[syhprum (OP)]

Why is it heresey to talk of an æther, we are told space is pervaded by the Higgs field, masses of virtual particles, we know the CMBR is there because we can measure it not to mention Mach's generalised gravitational field and lots of dark matter and Neutrino,s.
Surely we have something to refer to.

[JP]

The luminiferous ether was a theory that light behaved like water or sound waves.  The ether would act like water or air, and would wave up/down or back/forth as light moved through it to carry the wave, just like air does for sound waves.  Part of this theory is that, like sound waves, if you move quickly in the ether, you would eventually overtake light.  That proved false, and the ether theory fell out of favor. 

Now, we do know that there are all sorts of fields pervading the universe and that space-time itself also has properties that keep the speed of light constant, but none of these have anything to do with the above theory of luminiferous ether.  Some people propose to use the word "ether" to describe space-time, but that's not really accurate, and it can be necessarily confusing to name it after a defunct and unrelated theory.

[syhprum (OP)]

Are we not as guilty as the pre copernicans when we assume the characteristics of space in our local area are the same over the whole universe, if it is correct that dark matter holds the rotating galaxy together are we not immersed in that same dark matter yet we assume that every thing is the same in the universe that is mostly outside it.

[JP]

Are we not as guilty as the pre copernicans when we assume the characteristics of space in our local area are the same over the whole universe . . .

How so?  Pre-Copernicans made assumptions without considering observational or experimental fact.  Today we use observations and experiments to develop theories that are in accordance those facts. 

[Phractality]

Sour grapes! Many attempts were made to describe the ether and how both waves and particles move thru it. All proposed ether models were proven wrong, or at least inadequate. Then Einstein came up with a mathematical description of space-time which made it unnecessary to describe the physical nature of space. The mathematical description works well, so we now pretend that space is nothing but math. We couldn't reach the grapes, so they were probably sour, anyway!

In his Leyden address, Einstein reluctantly conceded that, if there is an underlying ether, it lacks the property which he called "immobility". Every reference frame is equivalent, and all known phenomena work the same in every reference frame. As long as no faster-than-light (FTL) phenomenon is proven to exist, his argument remains valid. However, if we ever do prove the existence of an FTL phenomenon (such as quantum entanglement, which some claim is instantaneous), that will mean that there is only one preferred frame of reference in which the FTL phenomenon has the same speed in every direction. In other words, that frame of reference will be immobile, and the ether must have the property of immobility. If the ether is immobile, then it will no longer make sense to ignore its existence. 

Some scientists (myself included) are still pursuing the quest to adequately describe the ether, but they are the black sheep of the scientific community. Their ether models are outside the mainstream of science; on this website, they are relegated to the New Theories forum.

[JP]

Phractality, we asked you (on several occasions) to move your posts to New Theories because you were preaching new theories and that's the appropriate forum for new theories.  Constantly complaining about being asked to do so won't convince us otherwise and will only annoy the moderators.

As for whether the properties of space-time constitute "ether" or not, you're missing the point.  The point is that the word ether is strongly associated with "stuff" that supports light propagation and has a preferred reference frame in which it's immobile.  Unless you're talking about that stuff, why use the word ether?

[simplified]

Very fast gravitational winds are "ether".

[Phractality]

JP,
There is nothing new about the theory that there is a substance which is the medium of light. If you read Einstein's Leyden address, you would know that he, too, was a firm supporter of that theory. (Here, I am using the term "theory" loosely; "notion" would be a better description.) What's new is a variety of new ether models, each of which properly belongs in "New Theories". I have carefully avoided mentioning any particular ether model, new or old, while answering the question, "Why no ether?"

Recapitulating, we may say that according to the General Theory of Relativity space is endowed with physical qualities; in this sense, therefore, there exists an Aether. According to the General Theory of Relativity space without Aether is unthinkable; for in such space there not only would be no propagation of light, but also no possibility of existence for standards of space and time (measuring-rods and clocks), nor therefore any space-time intervals in the physical sense. But this Aether may not be thought of as endowed with the quality characteristic of ponderable media, as consisting of parts which may be tracked through time. The idea of motion may not be applied to it.
A. Einstein, from Leyden address

It is now widely claimed that, through quantum entanglement, a cause at A can instantaneously produce an effect across a finite distance at B. (Whether this may permit FTL communication is irrelevant to the question at hand.) What the popular news media fail to mention is that the effect cannot be instantaneous in every reference frame. Clocks which are synchronized in a different reference frame, having a component of motion parallel to the line A-B, will indicate that the cause and effect are not simultaneous. That is just basic special relativity, not new theory;

t'= γ(t-vx/c^2).

Proof of an FTL phenomenon would prove the existence of an immobile preferred reference frame, and the ether described by Einstein would then have the quality of immobility. Therefore, it would be a ponderable substance whose parts may be tracked through time. 

Einstein answered the question, "Why no ether?" based on the lack of any known FTL phenomenon. As long as no such phenomenon is proven to exist, his conclusion remains valid, and without introducing any new theories, that's why we have no ether in today's mainstream physics.

[Phractality]

Very fast gravitational winds are "ether".

Now, that's an example of new theory for you.

[simplified]

Very fast gravitational winds are "ether".

Now, that's an example of new theory for you.

Gravitation exists in space and has fast speed.It is not new theory.

[JP]

JP,
There is nothing new about the theory that there is a substance which is the medium of light. If you read Einstein's Leyden address, you would know that he, too, was a firm supporter of that theory.

The Leyden address was given over 90 years ago.  Einstein's use of (a)ether in that address bears no resemblance to how it's used in modern physics.  These days, the word ether means luminiferous ether (http://en.wikipedia.org/wiki/Luminiferous_aether), which I described above, and which isn't taken seriously as a theory because it requires that light speed isn't constant (and from extensive testing, it appears to be constant).  Citing an outdated use of the term, even if that use is by Einstein, doesn't change its modern definition. 

