Ether exists - dark matter does not!

[andyandy]

An interesting article in new scientist

It was declared dead over a century ago, but now "the ether" is being reincarnated to solve a weighty problem
From his office window, Glenn Starkman can see the site where Albert Michelson and Edward Morley carried out their famous 1887 experiment that ruled out the presence of an all-pervading "aether" in space, setting the stage for Einstein's special theory of relativity. So it seems ironic that Starkman, who is at Case Western Reserve University in Cleveland, Ohio, is now proposing a theory that would bring ether back into the reckoning. While this would defy Einstein, Starkman's ether would do away with the need for dark matter.

Nineteenth-century physicists believed that just as sound waves move through air, light waves must move through an all-pervading physical substance, which they called luminiferous ("light-bearing") ether. However, the Michelson-Morley experiment failed to find any signs of ether, and 18 years after that, Einstein's special relativity argued that light propagates through a vacuum. The idea of ether was abandoned - but not discarded altogether, ...

http://www.newscientist.com/channel...her-returns-in-a-bid-to-oust-dark-matter.html

they posit that ether is a field which permeates space time - which would exist if everything else was removed. This ether would boost the gravitational pull of stars and galaxies by increasing the flexibility of space time, thus making them seem heavier. This ether induced gravity boost would explain the observed high velocities of stars in galaxies currently attributed to the presence of dark matter.....

 

[Nancarrow]

I'd be interested to know to what extent the 'ether' in this new theory can be identified with the pre-SR 'ether'. If all they're talking about is a field that permeates all space, well then whoop-de-doo. We might as well call the gravitational field an 'ether'.

So I guess it all boils down to, whether or not the New Scientist is just gratuitously appropriating a term and robbing it of all meaning.

(Oh, andyandy, you ether apologist! )

 

[andyandy]

I'd be interested to know to what extent the 'ether' in this new theory can be identified with the pre-SR 'ether'. If all they're talking about is a field that permeates all space, well then whoop-de-doo. We might as well call the gravitational field an 'ether'.

So I guess it all boils down to, whether or not the New Scientist is just gratuitously appropriating a term and robbing it of all meaning.

(Oh, andyandy, you ether apologist! )

lol

I think the difference would be that if everything else in the universe was removed the "ether" would remain - whereas with conventional ideas about fields permeating space, it wouldn't be possible to separate them like this....

hmmm....i'm a little out of my depth here

 

[Dave1001]

I'd be interested to know to what extent the 'ether' in this new theory can be identified with the pre-SR 'ether'. If all they're talking about is a field that permeates all space, well then whoop-de-doo. We might as well call the gravitational field an 'ether'.

So I guess it all boils down to, whether or not the New Scientist is just gratuitously appropriating a term and robbing it of all meaning.

(Oh, andyandy, you ether apologist! )

Great question. At the least, to salvage the word "ether" and its theory, there has to be some relation to light needing it to propagate. Otherwise, what you said.

 

[andyandy]

Great question. At the least, to salvage the word "ether" and its theory, there has to be some relation to light needing it to propagate. Otherwise, what you said.

not really, the fundamental part of "ether" was the idea that everything was thought to exist in it.....

Aether (also spelled ether) is a concept used in ancient and medieval science as a substance. The aether was believed to be the substance which filled the region of the universe above the terrestrial sphere. Aristotle included it as a fifth element distinct from the other four, Earth, Water, Air, and Fire. Aether was also called Quintessence (from quinta essentia, "fifth element").

 

[Dave1001]

not really, the fundamental part of "ether" was the idea that everything was thought to exist in it.....

What kind of theory is that? Pshaw I say. And I suspect that this is "ether of the gaps". One might as well ascribe the thing that everything is thought to exist in to space time. By that I mean the fundamental part of "space time", of course.

 

[Dave1001]

Aether (also spelled ether) is a concept used in ancient and medieval science as a substance. The aether was believed to be the substance which filled the region of the universe above the terrestrial sphere. Aristotle included it as a fifth element distinct from the other four, Earth, Water, Air, and Fire. Aether was also called Quintessence (from quinta essentia, "fifth element").

This seems fundamentally wrong in a pre-Copernican sort of way. Because whatever people are positing fills the universe above the terrestrial sphere, they are also positing fills the terrestrial spehere, too.

 

[andyandy]

This seems fundamentally wrong in a pre-Copernican sort of way. Because whatever people are positing fills the universe above the terrestrial sphere, they are also positing fills the terrestrial spehere, too.

it's a theory which allows modifying gravity in such a way as to do away with all that unseen dark matter - certainly it's worth further study....

 

[Dave1001]

it's a theory which allows modifying gravity in such a way as to do away with all that unseen dark matter - certainly it's worth further study....

can't argue with you there.

 

[Silly Green Monkey]

But...they've detected the presence of dark matter....

 

[andyandy]

But...they've detected the presence of dark matter....

dark matter as prescribed in large quantities has been used to explain the current disrepancies in gravity projections.....

this theory would mean that it isn't necessary to explain that discrepancy....

 

[nescafe]

dark matter as prescribed in large quantities has been used to explain the current disrepancies in gravity projections.....

this theory would mean that it isn't necessary to explain that discrepancy....

Ah, but we have recently observed the seperation of dark matter and baryonic matter. We even have pretty pictures.

