

See an animation (about light speed) below (if you wish).

http://www.extinctionshift.com

[Cuddles]

Change of incident light (by change of mirror's motion)
Lightspeed & frequency : Change, Wavelength : Unchangeable.

Change of reflected light (by change of mirror's motion)
Wavelength & frequency : Change, Lightspeed : Unchangeable.

No.


Both obey the c = frequency x wavelength formula, as you wrote.

No they don't. In that formula, c is a constant, by definition. It's not possible for a constant to change. That's what constant means.

Possibly what is confusing you is that you are thinking of the general equation that applies to any waves - v = f*l. In that case you would be correct that any of the three variables can, well, vary. However, that's not what we are dealing with here, we are dealing with a special case of that equation that applies specifically to light, and in this case, the general variable velocity is replaced by the constant c. Which can't vary. Because it's a constant.

[nakakayama]

Writers of book on relativity seem to be unfair. Allow me to touch on a little.

Following words are not seen. "Orbis", "speed gun", "wave number" or "extinction". It's not a little things. Never !! E.Mascart's 6 experiments on light are not seen also (There may be many other unfairness and irrationality).

And gross error of "Principle of Constancy of Light Velocity" (relative to observer) seems to be an open secret among not a few professionals. But none talks about. Because they are professionals (guilds-men), i think.

To Mr.Cuddles,

About latter part : No !!

[nakakayama]

To Mr.Cuddles,

If you wish to know why i write "No", see the first page of my web-site please.

http://www.geocities.co.jp/Technopolis/2561/eng.html

[Mulder]

See an animation (about light speed) below (if you wish).

http://www.extinctionshift.com

It's an animation. It shows whatever the animator wanted to show.


Following words are not seen. "Orbis", "speed gun", "wave number" or "extinction". It's not a little things. Never !! E.Mascart's 6 experiments on light are not seen also (There may be many other unfairness and irrationality).

Just as an example, why use the word 'wave number' when you are simply talking about frequency which is a more easily understood concept? By making things complicated, you might confuse things and come to wrong conclusions.

Since we do not seem to be getting very far with this thread, why not just give a link to an experiment that shows relativity to be wrong?

[Mulder]

Since we do not seem to be getting very far with this thread, why not just give a link to an experiment that shows relativity to be wrong?

The most obvious experiment would be one showing that light speed varies with a single medium or in a vacuum.

[Cuddles]

To Mr.Cuddles,

If you wish to know why i write "No", see the first page of my web-site please.

http://www.geocities.co.jp/Technopolis/2561/eng.html

I have no idea what your "no" is answer to here, and your website does not help clarify in the slightest. It is simply repeating the same stuff you have said here, and it is just as wrong as it was the first time you said it. I originally thought this may have been due to a basic misunderstanding, but since you continue repeating the same nonsense after being corrected several times, I can only conclude that you are just another true believer who thinks that despite having no understanding of relativity you have somehow proven centuries of established science wrong.

If at some point you decide to actually learn something about relativity and take part in a sensible conversation, I will still be here. However, as long as you just continue to repeat the same nonsense over and over again without listening to anyone, I'm not going to bother trying to reason with you.


Just as an example, why use the word 'wave number' when you are simply talking about frequency which is a more easily understood concept? By making things complicated, you might confuse things and come to wrong conclusions.

Actually, wave number is used quite commonly. It's just the reciprocal of the wavelength, and it's often more convenient to use in equations. Nakakayama is simply wrong in his claim that textbooks never use it.

[nakakayama]

To Mr.Cuddles,

Thank you for reading. And i have nothing to say any more.

To Mr. Mulder,

i'm talking about "Principle of Constancy of Light Velocity" (to observer) only (the first step of "all"). And as for my approach, logic only is suitable. Any test is no need. (No, test is done infinitely : It's Doppler effect).

P.S. : Fortunately, my web-site entered into google's directory (physics > relativity > alternative) last year.　

[nakakayama]

Now, let's take a short rest. Dessert is Doppler effect. Logic is very simple also.

Common view says that Doppler effect of sound and light are different. But except for one situation, both may be the same (in the air, quite the same). Because, sound and light both propagate through medium at constant speed (in the vacuum, light propagate through the aether). Only in the vacuum, and moreover immediately after the emission from light source (may be a few second), Doppler effect of light may be unique.

Note : (1) In the vacuum, light may follow Ritz's emission theory for a few second. (2) Aether may be one of media.

