
	Where results make sense

Topic: Unruh effect

Related Topics

Quantum field theory in curved spacetime

Quantum field theory

Rotating black hole

Quantum gravity

Process physics

Hawking radiation

Micro black hole

Equivalence principle

Virtual particle

Perturbation theory (quantum mechanics)

Loop quantum gravity

Cosmic censorship hypothesis

Immirzi parameter

Black hole information paradox

Black hole

In the News (Fri 4 Dec 09)

Northern Trust

Marvin Harrison

Peter Chernin

Gary Locke

Match Play

Penelope Cruz

Mickey Rourke

AR Rahman

Danny Boyle

Hugh Jackman

	Unruh effect - Wikipedia, the free encyclopedia
		The Unruh effect, discovered in 1976 by Bill Unruh of the University of British Columbia, is the prediction that an accelerating observer will observe fl-body radiation where an inertial observer would observe none.
		Unruh demonstrated that the very notion of vacuum depends on the path of the observer through spacetime.
		On the other hand, the Unruh effect shows that the definition of what constitutes a "particle" depends on the state of motion of the observer.
	en.wikipedia.org /wiki/Unruh_effect (581 words)

	3 Hawking Radiation
		An approach to investigating this issue was first suggested by Unruh [92], who noted that a close analog of the Hawking effect occurs for quantized sound waves in a fluid undergoing supersonic flow.
		A mathematically rigorous proof of the Unruh effect in Minkowski spacetime was given by Bisognano and Wichmann [23] in work motivated by entirely different considerations (and done independently of and nearly simultaneously with the work of Unruh).
		On the other hand, in the Unruh effect and its generalization to curved spacetimes, the state in question (usually referred to as the ``Hartle-Hawking vacuum'' [52]) is globally nonsingular, and all modes of the quantum field in the ``left and right wedges'' are thermally populated.
	relativity.livingreviews.org /Articles/lrr-2001-6/node3.html (1694 words)

	Physicists hope to simulate a black hole event horizon in the lab: 6/00
		Although the Unruh effect induced by acceleration is not precisely the Hawking effect from fl holes, it nevertheless shares many common characteristics.
		Unruh himself suggested that sound waves propagating in a supersonic fluid behave similarly to quantum fields propagating in the vicinity of a fl hole.
		The late John Bell of the Geneva-based European Organization for Nuclear Research (CERN) and Jon Leinaas of the University of Oslo in Norway suggested that the known polarization effect of high-energy electrons in circular accelerators is actually a manifestation of the Unruh effect.
	www.wam.umd.edu /~crgalley/scratch/hu/blackholes67.html (1191 words)

	Bill Unruh - Wikipedia, the free encyclopedia
		William G. Unruh (born August 28, 1945) is a Canadian physicist at the University of British Columbia, Vancouver, who discovered the Unruh effect.
		Unruh contributed to theories on gravity and fl holes, early cosmology, and various quantum phenomena.
		Today, Unruh continues active research in the field of Quantum gravity.
	en.wikipedia.org /wiki/Bill_Unruh (208 words)

	sciforums.com - Unruh Implications
		Extended testing of an Unruh affect for relative velocity, then it may be shown that there is no actual mass increase but the extra energy required to increase velocity (accelerate) is being stored in space and not applied to the acceleration.
		I am prohibited from discussing this further since the prediction of an Unruh type function (energy for acceleration being stored in space in lieu of actual mass increase that requires more energy) is from a non-scientific theory that is easily rejected as being obviously flawed.
		The Unruh effect is a CAUSE from the EFFECT of accelerating.
	www.sciforums.com /showthread.php?t=29437 (3297 words)

	Unruh effect
		Unruh realized that the notion of vacuum depends on the path of the observer through spacetime.
		Although the Unruh effect came as a shock, it makes intuitive sense.
		The vacuum is, by definition, the lowest energy state of the Hamiltonian, the Hamiltonian depends on the choice of time coordinate and, according to special relativity, two observers moving relative to each other must use different time coordinates.
	www.sciencedaily.com /encyclopedia/unruh_effect (362 words)

	Violent Acceleration and the Event Horizon (June 6, 2000)
		In 1976, Bill Unruh of the University of British Columbia in Canada showed that an accelerated observer would experience a similar "heat bath" of photons around him, due also to the existence of an event horizon in this case (See Figure 1).
		Although the Unruh effect induced by acceleration is not precisely the Hawking effect from fl holes, it nevertheless shares many common characteristics with the Hawking effect.
		One major challenge with detecting Unruh radiation is that enormous accelerations are required to produce a sufficient amount of radiation.
	www.slac.stanford.edu /slac/media-info/20000605/chen.html (1196 words)

	Experimental Unruh Radiation?
		Even the detection of the Hawking radiation that is expected to arise from condensed matter analog models for general relativity, while much more accessible than that from true gravitational fl holes, is also currently far from laboratory realization.
		This additional acceleration-related radiation has a characteristic acceleration dependence (a distorted thermal spectrum) and a characteristic angular dependence, which should in principle be measurable in the not too distant future.
		[3] On the estimates to Measure Hawking Effect and Unruh Effect in the Laboratory.
	www.phys.lsu.edu /mog/mog17/node8.html (573 words)

