If there is no Ether how can we talk about light being a wave?

[protonman]

Originally posted by Nereid
http://members.aol.com/intwg/trolls.htm#WIAT "What Can be Done about Trolls?

When you suspect that somebody is a troll, you might try responding with a polite, mild message to see if it's just somebody in a bad mood. Internet users sometimes let their passions get away from them when seated safely behind their keyboard. If you ignore their bluster and respond in a pleasant manner, they usually calm down.

However, if the person persists in being beastly, and seems to enjoy being unpleasant, the only effective position is summed up as follows:

The only way to deal with trolls is to limit your reaction to reminding others not to respond to trolls.[/color]

When you try to reason with a troll, he wins. When you insult a troll, he wins. When you scream at a troll, he wins. The only thing that trolls can't handle is being ignored."

I agree. Let's ignore the troll. What user is he?

 

[Zero]

Is this thread even about anything anymore, or shall we lock it and be done with it?

 

[Eyesaw]

Originally posted by ahrkron
Oh boy,

Physics is well beyond the stage of validating or even discussing about SR. It is not even a controversial matter any more among professional physicists.

This is NOT because of any conspiracy, or a desire to "maintain the status quo" (come on! the very idea is laughable), but because it is now firmly established (via experiment) and well understood.

Nowadays, relativistic corrections are used in myriads of experiments, and of course each one of them is first calibrated and tested with known magnitudes, to make sure that the gadget (or the 100 ton detector) measures things correctly. Any discrepancy would have been detected and studied long ago.

Due to the level of precision that current technology allows for experimental measurements, SR effects are extemely well tested. The current frontier of our knowledge is in a very different place.

Please list these experiments. Or just one at a time if you please.
I'd like to hear how SR time dilation has been tested in particular. But really, Einstein himself said that SR was not applicable if spacetime was not flat so if all experiments are done in a gravitational field, how can anyone claim SR has been tested? This seems a bit disingenuous at least.

The only tests that can be performed where spacetime is not flat are GR effects. Since Einstein himself said space-time is a kind of aether, all tests that are claimed to confirm GR then have confirmed the ether.

 

[Nereid]

Originally posted by Eyesaw
Please list these experiments. Or just one at a time if you please.
I'd like to hear how SR time dilation has been tested in particular. But really, Einstein himself said that SR was not applicable if spacetime was not flat so if all experiments are done in a gravitational field, how can anyone claim SR has been tested? This seems a bit disingenuous at least.

Here's a list of experimental tests of SR, and http://relativity.livingreviews.org/Articles/lrr-2001-4/ . Someone else may have a more comprehensive or up-to-date list.

 

[Hurkyl]

But really, Einstein himself said that SR was not applicable if spacetime was not flat so if all experiments are done in a gravitational field, how can anyone claim SR has been tested? This seems a bit disingenuous at least.

The same way one can say classical mechanics has been tested. Experiments have been performed, and they agreed with results of SR.

One of the basic principles of GR is that, to put it loosely, it looks like SR on small scales. (such as a laboratory) So, if GR is an accurate description of reality, then SR should be an accurate description of reality on the small scale.

(Just like classical mechanics is an accurate description of the macroscopic world at low velocities)

Since Einstein himself said space-time is a kind of aether, all tests that are claimed to confirm GR then have confirmed the ether.

I would like to point out that the "aether" of GR is not a "classical" aether. (Just like the particles of QM are not classical particles)

 

[Eyesaw]

Originally posted by Nereid
Here's a list of experimental tests of SR, and http://relativity.livingreviews.org/Articles/lrr-2001-4/ . Someone else may have a more comprehensive or up-to-date list.

Yes, I have looked at that webpage before. But before we go
over these experiments, I'd still like an answer to how any test
can be claimed to have confirmed SR as I keep hearing,
especially from this fanatic russ_waters guy.

