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The classical aether vs. the modern vacuum

  1. Sep 26, 2007 #1
    I have been reading a few old texts from around the turn of the 20th C. and have noticed that in at least two there is mention of the aether in connection with electromagnetic phenomena. In these texts a statement to the effect of "the space around the coil is altered in some way by the passage of current in the wire". Or one even says "the medium surrounding the magnet is clearly stressed by the flow of charge..."

    These are intriguing statements that have an undertone of some deep intuition on the part of the writers.

    We know now that the "medium" of the aether is nonexistent . But is it really? Maybe it isn't a gaseous fluid such as early thinkers thought, but is it any less real?

    The modern quantum vacuum, while far stranger than anything 19th C minds were grasping, is for every aspect as far as classical EM is concerned, the aether is it not?

    Space being filled with this quantum fluid, as it sometimes behaves, makes alot of things intuitively satisfying. The spatial "stresses" of electric and magnetic fields, the propagation of light through "empty" space, maybe even inertia seem to "feel better" in this view.

    Am I just totally off base with this? I know there are some semantics between old and new descriptions of phenomena, and even new ideas that didn't exist in the aether heyday. But were the Grand Old Men of electrodynamics, who clearly possessed some sort of deep physical intuition on the nature of matter, all that wrong?
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  3. Sep 26, 2007 #2


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    Why would one give the name "aether" to the vacuum (of QM) when it already has a perfectly good name?
    Last edited: Sep 26, 2007
  4. Sep 26, 2007 #3


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    A rhinoceros shares some features with the mythical unicorn. Should we therefore think of a rhinoceros as a sort of unicorn?
  5. Sep 26, 2007 #4
    No, perhaps a unicorn as a rhinoceros. I think what I mean is aren't they the same? Just because they called it "aether" and ascribed the properties of a massless gas to it makes it less real? I think these 19th C scientists were aware of the vacuum of modern theory. Just lacking the proper tools to really study and define it. They imagined it had properties that "made sense", but that doesn't work all the time for a quantum field, so turns out that what properties they were looking for and at what energies and levels they were looking at, are nonexistent.

    That isn't, however, proof of it being absolutely unreal. The relativists came along and suddenly you are a crackpot if you believe in any slight way in the existence of a universe-pervading "fluid" that under different stresses manifests itself as various kinds of fields. But Relativity doesn't require us to cast the "aether" out. What what we are told, by SR, is that an absolute frame of reference is unnecessary and nonexistent. Therefore, if you are an early 20th C physicist and you believe that the "aether" is Newton's absolute frame, then yes, you are wrong.

    Then along comes the quantum theorists, and things get a little weird, and older guys, like our "aetherians", already cowed by a berating from the relativists, fade into history, without ever speaking up again. Dirac and his ilk come about and talk of the vacuum as a real thing that can be teased to produce a variety of fields and particles, given the right conditions. They call it a quantum vacuum and space is seething with energy and properties all it own, and not the same emptiness of the relativists.

    Basically, aether supporting scientists were ahead of their time. They were trying to describing the spacetime of Dirac with the thermodynamics of Clausius. They were, then, wrong about many aspects of it. But the general field was correct. Had they kept researching, they may have eventually derived some of the concepts of quantum mechanics. But that is now moot.

    Perhaps, in an attic somewhere, in an old desk drawer of some shunned and long-dead aether theorist, we may find a breakthrough paper, written 100 years ago but outcast and ridiculed by the research and publication community for being crackpot.
  6. Sep 26, 2007 #5
  7. Sep 26, 2007 #6
    Thanks, Eugene. But referring to my last post, you will see that I am not arguing the aether as an absolute frame of reference. That, I believe, is incorrect.

