Partial map of the Local Group of galaxies.  Credit:  Planet Quest

The Universe Is Not Expanding Uniformly

11 Oct , 2008 by

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A few weeks ago, researchers announced the discovery of a “dark flow” of invisible matter tugging at distant galaxy clusters at the edge of the universe. Now comes more evidence of unseen and unknown forces in the cosmos, but this time its closer to home. A group of researchers have discovered that our particular part of the Universe — out to a distance of 400 million light years — is not expanding uniformly in all directions as expected. To be exact, the expansion is faster in one half of the sky than in the other. “It’s as if, in addition to the expansion, our ‘neighbourhood’ in the Universe has an extra kick in a certain direction,” says Mike Hudson from the University of Waterloo in Ontario, Canada. “We expected the expansion to become more uniform on increasingly larger scales, but that’s not what we found.” If confirmed, their findings will result in a new understanding of the origin of structure in the universe and possible revisions to the standard cosmological model.

Hudson and two other scientists have been conducting research on large-scale cosmic flows and the general expansion of the universe. This expansion increases the distances between galaxies steadily with time, and is called the Hubble flow. Deviations of the velocity of galaxies from the overall Hubble flow is called the “peculiar velocity.” By examining the peculiar velocities of clusters and superclusters scientists can obtain estimates of local mass concentrations that may be responsible for causing any deviations from the Hubble flow.

In particular, these researchers were attempting to address a longstanding question about the origin of the approximately 600 km/s peculiar velocity of the Local Group of galaxies, with respect to the Cosmic Microwave Background.

Using several different surveys they discovered that about 50% of the Local Group’s motion is faster than anticipated. To produce this motion, they believe there must be large unseen and unknown structures in the universe. They write, “The large value of the residual motion implies that there are significant velocities generated by very-large scale structures,” and the structures lie beyond the Local Group.

Brian McNamara, a University Research Chair in UW’s department of physics and astronomy, says Hudson is finding that much of the matter in the nearby universe moves as an ensemble with a surprisingly high speed. “If the work he and others are doing is confirmed, it will require a major revision in the way we think the universe came into being and how it evolved.”

Hudson and his colleagues have submitted a paper to the Royal Astronomical Society, and a preprint version is available here.

Sources: arXiv, University of Waterloo


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Stephen R. Deens
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Stephen R. Deens
October 11, 2008 9:16 PM

Yes,

this is EXACTLY the sort of non uniformity evidence I was expecting;

The BIG BANG THEORY proposed by the Belgium monk: Georges Lemaître and supported by Hubble’s observations are now also in question and the non uniformity/ non isotropic arguments are now going to resurface;

moreover, if Frederick Hoyle were alive to day he would be delighted; he passed away recently in 2001.

intellgent design IMHO started this universe, not just a random uniform Big Bang from a single point in time. The universe is much less uniform than Hubble or Lemaître realized. The Masons call this the Grand Architect of creation.

Greg
Member
Greg
October 11, 2008 10:11 PM
The last post sounds a wee bit biased. I think that this finding supports the “dark flow” findings. The explanation for it will be the same and it will require revision of the standard model to account for this. The early period of inflation will have to be redefined to allow for super massive structures to form that create these flows that we see today. The existence of such massive structures would help explain dark energy in that they would restrict the expansion pressure of dark energy in a smaller universe which is why dark energy appears to become more powerful as the universe expands. It may be that the gravitational pull of these structures is weaking as… Read more »
Molecular
Member
Molecular
October 11, 2008 11:23 PM

This sort of reminds me of a lava flow moving down the side of a mountain, areas of the lava that are cooling move slower than those that are still red hot. Still, you’d expect that anything that is expanding in such a way that it is often illustrated using a ballon as a model, that it wouldn’t more faster in some areas, and not so fast elsewhere, doesn’t make sense.

Hans-Peter Dollhopf
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Hans-Peter Dollhopf
October 12, 2008 12:52 AM

Isn’t the expansion of the universe to be understood as an expansion of space itself, which is the reason for increased travel speed on the edges of the observable university? So not the speed of the objects by themselves is the reason why they get out of sight but the stretching of space between here and there?

But what has this general expansion to do with the velocity of “nearby” local objects due to attraction by a yet not directly observed very-large scale structure adjacent to the Local Group?

Thorkil2
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Thorkil2
October 12, 2008 12:57 AM

It’s always been my understanding that relative local velocities could not be used to support the idea of the broader expansion of the Universe. Andromeda is headed our way at a pretty good clip. Galactic collisions are fairly commonplace. Of course there are going to peculiar velocities, even with regard to larger structures. The Universe was set in motion with the big bang, and a certain amount of turbulence would hardly be surprising. Add gravitional effects to that and it hardly seems likely that expansion would have any meaning at all on any but the broadest scales.

