Seven Year Microwave Sky (Credit: NASA/WMAP Science Team)
Seven Year Microwave Sky (Credit: NASA/WMAP Science Team)

Cosmology

Testing the Multiverse… Observationally!

3 Aug , 2011 by

[/caption]The multiverse theory is famous for its striking imagery. Just imagine our own Universe, drifting among a veritable sea of spontaneously inflating “bubble universes”, each a self-contained and causally separate pocket of higher-dimensional spacetime. It’s quite an arresting picture. However, the theory is also famous for being one of the most criticized in all of cosmology. Why? For one, the idea is remarkably difficult, if not downright impossible, to test experimentally. But now, a team of British and Canadian scientists believe they may have found a way.

Attempts to prove the multiverse theory have historically relied upon examination of the CMB radiation, relic light from the Big Bang that satellites like NASA’s Wilkinson Microwave Anisotropy Probe, or WMAP, have probed with incredible accuracy. The CMB has already allowed astronomers to map the network of large-scale structure in today’s Universe from tiny fluctuations detected by WMAP. In a similar manner, some cosmologists have hoped to comb the CMB for disk-shaped patterns that would serve as evidence of collisions with other bubble universes.

Seven Year Microwave Sky (Credit: NASA/WMAP Science Team)

Now, physicists at University College London, Imperial College London and the Perimeter Institute for Theoretical Physics have designed a computer algorithm that actually examines the WMAP data for these telltale signatures. After determining what the WMAP results would look like both with and without cosmic collisions, the team uses the algorithm to determine which scenario fits best with the actual WMAP data. Once the results are in, the team’s algorithm performs a statistical analysis to ensure that any signatures that are detected are in fact due to collisions with other universes, and are unlikely to be due to chance. As an added bonus, the algorithm also puts an upper limit on the number of collision signatures astronomers are likely to find.

While their method may sound fairly straightforward, the researchers are quick to acknowledge the difficulty of the task at hand. As UCL researcher and co-author of the paper Dr. Hiranya Peiris put it, “It’s a very hard statistical and computational problem to search for all possible radii of the collision imprints at any possible place in the sky. But,” she adds, “that’s what pricked my curiosity.”

The results of this ground-breaking project are not yet conclusive enough to determine whether we live in a multiverse or not; however, the scientists remain optimistic about the rigor of their method. The team hopes to continue its research as the CMB is probed more deeply by the Planck satellite, which began its fifth all-sky survey on July 29. The research is published in Physical Review Letters and Physical Review D.

Source: UCL

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By  -    
Vanessa earned her bachelor's degree in Astronomy and Physics in 2009 from Wheaton College in Massachusetts. Her credits in astronomy include observing and analyzing eclipsing binary star systems and taking a walk on the theory side as a NSF intern, investigating the expansion of the Universe by analyzing its traces in observations of type 1a supernovae. In her spare time she enjoys writing about astrophysics, cosmology, environmental science, biology, and medicine, making delicious vegetarian meals, taking adventures with her husband and/or Nikon D50, and saving the world. Vanessa is currently a science writer at Brown University.



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soliton1
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soliton1
August 3, 2011 8:32 PM

I had always been led to believe that the human brain was much better at pattern recognition than any computer. Sounds like a project for Zooniverse.

Ivan3man_At_Large
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Ivan3man_At_Large
August 3, 2011 8:44 PM
Rick Ryals
Member
Rick Ryals
August 3, 2011 8:58 PM

This is the kind of garbage that physicists do when they can’t advance the theory to the point that the multiverse is justified by a complete theory. What a bunch of crap.

Me Meee
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Me Meee
August 3, 2011 9:21 PM

U mad?

Theory is verified with observational evidence. If the evidence is not there, then it doesnt advance the theory. If the evidence is there, then it does. What part of this are you struggling to understand?

All I can see are your rantings of ignorance. What a bunch of crap.

