First Observational Test of the Multiverse

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First Observational Test of the Multiverse








The signatures of a bubble collision at various stages in the analysis pipeline. A collision (top left) induces a temperature modulation in the CMB temperature map (top right). The 'blob' associated with the collision is identified by a large needlet response (bottom left), and the presence of an edge is highlighted by a large response from the edge detection algorithm (bottom right). In parallel with the edge-detection step, we perform a Bayesian parameter estimation and model selection analysis. (Credit: Image courtesy of University College London)

ScienceDaily (Aug. 3, 2011) — The theory that our universe is contained inside a bubble, and that multiple alternative universes exist inside their own bubbles -- making up the 'multiverse' -- is, for the first time, being tested by physicists.


Two research papers published in Physical Review Letters and Physical Review D are the first to detail how to search for signatures of other universes. Physicists are now searching for disk-like patterns in the cosmic microwave background (CMB) radiation -- relic heat radiation left over from the Big Bang -- which could provide tell-tale evidence of collisions between other universes and our own.

Many modern theories of fundamental physics predict that our universe is contained inside a bubble. In addition to our bubble, this `multiverse' will contain others, each of which can be thought of as containing a universe. In the other 'pocket universes' the fundamental constants, and even the basic laws of nature, might be different.

Until now, nobody had been able to find a way to efficiently search for signs of bubble universe collisions -- and therefore proof of the multiverse -- in the CMB radiation, as the disc-like patterns in the radiation could be located anywhere in the sky. Additionally, physicists needed to be able to test whether any patterns they detected were the result of collisions or just random patterns in the noisy data.

A team of cosmologists based at University College London (UCL), Imperial College London and the Perimeter Institute for Theoretical Physics has now tackled this problem.

"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," says Dr Hiranya Peiris, co-author of the research from the UCL Department of Physics and Astronomy. "But that's what pricked my curiosity."

The team ran simulations of what the sky would look like with and without cosmic collisions and developed a ground-breaking algorithm to determine which fit better with the wealth of CMB data from NASA's Wilkinson Microwave Anisotropy Probe (WMAP). They put the first observational upper limit on how many bubble collision signatures there could be in the CMB sky.

Stephen Feeney, a PhD student at UCL who created the powerful computer algorithm to search for the tell-tale signatures of collisions between "bubble universes," and co-author of the research papers, said: "The work represents an opportunity to test a theory that is truly mind-blowing: that we exist within a vast multiverse, where other universes are constantly popping into existence."

One of many dilemmas facing physicists is that humans are very good at cherry-picking patterns in the data that may just be coincidence. However, the team's algorithm is much harder to fool, imposing very strict rules on whether the data fits a pattern or whether the pattern is down to chance.

Dr Daniel Mortlock, a co-author from the Department of Physics at Imperial College London, said: "It's all too easy to over-interpret interesting patterns in random data (like the 'face on Mars' that, when viewed more closely, turned out to just a normal mountain), so we took great care to assess how likely it was that the possible bubble collision signatures we found could have arisen by chance."

The authors stress that these first results are not conclusive enough either to rule out the multiverse or to definitively detect the imprint of a bubble collision. However, WMAP is not the last word: new data currently coming in from the European Space Agency's Planck satellite should help solve the puzzle.




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 Looks like the premise is,

 Looks like the premise is, that universes exist separately from each other and therefore may collide. I never agreed much with the multiverse idea, the infinite other universes, with different choices along the history and so on. Every time there is in nature something potentially infinite, another natural law steps in and limits it into very finite values. For example, electric current at induction, etc. There is no reason why the universe should be so wasteful with other universes.

I think a better line of research would be to search for interpenetrating universes of different material qualities, which overlap our universe. Something like dark matter, but even more subtle than that. 

I'd like to understand why the string theorists say that the other seven dimensions are infinitesimally small, and yet they occupy every point in our space. Or something like that. I know the intuition is somewhat mistrusted on this board, but I like to imagine the universe as a N-dimensional space, which the various material particles and waves choose to ride in our case 3-dimensionally, while other universes choose to move about in a less restricted way, but all of these universes ultimately belong to the same space. 

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Actually, I am rereading Brian Green's most excellent book on this very topic right now. It is called “The Hidden Reality” and it covers a great many theories about other universes.


From that image, it is hard to say if it is really a collision though. Another theory that could match up with that is a quantum tunnel across the “cosmic landscape”. See Lawrence Susskind's book by that title for details on that theory.


Past that, Luminon, You should know that at the edge of science there is very little of “scientists say...” material. The thing about there being other dimensions that are all curled up is really only an inspired guess. It seems to make sense but we don't have any experimental data on that just yet.


Possibly when the LHC gets its planned luminosity upgrade we will get data on that but today, not so much.


Now, the reason for that is that it is known where our best theories break down. So scientists keep coming up with guesses that could fill in our gaps. Now after time and actual evidence is collected, those gaps will be filled in. If there had been five different guesses that could have done the job, then four of them must have been wrong.


One of those gaps concerns the fact that we can describe how electromagnetism works but we can't do so in a way that integrates with relativity. At least not in four dimensions. If we add a fifth dimension, then it kind of falls into place. Actually, it exactly and precisely falls into place. So that leaves us having to explain why we don't see a fifth dimension anywhere. One guess is that it is real but our best experiments are just not precise enough to pick up on it if it is a tiny little thing which is all curled up.


From that, if you add enough extra dimensions that are also small, you can then come up with a theory that accounts for all of known science in a tidy package. Again, we don't know that that is the case. A different guess, possibly one that nobody has come up with just yet might be what we really need. However, for now, the 11 dimension idea sounds pretty good.

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Luminon, FYI,you seem to be

Luminon, FYI,

you seem to be mixing up the idea of "many-worlds" idea from Quantum Theory, the idea that each alternate world based on different 'choices' exists in some way, with an entirely different idea, that there might be more than one Big-Bang universe, within a larger 'Metaverse', which is what is being discussed here.

These other universes would be like a larger version of the existence of other galaxies within our Universe. They are not to be thought of as versions of our Universe with just different choices, with different versions of ourselves, but independent environments in their own right, with maybe entirely different versions of even our physical laws, or at least our 'fundamental constants'.

There is no necessary implication that there would an infinite number of them, either.

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Really cool stuff, but if I

Really cool stuff, but if I had a dollar for every time a pattern was discovered in the background radiation map, I'd have at least five dollars.  And that's from noteworthy sources, I'm sure there are a lot of wackos out there that see their dead dog in it by staring long enough.  I remember being "chemically" influenced and staring at the snowy picture on the TV.  I used to see quite a bit of stuff. 

That being said, it is interesting, and definitely something worth investigating.  I just wouldn't hold my breath. 


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