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One Big Bang, Or Many?
butterwise writes "From the Guardian Unlimited: 'The universe is at least 986 billion years older than physicists thought and is probably much older still, according to a radical new theory. The revolutionary study suggests that time did not begin with the big bang 14 billion years ago. This mammoth explosion which created all the matter we see around us, was just the most recent of many.'"
From TFA (emphasis mine): And also from TFA (again, emphasis mine):
Now, I'm no cosmologist, but these two descriptions of the theory seem to be in conflict...does the matter in the universe come together in the Big Crunch, or does it fly off into space forever, replenished by subsequent Big Bang events?
If the Guardian Unlimited doesn't even know what the theory is proposing, why are they reporting it?
Fortunately, we needn't depend upon Guardian Unlimited for our cosmology news...Nature.com happens to have a much more informative article on the subject. What's especially amusing is that they've had this article since April 26th of 2002.
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...or even news? The Big Crunch theory has been around for a long time.
'Cyclic universe' can explain cosmological constant
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The cyclic model has been around for several years, and there is plenty I don't understand about it, but it is distinct from the old big bang-big crunch ideas. The "cycle" is the repeated collision between two sub-universes, called branes. We live in one of these sub-universes. Each collision resets our sub-universe with a new big bang... Our universe is constantly expanding; there is no crunch.
Importantly, the cyclic theory has detectable differences from the standard big bang scenario. For example, primordial gravity waves, detectable through their influence on the polarization of the cosmic microwave background, are present in the standard big bang scenario and absent here. Thus their possible detection by a future microwave experiment could rule out this theory.
The purpose of this new work is to argue that the cosmological constant (the factor which make the expansion of the universe accelerate) is naturally small and positive in the cyclic model. This is as we observe it. The standard big bang theory does not make a prediction for the size of the cosmological constant (it's just a parameter), while in string theories the expected size of the constant is vastly larger.
Steinhardt has many materials (including a cartoon movie of the brane collision) on his homepage.
The article is none too clear, but it seems that the major claims of this new theory are that the Cosmological Constant:
a) Might diminish over time, and
b) Might be able to survive a Big Crunch/Bang cycle, and
c) Seems to be smaller than it "should" be if the universe was created 14 billion years ago.
From these, they propose that:
d) The universe is actually much older and has gone through many Big Crunch/Bang cycles, allowing enough time for the CC to shrink to its current level.
However, I'd like to see some hard evidence for a), b), and c) before I accept that d) might be true.
The most rabid believers in American Exceptionalism are the exact same people whose policies are destroying it.
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Except that Big Bang Theory neither requires nor expects a crunch. In fact, most modern cosmologists think that we live in an open universe, meaning that we will eventually suffer heat death. There's a lot of literature on this, but I highly recommend Guth's The Inflationary Universe for a layman physics treatment. The book is quite interesting, has little math and lots of references if you want to go look up where he's coming from. To say that Guth is an expert on cosmology would be a gross understatment.
Here's some lazy links:
Big Bang
Heat Death
I currently have no clever signature witicism to add here.
Unfortunately, your model breaks down in the face of binary star systems. In fact, in all gravitational systems the bodies involved actually orbit one another. For example, while the Moon orbits the Earth, the Earth also orbits the Moon. The Earth is so much more massive than the Moon, however, that the centre of the orbital motion (the centre of mass of the Earth-Moon system) is actually within the Earth itself. However, it is *not* at the Earth's centre; the Earth "wobbles" due to its orbiting the Moon.
Similarly, the centre of mass of the solar system is within the Sun, but still the Sun has a wobble due to its orbiting of the rest of the bodies in the system. That's more complex, of course, as with so many bodies, they tend to be at different points around it. Also the Sun is so much more massive than the other solar bodies as to render the effect essentially negligible.
The effect tends to be more noticeable in binary star systems as the two stars tend to be more closely matched in terms of mass. In that case, the centre of mass of the system is more nearly half-way between them. They both orbit something, but that something is a point of empty space.
Incidentally, this effect is how we've detected some extra-solar planets - particularly massive ones orbiting relatively small stars cause a noticeable wobble.
It's official. Most of you are morons.
Hey Slashdot Editors: Try Googling a couple of clicks worth before accepting submissions depending on The Guardian's science reporting, please.
i cuniverse.htm
From http://www.princeton.edu/pr/pwb/02/0506/0506-cycl
"Princeton University
April 25, 2002
New Theory Provides Alternative to Big Bang"
These guys, Tourok and Steinhardt, published this four years ago! News?