If a theory is based on non gravity, how can it ever be applicable
to the real world? This is especially puzzling when space-time
itself in GR is endowed with these gravitational effects so that no travel is possible by any matter through it without being affected in a gravitational manner. Using GR tests to confirm SR is very weak inductive reasoning if not a logical fallacy entirely. How do we know that in the absence of gravity, matter will move at all? How do we know that matter doesn't generate its own gravitational fields so
that one can never have a flat spacetime if matter exists? What evidence do we have that in the absence of space-time, light can move at all or even exist?

 

[Eyesaw]

Originally posted by Hurkyl
The same way one can say classical mechanics has been tested. Experiments have been performed, and they agreed with results of SR.

One of the basic principles of GR is that, to put it loosely, it looks like SR on small scales. (such as a laboratory) So, if GR is an accurate description of reality, then SR should be an accurate description of reality on the small scale.

(Just like classical mechanics is an accurate description of the macroscopic world at low velocities)




I would like to point out that the "aether" of GR is not a "classical" aether. (Just like the particles of QM are not classical particles)

I think you have provided a very good example of how inductive reasoning can lead to conclusions which conflict with reality.
It's the very reason that classical mechanics had to be replaced
by quantum mechanics: assumptions we made about nature on the macroscopic scale did not accurately describe the quantum world,
even though inductively it should. In the same way, the assumptions about matter and motion through spacetime in GR may be very different from how nature behaves in the limit of GR.
Just as it is ridiculous to claim that tests on classical mechanics
are confirmations of Quantum mechanics, SR cannot be said to have been confirmed by tests of GR. But it's actually even worse since at least in Qm, we are still describing reality and not an imaginary universe as in SR.

 

[ahrkron]

Originally posted by Eyesaw
If a theory is based on non gravity, how can it ever be applicable to the real world?

Because there are many situations in which the gravitational field is so close to a flat metric (i.e., what you call "non gravity") that the effect of the curvature is extremely small compared to the SR effects.

Pretty much all experimental science works this way: you care for the main effects first, neglecting other things that produce small deviations, and verify that your theory accounts for what you can measure.

You never can take into account all minute distorsions due to all imaginable effects, but that is ok because they usually introduce deviations that are smaller than your experimental precision. Think of any theory with which you are comfortable. Say, thermodynamics. Does it take into account electromagnetic fields? QCD effects? Cosmic rays? radiation pressure? background radioactivity? no, but even when all of these effects are always present, the theory is still valid since it has been proven that the only important quantities are Volume, Pressure and Tempreature (how? by varying these quantities and observing if their correlation with experiment is consistent throughout many experiments, regardless of the values of all the other quantities).

 

[russ_watters]

Originally posted by Eyesaw
Yes, I have looked at that webpage before. But before we go
over these experiments, I'd still like an answer to how any test
can be claimed to have confirmed SR as I keep hearing,
especially from this fanatic russ_waters guy.

If a theory is based on non gravity, how can it ever be applicable
to the real world? This is especially puzzling when space-time
itself in GR is endowed with these gravitational effects so that no travel is possible by any matter through it without being affected in a gravitational manner. Using GR tests to confirm SR is very weak inductive reasoning if not a logical fallacy entirely. How do we know that in the absence of gravity, matter will move at all? How do we know that matter doesn't generate its own gravitational fields so
that one can never have a flat spacetime if matter exists? What evidence do we have that in the absence of space-time, light can move at all or even exist?

I'm a little confused. Are you asking how any test can be valid if there is more than one effect at work? There are always multiple effects being observed in experiments - the trick is knowing what is doing what.

Some of the predictions of SR are extremely simple and testing them is a relative piece of cake. GPS clocks and time dilation (my favorite) for example. Both the SR and GR effects are specific and with the equations known you can test for both at the same time.

 

[Deeviant]

Originally posted by Eyesaw
Yes, I have looked at that webpage before. But before we go
over these experiments, I'd still like an answer to how any test
can be claimed to have confirmed SR as I keep hearing,
especially from this fanatic russ_waters guy.