Greg
Member
Greg
October 12, 2008 1:20 AM

Some of the last posts are missing a key point. Regarless of the individual local group members relative to each other, all of the local group is moving in a certain direction at the same speed, the so-called peculiar velocity. Therefore some object or structure is responsible. The first thing that came to mind was that a galaxy cluster could be responsible, but it seems that what is implied is something more massive, which sounds alot like dark flow.

Hans-Peter Dollhopf
Member
Hans-Peter Dollhopf
October 12, 2008 1:47 AM

“it seems that what is implied is something more massive, which sounds alot like dark flow.”

There is “flow”. It is but just a different word for the description of the observed movement.

What does “dark” mean? That the cause is “dark”? Is “dark flow” not just an explanation by labeling with attributes?

Prime
Member
Prime
October 12, 2008 9:11 AM

Hubble would be rolling over in his grave, if he knew what establishment cosmology was doing.
http://etheric.com/Cosmology/redshift.html
Cold Plasma filament interaction should not be mistaken for dark fudge.

Prime

paul
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paul
October 12, 2008 2:34 AM

It seems to me that theory is a major component of this equation,the bottom line is we don’t know,the more we think we know the further away we get from fact.

Excalibur
Member
Excalibur
October 12, 2008 2:38 AM

To Stephen R Deens

“Yes,

this is EXACTLY the sort of non uniformity evidence I was expecting;

This is exactly NOT what you have predicted.

“intellgent design IMHO started this universe…”

That’s your personal opinion, likely biased, and not supported by any predictions made…

HeadAroundU
Guest
HeadAroundU
October 12, 2008 2:58 AM

1.Dark energy = Hubble flow
2.Dark matter = Dark flow
3.Gravitation

amiright? imsoright!

Don Cox
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Don Cox
October 12, 2008 3:28 AM

The local group is a very small patch of the whole visible universe. It is not surprising that it is moving relative to the general background. Simple turbulence in an expanding gas (such as a cloud of steam) will give similar effexts.

The immediate cause of the movement could be attraction by some large “dark” body or group of bodies. Or it could be inherited from turbulence in the early universe, just as the Earth’s spin is inherited from rotational turbulence in the gas-and-dust cloud that developed into the solar system.

Jeff J
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Jeff J
October 12, 2008 4:26 AM

Since everything in the cosmos seems to have a ‘spin’ to it, why can’t our local group be spinning on a central axis as it expands away from the center of the universe? Wouldn’t this account for half of it seeming to be expanding faster than the other half?

Lostin Space
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Lostin Space
October 12, 2008 4:54 AM

If, as I believe, there are other dimensions then presumably the matter of those dimensions would form structures.
Lets say for example, that we live in dimension 7, then for all we know a galaxy in dimension 6 could be influencing the particles that we have in common.
It could just be, as in music, that dimension 6 is just a higher harmonic of what we understand as the universe.
Note to self: must buy better tuning fork smile

Ron
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Ron
October 12, 2008 6:45 AM

Stephen R. Deens needs to stay out of the Sun for a while.

BIAS
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BIAS
October 12, 2008 6:46 AM

Dear Nancy Atkinson, the bulk flow found by Hudson et al. does not belong to another “unseen and unknown force” in the universe. It is part of the much bigger dark flow discovered some time earlier and with methods designed for much greater distances.

I cite Sasha Kashlinsky (one of the authors of the dark flow papers):

” Interestingly, the results from a recent study done by Watkins, Feldman and Hudson (arXiv:0809.4041) “Consistently Large Cosmic Flows on Scales of 100h^-1Mpc: a Challenge for the Standard LCDM Cosmology” , which appeared after our papers have been posted, are in excellent agreement with our results, albeit done on smaller scales and obtained with different methods”

Taken from here:
http://www.kashlinsky.info/anima/skash.nsf/projects

Bill Illis
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Bill Illis
October 12, 2008 7:37 AM

400 million light years is a very large space – 3% of the distance of the observable universe.

Given this extent would cover dozens of galaxy superclusters and galactic voids, it is expected there would be speed differences in this space.

Nice website here zoomable in to 50,000 light years all the way out to 14 billion light years.

http://www.atlasoftheuniverse.com/superc.html

expanding universe
Guest
expanding universe
October 12, 2008 8:32 AM

ok, so if at the beginning of the universe everything started expanding, it would be like a sphere growing constantly, and if we were somewhere (not in the middle) of this sphere and we watched this expansion, wouldnt it be expected that we wouldnt see things expand uniformly relative to our position?

Numptie
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Numptie
October 12, 2008 10:54 AM

Don’t really surprise me much .
Just another step forward from the realisation that we are not the centre of the universe. Although ain’t too sure where we go from here. Just want to wish all fellow stargazers out there, dark skies

quantum_flux
Member
October 12, 2008 12:31 PM

Did they take out the blueshift/redshift pattern due to the rotation of the Earth!?

wpDiscuz