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Cougar
2003-Oct-29, 09:29 PM
Biggest Map of Universe Clinches Dark Energy (http://www.newscientist.com/news/news.jsp?id=ns99994314)

This would seem to be pretty big news. From the above article.... (emphasis mine)


Astronomers have compiled the largest, most detailed map of the Universe so far and believe that it shows beyond doubt the presence of an all-pervading "dark energy" throughout the cosmos....

In February 2003, the merging of a large-scale galaxy map from the Anglo-Australian 2dF galaxy redshift survey with data on the afterglow of the Big Bang from NASA's WMAP spaceprobe showed strong evidence for dark energy.

The new work - using different galaxies, instruments, personnel and analysis - provides the same result to better precision, and puts the existence of dark energy beyond doubt. One of the astronomers leading the project, Max Tegmark at the University of Pennsylvania, told New Scientist: "There is no longer any single data set to blame. The web of evidence is very strong and all observations are pointing to dark energy."

Carlos Frenk, at Durham University, UK, was involved in the 2dF work and agrees: "This new work provides a powerful confirmation that this quality exists in the Universe. Dark energy is unassailable now and that was not the case a year ago."

With dark energy observationally confirmed, theorists must now come up with an explanation of exactly what it is. :oops:

Would seem to be an area of research guaranteed to be very active.... Perhaps this should no longer be in Against the Mainstream.

Cusp
2003-Oct-29, 10:02 PM
Funny how this gets more of a spash than the 2dF/WMAP result.

Yes, dark energy is a big topic of research at the moment, but of course it all only holds together if the GR description of the large scale properties of the universe holds. Several astronomers I have spoken to have likened the current attitude to that of Victorian Science at the end of the 1800s, with proclaimations that there is nothing left to do except get more precise results.

Now, as then, we could be heading for a fall (which is good because it will open up many more research fields)

Alex W.
2003-Oct-30, 02:03 PM
Is dark energy the new "ether" (in the physics sense, no the chemical one)?

Cougar
2003-Oct-30, 02:35 PM
Is dark energy the new "ether" (in the physics sense, no the chemical one)?
I imagine that many (ethermaniacs) would like to make that connection, but I think it would be a false connection because the ether was hypothesized to be the medium that was thought to be necessary for light to propagate. Dark energy really has nothing to do with the propagation of light. It is implied for completely different reasons. The only similarity is that it's all-pervasive throughout space. Calling it the ether would be like observing an eagle to have wings and concluding "That's a duck!" because ducks also have wings.

ExpErdMann
2003-Oct-30, 03:05 PM
Now, as then, we could be heading for a fall (which is good because it will open up many more research fields)

That we're heading for a fall is a certainty, not just in cosmology but in physics and geology too.

I have a question about this dark energy business though. Were the WMAP studies concerned about finding dark energy initially, or did this become important only after the supernova teams claimed to find it?

JS Princeton
2003-Oct-30, 03:47 PM
Supernovae studies are older than WMAP.

And "that a fall is a certainty" sounds like a religion to me. I always suspected as much.

ExpErdMann
2003-Oct-30, 03:56 PM
Supernovae studies are older than WMAP.

And "that a fall is a certainty" sounds like a religion to me. I always suspected as much.

Au contraire, JS. It is your unquestioning faith in the Big Bang that comes across religion-like.

JS Princeton
2003-Oct-30, 03:58 PM
Who told you I don't question. I'm not the one who spoke in certainties.

ExpErdMann
2003-Oct-30, 04:41 PM
You preach chapter and verse from the Big Bang pulpit. If you really did question you would have picked up Arp's Seeing Red long ago. But you don't really like to be challenged that hard, do you.

JS Princeton
2003-Oct-30, 05:29 PM
You preach chapter and verse from the Big Bang pulpit. If you really did question you would have picked up Arp's Seeing Red long ago. But you don't really like to be challenged that hard, do you.

Wait, did you get some omniscience that has allowed you to determine that I haven't read Arp's horrendous piece of garbage? My goodness, if it's not religious to think that everyone who reads a book by Arp must believe in its critique, I don't know what religion is.

