Space.com (March 17, 2010)
"The puzzling migration of matter in deep space – dubbed 'dark flow' – has been observed at farther distances than ever before, scientists have announced.
"Distant galaxy clusters appear to be zooming through space at phenomenal speeds that surpass 1 million mph. The clusters were tracked to 2.5 billion light-years away – twice as far as earlier measurements.
"This motion can't be explained by any known cosmic force, the researchers say. They suspect that whatever's tugging the matter may lie beyond our observable universe.
"The notion is a controversial one because it has only been measured by one group of scientists in one set of data so far.
"'We understand why this idea is so annoying at times,' said study leader Alexander Kashlinsky at NASA's Goddard Space Flight Center in Greenbelt, Md. 'In fact, part of the motivation for our ongoing project was precisely to rule it out. But it is in the data, we don't see it going away.'..."
Research results like this being "controversial" doesn't mean they're wrong. Or right. Continental drift was "controversial" in this sense, until enough measurements were made, precisely enough, to show that the 'solid earth' we stand on is moving. (Normally, we don't notice it. Sometimes, we do. ("Chile City Moved 10 Feet West: Change Happens" (March 10, 2010))
This dark flow seems to be moving in the direction of Centaurus and Hydra, in our sky's southern hemisphere.
I can see how this research has raised eyebrows. The article summarizes what they did:
"...The new study is based on a larger data set of about 1,500 galaxy clusters and CMB measurements taken over five years by space and ground-based telescopes. The researchers say their new results strengthen indications that the dark flow is real...."
Astronomers and cosmologists have long ago come to terms with the idea that the five visible planets aren't the only things that move around: Although using the Big Bang's afterglow as a frame of reference seems to be something new. We haven't been able to, until fairly recently.
What's really bothersome, I think, about dark flow is that it shouldn't exist. Sure, things like planets, stars, and clusters of galaxies move in relation to each other: but all those (relatively) small things should average out to zero. That Big Bang microwave radiation is - or should be - a sort of stationary reference. Everything we observe is a sort of debris from that cosmic explosion.
Or we're living in a garbanzo bean in somebody's microwave oven - which I rather doubt. Old idea, from the days when we were discovering electrons, where some imaginative writers played with the idea that stars and planets were the electrons and nuclei of atoms in a bigger universe.
Back to the article:
"...'It looks indeed that the entire observable universe is moving with respect to the CMB radiation,' Kashlinsky told SPACE.com. 'We can now say that more confidently than our initial supposition.'
"The researchers think dark flow may be caused by structures that lie beyond the horizon of our own universe. As odd as that may sound, some cosmologists think that our universe is actually only a bubble of space-time that was created during a period of rapid cosmic expansion, called inflation, after the Big Bang. Other bubbles may also have been created where inflation took place at a different rate, and perhaps something in one of the other bubbles is tugging at our universe...."
Like I said, dark flow is a bit bothersome, in part because if it exists one of the simpler explanations is that there's another 'universe' off in the general direction of Centaurus and Hydra.
Which changes the idea of other universes existing from an intriguing subject for informed speculation to a serious hypotheses that has to be tested. And that is a lot more work than building elegant mathematical models that don't have to conform to observations.
It'll be interesting, to me at least, to see where this line of research leads.
I've used this quote before:
"Not only is the universe stranger than we imagine, it is stranger than we can imagine." (Sir Arthur Eddington English astronomer (1882 - 1944))
Probably so, but that won't keep us from trying.
- "It's Just a Comic Book? Yes: But the Science Behind it is Stranger"
Drifting at the Edge of Time and Space (December 4, 2009)
- "Physicists Visualize Extra Dimensions (Caution! Geeky Content!)"
(May 23, 2009)
- That's "dimensions" - not "universes"
- In physics and cosmology, there's a difference
- That's "dimensions" - not "universes"
- "That's the Size of It: Local Galaxies to Quarks"
(February 21, 2009)
- "It's About Time, Entropy, and Other Universes"
(June 4, 2008)
- "The Science Behind Marvel Comics' New Cosmic Tale"
Space.com (December 4, 2009)
The December 4, 2009, Space.com article uses a Marvel Comics release as the starting point for a discussion of quantum energy and logical extrapolations from what we're discovering about how the (observable) universe works. The part that ties in with this post:
"...Other universes, space-time tears
"One consequence of quantum physics is the 'many-worlds interpretation,' which suggests a virtually infinite number of universes exist, altogether comprising every possible outcome to every event — including, perhaps, the truly horrifying possibilities seen in 'Realm of Kings.'
"But how would one adventure to another universe? The answer could be increasingly familiar tears in the space-time continuum known as wormholes. Einstein proposed that mass and energy curve space-time, creating the force we know as gravity. One consequence of his theories is that enough mass or energy concentrated in one place can warp space-time enough to create distortions allowing shortcuts in space, travel back in time and even voyages to other universes.
"The main problem with any concept involving wormhole is keeping them open enough for travel, as they naturally want to slam closed and form black holes. However...."