Rick Ryals
Member
Rick Ryals
August 3, 2011 9:31 PM

Um, no, without a complete theory, this represents nothing more than designed speculation that the theory is being verified observationally. And they do it because they can’t advance the lame gravity theory.

Ivan3man_At_Large
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Ivan3man_At_Large
August 3, 2011 9:25 PM

What a bunch of crap.[Citation needed]

Dolmance
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Dolmance
August 3, 2011 11:10 PM

Too cranky by far. You must be awful to be around, especially at home. Sounds like an alcohol problem.

Lawrence B. Crowell
Member
Lawrence B. Crowell
August 4, 2011 3:44 AM

I read into the first of these papers. It involves Weiner filter or transformation stuff. The data examined is numerical, and the picture we see is a visual representation. These analyses work with the actual power spectrum in numerical form.

LC

Jon Hendry
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Jon Hendry
August 4, 2011 12:26 AM

This sounds a bit like Gurzadyan & Penrose’s “concentric circles” in the WMAP data that supposedly might be evidence of pre-Big-Bang activity.

http://arxiv.org/abs/1011.3706

If I recall correctly this paper didn’t get a very positive reception.

Torbjorn Larsson OM
Member
Torbjorn Larsson OM
August 4, 2011 8:06 AM
You may remember this article that described their earlier work. Their previous statistical analysis seems good enough: “We assess which of the two models [the bubble collision hypothesis vs the standard hypothesis of fluctuations in a nearly Gaussian field] better explain the data by evaluating the Bayesian evidence for each. The evidence correctly accounts for the fact that a more complex model (the bubble collisions, in this case) will generally fit the data better simply because it has more free parameters. This is the self-consistent statistical equivalent of applying Ockham’s Razor.” In loose words, I believe they use the same approach that biologists use to find the (set of) most predictive trees. And as the biologists do when… Read more »
Torbjorn Larsson OM
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Torbjorn Larsson OM
August 4, 2011 8:15 AM

The Gurzadyan and Penrose critique is correct. You can click through my first link in my first comment to a good summary by Sean Carroll and a G&P response.

Essentially, as all greedy pattern searchers, G&P have found patterns but failed to test the null hypothesis sufficiently. Their patterns are predicted by the standard cosmology.

As you can see from the article and my previous comment, Peiris et al explicitly try to avoid that. “a statistical analysis to ensure that any signatures that are detected are in fact due to collisions with other universes, and are unlikely to be due to chance.”

Torbjorn Larsson OM
Member
Torbjorn Larsson OM
August 4, 2011 9:06 AM
The reluctance to accept environmental selection reminds me of early, purely philosophical, rows over different types of prediction. It goes something like this: 1) Standard “black box” prediction of effective theories: You see a wall enclosing an area, but can’t see over it. You predict that it is inhabited, because, well, that is what people can do. You throw a stone over the wall, because you expect inhabitants to clean the area. After a while the stone is thrown back. Case closed. 2) Standard multiverse prediction: You live in a room, but can’t open the doors. You predict that if there are other rooms, some sloppy inhabitants may have drilled through when trying to hang paintings. After some… Read more »
Lawrence B. Crowell
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Lawrence B. Crowell
August 4, 2011 1:48 PM
This is not the same as the theory of Gurzadyan and Penrose. That involved an extension of the conformal past “to infinity,” where the big bang is a past Cauchy surface where the minimal information content of the universe is globally available. Some type of transition occurs with the occurrence of an event horizon. The cosmology tested here involves nucleation bubbles. It is analogous in some ways to ferromagnetism. Above the Curie temperature Iron atoms, which are little magnets, are oriented arbitrarily. If one applies a magnetic field to the hot iron these atoms orient accordingly. Once the temperature is lowered below the Curie point there is a scale at which this freedom of orientation of these atomic… Read more »
Lawrence B. Crowell
Member
Lawrence B. Crowell
August 4, 2011 1:48 PM
This is not the same as the theory of Gurzadyan and Penrose. That involved an extension of the conformal past “to infinity,” where the big bang is a past Cauchy surface where the minimal information content of the universe is globally available. Some type of transition occurs with the occurrence of an event horizon. The cosmology tested here involves nucleation bubbles. It is analogous in some ways to ferromagnetism. Above the Curie temperature Iron atoms, which are little magnets, are oriented arbitrarily. If one applies a magnetic field to the hot iron these atoms orient accordingly. Once the temperature is lowered below the Curie point there is a scale at which this freedom of orientation of these atomic… Read more »
Anonymous
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Anonymous
August 6, 2011 12:44 PM