[cjr23]

Shouldn't this be in the physics subfora? I have not got the slightest idea about the speed of light, but I do find the argument that is can not change because it is a constant curiously circular. Sure, it is set by definition since 1983 - but measurements had varied, even after one thought we should be getting close with improved technical accuracy. See http://www.sigma-engineering.co.uk/light/lightindex.shtml

If it changes it's not a constant. And Einstein was wrong - but that is by no means impossible. A lot of physics and cosmology could work just fine with a shifting c as far as I can see, but then I'm pretty dumb. But to argue it can't move because it's a constant is really just an argument by definitions, you define it as a constant, so it's can't move. I have no idea if Nakakayama is talking nonsense or a genius, but on those grounds I will remain cautiously agnostic here.

cj x

[Cuddles]

Shouldn't this be in the physics subfora?

No, it's very much pseudoscience.


I have not got the slightest idea about the speed of light, but I do find the argument that is can not change because it is a constant curiously circular.

It would be circular if that were actually the argument. However, the only reason I brought that up is because the entire claim here rests on a misunderstanding of the equation c = f*l. Nakakayama says that since in a general equation of that for changing one variable can cause the other two to change, that means that c cannot be a constant. What he doesn't understand is that we already know c is a constant and is defined as such in that equation, therefore his argument is complete nonsense.

As for how we know c is a constant, there are a few ways. Firstly, we've measured it. Secondly, the predictions of Maxwell's equations and special and general relativity match observations extremely closely. If someone is going to claim this is wrong, they're going to have to do a lot more than point at an equation which includes the constancy of c as an assumption and say that since c could change if it was a variable, it must be a variable.


I have no idea if Nakakayama is talking nonsense or a genius, but on those grounds I will remain cautiously agnostic here.

Someone who can't understand basic maths or physics claims to have overturned one of the most thoroughly tested theories ever to have existed, and you're going to remain agnostic? That makes about as much sense as Makakayama's claims.

[cjr23]

Someone who can't understand basic maths or physics claims to have overturned one of the most thoroughly tested theories ever to have existed, and you're going to remain agnostic? That makes about as much sense as Makakayama's claims.

Bit more to it than that, but I understand your frustration with me. :) After all I know nothing worth while about physics, and your explanation appears absolutely sound. I'll write what puzzles me on my return on Sunday - I certainly have no problem with relativity, unlike Nakayama, but I'm not convinced the speed of light could not vary... at least in theory. Don't stress, I freely conffess my ignorance, but I have thought it through a little, and I'm sure you can show me why I am wrong! At least I will learn... anyway have to dash as need to get train to Derby inn morning. Look forward to whittering on Sunday...

cj x

[Matt]

CJ

Here's the thing. The speed of light can we worked out from two other universal constants.

You see if we know http://upload.wikimedia.org/math/a/b/8/ab82693a5e8a4fdb87b2d4e768d6c226.png, the electric constant and http://upload.wikimedia.org/math/e/5/b/e5b8528893baadd2def6907923c133ac.png, the magnetic constant and we know maxwells equations then the speed of light just falls out of these equations. It has no latituiute to change.

Howeer I guess this might be seen to be one of those infinite regression things. How do I know that those two values are in fact constant.

If http://upload.wikimedia.org/math/a/b/8/ab82693a5e8a4fdb87b2d4e768d6c226.png wasn't in fact constant then c could be variable too.

Except that http://upload.wikimedia.org/math/a/b/8/ab82693a5e8a4fdb87b2d4e768d6c226.png is kinda important. It's one of those contstants used in those fine tuning arguments we've encountered in discussion of the anthropic principle If http://upload.wikimedia.org/math/a/b/8/ab82693a5e8a4fdb87b2d4e768d6c226.png were to change even the tiniest amount then the properties (and spectrum) of hydrogen would change. Except that we know that the spectrum of hydorgen is the same accross the known universe going back some 13 billion years.

That's as close to a practical defiition of constant as you're going to get.

A similar argument can be made for http://upload.wikimedia.org/math/e/5/b/e5b8528893baadd2def6907923c133ac.png going via the "fine structure constant"

Basically if http://upload.wikimedia.org/math/e/5/b/e5b8528893baadd2def6907923c133ac.png or http://upload.wikimedia.org/math/a/b/8/ab82693a5e8a4fdb87b2d4e768d6c226.png weren't constant then we just wouldn't have matter or at least not in any recognisable form.