Good intro to cyclash universe by Steinhardt

In summary, Steinhardt's "cyclash" universe theory proposes that the universe undergoes a cyclical process where two 3D manifolds repeatedly "bump" into each other, causing expansion and contraction. This model does not require inflation and addresses many cosmic puzzles. While some may find the name "THE Cyclic Universe" pretentious, Steinhardt's essay on the topic is well-written and provides strong criticism of inflation scenarios. It is available on his website and is called "Vaasrev.pdf", suggesting it is a review article for the science writer/editor Vaas. While there may be other ways to solve cosmic puzzles, it is worth reading Steinhardt's theory as he is a respected and insightful scientist.
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marcus
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Good intro to "cyclash" universe by Steinhardt

There are a lot of cyclic theories of the universe----different ways a bounce could occur, or something like a bigbang occur repeatedly. Penrose just came up with a new one, as if there weren't enough already. Now Steinhardt is an outstanding scientist and an exceptionally good writer, but it is a misleading and pretentious of him to call his model THE Cyclic Theory of the Universe, or on other occasions call it THE Cyclic Universe. What about all the other cyclic models?

That said, we should still know about his (and Turok's) model and Steinhardt has a really good essay for beginners on it that presents both the stringy and the more recent NONstringy version, and which MOTIVATES the model and also strongly criticizes the fashionable scenarios of inflation. His model doesn't need inflation, and takes care of the same cosmic puzzles.

An earlier version of it was called "ekpyrotic". The gist is that two 3D manifolds repeatedly BUMP each other. And then they rebound off again, and while they are rebounding they each SPREAD OUT some. In a 3D sense as in usual expanding universe pictures. So after about a trillion years they have each expanded so much they look blank and empty and they fall together and BUMP again.

Even in the nonstringy version he calls the flexible clashing 3D continuums "branes" short for membranes. There is only one extra dimension to make the surround 4D so the 3D things can clash and rebound in it.

Well the essay is really good and what's interesting to me is the motivation and the strong criticism of inflation scenarios.

I found it at Paul Steinhardt's Princeton website.
http://wwwphy.princeton.edu/~steinh/
The URL tag for this particular essay is VAASREV.pdf
It is not on arxiv and seems only available in PDF here at his site
http://wwwphy.princeton.edu/~steinh/vaasrev.pdf

"Vaasrev.pdf" does sound a bit like Vaas, the science writer/editor, suggesting it's a review article written for Vaas book.

It's too pretentious to call this particular clash-type cyclic model "THE Cylic Universe" so I am privately calling it the CYCLASH universe.

It could be that both Inflation and Cyclash are wrong and that there are still other ways of solving to those puzzles (flatness, uniformity of temperature, absence of mag monopoles...)

I don't advocate Steinhardt's clash-type cosmology----even if it doesn't need string theory and only takes 4D space I still find it dubious. But I think as many of us as possible should read it because he's a bright creative scientist who writes well (and I think has a strong commitment to empiricism).
 
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Better name "Accordion-like model"
 

1. What is the "cyclash" universe?

The "cyclash" universe is a theoretical concept proposed by physicist Paul Steinhardt. It is an alternative model to the widely accepted Big Bang theory, which suggests that the universe began with a rapid expansion from a single point. In the cyclash model, the universe undergoes a series of cycles of expansion and contraction, with each cycle beginning and ending with a "big bounce."

2. How does the cyclash universe differ from the Big Bang theory?

Unlike the Big Bang theory, which suggests a singular beginning of the universe, the cyclash model proposes a cyclical nature of the universe. It suggests that the universe undergoes repeated cycles of expansion and contraction, with no true beginning or end.

3. What evidence supports the cyclash universe theory?

Currently, there is no conclusive evidence that supports the cyclash universe theory. It is a theoretical concept that is still being explored and studied by scientists. However, some observations, such as the uniformity of the cosmic microwave background radiation and the distribution of galaxies, could potentially be explained by the cyclical nature of the universe proposed by the cyclash model.

4. What are the implications of the cyclash universe theory?

If the cyclash universe theory is proven to be true, it would challenge the widely accepted Big Bang theory and significantly change our understanding of the origin and evolution of the universe. It would also have implications for our understanding of time, space, and the laws of physics.

5. How is the cyclash universe theory being tested?

Currently, the cyclash universe theory is primarily being tested through theoretical calculations and computer simulations. Scientists are also looking for potential observational evidence that could support the theory, such as patterns in the cosmic microwave background radiation or evidence of previous universes in the form of black holes. However, further research and advancements in technology are needed to fully test and confirm the cyclash universe theory.

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