Open Questions: Cosmological Models
See also: Cosmic inflation --
Why should the universe be unique? Why should there be just one
Those seem, at first glance, like strange questions, if by "universe" we
there is". However, if instead we mean simply "everything we can possibly
observe with our current technology", then the questions aren't so
unreasonable. In fact, they are rather intriguing.
Sites with general resources
Paul J. Steinhardt
- Personal Web site. Steinhardt is one of the main proponents
of the "cyclic universe" cosmology. The site contains a number of
articles and papers on the subject. There are also articles on
other topics in cosmology, such as dark matter, dark energy,
Surveys, overviews, tutorials
- Article from
Loop Quantum Cosmology
- Detailed article by Martin Bojowald in
Living Reviews in Relativity.
Which mathematical structure is isomorphic to our universe?
- In spite of the title and the "theory of everything" reference,
the topic here is multiple universes. The page introduces a
technical article by
Is "the theory of everything" merely the ultimate ensemble theory?
- Introduction to a
of the same title, by
Four levels of the concept of "multiple universes" are discussed.
There is also a list of frequently asked questions stimulated
by the article.
My So-Called Universe
- Interesting but brief examination of philosophical arguments
for and against multiple universes, by Jim Holt.
Surveying the Landscape
- December 2005 article from Seed Magazine, consisting
mostly of brief quotes from cosmologists about the idea of
Are There Other Universes?
- February 2002
article from Space.com.
Discusses theories of "parallel" universes and whether or not
the theories can be tested.
'Brane-Storm' Challenges Part of Big Bang Theory
- April 2001
article from Space.com.
Discusses Paul Steinhardt's "ekpyrotic" theory.
The Structure of the Multiverse
- Technical paper by David Deutsch.
"The structure of the multiverse is determined by information flow. "
The Endless Universe: A Brief Introduction to the Cyclic
- November 2001 overview paper by
Paul Steinhardt. A slightly later (May 2002)
paper by Steinhardt on this model is
A Brief Introduction to the Ekpyrotic Universe
- Brief overview by
Cyclic model FAQs
- Questions and answers concerning the cyclib model, by
Echoes from Before the Big Bang May Be Inaudible
- July 2007 Scientific American article, subtitled
"New theory calls into question whether we'll ever know
what the universe was like before the big bang."
A Recycled Universe
- February 2002 Scientific American In Depth article,
subtitled, "Crashing branes and cosmic acceleration may power an
infinite cycle in which our universe is but a phase."
Colliding Branes and the Origin of the Hot Big Bang
- Slide presentation on his ekpyrotic universe theory,
by Paul Steinhardt, at the
2001: A Spacetime Odyssey conference.
Inflationary Theory versus Ekpyrotic/Cyclic Scenario
- Technical paper by
Andrei Linde, which argues that the ekpyrotic/cyclic
cosmology, as originally proposed, does not solve any of the
major cosmological problems, such as the flatness and entropy
problems. A modification is suggested which simplifies the
scenario, solves the problems, and produces a theory equivalent
to the usual chaotic inflation scenario.
Big Bang or Big Bounce?: New Theory on the Universe's Birth
Scientific American, October 2008
When worlds collide
Science News, June 7, 2008
The Myth of the Beginning of Time
Scientific American, May 2004
- When Branes Collide
Astronomy, May 2002, pp. 34-39
- The so-called "ekpyrotic theory" may offer an alternative
to inflation as a scenario for the earliest moments of the
universe. The idea is based on M-theory -- the latest version of
superstring theory -- and suggests that the universe as we know
it originated in the collision of two parallel 5-dimensional
M-theory objects known as "branes".
When Branes Collide
Science News, September 22, 2001, pp. 184-186
- A new theory of the origin of the universe might explain
everything that the inflationary big bang theory does, but also
have a closer relation to superstring theory.
- Martin Rees -- Our Cosmic Habitat
Princeton University Press, 2001
- Rees, Great Britain's Astronomer Royal has written a number
of books on cosmology for a general audience. This is another,
which once again surveys basic concepts of cosmology and the
big bang. Some of his recent books have considered the
interesting fact that certain aspects of our universe seem to
be uniquely adapted to allow the existence of sentient life.
The most natural explanation for this is the existence of
innumerable universes with hugely varying characteristics,
out of which only a very small number have (like our universe)
the necessary very special properties that allow life.
Copyright © 2002 by Charles Daney, All Rights Reserved