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Topic: Accelerating universe

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	Accelerating universe - Wikipedia, the free encyclopedia
		The accelerating universe is related to the Hubble Law: while the Hubble parameter may be decreasing with time, it is doing so slowly enough that distant objects continue to accelerate away from us.
		Measurements of acceleration are crucial to determining the ultimate fate of the universe in big bang theory.
		This theory relies on a decelerating universe, which for many years was the dominant model in cosmology, since (in the absence dark energy) the gravitational attraction of ordinary matter in the universe would act to slow the expansion.
	en.wikipedia.org /wiki/Accelerating_universe (455 words)

	Emilyís Astrophysics Project: The Accelerating Universe (Site not responding. Last check: 2007-10-20)
		So the idea of the acceleration of the expansion of the universe was proposed because distant supernovae are observed to be dimmer than expected based on their redshift values.
		Acceleration implies that in addition to the string force, weak force, electromagnetic force, and gravity, there could be a fifth force at work in the universe.
		Since the boundaries of the universe are expanding outward at an ever-increasing rate, on a time-scale of billions of years there could be far fewer stars visible in the sky.
	astro.uchicago.edu /home/web/olinto/courses/A18200/emilyg.htm (1767 words)

	"Accelerating Universe Expansion"
		(“Universal Space” is all space in the universe.) It is Universal Space itself that, requires a force be exerted on a body, for it to accelerate.
		The acceleration of the matter toward the boundary of the universe must be rather modest.
		Near the boundary of the Universe the matter is traveling at tremendous speed, approaching Inertial Infinity (the speed of light), despite the immense amount of radiation the stars are emitting.
	pages.prodigy.com /suna/cosmol.htm (4604 words)

	Frequently Asked Questions in Cosmology
		If the expansion of the Universe is accelerating due to a cosmological constant, then the expansion was slower in the past, and thus the time required to expand by a given factor is longer, and the distance NOW is larger.
		The age of the Universe is determined from its expansion rate: the Hubble constant, which is the ratio of the radial velocity of a distant galaxy to its distance.
		The vast majority of the entropy of the Universe is in the cosmic microwave background radiation because the vast majority of particles in the Universe are the photons of the CMB.
	www.astro.ucla.edu /~wright/cosmology_faq.html (4805 words)

	Is the universe still accelerating? (Site not responding. Last check: 2007-10-20)
		In a matter-dominated universe, then, the right-hand side of (2) is decreasing as the universe expands, resulting in deceleration.
		Since any effect which would diminish the brightness of distant supernovae without noticeably affecting their spectra could mimic the effects of an accelerating universe, it is sensible to ask whether these apparently dramatic results can be explained in terms of conventional astrophysics without invoking new cosmological phenomena.
		Our best current understanding, therefore, continues to favor an accelerating universe, and in a short while the case could be nailed down to a near certainty; in that case the task of theorists to explain a small but nonzero vacuum energy will become especially urgent.
	pancake.uchicago.edu /~carroll/mog (956 words)

	How to Think About.... The Universe Robert Kirshner
		A human lifetime is about 10 to the minus 8th of the age of the universe, a hundred millionth of the age of the universe.
		That is, if the universe has been speeding up or slowing down, that means that the expansion rate in the past would have been higher or lower, and the relation between velocity and distance would be different.
		If that's really true, then it means that a universe that we see today, which is full of all those galaxies, as time goes by, the expansion will get faster and faster, and the piece of the universe that we can see will have fewer and fewer galaxies in it.
	www.nieman.harvard.edu /events/reunions/2000/Universe.html (10900 words)

	An Accelerating Universe, or Light Slowing Down? (Site not responding. Last check: 2007-10-20)
		Astronomers have recently announced that the universe appears to be expanding at an accelerating rate.
		This is inferred because distant supernovae are unexpectedly dim.
		However, the accelerating expansion of the universe was inferred because distant supernovae are fainter than expected based on their red shift.
	www.cs.unc.edu /~plaisted/ce/accelerating.html (642 words)

	More evidence for the accelerating universe (September 1999) - News - PhysicsWeb
		However, the data were also consistent with an open universe - a universe that would expand forever because the total energy density was less than the so-called critical density - with a low mass density and no cosmological constant.
		The energy density of the universe is composed of matter (both ordinary visible matter and invisible or "dark" matter) and the energy density of the vacuum.
		However, they add that "this type of universe seems to require a degree of fine tuning of the initial conditions that is in apparent conflict with 'common wisdom'".
	physicsweb.org /article/news/3/9/6/1 (374 words)