Do I read 2 breaking news stories here?
1. Higgs probably doesn’t exist, p=0.98
2. Eternal inflationary cosmology appears to be wrong. Does that also mean inflationary theory in general is in jeopardy? Since cosmological inflation seems to be eternal the way it is theorised if I’m well informed.

Lawrence B. Crowell
Member
Lawrence B. Crowell
August 7, 2011 12:54 AM

There is Higgs-like behavior. By this it means that quantum field theory goes haywire otherwise. The Higgs mechanism is really a form of phase transition similar to the onset of superconductivity. The standard Higgs model is a simple doublet of spinors, where 3 degrees of freedom, the goldstone boson are absorbed into the Z and W^{+/-} particle and the other at high enough energy is the Higgs condensate. The problem appears to be how we are assigning modes to the vacuum.

As for eternal inflation, that could be in trouble. When it comes to inflation, the old standard model of Guth, that is still good. Observational evidence for it is quite strong.

LC

Torbjorn Larsson OM
Member
Torbjorn Larsson OM
August 7, 2011 4:45 PM
I think you make some leaps here, to paint a pattern that you like: “Eternal inflation posits an inflation which occurs at below the Planck scale,” Haven’t we had this discussion before? As I understand it the new slow-roll inflationary models do not occur at Planck scales. The only requirement for eternal inflation is that the field is unbounded, so fluctuations restart inflation often enough. That takes the inflation field to below Planck scales. The way to understand this is, I think, that the new observations putative indication of absence of structure at Planck scales means there is no spacetime magic connection to it. Likely the field model is an effective theory of inflation, which happens instead of… Read more »
Anonymous
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Anonymous
August 7, 2011 9:37 PM

So in a few months, news headlines will be: “Global financial system collapses; Higgs particle discovered”

Anonymous
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Anonymous
August 7, 2011 9:37 PM

So in a few months, news headlines will be: “Global financial system collapses; Higgs particle discovered”

Anonymous
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Anonymous
August 7, 2011 9:37 PM

So in a few months, news headlines will be: “Global financial system collapses; Higgs particle discovered”

interI0per
Member
interI0per
August 4, 2011 1:57 PM

the assumption is that there are a lot of adjacent ‘bubbles.’
the next one may be far away indeed.
so, how to map the impingement profile?
map the z (redshift)!
is this a poem about the foam?

Anonymous
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Anonymous
August 6, 2011 12:53 PM

If the extrauniversal bubbles are not adjacent to our universe, their existence cannot be demonstrated in this way. Nor in any other way probably. Science is limited to what is observable..

Torbjorn Larsson OM
Member
Torbjorn Larsson OM
August 7, 2011 3:32 PM

You may want to read the post above.

Anonymous
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Anonymous
August 7, 2011 10:02 PM

I suppose you mean the article by Bousso et al? You just showed me a whole new world: The entropic principle etc., I tried to read it but it’s so hard… Do you think by this method any detailed information about non-adjacent universes can be obtained? Doesn’t a change in entropy only tell us how much complexity is changed simultaneously, not how it is changed? In other words, by this method could we determine that something must be going on outside our universe, but we still can’t say what that would be, only how much is going on?

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