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	Ekpyrotic - Wikipedia, the free encyclopedia
		The ekpyrotic universe or ekpyrotic scenario is a cosmological theory of the origin of the universe.
		The ekpyrotic scenario was proposed by Khoury, Ovrut, Steinhardt and Turok in 2001.
		An important distinction between the ekpyrotic scenario and cosmic inflation is that in the ekpyrotic scenario, the primordial nearly scale invariant spectrum of quantum vacuum fluctuations, which is the seed for all structure in the universe today, is generated in a contracting universe, before the big crunch.
	en.wikipedia.org /wiki/Ekpyrotic (649 words)

	Cyclic model - Wikipedia, the free encyclopedia
		There were problems with the old ekpyrotic picture having to do with the very special, nearly supersymmetric initial state required in order to end up with a nearly homogeneous universe: the problems solved by cosmic inflation, such as the monopole, flatness and homogeneity problems were shifted to a set of fine-tuned initial conditions.
		The ekpyrotic picture was not connected to the issue of dark energy.
		For example, in the ekpyrotic model, they are D-branes; while in the cyclic model, they are orbifold planes.
	en.wikipedia.org /wiki/Cyclic_model (511 words)

	When Branes Collide: Science News Online, Sept. 22, 2001
		In the ekpyrotic scenario, the fifth dimension is finite in size and bounded on either side by a three-dimensional brane.
		In a modified version of the ekpyrotic theory, posted Aug. 26 on the Internet (http://xxx.lanl.gov/abs/hep-th/0108187), Steinhardt, Nathan Seiberg of the Institute of Advanced Study in Princeton, N.J., and their collaborators say such concerns are now unwarranted.
		Moreover, Linde claims that the branes in the ekpyrotic model are not truly uniform in structure and therefore can't account for the large-scale uniformity of the universe.
	www.sciencenews.org /articles/20010922/bob9.asp (2598 words)

	MATH / PHYSICS Research Group Research
		The Ekpyrotic collision, in addition to producing the expansion and heat of the Big Bang, simultaneously, via a small instanton transition, can produce a standard-like model with the correct gauge group and three families of quarks and leptons.
		The theory of superpotentials for the transition moduli of vector bundles is of importance in Ekpyrotic theory and is currently under study.
		Ekpyrotic theory is the direct outgrowth of truly interdisciplinary collaboration between mathematicians, physicists and cosmologists.
	dept.physics.upenn.edu /mprg/resprograms.html (2685 words)

	[No title]
		The Ekpyrotic Model of the Universe proposes that our current universe arose from a collision of two three-dimensional worlds (branes) in a space with an extra (fourth) spatial dimension.
		One proposal is the "inflationary theory" of the universe, which proposes that the universe began hot and dense, and underwent a period of hyperexpansion.
		The ekpyrotic model is a new alternative, which is, in many ways, a more radical departure from the Big Bang concept.
	wwwphy.princeton.edu /~steinh/npr (1187 words)

	Ekpyrotic Universe
		Although I like the implications of activities of topological forces, these descriptions of brane "tension" are not sufficiently well derived, and the entirety of the development of the thesis depends on this derivation.
		Their model was called the ekpyrotic universe, from the Greek-derived word ekpyrosis.
		In summary, I think that the Ekpyrotic Universe is very good press agentry (good in the capability/skill sense, not in the moral sense) and very bad (in all senses) physics.
	www.rialian.com /rnboyd/ekpyrotic.htm (802 words)

	Science & Technology at Scientific American.com: The Myth of the Beginning of Time -- [ COSMOLOGY ] -- String ... (Site not responding. Last check: 2007-09-01)
		The opposite is true for the ekpyrotic scenario, in which the collision occurs when forces are at their weakest.
		The developers of the ekpyrotic theory initially hoped that the weakness of the forces would allow the bounce to be analyzed more easily, but they were still confronted with a difficult high-curvature situation, so the jury is out on whether the scenario truly avoids a singularity.
		Also, the ekpyrotic scenario must entail very special conditions to solve the usual cosmological puzzles.
	www.sciam.com /article.cfm?chanID=sa006&articleID=00042F0D-1A0E-1085-94F483414B7F0000&pageNumber=6&catID=2 (692 words)

	The Ekpyrotic Universe and its Cyclic Extension Transparency 4
		The Ekpyrotic Universe and its Cyclic Extension Transparency 4
		The Ekpyrotic Universe and its Cyclic Extension Transparency 5
		The Ekpyrotic Universe and its Cyclic Extension Transparency 3
	www.damtp.cam.ac.uk /talks/ngt1000/annecy/node04.html (80 words)

	ekpyrotic theory and the 2nd law of thermodynamics - TheologyWeb Campus
		ekpyrotic theory and the 2nd law of thermodynamics
		Seriously, I've been puzzling over the implications of ekpyrotic theory for the cosmological argument.
		If I'm right, then that would seem to suggest that the ekpyrotic theory does not avoid the finitude of time, nor the necessity for energy to be put into the system from without the system at some finite point in the past.
	www.theologyweb.com /campus/showthread.php?t=22166 (1847 words)