	Spaceflight Now \| Breaking News \| Supernova found to confirm accelerating universe
		The serendipitous discovery of a distant supernova has confirmed that the universe is expanding at an accelerating rate because of the presence of a pervasive, mysterious "dark energy," astronomers reported Monday.
		To their surprise, astronomers found several years ago that the expansion of the universe was not slowing down, as had been assumed, but was actually accelerating under the influence of an unknown force.
		Turner believes it is the "number one problem" in both physics and astronomy today, and considers the discovery of the accelerating universe one of the biggest discoveries in astronomy since Edwin Hubble discovered the expansion of the universe.
	spaceflightnow.com /news/n0104/03supernova (1220 words)

	SpaceViews Article: Contradictory Findings on Accelerating Universe
		The discovery that the expansion of the universe may be accelerating, and not slowing down as once thought, was named the top science story of 1998 by the journal Science Thursday, December 17.
		The acceleration also implies that an unknown force is at work to cause galaxies to speed up.
		Peterson reported that observations of distant gas clouds showed that their angular size -- about one-half of a degree of arc -- was exactly that predicted for a universe whose rate of expansion is slowing as predicted by inflation theory.
	www.timeenoughforlove.org /saved/ContradictoryAcceleratingUniverse.htm (467 words)

	Scientific Evidence the Universe had a Beginning
		It is safe to conclude that the universe is dying and will become a place of darkness, extreme cold, and loneliness.
		However, please make sure you read the evidence that supports the universe is dying, which will lead you sequentially back the issue of whether there are hidden universes.
		NASA WMAP Satellite scientists conclude that the universe is accelerating.
	www.harvardhouse.com /Accelerating_Universe.htm (791 words)

	Spaceflight Now \| Breaking News \| New evidence that expansion of universe is accelerating
		A team of UK and Australian astronomers has discovered new, independent evidence that the expansion of the universe is accelerating.
		Three years ago, two teams of astronomers rocked the scientific world by finding evidence that the expansion of the universe is accelerating rather than slowing down as had generally been expected because of the gravitational attraction between the matter within it.
		Their results show that the universe is full of dark energy, completely consistent with the earlier supernovae results.
	www.spaceflightnow.com /news/n0203/22expansion (703 words)

	Universe - Wikipedia, the free encyclopedia
		In strictly physical terms, the total universe is the sum of all matter that exists and the space in which all events occur or could occur.
		In cosmological terms, the universe is thought to be a finite or infinite space-time continuum in which all matter and energy exist.
		The comoving distance to the edge of the visible universe is about 46.5 billion light years in all directions from the earth; thus the visible universe may be thought of as a perfect sphere with the earth at its center and a diameter of about 93 billion light years.
	en.wikipedia.org /wiki/Universe (1749 words)

	New Theory Links Neutrino's Slight Mass to Accelerating Universe Expansion
		Now three University of Washington physicists are suggesting the two discoveries are integrally linked through one of the strangest features of the universe, dark energy, a linkage they say could be caused by a previously unrecognized subatomic particle they call the "acceleron."
		Understanding the phenomenon could help to explain why someday, long in the future, the universe will expand so much that no other stars or galaxies will be visible in our night sky, and ultimately it could help scientists discern whether expansion of the universe will go on indefinitely.
		Physicists have pursued evidence that could tell whether the universe will continue to expand indefinitely or come to an abrupt halt and collapse on itself in a so-called "big crunch." While the new theory doesn't prescribe a "big crunch," Nelson said, it does mean that at some point the expansion will stop getting faster.
	universe.nasa.gov /press/2004/040727a.html (691 words)

	WMAP Cosmology 101: Cosmological Constant
		Einstein thought the universe was static, so he added this new term to stop the expansion.
		When Hubble's study of nearby galaxies showed that the universe was in fact expanding, Einstein regretted modifying his elegant theory and viewed the cosmological constant term as his "greatest mistake".
		For this energy density to be comparable to other forms of matter in the universe, it would require new physics: the addition of a cosmological constant term has profound implications for particle physics and our understanding of the fundamental forces of nature.
	map.gsfc.nasa.gov /m_uni/uni_101accel.html (474 words)

	Physics Today December 2000
		If gravity were the only force acting to alter the expansion rate, then the universe would be expected to be decelerating or, in the extreme case of a universe with essentially zero mass, expanding at a constant rate.
		Acceleration implies that the cosmological constant postulated and then discarded by Einstein is in fact not zero.
		The initial evidence for acceleration came from a particular type of supernova explosion that in all cases reaches a uniform (or at least easily calibrated) intrinsic luminosity.
	www.physicstoday.org /pt/vol-53/iss-12/p68.html (772 words)

	Supernovae, an accelerating universe and the cosmological constant -- Kirshner 96 (8): 4224 -- Proceedings of the ...
		Supernovae, an accelerating universe and the cosmological constant
		Astronomers have known since Hubble's observations in 1929 that the universe is expanding (2).
		Cosmic acceleration is not a new idea (21) and an energy component to the universe that might have an accelerating effect
	www.pnas.org /cgi/content/full/96/8/4224 (3106 words)