[Phractality]

JP,
There is nothing new about the theory that there is a substance which is the medium of light. If you read Einstein's Leyden address, you would know that he, too, was a firm supporter of that theory.

The Leyden address was given over 90 years ago.  Einstein's use of (a)ether in that address bears no resemblance to how it's used in modern physics.  These days, the word ether means luminiferous ether (http://en.wikipedia.org/wiki/Luminiferous_aether), which I described above, and which isn't taken seriously as a theory because it requires that light speed isn't constant (and from extensive testing, it appears to be constant).  Citing an outdated use of the term, even if that use is by Einstein, doesn't change its modern definition.

The way the word "ether" is used by people who don't believe in it has little to do with the way the word is used by people who have theories about what ether is. I agree that the speed of light is the same in every direction in every reference frame. I only disagree with the mainstream belief that there is no preferred reference frame. Detecting something special about that special reference frame may not be possible until it is proven that certain FTL phenomena are real.

Syphrum posed the question, "Why no ether?" He wants to know why mainstream physics has abandoned the idea that light requires a ponderable medium. I have merely provided the historical context which has led the mainstream to that conclusion. The reasoning that went into the Leyden address remains valid, given that no one has yet proven the existence of FTL phenomena. Because of recent experiments which claim to have detected FTL phenomena, I think it is prudent to prepare ourselves for the implications in case they are proven right. Those implications are not new theory, but straightforward corollaries to the accepted theory of relativity.

[JP]

The way the word "ether" is used by people who don't believe in it has little to do with the way the word is used by people who have theories about what ether is.

This is fortunate.  Science would be a confusing mess if anyone could redefine terms to fit their personal theories.  Since this is a science forum, it's probably best to stick to scientific terminology.

[Phractality]

The way the word "ether" is used by people who don't believe in it has little to do with the way the word is used by people who have theories about what ether is.

This is fortunate.  Science would be a confusing mess if anyone could redefine terms to fit their personal theories.  Since this is a science forum, it's probably best to stick to scientific terminology.

Let me use a metaphor to describe our difference of opinion; okay? A century ago, the lack of physical evidence for the existence of a real person named Santa Clause caused grownups to declare that Santa does not exist. Faced with open rebellion from their children, the grownups conceded that Santa exists but only as an idea, not as a real person. But some kids grew up still believing that Santa is a real person. Of course each true believer has a different idea of what Santa looks like, where he lives, how many reindeer pull his sleigh, and whether his sleigh actually flies, but they all believe Santa is a real person, not just an idea. You are accusing those true believers of changing the meaning of Santa Clause to suit their own pet theories. They're not the ones who changed the meaning of Santa; it's the unbelievers who changed the meaning. Someday, the real Santa may reveal himself, and he probably won't resemble any of the popular legends about him.

[Geezer]

Let me use a metaphor to describe our difference of opinion; okay? A century ago, the lack of physical evidence for the existence of a real person named Santa Clause caused grownups to declare that Santa does not exist. Faced with open rebellion from their children, the grownups conceded that Santa exists but only as an idea, not as a real person. But some kids grew up still believing that Santa is a real person. Of course each true believer has a different idea of what Santa looks like, where he lives, how many reindeer pull his sleigh, and whether his sleigh actually flies, but they all believe Santa is a real person, not just an idea. You are accusing those true believers of changing the meaning of Santa Clause to suit their own pet theories. They're not the ones who changed the meaning of Santa; it's the unbelievers who changed the meaning. Someday, the real Santa may reveal himself, and he probably won't resemble any of the popular legends about him.

True, but religions are based on belief. Science isn't.

[Phractality]

True, but religions are based on belief. Science isn't.

If scientists change the definition of God, are priests then wrong to continue using their old definitions? Would you accuse the Pope of changing the definition of God when he continues to define God the way his predecessors have done for two millennia, instead of the definition made up by scientists a century ago?

[Geezer]

If scientists change the definition of God, are priests then wrong to continue using their old definitions? Would you accuse the Pope of changing the definition of God when he continues to define God the way his predecessors have done for two millennia, instead of the definition made up by scientists a century ago?

That seems to be entirely hypothetical. I do not understand what it has to do with science. I'm not aware of any science that purports to change the definition of any god.

Science is really very simple. All we have to do is come up with a testable theory and put it to the test. Until it passes the test, it's supposition.

[Phractality]

Science is really very simple. All we have to do is come up with a testable theory and put it to the test. Until it passes the test, it's supposition.

They dreamt up a number of tests (like Michelson-Morley) to find out if aether is a ponderable substance. Unfortunately, all the tests were flawed because they lacked a valid model of the aether. The test failed, so they declared that the aether does not exist. Then, they resumed using the term "aether", but with a whole new meaning. If they had a proper model of aether, they might have dreamt up a valid test and gotten a positive result. However, since the math works sufficiently well, they see no reason to try and fix the model. As far as they're concerned, it ain't broke, so don't try to fix it. I look forward to the day when they discover that the model has been broke all along.

[JP]

Phractality, if you keep moving the goalposts, of course you'll always be able to win the game.  As Geezer says, science doesn't work that way.  Continue moving the goalposts all you like, but you've left the realm of science.

[syhprum (OP)]

This discussion seems to have taken paths that I really did not intend it too, I had in mind was there a fixed reference against which our motion could be measured and was our conception of intergalactic space coloured by our presence in a galaxy.
Hertz tells us that the speed of light is determined by the permittivity and permeability of the vacuum if we constructed  a vacuum capacitor and measured is capacitance at our present location immersed in a sea of dark matter and in intergalactic space would it be the same.