	Ekpyrotica \| Where Branes Collide (Site not responding. Last check: 2007-09-01)
		These reactions or ekpyrotic scenarios cause parallel brane universes to collide with each other with any result that is possible in the realm of physics.
		The Ekpyrotic Scenario attempts to provide a viable solution to the original theory of ekpyrosis.
		You are invited to continue with the introduction.
	physix.faithweb.com (152 words)

	Open Questions: Multiple Universes
		Slide presentation on his ekpyrotic universe theory, by Paul Steinhardt, at the 2001: A Spacetime Odyssey conference.
		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.
		The so-called "ekpyrotic theory" may offer an alternative to inflation as a scenario for the earliest moments of the universe.
	www.openquestions.com /oq-co014.htm (511 words)

	One Mormon's View of the Science -- Religion Debate "ekpyrotic universe" "big bang" mormon lds (Site not responding. Last check: 2007-09-01)
		A few cosmologists, after several years of mathematical development, have introduced a new model, based on string theory, which explains how the Big Bang might have occurred.
		The result of this theory is the concept of an Ekpyrotic Universe.
		There are parallels between the Ekpyrotic Universe and the Mormon understanding of the creation of the Cosmos.
	www.leigh.org /sciencereligion/ekpyrotic.html (132 words)

	altvw111
		It is called "ekpyrotic cosmology", and it describes an early universe in which there was no Big Bang at all, but instead a collision of higher-dimensional "branes".
		This new ekpyrotic cosmology derives its name from the ancient Greek stoic philosopher’s notion that the universe was cyclically destroyed and re-created by fire.
		And the ekpyrotic universe, even at the instant of the Big Clap, was never hot enough or close enough to a singularity to produce the flood of monopoles that the simple Big Bang model predicts.
	www.npl.washington.edu /AV/altvw111.html (1967 words)

	Re: ekpyrotic/cyclic big bang scenario
		In the ekpyrotic scenario, are the branes supposed to be brane-antibrane
		Is the\npotential needed in order for something ekpyrotic to make sense?\n\n\nandgt; exponential so that most of the time the brane moves slowly and only\nandgt; significantly accelerates just before the collistion.
		I suppose you could say it resembled ekpyrotic in that\nthere is a brane which moves and collides, but the details are rather\ndifferent.\n\n\nandgt; andgt; Now, could this apply also to the end-of-the-world branes in M-theory?\nandgt; andgt; (E.g.
	www.physicsforums.com /showthread.php?p=237263 (7147 words)

	WORKSHOP on the EKPYROTIC UNIVERSE (Site not responding. Last check: 2007-09-01)
		The "ekpyrotic universe" is a recently proposed alternative to the inflationary scenario in cosmology.
		The purpose of this workshop will be to offer the opportunity to discuss issues such as the connection with M-theory and cosmological perturbations in the ekpyrotic scenario.
		The organizers are ready to provide any practical or touristic information for having a pleasant time before or after the conference.
	wwwlapp.in2p3.fr /~lesgourg/EKPY/ekpy.htm (236 words)

	What about string theory?
		The latest version of braneworld cosmology is the giant brane collision model, also known as the Ekpyrotic Universe, or the Big Splat.
		The Ekpyrotic Universe starts out as a cold, flat, static five-dimensional spacetime that is close to being a supersymmetric BPS state, meaning a state invariant under some special subalgebra of the supersymmetry algebra.
		The four space dimensions of the bulk are bounded by two three-dimensional walls or three-branes, and one of those three-branes makes up the space that we live on.
	superstringtheory.com /cosmo/cosmo5a1.html (904 words)

	cobalt blue tony Science!!! (Site not responding. Last check: 2007-09-01)
		The difference results in one distinctive observational prediction, though: Inflationary cosmology predicts a spectrum of gravitational waves that may be detectable in the cosmic microwave background.
		The ekpyrotic model predicts no gravitational wave effects should be observable in the cosmic microwave background.
		In the ekpyrotic model, when the two three-dimensional worlds collide and “stick,” the kinetic energy in the collision is converted to the quarks, electrons, photons, etc. that are confined to move along three dimensions.
	www.cobaltbluetony.com /Ekuni.html (1843 words)

