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Cyclic Universe a Possibility
An Anonymous Coward writes "Spacedaily has a post(from Science) about a new theory at odds with the big bang theory. The researchers claim that this theory of an oscillating energy field could be experimentally tested in the coming years."
On April 25, All Things Considered on NPR did a five-minute story on this new Science article. Highly recommended, gives some good background not only on how this theory fits better with some of the current data that we are collecting, but also talks about how difficult it is for a new theory to gain acceptance in the scientific community when it flies in the face of a long-established theory.
modern choral music...
The Cyclic Universe: An Informal Introduction
Authors: Paul J. Steinhardt, Neil Turok
The Cyclic Model is a radical, new cosmological scenario which proposes that the Universe undergoes an endless sequence of epochs which begin with a `big bang' and end in a `big crunch.' When the Universe bounces from contraction to re-expansion, the temperature and density remain finite. The model does not include a period of rapid inflation, yet it reproduces all of the successful predictions of standard big bang and inflationary cosmology. We point out numerous novel elements that have not been used previously which may open the door to further alternative cosmologies. Although the model is motivated by M-theory, branes and extra-dimensions, here we show that the scenario can be described almost entirely in terms of conventional 4d field theory and 4d cosmology.
In spite of the "informal" claim, the paper is fairly dense - IAAPA (I am a professional astronomer) and I found it heavy going. But the link above has PDF versions if you're interested.
"I will take the Ring," he said, "though I do not know the way."
Some more info on,
http://feynman.princeton.edu/~steinh/
Sky and Telescope also covered this story, but didn't obscure it with piss-poor scientific writing like this other source did.
As an aside, the other source over simplifies things, and leaves you with the feeling that you learned nothing but marketing hype. It's target is obviously non-astronomers (or we would have read the original paper in an original journal.) Because of that, they should have explained "branes" (and other terms) with more than sound-bytes from involved physicists. Think diagrams, break-out boxes, etc.
It all goes downhill from first post
You have the right idea, just that your a bit confused. The idea is that heat will be lost when the unvierse expands and heat will be generated when the universe colapses. (The whole idea of friction and the galaxies rubbing up against each other creating a singularity hotter then the average sun... but that according to this new theory isn't the case ;) Anyways... that's about as basic as it gets.
eh, food for thought...
Interestingly, Aristotle proposed that the world was created in eternity. St. Thomas Aquinas argued that God could have created the world either in time OR in eternity, but there was no way to prove one way or the other. He did note, however, that God must have created the universe, since the universe is not pure act. BTW, I've never read a decent refutation of Thomas' "first way." The argument of God's existence from motion. Anyone have a good counter argument?
Okay, a lot of people have been saying that an infinite cycle of exands and contracts would NOT generate infinite heat. Here's what Steven Weinberg has to say:
"Some cosmologists are philosophically attracted to the oscillating model, especially because, like the steady-state model, it nicely avoids the problem of Genesis. It does, however, face one severe theoretical difficulty. In each cycle the ratio of photons to nuclear particles (entropy per nuclear particle) is slightly increased by a kind of friction (known as "bulk viscosity") as the universe expands and contracts. As far as we know, the universe would then start each new cycle with a new, slightly larger ratio of photons to nuclear particles. Right now this ratio is large, but not infinite, so it is hard to see how the universe could have previously experienced an infinite number of cycles."
Pysicist Sidney A. Bludman says:
"Our Universe cannot bounce in the future. Closed Friedman universes were once called oscillatory universes. We now appreciate that, because of the huge entropy genereated in our Universe, far from oscillating, a closed universe can only go through one cycle of expansion and contraction. Whether closed or open, reversing or monotonically expanding, the severely irreversible phase transitions give the Universe a definite beginning, middle and end."
If any of you have counter-quotations from equally famous physicists, I would love to read them. This is all I have found on the matter so far.
It's all going according to
Yes. Indeed, the "dark energy" responsible for this expansion is central to their theory. Read their paper on the LANL arXiv (cited elsewhere in the comments), particularly pages 3 and 4. The expansion only continues forever if the "dark energy" contribution to the acceleration is constant, but in their theory it "rolls down a potential".
Who said we'd turn into a "black holish sort of thing"?
Really? What part of relativity?
Page 5 of their paper discusses the relativistic model of the crunch/bounce phase.
That concerns mechanical work from a source external to a system. The theory here obeys the ordinary laws of thermodynamics, as discussed on p. 4 of the paper.
While there's a superficial resemblence, there's a huge difference between the old oscillatory models and this one.
In the old models, the universe collapsed from many billions of light years across (or even larger - we really have no idea of how big the universe is) back to the singularity of the big bang.
In this model, the universes (plural) only have to move a few millimeters. The big bang occurs when the branes separate (we're in one brane, the other universe is in another), and the big crunch occurs when they collapse again. The point of intersection can even travel faster than the speed of light without violating relativity - it's okin to the scan of a lighthouse beam against a wall a very long distance away.
For every complex problem there is an answer that is clear, simple, and wrong. -- H L Mencken
Why is that? Science relies heavily on the concept of infinity, and it has no nature to be discussed. There are many mathematical properties that involve it, yet do those express its true nature?
Infinity was unclear once upon a time, but not any more.
Largely through the work of Georg Cantor, the nature and properties of infinity have been absolutely described.
There was a time when this was unclear and this bothered people. So they went ahead and cleared up the ambiguities.
While this doesn't give a definitive answr to the issue in question, your example did just turn around and bite you on the ass.