bubble bubble toil and trouble dept.
Perimeter Associate Faculty member Matthew Johnson and his colleagues are working to bring the multiverse hypothesis, which to some sounds like a fanciful tale, firmly into the realm of testable science.
Never mind the big bang; in the beginning was the vacuum. The vacuum simmered with energy (variously called dark energy, vacuum energy, the inflation field, or the Higgs field). Like water in a pot, this high energy began to evaporate — bubbles formed.
Each bubble contained another vacuum, whose energy was lower, but still not nothing. This energy drove the bubbles to expand. Inevitably, some bubbles bumped into each other. It's possible some produced secondary bubbles. Maybe the bubbles were rare and far apart; maybe they were packed close as foam. But here's the thing: each of these bubbles was a universe. In this picture, our universe is one bubble in a frothy sea of bubble universes. That's the multiverse hypothesis in a bubbly nutshell.
Conclusion: The real significance of this work is as a proof of principle: it shows that the multiverse can be testable. In other words, if we are living in a bubble universe, we might actually be able to tell.
http://www.perimeterinstitute.ca/news/universe-bubble-lets-check
The full article appears in the open access Journal of Cosmology and Astroparticle Physics as: Simulating the universe(s): from cosmic bubble collisions to cosmological observables with numerical relativity.
(Score: 4, Interesting) by bob_super on Friday July 18 2014, @06:11PM
In the beginning, there was nothing, which exploded.
In the beginning, there was a small ball of everything.
In the beginning, there was a big field of energy, which did stuff.
Why am I having trouble with the definition of "beginning"?
(Score: 3, Interesting) by Horse With Stripes on Friday July 18 2014, @06:57PM
In the beginning of this incarnation of this universe the previous universe's collapse was complete, down to a tiny singularity, which exploded with such force that it violated the laws of physics as we understand them.
(Score: -1, Troll) by Anonymous Coward on Friday July 18 2014, @07:12PM
implying that physicists may not understand everything about the universe implies that they may be wrong about things like faster than light and perpetual motion etc... i thought the 1st law of physics was 'physicists are always right'? or is it 'thou shalt not discuss the possibility of physicists being wrong'?
(Score: 1) by Horse With Stripes on Friday July 18 2014, @08:30PM
That may be true, but as a programmer I always start counting at 0. The 0th rule of physics is "there are far too many layers to this onion for any creature to perceive, let alone understand."
(Score: 2) by maxwell demon on Friday July 18 2014, @09:24PM
No. The rule is: Physicists may be wrong, but they are less wrong than others.
The Tao of math: The numbers you can count are not the real numbers.
(Score: 2) by Oligonicella on Friday July 18 2014, @10:04PM
Except of course, when they start creating their own mythology at which point they are *exactly* like the "others".
(Score: 2) by Jeremiah Cornelius on Saturday July 19 2014, @12:31AM
Voice Of God:
"Before the Beginning there was this Turtle. And the Turtle was alone. And he looked around, and he saw his neighbor, which was his Mother. And he lay down on top of his neighbor, and behold, she bore him in tears, an oak tree. Which grew all day, and then fell over, like a bridge. And lo, under the bridge there came a Catfish, and he was very big, and he was walking, and he was the biggest he had seen....
And so were the fiery balls of this fish, one of which is the Sun, and the other, they called the Moon..."
Expert Voice:
"Yes, some uncomplicated peoples still believe this myth. But here, in the technical vastness of the Future, we can guess that surely the Past was very different. We can surmise, for instance, that these two great balls..."
Dr. Technical:
"We know for certain, for instance, that for some reason, for some time in the beginning, there were hot lumps. Cold and lonely, they whirled noiselessly through the black holes of space.
Those insignificant lumps came together to form the first union - our Sun, the heating system. And about this glowing gasbag rotated the Earth, a cat's-eye among aggies, blinking in astonishment across the Face of Time..."
You're betting on the pantomime horse...
(Score: 1, Insightful) by Anonymous Coward on Friday July 18 2014, @10:37PM
physicists, like most scientists, take pride in being able to tout whatever theory they have, belittle anyone who disagrees with them, and avoid all liability if they are proven wrong (after which the engineers usually come in and clean up the mess).
