Oh, I don't know. I think everyone can change if they really want to...
Posted on 01/13/2006 3:38:06 AM PST by PatrickHenry
Contrary to all expectations, the mysterious dark energy that is pushing the Universe apart may be changing with time.
By observing distant, powerful bursts of gamma rays (gamma-rays), Brad Schaefer says he has preliminary evidence that the strength of dark energy is different today from when the Universe was very young. Schaefer, an astronomer at Louisiana State University in Baton Rouge, presented his results at an American Astronomical Society meeting in Washington DC.
Just minutes after the data were presented in a late afternoon session, some astronomers were already calling the bold claim into question.
An idea that arose in the late 90s, dark energy seems to act over very large distances, pushing the Universe apart at an ever increasing speed. At the moment, many researchers believe that dark energy may be a foam of quantum particles that exists throughout the vacuum of space. Under that scenario, dark energy would be a constant and unchanging force, according to Michael Turner, a cosmologist from the University of Chicago, Illinois.
Schaefer's findings, if they are true, would turn that idea on its head.
Big, bright bursts
Schaefer began by examining 52 bursts of high-energy gamma-rays that were recorded by six satellites. The bursts came from the explosions of distant, super-massive stars that were billions of light years away. The explosions were so distant that the ones we see now occurred when the Universe was only 1.5 billion years old, a tenth of its current age.
Schaefer used various properties of the bursts, such as the way their brightness changed over time, to work out how intrinsically bright they were and how far away the explosion was. Twelve of the most distant of the bursts examined by Schaefer turned out to be brighter than would be expected if dark energy had remained a constant.
"I would not characterize this as proof," Schaefer cautions. "Before we can be confident, we will have to see these results reproduced."
The old ways
Many questions surround Schaefer's result, says Dieter Hartmann, a gamma-ray astronomer at Clemson University in South Carolina.
For one, says Hartmann, the findings are dependent on understanding just how the ancient, massive stars lived and died. "The births of these stars will be different, and the environment in which they ultimately explode is different," he says. Without understanding the physics of these explosions, the estimate of their intrinsic brightness is very uncertain, he says.
Others are still more sceptical. "I think he's wrong," says Adam Riess, an astronomer at the Space Telescope Science Institute in Baltimore, Maryland. Riess says that Schaefer's failure to include nearby and recent gamma-ray bursts to calibrate the results make his conclusions about the much more distant bursts highly questionable.
"This is an intriguing result," admits Turner. But it certainly doesn't add up to a Nobel prize without further confirmation, he says. "I don't think it's a ticket to Sweden."
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"Contrary to all expectations, the mysterious dark energy that is pushing the Universe apart may be changing with time."
Interesting. I hope that it doesn't push the universe apart before I finish my laundry.
That'd be the mother of all spin cycles.....:D
Well, speaking from personal experience, my wife mentioned a few nights ago that dark energy just didn't seem as strong as it was when we were kids.
After thinking it over for a couple of minutes, I had to agree.
So, mebbe this guy is on to something!
Are they talking about Jessy Jackson? Cause if they are, well he looks like he is changing he gets fatter and dumber every year.
Bush, Cheney, Rove, Halliburton's fault....messing with the universal environment.....
Seriously, if this result holds up, it could be a sign of the relaxation of the compactification scale for an extra dimension. I doubt they can calibrate the absolute brightness, though.
..."I think he's wrong,"...
Me too! I blame worker incompetence. The universe should have upgraded it's hiring practices eons ago...
...ITS hiring practices...
D'oh!
Oh, I don't know. I think everyone can change if they really want to...
Thanks for the ping!
The extra dimensions are usually described for nonspecialists as being "rolled up", like every point in normal space has a little (**Very** little) n-sphere attached to it.
If this is basically the idea, do you mean that the radius of the n-sphere is increasing or decreasing? As we look at things further and further away, the radius is larger or smaller?
I guess at the big Bang itself, all dimensions were restricted to the same size, whatever that could mean?
I doubt they can calibrate the absolute brightness, though.
The article didn't say how they estimated the distance to these bursts. Are they correlated with visible galaxies?
Thanks for the link. Always a lot of intersting stuff when the astronomers hold their meeting.
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