If a theory is based on non gravity, how can it ever be applicable
to the real world? This is especially puzzling when space-time
itself in GR is endowed with these gravitational effects so that no travel is possible by any matter through it without being affected in a gravitational manner. Using GR tests to confirm SR is very weak inductive reasoning if not a logical fallacy entirely. How do we know that in the absence of gravity, matter will move at all? How do we know that matter doesn't generate its own gravitational fields so
that one can never have a flat spacetime if matter exists? What evidence do we have that in the absence of space-time, light can move at all or even exist?

SR did have some shortcommings which is exactely why Einstien developed the General Theory of Relativity. GR does not blow up when objects are subjected to gravity(and neither does SR with GR). The principle of equivalence allows for gravity to be incorporated into Realativity quite nicely and also imples the local validity of SR. Oh yeah, there was just yet another successful experimental test of SR by Achim Peters of the University of Konstanz in Germany. I'll even give you a link http://www.physicsweb.org/article/news/6/1/2

If your going to attack SR, then your really going attack GR as well, which, of course you couldn't do because it is such a wildly successful and widely proven theory. Even if GR & SR is not the final answer so to speak, they do have incredible explanatory power of the universe around us that we use everyday in science with a decree of precision that would be simply impossible for a theory that is just flat out wrong.

If you want more experimental confirmation, I would suggest you talk to any scientists that works with a particle accelerator, or any those that worked on the GPS sattelite network which needed timing so accurate had to be corrected for time dilation described by SR else they would be off by tens of meters.


The truth of the matter is that relativity works(both GR and SR). If you have something that works better, I'm all ears. If you want to continue asking "what ifs" until your face turns blue, be my guest, but you won't get very far in science by challenging realativity unless you have an alternate, more successful theory.

 

[Eyesaw]

Originally posted by ahrkron
Because there are many situations in which the gravitational field is so close to a flat metric (i.e., what you call "non gravity") that the effect of the curvature is extremely small compared to the SR effects.

Pretty much all experimental science works this way: you care for the main effects first, neglecting other things that produce small deviations, and verify that your theory accounts for what you can measure.

You never can take into account all minute distorsions due to all imaginable effects, but that is ok because they usually introduce deviations that are smaller than your experimental precision. Think of any theory with which you are comfortable. Say, thermodynamics. Does it take into account electromagnetic fields? QCD effects? Cosmic rays? radiation pressure? background radioactivity? no, but even when all of these effects are always present, the theory is still valid since it has been proven that the only important quantities are Volume, Pressure and Tempreature (how? by varying these quantities and observing if their correlation with experiment is consistent throughout many experiments, regardless of the values of all the other quantities).

I think Maxwell's equations point out that the speed of light
in vacuum is related to the permitivitty and permeability of the vacuum, and Einstein used his equations to arrive at the constancy of speed of light postulate in SR, no? I would think that permitivitty and permeability are descriptions only
valid for a medium, which for the vacuum was termed the luminiferous ether at the time, so if that is how one obtains the speed of
light as constant, how does Einstein get a constant c without
a medium?

And if in GR, one of the properties of space-time (which is for all purposes a light-speed determining medium except by name), curvature, is dependent on the presence of matter, how can we be sure that space-time can have any properties at all without matter? In SR's imaginary universe without matter then, light may not move at all or it could move at an infinite velocity- who knows? Surely it would depend on the permittivity and permeability of space in that case, anyhow, and if those were 0, can the speed of light still be c?

Basically, I don't think it's appropriate to consider a flat space-time to have any permitivitty and permeability properties since SR denies the existence of a light-carrying medium in its postulate of the constancy of c. The historical relevance of SR was supposed to be its elimination of the necessity for a luminiferous ether, so I'd like to see the correct version of SR right now- one in which the constancy of speed of light was derived without the permittivity and permeability of the vacuum. Anyone who thinks GR is reduced to SR in flat-spacetime has the obligation to
produce Einstein's secret derivation of the constancy of c without Maxwell's equations.