(Score: 2) by FatPhil on Friday July 18 2014, @10:39PM
I'm sorry, but I hear as much total bollocks from phyicists as I do from any other sector of society. OK, I tend to be more surrounded by physicists than other types of folk, but still, the "blue sky" thinking that some of them are proposing is on par with anyone Randi ever went up againt. (i.e. kooks)
However, I have to interrupt my post to bow to the temple of Nima Arkani-Hamed, the almighty savour of physics, whose theories "must be true", no matter if every experiment he's predicted the outcome of has ever satisfied his hallucin^H^H^H^H^H^H^H^Hprediction.
Great minds discuss ideas; average minds discuss events; small minds discuss people; the smallest discuss themselves
(Score: 1) by Horse With Stripes on Friday July 18 2014, @10:43PM
I attended a lecture by Dr Sheldon Cooper. Talk about a whack job ...
(Score: 1) by dak664 on Friday July 18 2014, @08:19PM
Instead of a point in time think of it as referring to the basis of a structure (compare the original meaning of the greek arche "foundation" which came to mean "beginning" through later metaphor).
No problem having multiple entities in a foundation. A beginning in time is a backward extrapolation of all structural patterns to a single pattern, aka purity, and that may not have much meaning.
(Score: 3, Interesting) by tangomargarine on Friday July 18 2014, @06:15PM
This sounds kinda like a restatement of vacuum collapse [wikipedia.org].
And I'm trying to grasp how this makes it "testable" at all. Wouldn't we still need to inspect the edge of the universe, which is how many lightyears away, again? Or we pull a "Dr. Rush" and examine the underlying fabric of space for secret messages from the aliens?
"Is that really true?" "I just spent the last hour telling you to think for yourself! Didn't you hear anything I said?"
(Score: 2) by maxwell demon on Saturday July 19 2014, @10:20AM
How do you know about the sun? Have you ever been there?
No, you haven't been there. But you get the light of it. And from the light you can derive its existence and its properties (and you can also get neutrinos and learn even more about it). Note that this is no different to most things here on earth. If you see a mountain, you don't say "oh, how do I know that it is really a mountain, and which shape it has, and so on, when all I have is this pesky electromagnetic radiation (aka light) coming from there?" You say "Oh, I see a mountain, therefore there is a mountain."
And this is the very same: You look at the electromagnetic radiation from the edge of the universe (in this case, not the light, but the microwaves). There's no need to travel to the edge of the universe to look, just as there is no need to travel to the sun to verify that is is a hot ball of gas, or to travel to a mountain to verify that there's indeed a huge pile of stone.
The Tao of math: The numbers you can count are not the real numbers.
(Score: 2) by tangomargarine on Monday July 21 2014, @03:01PM
There's a big difference between using a spectrometer on the sun and observing things that potentially aren't even in our light cone, and you know it. Don't inflate the argument to ridiculous proportions.
I didn't say we had to GO to the edge of the universe, either; it's still going to take a hell of a long time for radiation from there to get to earth. According to Wikipedia, the "observable universe is about 46 billion light years in radius." So anything farther than that out from us...you can jump around and wave your arms and shout, "SCIENCE!!!" all you like but we're not going to be able to measure it for now unless you have a secret FTL telescope in your basement.
P.S: Microwaves are pretty much the same as light in some ways, they're just outside our visible spectrum. Aren't they still constrained by the speed of light? We use radio waves (or something) to communicate with distant space probes and that still has noticeable lag.
"Is that really true?" "I just spent the last hour telling you to think for yourself! Didn't you hear anything I said?"
(Score: 2) by maxwell demon on Tuesday July 22 2014, @06:08AM
The paper in question makes predictions about what observers located inside the universe would observe. Not what an observer "at the edge" would observe. There's absolutely no need to go anywhere, or to use any sort of FTL instrument, to observe the CMB received at the very place you happen to be.
And yes, of course we could only see it if it happened inside out light cone. But unless you have any indication that this event can only happen outside our light cone, that only means that not observing it would not prove the theory wrong.
The Tao of math: The numbers you can count are not the real numbers.
(Score: 2) by tangomargarine on Tuesday July 22 2014, @02:24PM
So in other words, you're saying it's not really falsifiable. Oh good. That makes everything fine then.