	SPACE.com -- 'Brane-Storm' Challenges Part of Big Bang Theory
		Faster than you can say "Ekpyrotic Universe," a movement has taken hold -- albeit like fingers on a ledge of eternal skepticism -- that would blow one of the basic tenets of the Big Bang to smithereens.
		The Ekpyrotic Universe draws its name from the ancient Greek word ekpyrosis, meaning "conflagration" (disastrous fire or conflict).
		According to an ancient cosmological model with this name, the universe was created in a sudden burst of fire.
	space.com /scienceastronomy/astronomy/bigbang_alternative_010413-1.html (635 words)

	CalendarHome.com - Dating Creation - Calendar Encyclopedia
		It is not necessarily creation per se, as that word may be seen as implying the existence of a creator, additionally the theory does not describe the creation of matter itself, but rather the singular point in space-time, after which the laws of physics we know describe the history of the universe.
		Moreover, it has to be emphasized that early universe history might be somewhat different than what we intuitively think about when referring to a "Big Bang" (see ekpyrotic universe, for example).
		Therefore the "age" of the Universe refers to the time that elapsed since the last hot and dense epoch the region of the Universe we live in has experienced.
	encyclopedia.calendarhome.com /Estimates_of_the_date_of_Creation.htm (1200 words)

	The Ekpyrotic Universe and its Cyclic Extension Transparency 21
		The Ekpyrotic Universe and its Cyclic Extension Transparency 21
		The Ekpyrotic Universe and its Cyclic Extension Transparency 22
		The Ekpyrotic Universe and its Cyclic Extension Transparency 20
	www.damtp.cam.ac.uk /talks/ngt1000/annecy/node21.html (80 words)

	The Ekpyrotic Universe and its Cyclic Extension Transparency 18
		The Ekpyrotic Universe and its Cyclic Extension Transparency 18
		The Ekpyrotic Universe and its Cyclic Extension Transparency 19
		The Ekpyrotic Universe and its Cyclic Extension Transparency 17
	www.damtp.cam.ac.uk /talks/ngt1000/annecy/node18.html (80 words)

	Citebase - Isocurvature perturbations in the Ekpyrotic universe
		Authors: Notari, A. Riotto, A. The Ekpyrotic scenario assumes that our visible Universe is a boundary brane in a five-dimensional bulk and that the hot Big Bang occurs when a nearly supersymmetric five-brane travelling along the fifth dimension collides with our visible brane.
		We show that the generation of isocurvature perturbations is a generic prediction of the Ekpyrotic Universe.
		This is due to the interactions in the kinetic terms between the brane modulus parametrizing the position of the five-brane in the bulk and the dilaton and volume moduli.
	citebase.eprints.org /cgi-bin/citations?id=oai:arXiv.org:hep-th/0205019 (197 words)

	New frontiers: origins; The Endless Universe: Introduction to the Cyclic Universe By Paul J. Steinhardt
		The cyclic model builds on lessons learned from the ekpyrotic example to produce a picture with remarkable predictive and explanatory power.
		4) The "ekpyrotic scenario" is based on the concept that the hot big bang arose from a collision of branes in extra dimensions.
		See "The Ekpyrotic Universe: Colliding Branes and the Origin of the Hot Big Bang," J. Khoury, B. Ovrut, P.J. Steinhardt and N. Turok (2001), available as downloadable PDF file at http://xxx.lanl.gov/PS_cache/hep-th/pdf/0103/0103239.pdf (accessed May 01,2002)
	www.actionbioscience.org /newfrontiers/steinhardt.html (1952 words)

	Energy Citations Database (ECD) - Energy and Energy-Related Bibliographic Citations
		We study the generation of density perturbations in the ekpyrotic scenario for the early universe, including gravitational backreaction.
		Our analysis includes a detailed proposal of how the perturbations generated in a contracting phase may be matched across a 'bounce' to those in an expanding hot big bang phase.
		For the physical conditions relevant to the ekpyrotic scenario, we reobtain our earlier result of a nearly scale-invariant spectrum of energy density perturbations.
	www.osti.gov /energycitations/product.biblio.jsp?osti_id=20495449 (222 words)

	Justin Khoury Seminar Abstract (Site not responding. Last check: 2007-09-01)
		There is no inflationary era after the big bang, and thus the model is a candidate alternative to the standard inflationary paradigm.
		However there is a key observational difference: inflation also predicts a nearly scale-invariant spectrum of gravitational waves, while the ekpyrotic model does not.
		In this talk I will review some of the essential elements of ekpyrotic/cyclic cosmology, as well as describe recent work on parallels and contrasts with inflationary cosmology.
	www-ctp.mit.edu /cosmo/y0405/khoury_abs.html (112 words)

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