Since I don't believe such a derivation exists, the speed of light in a vacuum then depends on the permitivvity and permeability of the vacuum and can not be a constant if the permittivitty and permeability of the vacuum are variable properties.

 

[Peterdevis]

the speed of light then depends on the permitivvity and permeability of space and is not really a constant if those properties of space were not constant.

I think you' re right here. Permitivvity and permeability are dependend of the "medium" light is traveling. The permitivity of glass is quite different of that of vacuüm. So the speed of light is variable.
Nevertheless, this is no problem for GR. Because the fundation of GR is the (einstein)Equivalence principle:"In small enough regions of spacetime, ALL laws of physics reduce to those of special relativity, it is IMPOSSIBLE to detect the existence of a gravitational field"
This mean that , no matter in which coördinate system we are, the result of measering permitivvity and permeability of a "medium" must be the same and the speed of light is constant for that medium.

so what is your problem?

 

[Eyesaw]

Originally posted by Peterdevis
I think you' re right here. Permitivvity and permeability are dependend of the "medium" light is traveling. The permitivity of glass is quite different of that of vacuüm. So the speed of light is variable.
Nevertheless, this is no problem for GR. Because the fundation of GR is the (einstein)Equivalence principle:"In small enough regions of spacetime, ALL laws of physics reduce to those of special relativity, it is IMPOSSIBLE to detect the existence of a gravitational field"
This mean that , no matter in which coördinate system we are, the result of measering permitivvity and permeability of a "medium" must be the same and the speed of light is constant for that medium.

so what is your problem?

My problem is that the c in Maxwell's equation depended on a
medium, which for the vacuum was called the luminiferous ether
in the 19th century. Since SR eliminated the ether, it becomes inconsistent to use Maxwell's equation to derive the speed of light, which Einstein did in SR.

 

[Peterdevis]

My problem is that the c in Maxwell's equation depended on a
medium, which for the vacuum was called the luminiferous ether
in the 19th

It is not because maxwell believed in an ether, that there must be an ether too derive Maxwell's equations.
An theory is independent of the scientist, what maxwell, einstein, Newton... thinks of a theory is not important. But the ability of prediction is what a theory makes usefull.

So where we need an ether to derive Maxwell's equations?

 

[protonman]

Originally posted by Eyesaw
The whole notion of an ether was incorporated into Maxwell's
equations for EM waves. Hence the equations for propogation
are wave equations and their propogation speed only dependent
on the permitivitty and permeability of the medium. Without a medium, there can be no waves so you won't have Maxwell's equations- you'd have Einstein's Undiscoverable Equations.

Eyesaw is making a very good point and the responses to his question have not really addressed the issue. I think the answer is that the medium that light travel through is space. For example, if light bends in the presense of a gravitational field it must be moving through something that has the ability to bend.

 

[russ_watters]

Originally posted by Peterdevis
I think you' re right here. Permitivvity and permeability are dependend of the "medium" light is traveling. The permitivity of glass is quite different of that of vacuüm. So the speed of light is variable.

Light transmission through glass happens via absorption, delay, re-emission of the photons, making it appear to travel more slowly when you observe it macroscopically. Light always travels at C.

As said before, the fact that space-time has physical properties does not make it a classical "ether."

what maxwell, einstein, Newton... thinks of a theory is not important.

Except insofar as they wrote their theories of course!

I think the answer is that the medium that light travel through is space. For example, if light bends in the presense of a gravitational field it must be moving through something that has the ability to bend.

That is quite true, protonman, but it does not make space a classical ether.

 

[Eyesaw]

Originally posted by Peterdevis
It is not because maxwell believed in an ether, that there must be an ether too derive Maxwell's equations.
An theory is independent of the scientist, what maxwell, einstein, Newton... thinks of a theory is not important. But the ability of prediction is what a theory makes usefull.

So where we need an ether to derive Maxwell's equations?

Well, Maxwell's equations for EM radiation are wave equations,
so they need a medium since waves don't exist as far everyday
observations go, independent of a medium. To derive Maxwell's
equations without an ether then would require one to show
that the vacuum is completely empty, else one can always assume
a medium that is just too small to be observed.