ExpErdMann
2003-Oct-30, 05:34 PM
Wait, did you get some omniscience that has allowed you to determine that I haven't read Arp's horrendous piece of garbage? My goodness, if it's not religious to think that everyone who reads a book by Arp must believe in its critique, I don't know what religion is.

Are you saying that you have picked it up, at least to look at the cover?

JS Princeton
2003-Oct-30, 05:38 PM
I read that book 3 years ago for the first time. It has only gotten worse with time.

ExpErdMann
2003-Oct-30, 05:41 PM
I read that book 3 years ago for the first time. It has only gotten worse with time.

Well, I give you credit for that! At least you are looking at alternatives.

Cougar
2003-Oct-30, 06:04 PM
"...there is a difference between an open mind and an open sink. The open mind allows for the critical examination of ideas, and it is receptive to new ones; the open sink is willing to accept anything and everything as worthy of examination without any responsible filtering process."

Kebsis
2003-Oct-31, 04:56 AM
So are you guys (proponents of 'a big fall' i mean) implying that you feel cosmology and physics are headed in the wrong direction?

Jim
2003-Oct-31, 01:27 PM
... and puts the existence of dark energy beyond doubt. ... "Dark energy is unassailable now..."

Talk about a Pollyanna attitude! These folks are taking dark energy as "unassailable" when there are still people arguing for the Bohr atom. Or against atoms in general.

Still, it is an interesting observation, and does support dark energy. It will be equally interesting to see how it stands up to the arguments and assaults to come.

russ_watters
2003-Oct-31, 01:56 PM
So are you guys (proponents of 'a big fall' i mean) implying that you feel cosmology and physics are headed in the wrong direction? The scientific process just doesn't make that a realistic possibility. More data+better defined models = clearer picture of the universe.

To use a popular example, some would see relativity as a huge upheaval in physics and the discarding of the old way (Newtonian physics) of modeling the universe. Thats not strictly true. Newton's laws had known limitations/flaws shortly after their introduction. It was known that they would need to be augmented/replaced eventually with something that could account for the discrepancy. And even after being replaced, Newtonian gravity is still very useful.

So to, today. The formuation of a new theory will NOT diminish the utility of relativity but will only serve to fill in known gaps.

Cougar
2003-Oct-31, 02:59 PM
Talk about a Pollyanna attitude! These folks are taking dark energy as "unassailable" when there are still people arguing for the Bohr atom. Or against atoms in general.... Still, it is an interesting observation, and does support dark energy. It will be equally interesting to see how it stands up to the arguments and assaults to come.

Yes, they are being pretty optimistic. You're right - their observation supports the existence of dark energy.

But perhaps this optimistic attitude can be understood better when their observational support is seen as additional observational support. Remember - two different teams using different methods made this initial finding for dark energy. They were both very careful in ruling out any systemic misreadings that would throw off their conclusion. Further investigation from these teams has further verified their initial result. And the rest of the scientific community has had years to test and challenge the finding, but there have been no "deal-breakers". And now we have a completely different approach that leads to the same conclusion. I suppose the media are not tremendously impressed if an unemotional scientist says, "Our observations strongly support the theory." They want you to say, "This really clinches it!" Perhaps it would be best to say, "This really strongly supports it!"

Spaceman Spiff
2003-Oct-31, 08:14 PM
Talk about a Pollyanna attitude! These folks are taking dark energy as "unassailable" when there are still people arguing for the Bohr atom. Or against atoms in general.... Still, it is an interesting observation, and does support dark energy. It will be equally interesting to see how it stands up to the arguments and assaults to come.

Yes, they are being pretty optimistic. You're right - their observation supports the existence of dark energy.