 

[daenku32]

I agree with someone that gravity is merely about matter adjusting to bends in spacetime. Even tiniest things give spacetime curvature. Especially since they tend to move so quickly. Not sure how to prove this.

 

[Tez]

A kind of dirty secret is that there have been physicists advocating one sort of an ether or another for the last hundred years. Of course they are sophisticated enough models so as to not violate relativity. To be honest quantum field theory has done a lot to reinforce the conception that empty space is not so empty. Sakharov proposed a particularly interesting ether type theory as a way of understanding curvature of spacetime in general relativity. I personally am quite partial to thinking of the curvature of space and time in terms of physical deformations of the matter making up our rods and clocks by which we measure spacetime, rather than thinking of "spacetime" as this deformable nebulous entity with its own independent existence...

 

[tracer]

Aether (also spelled ether) is a concept used in ancient and medieval science as a substance. The aether was believed to be the substance which filled the region of the universe above the terrestrial sphere. Aristotle included it as a fifth element distinct from the other four, Earth, Water, Air, and Fire. Aether was also called Quintessence (from quinta essentia, "fifth element").

Dude?

The "aether" that Aristotle proposed was a perfectly hard, crystalline substance. It was what the spherical shells that held the moon, planets, and sun (in their orbits around the Earth) were all supposed to be made of.

To include Aristotle's aether in any scientific discussion of the "sublumiferous ether" theory is like digging a hole in your back yard and claiming you've created an apricot seed because both are "pits".

 

[andyandy]

Dude?

The "aether" that Aristotle proposed was a perfectly hard, crystalline substance. It was what the spherical shells that held the moon, planets, and sun (in their orbits around the Earth) were all supposed to be made of.

To include Aristotle's aether in any scientific discussion of the "sublumiferous ether" theory is like digging a hole in your back yard and claiming you've created an apricot seed because both are "pits".

was it? ok, who had the space-ether idea?

 

[Cuddles]

Ah, but we have recently observed the seperation of dark matter and baryonic matter. We even have pretty pictures.

Unfortunately they announced this as "proof" without bothering to check if the alternative theories can explain it as well. Which they can.

http://www.newscientistspace.com/article/mg19125684.200-dark-matter-proof-called-into-doubt.html

 

[Nancarrow]

Yo, andyandy, just a quick answer between my boss's circuits of the office...

The ether that pertains to the discussion of special relativity (and, we presume, is the one being 'resurrected' by this NS article) is a completely different concept from whatever Aristotle meant by the term. It was posited in the 19th century as the medium in which light waves propagate.

Basically, say you've got sound waves. They move through space, but what's actually 'doing the moving'? Sound waves are vibrations of air molecules. The vibrational motion is what is propagating through space, not the molecules themselves. The molecules are moving, in that they're each vibrating around a mean position, but they're not scooting along with the wave itself.

Similarly we have water waves, in which it's the actual disturbance of water molecules that is moving along, not the water molecules themselves.

So it intuitively stands to reason that if you have 'waves' they must be waves through some medium. (my boss has gone home) The 19th c. 'aether' was the postulated medium through which light propagates. It's this aether, the properties of which were found to be inconsistent in experiments of the late 19th c, and the need for which was done away with in special relativity. This is what Dave1001 (may I call you Dave9?) was getting at in post #4.

Aristotle's ether != Maxwell's ether != chemical ether which is fun stuff and helps you understand general relativity.

I think you're right in post #3 though... presumably the ether of light propagation was some kind of medium which would exist even if matter did not.

I'd also like to know how the ideas referenced in the NS article are related to MOND. I've had a soft spot for MOND ever since I first heard of it. I never understood the idea that Occam's razor should prefer dark matter to MOND. Hmm... the "universe has ten times as much matter as we thought it did, and we can't see it (and it can't be 'normal' baryonic stuff apparently)", vs "Newton's Law is a teensy teensy bit different from how we thought, over a length scale we never tested". I heard about the latest 'bullet observation' but don't yet grok it.

Ehhh, rant over.

 

[Yllanes]

I'd also like to know how the ideas referenced in the NS article are related to MOND. I've had a soft spot for MOND ever since I first heard of it. I never understood the idea that Occam's razor should prefer dark matter to MOND. Hmm... the "universe has ten times as much matter as we thought it did, and we can't see it (and it can't be 'normal' baryonic stuff apparently)", vs "Newton's Law is a teensy teensy bit different from how we thought, over a length scale we never tested". I heard about the latest 'bullet observation' but don't yet grok it.

Most MOND models are now either disproved or require some dark matter to work. [1] You must take into account that we have several clues leading into DM. Galactic rotation, the Cosmic Microwave Background, etc. You can formulate modified theories that account for some of the evidence, but it is very difficult to address all of it modifying Newton's Law without any dark matter. Remember that your models must reproduce the observations quantitatively, not only qualitatively.

See this post by TV's Frank for a good summary of why DM is our best theory right now. This post by Sean Carroll at Cosmic Variance is also very good and explains the most recent observations.

_______
[1] Cuddles linked to a different proposal of which I know little. There is a trackback in the arXiv that leads to this discussion. I have not read the paper, but the author admitted that his results are only qualitative, pending a more detailed numerical analysis. His paper intends to show that MOG can account for the lensing properties of the cluster without DM, so the recent observations would not necessarily be a direct proof of DM. However, DM would have much more evidence behind it. So while we cannot completely dismiss alternative explanations, DM is still the most likely theory.