Was There Only One Big Bang? 295
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."
Old hat (Score:2, Interesting)
Pretty old theory (Score:2, Interesting)
Pretty old theory, that gave rose to various philosophical question, like if it is recurring, is the outcome always the same, or different every time?
http://en.wikipedia.org/wiki/Eternal_return
Indians first came this theory to light, Nietzsche spend quite sometime thinking about this, Kundera wrote a book around it: The Unbearable Lightness of Being.
Re:Old hat (Score:5, Interesting)
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.
Re:Old hat (Score:5, Interesting)
Many Big Bangs / inflations doesn't even have to mean complete recycling of, well, everything - for example [wikipedia.org].
oblig... (Score:3, Interesting)
Pulse (Score:4, Interesting)
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..
Re:Old hat (Score:3, Interesting)
Hindu Philosophy (Or More Specifically Dharmic Philosophy, which coveres a than just Hinduism/Religion) Has always seen the universe as a creation/destruction cycle, with multiple cycles of creation/destruction.
Re:New? (Score:3, Interesting)
Since our physics don't apply anywhere near the big bang, there are no calculations that can tell you what goes on if such an event were to occur; likewise, while projecting backwards until you get to something ridiculous (cosmologists call the ridiculous point a singularity, but what they mean is that nothing we know applies there, which is ridiculous from the standpoint of continuing with any attempt at explanation (no framework).) Once you've reached the ridiculous, traipsing onward and trying to imagine what led to this undefinable, non-rule-following thing you're talking about, not jsut multiple times, but even once, is absurd. Without a working physics model, it's all hand waving.
Cosmology at this level is about as sensible as religion. That is to say, not at all.
Re:No...this is the third matrix. (Score:3, Interesting)
No. This is an episode of Futurama. [wikipedia.org]
I just wonder how many feet below the last one this universe is.
Re:New? (Score:5, Interesting)
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
Re:Turok and Steinhardt also postulate this (Score:4, Interesting)
Well then, we're in agreement. :-P
I wasn't saying that you could use ancient Hindu or Buddhist cosmology to say anything predictive about modern scientific cosmology. Merely that they had arrived at that conclusion 4000+ years ago -- either through observations or lucky guess.
Oh yeah, baby ... noodles, pottery, writing, navigation, iron, running water. Talk dirty to me. ;-)
Cheers
Re:Turok and Steinhardt also postulate this (Score:2, Interesting)
No offence meant, btw. For some reason I just felt like having a go at people linking religion and cosmology and kind of got off-topic from your post :)
Also, you forgot fireworks.
Re:Expansion (Score:2, Interesting)
i'm not knowledgeable about philosophy, unfortunately :( but i wouldn't say it implies eternal recurrence as i understand it -- such that everything that happens repeats. the problem is that the things that are repeating are cosmological, so it's only things on the very largest scales. that means that the bulk properties of hte universe would repeat in a cyclic model (although entropy is an issue in that), but it doesn't say that anything on smaller scales will. each time it's extremely likely that the actual distribution of matter will be different since gravitational collapse is an extremely complicated process (and can be chaotic), and that means that even the massive networks of galaxy clusters will look different on each cycle, let alone the suns, planets and sentient beings.
this is because the initial perturbations, in almost every model, are quantum in nature and seeded in the first microseconds (or before) -- being quantum in nature they're also random in nature. so each time through the universe as a whole will be identical, but you'll get different ripples on top of it and a different "micro-structure", if i can use "micro-structure" to describe objects as large as superclusters of galaxies.
not sure if that answers your question though, unfortunately.
Re:New? (Score:2, Interesting)
Yep, not long after the CMB anisotropies were first predicted, too.
It's a bit of a crime that there were no Nobel prizes forthcoming for any of this, except for Penzias and Wilson, who originally thought it might be pigeon shit in their antennae. (To be fair to them they had to rule out all possible sources of noise -- but the people who initially predicted the existence of the thing such as Gamow and his ilk, and then the structure of it, were totally overlooked. It seems seriously unfair. I still feel that Jim Peebles should get a very belated Nobel for his services to statistical cosmology.)