	Cosmologists Present Explanation For Accelerating Expansion Of The Universe
		This accelerating expansion seemed to be explicable only by the presence of a new component of the universe, a "dark energy," representing some 70 percent of the total mass of the universe.
		However, the new report proposes no new ingredient for the universe, only a realization that the present acceleration of the universe is a consequence of the standard cosmological model for the early universe: inflation.
		These ripples were stretched by the expansion of the universe and extend today far beyond our cosmic horizon, that is over a region much bigger than the observable universe, a distance of about 15 billion light years.
	www.spacedaily.com /news/cosmology-05n.html (862 words)

	New South Pole Telescope to Help Explain Why Universe is Accelerating
		It pushes the universe apart and overwhelms ordinary gravity, the attractive force exerted by all matter in the universe.
		That is critically dependent on the nature of the dark energy, this elusive component of the universe," said the University of Chicago's John Carlstrom, who heads the project.
		Carlstrom's partners in the project are Stephan Meyer, Clem Pryke and Erik Leitch, University Chicago; Joe Mohr, University of Illinois, Urbana-Champaign; Bill Holzapfel and Adrian Lee, University of California, Berkeley; John Ruhl, Case Western Reserve University; and Tony Stark, Harvard-Smithsonian Center for Astrophysics.
	universe.nasa.gov /press/2002/020829a.html (908 words)

	New theory links neutrino's slight mass to accelerating universe expansion
		Today's universe is expanding at an accelerating rate because 'dark energy' counteracts the force of gravity.
		In the early universe matter was closer together, and gravity still slowed its expansion.
		Two of the biggest physics breakthroughs during the last decade are the discovery that wispy subatomic particles called neutrinos actually have a small amount of mass and the detection that the expansion of the universe is actually picking up speed.
	www.physlink.com /News/072704ExpansionUniverse.cfm (729 words)

	Science lists 1998’s biggest breakthroughs - - MSNBC.com
		“Although the nature of the universe was once chiefly the realm of philosophers, in 1998 it seems that cosmology is grounded in data, as visions of distant supernovae revealed the true nature — and perhaps the future — of the cosmos,” Glanz said.
		He noticed that the characteristic signature of starlight from distant sources appeared to be shifted toward the red end of the spectrum — meaning that the light waves had been stretched during their journey to Earth.
		On the largest scale imaginable, the universe’s galaxies appear to be flying away from each other faster and faster as time goes on.
	www.msnbc.msn.com /id/3077857 (1304 words)

	Accelerating Universe and The Regenerating Universe Theory
		It describes in detail a fully functional structure of universe, including how the universe expands; how it evolves and regenerates with explanations.
		A full account on the origin of gravity and of the entire continuous spectrum of electromagnetic radiations is described, together with how and why the speed of light is constant.
		It then goes on to explain the true age of the universe and lots more...
	www.regenerating-universe.org (155 words)

	Accelerating universe? (Site not responding. Last check: 2007-10-20)
		If this is the case then that would mean the universe has not decelerated as in that model and may well have accelerated in its expansion since that light was first emitted.
		In an infinite and homogeneous Universe, the gravity force on each single galaxy should be practically cancelled out (I do not consider here local, but overall effects) as the vectorial sum of the mass distribution all around up to an infinite distance, so that gravity should not decelerate the expansion due to symetry reasons.
		Early in the Universe's development, there was actually a period of deceleration caused by gravitational 'braking' between relatively near galaxies (relatively near because the Universe hadn't enough time to sufficiently grow to make intergalactic gravitational attraction negligible).
	www.physicsforums.com /showthread.php?t=115260 (2154 words)

	Science and the Quran, Accelerating Universe, Expanding Universe, Big Crunch, Collapsing Universe, big crunch in the ...
		Since 1998, scientists have concluded that the universe is expanding at an accelerating rate.
		In 2002 to 2006, analysis of data collected from the NASA WMAP Satellite has permitted scientists to conclude that the universe is accelerating.
		The conclusion that the universe will expand forever at an accelerating rate is based on the analysis of more than 800 Cepheid Variable Stars, more than 80 Type 1A Supernova, and more than 3 years of continuous data collection from the NASA WMAP Satellite.
	www.harvardhouse.com /expanding_universe_quran.htm (1743 words)

	Dark Energy in the Accelerating Universe (Site not responding. Last check: 2007-10-20)
		Their goal was to measure changes in the expansion rate of the universe, which in turn would yield clues to the origin, structure, and fate of the cosmos.
		Like everyone else, the researchers assumed that expansion had been slowing under the gravitational attraction of matter since shortly after the Big Bang, and that this deceleration rate could be used to determine the average density of matter in the universe.
		Word soon spread beyond the scientific community; "the accelerating universe" made front-page news around the world and touched the imaginations of people everywhere.
	snap.lbl.gov /brochure/foreword.html (197 words)

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