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Was There Only One Big Bang?
goldaryn writes "Physorg.com is running an interesting story about the work of Oxford-based theoretical physicist Roger Penrose. Penrose has been studying CWB radiation and believes it's possible that space and time did not come into being at the Big Bang but that our universe in fact continually cycles through a series of 'aeons.' He believes that he has found evidence supporting his theory that the universe infinitely cycles."
There is a BBC Horizon episode up on youtube called What Happened Before the Big Bang. Interviews with several physicists about different ideas on the topic of what might have preceded our universe.
The Long Now Foundation
According to the article, concentric circles of temperature variation in the cosmic background radiation were caused by successive massive black holes, some of which supposedly predate the big bang.
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Galactus, the sole survivor of the universe existing before the Big Bang, disagrees.
Proven with what? Our grasp of physics can only let us understand what probably happened minutes after the Big Bang occured. According to this model, complete removal of information occurs at the end of the cycle, or aeon, when black holes evaporate and the universe returns into a pristine state, just like a blank slate.
I think it's easier to understand what we are talking about if you imagine the universe as a white blanket.
Before the big bang occurs, the blanket perfectly smooth, just like it was well ironed. Then, a massive jolt causes it to fold, crease and wrinkle: this is information, i.e. matter. Entropy could probably act as a gradual, unstoppable force that gradually puts the blanket under tension again.
The end of universe, therefore, is the return to a pristine state completely devoid of information. Suppose you spill a cup of coffee over the blanked: it is now tainted, but this doesn't necessary interfere with the distension process of prohibit the blanket from returning to a perfectly smooth state. However, if you take a look at the tainted blanket, it obviously isn't perfectly white as before.
Therefore, the Big Bang acts as a creator of new information, not as a destructor of previous information.
Hack your mind out of its sandbox.
Many Big Bangs / inflations doesn't even have to mean complete recycling of, well, everything - for example.
One that hath name thou can not otter
...and boy are it's legs tired.
... it was rather dumbed down with lots of silly graphics and other dicking about from the guy in the editing suite, shots of people walking backwards and forwards and a narrator asking loads of questions that the program didn't really give the interviewees enough time to answer properly. And when they did it was obvious they'd been told to keep it simple. Which was a shame , it had great potential but there seems to be a line of thought in British TV at the moment , not just the BBC, that people just can't handle difficult science in more than 30 second dollops before the viewing needs a break. Thank heavens for TED.
It may even be that "our" big bang and "our" universe is one of many in the great infiniteness of the.. universe. Just like there are more planets, more solar systems, more galaxies other than our own. Just like cells in the human body, and atoms within the cells...
Time is irrelevant unless measured, eg by a human. So this pulse may be as normal as any pulsating object, large or small.
The mind wanders..
Waiting for you by the bridge
no to big-bang-centricity ! your universe is not the center of the multiverse !
You bastard! You're trying to make us humans even more insignificant than we already are??
We already admitted that Europe isn't the center of the world.
We already admitted that the world isn't the center of the solar system/universe
We already admitted that the sun isn't the center of the galaxy
We already admitted that our galaxy isn't the center of the universe
You're trying to make us admit that even our universe isn't the center of the multiverses?
Damn you!
That's not really so much "consensus" as "the result of the model we're currently using". No-one *likes* the standard model of cosmology; it's obviously just phenomenology, but it happens to fit all the data at least as well as any alternative. The standard model of cosmology is "lambda CDM", the lambda being a cosmological constant which drives an accelerating expansion in the current universe, and the CDM being cold dark matter which was responsible for the clustering of matter and the formation of galaxies and so forth.
The problem is that if it *is* just a cosmological constant then it will grow to dominate the universe and things will, indeed, expand forever.
But it's probably not a cosmological constant. The "best" prediction from quantum field theory -- and it's not really a prediction so much as the only way of estimating the size of the constant -- comes from evaluating the vacuum energy. Doing this suggests that it should be about 10^120 times bigger than we see in reality. That's a pretty big difference. Weinberg described it as the most embarrassing mismatch between theory and observation in the history of science, and he's got a point. The conclusion is that there's probably some mechanism (coming from trans-Planckian physics, maybe, or something else) that cancels the cosmological constant. If that's true, then it's almost certain to cancel it perfectly because the fine-tuning necessary to produce the *observed* constant is horrific, whereas a symmetry principle could wipe the whole thing much more easily.
That leaves you open to more general dark energy models to explain the accelerating expansion and that's where you have more fun. There are plenty of ways to get an observed acceleration. Some of them lead to big rips, which is where eventually the universal expansion will tear galaxies, then solar systems, then stars, planets and eventually even atoms and nuclei apart. Others lead to the decay of whatever field is responsible for acceleration -- like if you couple a scalar field into dark matter you can tune it such that the scalar field grows to dominate and then starts transferring its energy into dark matter, which would cause the universe to reclump again (and then probably the dark matter would dump energy back into the scalar field causing more acceleration). Those models are horribly contrived and unrealistic, but at least they're alternatives.
And the cosmological constant is pretty contrived and unrealistic in the first place...
Anyway. Before I got side-tracked my point was that there isn't really a consensus so much as a model that fits observations and predicts eternal expansion, but that it's not the only model and it's not even the best motivated model, merely the simplest. Other models can still lead to crunches while fitting pretty much all the data as well. And others can lead to cyclic universes, which is ultimately what Penrose is talking about in one form or another.
Disclaimer: I am a cosmologist but I've not actually read the article. This is Slashdot, after all.