Since this can never be done, it's more economical to assume light, if it is a wave, requires like every observable wave phenomenon,
a medium for propogation. So you need an ether to derive Maxwell's equations.

An alternative would be to consider light as particles, in which case you would have to explain why their velocity is not source dependent like other ballistic particles.

Einstein did neither so his postulate of a constant c in SR then has neither physical nor mathematical basis since he disposed of the ether.

 

[Nereid]

Eyesaw wrote: *SNIP
Since this can never be done, it's more economical to assume light, if it is a wave, requires like every observable wave phenomenon, a medium for propogation. So you need an ether to derive Maxwell's equations.

An alternative would be to consider light as particles, in which case you would have to explain why their velocity is not source dependent like other ballistic particles.

So, here's some of what's been observed about light:
- double-slit experiment -> "wave-particle duality", well accounted for by quantum mechanics
- photoelectric effect -> light as photons
- gravitational bending and Shapiro time delay -> predicted and well accounted for by GR.

In summary, all observations match predictions of the theories.

If your view of 'waves' requires they need a medium for propogation, then either 'light is not a wave', or 'your view of the nature of waves is incomplete' (or both).

If your view of 'ballistic particles' requires that their velocity is source dependent, then either 'light is not a ballistic particle', or 'your view of the nature of ballistic particles is incomplete' (or both).

 

[quantumdude]

Originally posted by Eyesaw
Well, Maxwell's equations for EM radiation are wave equations,
so they need a medium since waves don't exist as far everyday
observations go, independent of a medium.

Why not? What substrate is implied by Maxwell's equations?

To derive Maxwell's
equations without an ether then would require one to show
that the vacuum is completely empty, else one can always assume
a medium that is just too small to be observed.

"Too small"?

The light that we see from the sun travels 93 million miles to Earth! In what sense is this supposed medium "too small"?

Since this can never be done, it's more economical to assume light, if it is a wave, requires like every observable wave phenomenon,
a medium for propogation. So you need an ether to derive Maxwell's equations.

Why is it more economical to add an assumption?

An alternative would be to consider light as particles, in which case you would have to explain why their velocity is not source dependent like other ballistic particles.

We do consider light as particles, when the intensity of the radiation is sufficiently weak. But why do we have to explain why the velocity of those particles is not source dependent? That is like demanding an explanation of why the charge of an electron has the value that it does.

Einstein did neither so his postulate of a constant c in SR then has neither physical nor mathematical basis since he disposed of the ether.

No, SR has both. Its mathematical basis follows from the (very well tested) Maxwell equations. Its physical basis follows from all the experiments that have been done to corroborate it.

 

[Phobos]

Mentor note:
This past page or two has been getting back on track to a decent discussion. If the nonsense of the first 5 pages starts again, then this topic is over.

 

[Nereid]

Originally posted by pelastration
Nereid,

have you even seen this quote of Maxwell?

"In speaking of the Energy of the field, however, I wish to be understood literally. All energy is the same as mechanical energy, whether it exists in the form of motion or in that of elasticity, or in any other form. The energy in electromagnetic phenomena is mechanical energy."
--- JAMES CLERK MAXWELL

I found that on a website of Joseph Newman, never found other oringinal references. But it fits in my ideas about multi-layered spacetime where membrane friction creates all other interactions.

AFAIK, Maxwell died before the results of the Michelson-Morley experiment were published (and he died even before M&M began their experiment?) So we cannot know how he would have felt, or what he would have thought, had he lived another few or 20 years. Certainly, Maxwell died before quantum weirdness was discovered.

As others have said here, we're on a journey, learning new things all the time ... finding new things doesn't diminish the great contributions of past giants, but neither would they wish us to stay stuck with only what they found.