FYI, this branch of argument was covered under my original "Dr. Rush talking to aliens" alternative.
"Is that really true?" "I just spent the last hour telling you to think for yourself! Didn't you hear anything I said?"
(Score: 2) by maxwell demon on Tuesday July 22 2014, @05:36PM
In the same sense as the theory that you are mortal is not really falsifiable. I congratulate you on your immortality. ;-)
The Tao of math: The numbers you can count are not the real numbers.
(Score: 5, Interesting) by HiThere on Friday July 18 2014, @07:48PM
There are several different multiverse hypotheses, and they aren't mutually exclusive. The simplest one is "There are entire universes that exist outside our light-cone". This is not at all the same as the Everett-Graham-Wheeler multiverse. And that's not the same as the unending inflation multiverse. And that's not the same as...
It sounds like the multiverse that they're trying to test isn't any of the one that I've mentioned, but there are others, and I don't try to keep track of them. My preferred one is the variation of the EGW hypothesis that goes "the quantum wave never collapses", but the "universes outside out light-cone" is so probable that I can't think of anyone who both understands it and doubts it.
Javascript is what you use to allow unknown third parties to run software you have no idea about on your computer.
(Score: 3, Funny) by tangomargarine on Friday July 18 2014, @09:48PM
Can't stop the signal, Mal. They can never stop the signal.
"Is that really true?" "I just spent the last hour telling you to think for yourself! Didn't you hear anything I said?"
(Score: 0) by Anonymous Coward on Friday July 18 2014, @08:00PM
TFS says a whole lot of nothing.
(Score: 3, Funny) by elgrantrolo on Friday July 18 2014, @09:43PM
First there was nothing, but then energy started doing things in vacuum? This is one subject that blows my mind.
(Score: 2) by FatPhil on Friday July 18 2014, @10:41PM
Great minds discuss ideas; average minds discuss events; small minds discuss people; the smallest discuss themselves
(Score: 2) by Oligonicella on Friday July 18 2014, @11:06PM
That white noise is coming from somewhere other than the hifi. Kind of shoots that analogy.
(Score: 2) by maxwell demon on Saturday July 19 2014, @10:22AM
Disconnect your amplifier from any source and turn up the volume. The noise you now hear is solely from the amplifier.
The Tao of math: The numbers you can count are not the real numbers.
(Score: 2) by Hawkwind on Friday July 18 2014, @10:31PM
Glad to see all of these wild theories can be tested to some extent via computer simulations. Granted there may be issues with the simulation but this is a start. Here are some highlights from the article:
... We're now at the point where if you have a favourite model of the multiverse, I can stick it on a computer and tell you what you should see ... By producing testable predictions, the multiverse model has crossed the line between appealing story and real science ... We're now able to say that some models predict something that we should be able to see, and since we don't in fact see it, we can rule those models out. ... The real significance of this work is as a proof of principle: it shows that the multiverse can be testable. In other words, if we are living in a bubble universe, we might actually be able to tell.
(Score: 0) by Anonymous Coward on Friday July 18 2014, @10:43PM
"In theory, it works. In practice, it don't."
(Score: 3, Informative) by Oligonicella on Friday July 18 2014, @11:11PM
A model can be made to simulate any fantasy. The model performs no testing whatsoever. Only reality can do that.
(Score: 2) by aristarchus on Saturday July 19 2014, @12:12AM
Yes, but the simulations can rule out those things that are logically or theoretically impossible. Unless we change the model.
(Score: 2) by maxwell demon on Saturday July 19 2014, @10:26AM
The computer can determine whether a model produces what it is supposed to produce. Also, it can tell you what you should observe if the model is right. You then can turn to your measurement/observation equipment and look whether you indeed observe that. If you don't see that, you know the model is wrong. Without the simulation, you'd not know what to look for.
The Tao of math: The numbers you can count are not the real numbers.
(Score: 1) by caffeinated bacon on Saturday July 19 2014, @04:27AM
As long as they're not planning to test it by popping the bubble.
Yes we have successfully determined that the universe was a bubble, oops.
(Score: 1) by mrkaos on Saturday July 19 2014, @03:33PM
don't burst it.
My ism, it's full of beliefs.