how is dark matter different from the old "ether" theory
In what ways do you suppose they are the same? Do you believe that the speculation is offered in the same manner, or do you mean something else?
im not exactly sure....could you maybe differentiate between the two plz?
This is a ridiculous premise for a thread. What do you understand about dark matter? What do you understand about the aether? What makes you think they are similar?
Dark matter interacts gravitationally but not with light.
The ether was supposed to provide the medium for light transmission, but wouldn't have interacted gravitationally.
thnx. what janus said is all i needed to know.
You might have been thinking about "Dark Energy v ether?"
In which case the difference would be that the aether in its original form would have been a medium against which an absolute frame of reference could be measured.
DE would provide no such absolute frame of reference.
The original aether theory was proved false by the Michelson–Morley experiment but was further revived for a short time by Lorentz. In its new guise the Lorentz transformations of moving rulers and clocks would render the aether always unobservable.
However, the standard interpretation was that if the aether was always unobservable then it did not exist and the theory of Special Relativity took its place on the world scientific stage.
Dark matter and ether have one thing in common they both are ways to explain why our equations are not working.
Not really, no. Ether theory was rejected because with it, our equations didn't work. You have it backwards.
Both "ether" and "dark matter" were offered as - in some respects - similar explanations. In the end the purposed theory for "ether" was rejected when what we knew advanced enough that the equations did not work out. We are not yet that far along with "dark matter". Both "ether" and "dark matter" are metaphors for something we do not understand. Both were presented as a sort of universal seemingly undetectable medium - and proposed as an answer to a current question.
Give the subject another fifty years, and they might both share the same chapter in a Physics textbook. Could just as meaningfully call "dark matter" and "dark energy" the "new theory of ether". The denotation is the same, only the connotations differ. :)
Guess it bugs me somewhat that "dark matter" and "dark energy" are talked about as though real and some sort of answer, when so far as I call tell all we have is the question. A vast and interesting question to be sure ... but so far only that.
Seems to me the question that started this thread is entirely reasonable.
why would motion relative to the aether be absolute?
Because the ether was thought to be the very fabric of space, acting much like air as a medium for sound.
so??? thats still relative not absolute.
The ether was not introduced to explain an error in a theory, it was assumed to exist based on the way previous theories worked. It was discarded when it was found that it didn't exist.
Dark matter, on the other hand, was theorized because previous theories produced inaccurate predictions, but scientists didn't think the error was big enough to scrap the entire theory.
There's another difference: there is evidence that dark matter exists. There was never any evidence that the ether existed. The very first attempt to find it failed.
If dark matter is eventually abandoned, history will likely view it as similar to Einstein's cosmological constant, not as similar to the ether.
Perhaps, but one way to look at the advancement of science is a narrowing of error margins. Because of the narrowing of error margins, the potential for error in current theory is much smaller than in the theories that existed 110 years ago.
You seem to be taking the question figuratively. We read it and answered it literally.
The story I remember about the state of Physics back 110 years ago (or a bit before), was a belief that pretty much everything had been discovered, and all that was left was a narrowing of error margins (more precise measurements). What we got a bit later was some fairly large conceptual leaps.
You could count that as just a narrowing of error margins, but I think conceptual leaps should count as non-linear - not linear - progress.
We use a lot of metaphors in trying to explain physical reality. Humans are only really good at understanding physical processes with which we have direct experience. To understand physics outside the range of human experience, we apply metaphors. If the metaphor is a reasonably close approximation to reality, what we "understand" advances (at least well enough to manipulate).
The comparison of "ether" to "dark matter" may be particularly appropriate if - once again - the old metaphors are in for a major revision. So far as I can tell, there is no evidence (past the initial set of observations) that "dark matter" is the right metaphor. A good first-approximation, yes, but no basis to assume this going to yield useful results.
See Michelson-Morley for how 'aether' was pinned to the theoretical mat -
No, it's not. The speed of sound is constant only relative only to the air that it is traveling through. It is not constant between objects moving though the air. Thus, the air is the one and only special/absolute rest frame from which the speed of sound can be measured to be constant.
Works the same for light and the aether.
not if objects shrink, become time dilated, and experience loss of simultaneity when moving through it. I really dont think that you've thought this through.
Michelson-Morley was a brilliantly designed experiment that works just fine in air, or any other 'ponderable' media, granpa. See
Me? This is Relativity I'm talking about. This is one of the most well-researched theories in science. I don't have to think it through, I'm just telling you what those thousands of physicists for the past 100+ years have figured out. And the belief that there was an absolute frame of reference (like for sound in air) is one of the primary reasons for it's creation - when that belief was found to be wrong (by the MM exp, as posted above).
There really isn't anything to discuss here. What you are arguing against isn't really even the theory itself, it is the historical facts of why these theories were developed. You may want to peruse the wiki on the aether for the history:
It makes specific mention of the history of the aether and it being believed to be a "universal" reference frame. In particular, the section on the aether and classical mechanics. They even use the analogy of sound traveling through air.
I never said it didnt.
I dont think that the argument against the aether was that it required absolute motion. my motion relative to the aether would be no more absolute than my motion relative to the earth.
rather the argument was simply that, due to relativity (which it does not contradict), it cant be empirically observed and therefore cant be assumed.
Please read the references provided, granpa. You are wrong on both counts.
Well grounded knowledge of classical physics is necessary to appreciate the MM experiment, and why it refutes the classical 'aether' concept. Part of the confusion arises from what was meant by 'aether' up to the early 20th centuries. It's worth reading up on, granpa. We will all be on the same page then.
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