    Why do most people automatically associate "aether" with only that specific usage? Just because SR doesn't require it and refutes its use as an absolute reference, doesn't mean that it is unreal. All that simply means is that special relativity doesn't use the vacuum for anything more than as space for events to occur in. Because SR doesn't require it as a frame of reference, we can drop that aspect of it, but we don't drop the whole thing, because, while wrong about absolute relative motion, the GRAND OLD MEN OF ELECTRODYNAMICS GLEANED A HINT OF OUR MODERN QUANTUM VACUUM AND CALLED IT THE AETHER, NEVER UNDERSTANDING, AS WE DO NOW, WHAT THEY WERE FOLLOWING. THESE IDEAS WERE SHUNNED AND PUSHED ASIDE AND NO LONGER PURSUED UNTIL, YEARS LATER, SOMEONE CAST IT IN A NEW LIGHT AS THE QUANTUM VACUUM.
  8. Sep 26, 2007 #7
    Caps lock much?
  9. Sep 26, 2007 #8
    Hi Maxwell's Beard,

    I have a (not very popular) point of view that there is no such a thing as "quantum vacuum". My understanding of quantum field theory (based on the "dressed particle" approach) tells me that vacuum is just an empty space (no particles) without any observable properties. In order to observe something there should be at least one physical particle, and I don't believe in any particle-vacuum interactions, such as those leading to particle "self-energies" or "vacuum polarization". For these reasons I cannot accept your vacuum/aether analogies.

  10. Sep 26, 2007 #9
    Beard, since you have entered this forum, you must want to communicate to us. To do this, you need to use the same names for concepts as we use, otherwise we won't understand your message.

    We use the name ether for the thing with the properties that your grand old men were thinking of, and we use the name quantum vacuum for the modern concept that you think is closely related (but we disagree).

    In addition to using the same language, it would be polite (which is good for you because we will respect you in return and thereby be more attentive to what you wish to say) if you also pay respect to the other customs we have accepted here. For example, seeing excessive capitalisation (in fact, any font style other than the default) to most of us is unpleasant like listening to shouting (since it is distracting, more difficult to read, and overrides the personal preferences we have configured for display of text on our individual computers). For another example, it is fine to ask for a discussion of the similarities and differences between the concepts of ether and quantum vacuum, but we don't want threads here to outright assert that those concepts should be identified with one another (nor any other assertion contrary to the mainstream physics viewpoint that we are aiming to learn).
    Last edited: Sep 26, 2007
  11. Sep 26, 2007 #10


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    How can any sort of physical "fluid" fail to have a rest frame? Just to be clear, when you say that you reject an absolute frame of reference, are you somehow proposing it makes sense to call something an "aether" even if it lacks any sort of rest frame (even locally), or are you saying you think there might be an aether with a rest frame, but you just aren't claiming that its rest frame is any sort of "absolute" frame? (much like how the cosmic microwave background radiation has a rest frame but this isn't taken as evidence for absolute space) If the latter, do you think the aether's rest frame would be measurable in some way, so that effects relating to the aether would not all be Lorentz-symmetric?
  12. Sep 26, 2007 #11
    Thank you CesiumFrog. I used caps to try to emphasis that I am not speaking of the aether in the sense of an absolute frame of reference. That seems to be a point which keeps popping up, which I keep refuting, on the grounds of SR.

    I am trying to convey my thoughts on the subject as clearly as I can in writing, which is very hard, and further complicated by the fact some aetherists were also subscribers to Newton's absolute reference frame, which seems to have caused everyone to rail against anyone using the term "aether" as an anti-relativist.

    I suppose I can see how it looks as if I want someone to tell me I'm right. But it is actually the contrary. I want someone to tell me why I'm wrong. No one has yet to do it without invoking the "because there is no absolute frame" argument. That argument is correct, and I agree whole-heartedly.

    Ok, I may be able to pose it this way, as you say that you disagree that the old aether is the new vacuum.

    Other than a lack of a better understanding and the acceptance of an absolute frame, what is all that different about a 19/20th C scientist saying a "stressed" aether gives rise to electric and magnetic fields, compared to a modern scientist believing that an "excited" vacuum gives rise to electromagnetic fields?
  13. Sep 26, 2007 #12
    So far you are neither right nor wrong. Stating that "aether = quantum vacuum" you haven't made any statement about physics. Physics is science about experimental observations. So, if you want to talk about physics you should tell what are the properties of your "aether", how it interacts with other objects (particles), in which experiments these properties and interactions can be measured, how your predictions are different from existing theories?...