But perhaps this optimistic attitude can be understood better when their observational support is seen as additional observational support. Remember - two different teams using different methods made this initial finding for dark energy. They were both very careful in ruling out any systemic misreadings that would throw off their conclusion. Further investigation from these teams has further verified their initial result. And the rest of the scientific community has had years to test and challenge the finding, but there have been no "deal-breakers". And now we have a completely different approach that leads to the same conclusion. I suppose the media are not tremendously impressed if an unemotional scientist says, "Our observations strongly support the theory." They want you to say, "This really clinches it!" Perhaps it would be best to say, "This really strongly supports it!"

I'll also comment that phrases such as "cinches it" or especially "unassailable" do not appear in the journal articles. A lot of hoopla is sometimes generated by both the media and the public relations guys that go to the media. Astronomers I know are aware of the uncertainties and assumptions, etc, and there's the accompanying hemming and hawing. The PR guys don't usually care to write about these "buts" or "complications", because they figure the average Joe and Jill wouldn't understand and in any case would go too deep (probably true). Astronomers are also human, and comments may be made to the PR guy, because he/she is caught up in the moment of a successful experiment, that would not stand up to scrutiny in peer-review. Or statements can be misconstrued, etc. As astronomers we should try to be careful.

As was observed by others above, these observations provide for evidence in favor of the presence of "dark energy".

Cougar
2003-Oct-31, 09:29 PM
I'll also comment that phrases such as "cinches it" or especially "unassailable" do not appear in the journal articles.
Ha. Quite right. Here's (part of) what the abstract says....

Our results are consistent with a "vanilla" flat adiabatic Lambda-CDM model without tilt (n=1), running tilt, tensor modes or massive neutrinos.
Now, there's a headline only an astrophysicist could love!

Jim
2003-Nov-01, 03:09 AM
I dunno...

Universe "plain vanilla" says physicist
But with a "dark filling"

Kebsis
2003-Nov-01, 05:26 AM
The scientific process just doesn't make that a realistic possibility. More data+better defined models = clearer picture of the universe.




Yeah, that's what I thought, but that's what I understood some of the folks in this thread to be saying, particularly about BB and dark energy theories.

dgruss23
2003-Nov-01, 03:37 PM
Many people may not be aware that in the first 60-70 years of the 1800's most astronomers thought that most "nebula" were external galaxies. The Great debate of the early 20th century in which it was finally concluded that many "nebula" were actually externally galaxies was actually the second time that the concept of external galaxies became the mainstream view.

So the interesting question is why? What caused astronomers to reject a correct idea that was initially accepted - the idea that nebula are external galaxies? There were a number of factors including the distribution of "nebula" on the sky. Since the nebula (today's external galaxies) were seen most concentrated near the galactic poles, it seemed to some astronomers that they must be a part of the Milky Way. Today we understand that this apparent distribution results from absorption in the galactic disk such that the galaxies behind the Milky Way cannot be seen. But Richard Anthony Proctor among other astronomers/writers of the time did not think absorption in the Milky Way was a factor, so they rejected that explanation.

Interestingly enough this paper (http://xxx.lanl.gov/abs/astro-ph/0310847) just came out which advocates that scattering from electrons in hydrogen gas could be the reason for the apparent dimming of Type Ia supernova at high z. They advocate the standard models without acceleration that were accepted into the mid-90's. So perhaps history will repeat itself here in that absorption (scattering in this case) was initially rejected as an explanation for what we see, but could come to be understood as the explanation of the supernova dimming. Either way, I think its safe to say that this debate will not take as long to resolve as the Great Debate of the 19th and early 20th centuries.

Alex W.
2003-Nov-04, 02:39 PM
Is dark energy the new "ether" (in the physics sense, no the chemical one)?
I imagine that many (ethermaniacs) would like to make that connection, but I think it would be a false connection because the ether was hypothesized to be the medium that was thought to be necessary for light to propagate. Dark energy really has nothing to do with the propagation of light. It is implied for completely different reasons. The only similarity is that it's all-pervasive throughout space. Calling it the ether would be like observing an eagle to have wings and concluding "That's a duck!" because ducks also have wings.

I meant, "Will the way it is viewed in the future be similar to the way ether is viewed now?".