 

[GRQC]

A question which was posed earlier, and I think needs re-iterating, is why do we need an ether? There is this prevailing notion from some posters that the universe must behave as Newtonian physics predicts, and that "fanciful" theories such as quantum mechanics and relativity theory must be incorrect because they contradict classical Newtonian intuition -- despite the fact that Newtonian physics is a limiting case in both theories.

Perhaps those calling for proof of why they should believe modern theories should in turn tell us why Newtonian physics is expected to be the ultimate theory.

 

[russ_watters]

Originally posted by GRQC
Perhaps those calling for proof of why they should believe modern theories should in turn tell us why Newtonian physics is expected to be the ultimate theory.

Its pretty simple: Newtonian physics 'makes sense.' A wave without a medium in which to propagate? Absurd!

That the coolest thing about QM: pretty much everything in the entire theory contradicts classical interpretations of how the world 'should work.' Its bizarre. Rediculous. Illogical. But with so much clear and incontrovertible evidence that the bizarre is for real, we have no choice but to change our view of how the world 'should work,' not look for a reason why QM could be wrong.

 

[protonman]

That is quite true, protonman, but it does not make space a classical ether. [/B]

Why not? It seems logical to consider space as the medium of propagation of light. Yes, not in the classical sense of an ether that can serve as an absolute reference frame but none the less a medium of propagation.

In addition, it may simply be the case that the medium of propagation has not been searched for properly. In any experiment there are assumptions. If the wrong ones are made the outcome will be incorrect or at least inconclusive.

 

[protonman]

Originally posted by Eyesaw
Well, Maxwell's equations for EM radiation are wave equations,
so they need a medium since waves don't exist as far everyday
observations go, independent of a medium. To derive Maxwell's
equations without an ether then would require one to show
that the vacuum is completely empty, else one can always assume
a medium that is just too small to be observed.

Since this can never be done, it's more economical to assume light, if it is a wave, requires like every observable wave phenomenon,
a medium for propogation. So you need an ether to derive Maxwell's equations.

An alternative would be to consider light as particles, in which case you would have to explain why their velocity is not source dependent like other ballistic particles.

Einstein did neither so his postulate of a constant c in SR then has neither physical nor mathematical basis since he disposed of the ether.

This is excellent work. What you are doing is here is a breath of fresh air. Another related question to raise is that if SR is incorrect how do you explain all the phenomena that have been explained using SR? For example, Pion decay experiements.

 

[protonman]

Originally posted by Nereid
So, here's some of what's been observed about light:
- double-slit experiment -> "wave-particle duality", well accounted for by quantum mechanics
- photoelectric effect -> light as photons
- gravitational bending and Shapiro time delay -> predicted and well accounted for by GR.

In summary, all observations match predictions of the theories.

If your view of 'waves' requires they need a medium for propogation, then either 'light is not a wave', or 'your view of the nature of waves is incomplete' (or both).

If your view of 'ballistic particles' requires that their velocity is source dependent, then either 'light is not a ballistic particle', or 'your view of the nature of ballistic particles is incomplete' (or both).

So basically when new evidence doesn't fit your previous definitions and rules just change the them.

 

[quantumdude]

Originally posted by protonman
So basically when new evidence doesn't fit your previous definitions and rules just change the them.

Exactly. It's the best anyone can do.

 

[protonman]

Why not? What substrate is implied by Maxwell's equations?

What is a wave?

 

[quantumdude]

Originally posted by protonman
What is a wave?

A wave is any traveling, periodic disturbance in a physical field.

My turn: What substrate is implied by Maxwell's equations?

 

[protonman]

We do consider light as particles, when the intensity of the radiation is sufficiently weak. But why do we have to explain why the velocity of those particles is not source dependent? That is like demanding an explanation of why the charge of an electron has the value that it does.

If you people were ever called to debate your views with those who know logic you would be laughed out of town.

Think about your attempt parallel reason. The reason you would have to explain why light is source independent is because everything else we know that is a particle is source dependent. You comparison to explaining the charge of an electron is completely off the mark.

This is what I have been saying all along. There are no more great thinkers. Just regurgitations.