  14. Sep 26, 2007 #13
    I'm saying that the difference between the the aether and the quantum vacuum is precisely the name. Sure the word "aether" makes one think of a classical (that is, non-quantum) fluid. But it was classical (that is, non-quantum) men who named such things. I do not wish to discuss what frame the aether represents, because it is not what my original post was about anywho. That, in my mind, is that same question as what frame does the vacuum represent.

    I have an old text that says something like, and I'm paraphrasing, forgive me, "the motion of the electric charges in the coil cause a change in the properties of the medium immediately surrounding it. It is this stress in the aether that is manifested to us as a magnetic field B surrounding the coil".

    This rings with modern quantum vacuum, even if it uses different wording. What is different about a "stressed aether" giving rise to electric and magnetic fields, compared to an "excited vacuum" giving rise to an electromagnetic field?
  15. Sep 26, 2007 #14
    I am not trying to make any statements about physics, I'm making a statement about physicists. I am not now, nor have I previously, attempted to state any new postulates about modern quantum mechanics or classical electrodynamics. I simply believe that the men that called the thing "aether" were really describing (incompletely, and in many ways incorrectly) what is now called the quantum vacuum. I suppose I am trying to credit these men, Faraday, Maxwell, Heaviside, et al, with being the first to recognize Dirac's vacuum, though through the lens of the 19th C.

    Please forgive me all if I have seemed pigheaded. But there is no experiment that I can do to validate my claims, as my claims are purely non-physical and rely on the fact that while words can be different, meanings can and often are one in the same.

    So I pose this question again: what is all that different about a "stressed aether" giving rise to electric and magnetic fields, compared to an "excited vacuum" giving rise to an electromagnetic field?
  16. Sep 26, 2007 #15


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    I don't think it makes sense to call a quantum field a "fluid", either quantum or classical, if it has nothing like a rest frame. Even a quantum fluid like a superfluid, or weird non-fluid states like Bose-Einstein condensates, still have some kind of expectation value for a rest frame I think (i.e. the frame where their position is most likely to remain constant).
  17. Sep 26, 2007 #16
    These two notions are, indeed, very similar, because they both are completely fictional and non-observable.

  18. Sep 26, 2007 #17
    The void has properties - the difficulty is in modeling it in terms of convention wisdom. How can space stretch as Robertson proposes, or rotate about a black hole, or link with local matter to bring about Newtonian reaction as Einstein deliberated, or exhibit a characacteristic impedance or a capacity or permitivity or communicate rotation via Thirring ...there does not seem to be a something that can exhibit all these characteristics - it is a classic case of the failure of traditional theories based upon particles and fields.

    There is an oft quoted phrase "absence of proof is not proof of absence" The existence of a medium has never been falsified, but to understand its nature seems at this point to require the abandonment of internal consistency
  19. Sep 26, 2007 #18
    It is frequently stated that Einstein renamed the "aether" space. He seemed to treat his space as having all the qualities of the classical ether except motion, which would have contradicted SR. The issue of the modern vacuum and the classical aether is subjective - it is not an issue that should be settled by majority vote - or who shouts the loudest on this forum, or most depreciative.
  20. Sep 26, 2007 #19


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    Upon what grounds do you make such an assertion?

    The ancient Greek philosopher Democretus talked about how all matter was made out of indivisible atoms. Do we credit him with the discovery of the atomic theory of matter? Of course not! Democretus' philosophy doesn't resemble Dalton's theory at all, except for that one superficial similarity!

    Why do you think this situation is any different?
  21. Sep 27, 2007 #20
    You are just picking at me now. You know full well that "fluid" doesn't mean any real fluid, classical or quantum. It is just a picture for the mind's eye. Even Dirac called the vacuum a "sea".
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