Milliseconds, not minutes, but yeah. At about t+4ms, the strong forces came into existence. Before that, the math completely falls apart, and we have no idea what was happening. We don't even know if time itself was constant, and as we percieve it those first 4ms could have taken a billion years or more.
This isn't, by any stretch, a new idea, though. It's very similar to the Hindu/Buddhist cosmologies, which have been around for thousands of years. Sure, the hindus do use the notion of Brahma and the Manus to explain the passing of cycles, but both faiths teach that the universe goes through an infinite cycle of expansion, stability, and collapse, and that time goes off into infinite in either direction from here. This scientist's "new idea"? It's been around for at least 5,000 years.
More people are alive today than all humans who have ever died.
That's an urban myth (how you defend it with flawed math probably nicely demonstrates our propensity to attaching to ourselves undue importance). 100+ billion homo sapiens dead already:
http://www.sciam.com/article.cfm?id=fact-or-fiction-living-outnumber-dead
http://www.prb.org/pdf/PT_novdec02.pdf
http://www.prb.org/Articles/2002/HowManyPeopleHaveEverLivedonEarth.aspx
One that hath name thou can not otter
I saw Penrose speak on this topic at the Perimeter Institute about two years ago. He has been working on this for quite a while.
You captured the essence of his hypothesis. The idea is that in the latter stages of a universe, you eventually get two supermassive black holes orbiting each other - each containing half of the matter in the universe. As they rotate around each other, they're effectively ripping each other apart from the massive gravity wells. His theory is that the point at which they finally coalesce after billions of years of orbit, space and time "reset", and in that same instant the big bang takes place.
His premise is that not all of the energy has been completely contained within the singularity. When the big bang happens, the outlying energy causes rings in the background radiation.
Funny thing was, two days before his talk he got the first results back from the radiation survey. They didn't find rings, they found ovals. And in his words "we have no idea what that means".
It's great to see that he's making progress.
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Hmmm, big question. I'll try and give the quick answer
The first ripples are seen on the cosmic microwave background radiation. This is a bath of microwave radiation that surrounds us, at almost exactly 2.71K and the most perfect blackbody ever observed. It is virtually impossible to explain the existence of this without having something very similar to modern cosmology. People tried when they were trying to keep steady-state cosmologies in the 60s but ultimately they failed; it's seriously difficult to explain something with a blackbody spectrum and isotropic to one part in a thousand (to one part in ten thousand if you subtract off a dipole which is almost certainly a Doppler shift caused by our motion with respect to the CMB) unless the universe started from a compact, very nearly uniform state.
Basically, if you link the isotropy of the CMB with the idea that the Earth isn't at the centre of the universe, you're lead almost inevitably to modern cosmology: the universe is isotropic around the Earth, but the Earth isn't at the centre, so the universe must be isotropic around *every place in the universe*. That means it's both homogeneous and isotropic.
The next assumption is that gravity is metric-based -- that is, that on scales larger than a few micometres, that the effects of gravity are due to distortions in space-time. This is an extremely safe assumption on solar system scales but it's only that - an assumption - on larger scales. Still, we've got no sensible alternatives so let's stick with it. (It's very hard to build a working model of gravity that isn't metric-based.)
The next assumption, and this is much weaker but is the best we can currently do, is that Einstein's general relativty applies on very large scales. GR is a particular form of a metric-based theory and is the simplest, most intuitively clean of them. So let's stick with it. But it's quite weak.
Doing that, we're lead to only one possible model for the universe -- the Friedman-LeMaitre-Robertson-Walker model. Basically that says that if you've got 3D spatial surfaces that have to be homogeneous and isotropic, you can chose to make them flat, saddle-shaped or spherical, and then pile them together to fill the whole of spacetime. It then tells you the behaviour of these surfaces given the matter you put into it.
An immediate consequence of saying "The universe contains photons and baryons" (which is obvious; as cosmologists use the word, *everything* is baryonic except for neutrinos and photons, and no-one would deny that we exist, or that photons exist, or that neutrinos exist, so you put them all in there) is the CMB. It exists, and we can calculate when it formed. The CMB is formed when the temperature of the universe becomes low enough that photons don't continuously reionise hydrogen. Basically a small universe is a hotter universe, so at some point in the distant past (which turns out to be before the universe was about 370,000 years old) the universe was hot enough that if an electron combined with a proton to form hydrogen, a photon immediately came along and smacked the electron back out again. This tied protons, electrons and photons together. The universe was opaque and it was all a massive chaotic game of pool. Without any pockets.
When the universe became cold enough that that no longer happened, the electrons all condensed into the protons, the universe suddenly went neutral, and the photons could stream free. Those photons are the CMB. Originally they were very hot but as the universe has expanded they've been redshifted until they reached teh current temperature barely above absolute zero.
Now, when the photons and protons were bound together it wasn't all *entirely* smooth. There are waves go through any plasma. (Without them the Sun would be a very boring place.) These waves are those ripples in the CMB I mentioned. At the formation of the CMB the photons suddenly broke free and the waves stopped, err, waving. This left an imprint of the ripples in the *baryons* on the photons. Ba
"Penrose works on a lot of whacky far-out ideas, none of which so far have panned out."
Yes he does, many of his early "wacky ideas" did indeed "pan out", such as the proof that black holes could form and the concept of cosmic censorship.
"I can generate whacky ideas without evidence just as fast as him"
Maybe, but I doubt you have the mathematical skill of Penrose to back it up.
And did you exchange a walk on part in the war for a lead role in a cage? - Pink Floyd.