	Unruh effect -- Facts, Info, and Encyclopedia article (Site not responding. Last check: 2007-09-19)
		The energy states of any quantized field are defined by the (Click link for more info and facts about Hamiltonian) Hamiltonian, based on local conditions, including the time coordinate.
		The existence of Unruh radiation can be linked to this apparent (Click link for more info and facts about event horizon) event horizon, putting it in the same conceptual framework as (Click link for more info and facts about Hawking radiation) Hawking radiation.
		This is because we need to decompose the (free) field into positive and negative frequency components before we can define the (An artifact that has been brought into existence by someone) creation and (Click link for more info and facts about annihilation operator) annihilation operators.
	www.absoluteastronomy.com /encyclopedia/u/un/unruh_effect.htm (533 words)

	Paul Davies \| The Australian Centre for Astrobiology
		This had immediate application to the creation of quantum particles by fl holes (the Hawking effect), and in the very early universe as a result of the rapid cosmological expansion.
		These ideas found later application to topics as diverse as the Casimir effect, the inflationary universe scenario, the holographic principle, wormholes and time travel.
		With my colleagues Steven Fulling and Bill Unruh, we were able to show, from a simple two-dimensional mathematical model, that the fl hole shrinks, not because energy is coming out, but because negative energy is flowing in.
	aca.mq.edu.au /PaulDavies/research/brief_history.htm (960 words)

	Introduction
		The discovery of Unruh effect (see also Davies [5]) sets off the first wave of activities on this subject.
		Unruh [12] performed an independent calculation and concurred with the findings of RSG to the extent that the energy-momentum tensor of the field as modified by the presence of the accelerating detector vanishes over most of the spacetime (except on the horizons).
		This physical effect is in a sense complementary to the effects manifested in the accelerated detector problem, where the probe does not backreact on the accelerated detector.
	www.uni-regensburg.de /Fakultaeten/nat_Fak_II/edv/workshops/wissinter/la2h/9510002/node1.html (1066 words)

	Varieties of Quantum Measurement - Unruh (ResearchIndex)
		The problem of quantum measurement has been with us since the foundations of the the theory were laid in the...
		0.1: On the Estimates to Measure Hawking Effect and Unruh Effect..
		Unruh, W.G. (1995), Varieties of quantum measurements, Ann.
	citeseer.ist.psu.edu /76224.html (282 words)

	Pyroelectricity (Site not responding. Last check: 2007-09-19)
		Pyroelectricity can be visualized as one side of a triangle, where each corner represents energy states in the crystal: kinetic, electrical and thermal energy.
		Although artificial pyroelectric materials have been engineered, the effect was first discovered in minerals such as quartz and tourmaline and other ionic crystals.
		The pyroelectric effect is also present in both bone and tendon.
	read-and-go.hopto.org /Thermodynamics/Pyroelectricity.html (395 words)

	No Title (Site not responding. Last check: 2007-09-19)
		Unruh, W. Origin of the particles in fl-hole evaporation, Phys.
		Unruh, W. Thermal bath and decoherence of Rindler spacetimes, Phys.
		Unruh, W. G., and Wald, R. What happens when an accelerating observer detects a Rindler particle, Phys.
	www.ictp.trieste.it /~shanki/pap-list-public/rindl-bh.html (1424 words)

	Re: Unruh effect (Site not responding. Last check: 2007-09-19)
		Explaining the physical consequences of the Unruh effect does require modeling how a particle detector interacts with a quantum field.
		At a deeper level, the Unruh effect illustrates how the formulation of the quantum theory of fields needs to be freed from the tyranny of inertial coordinates and observers.
		The two best references that I know of for the Unruh effect are the books: Quantum Field theory in Curved Spacetime and Black Hole Thermodynamics, by Robert M. Wald; and Quantum fields in curved space, by N. Birrell and P. Davies.
	www.lns.cornell.edu /spr/2000-07/msg0026861.html (174 words)

	OSLO-TP 1-04 (Site not responding. Last check: 2007-09-19)
		We study the generalized Unruh effect for accelerated reference frames that include rotation in addition to acceleration.
		We focus particularly on the case where the motion is planar, with presence of a static limit in addition to the event horizon.
		The effects are related to similar effects in the gravitational field of a rotating fl hole.
	www.fys.uio.no /teori/preprints/vis.php?pnr=1-04 (182 words)

	[No title]
		The Unruh effect says that accelerated observers feel the vacuum as a thermal state.
		For conformally covariant nets of von Neumann algebras, it is shown that the vacuum is a local KMS state for observers moving along a suitable conformal flow (Bisognano-Wichmann property).
		For rapidly expanding universes, as the de Sitter spacetime, the Gibbons-Hawking effect states that the vacuum temperature is positive.
	www.mat.uniroma2.it /~guido/research/themes.html (942 words)

	EARLY COSMOLOGY AND FUNDAMENTAL RELATIVITY
		It was shown that the quantization procedure proposed by Unruh implies setting a boundary condition for the quantum field operator and this changes drastically the topological properties and symmetry group of the spacetime which lead to the field theory in two disconnected left and right Rindler spacetimes instead of Minkowski spacetime.
		Thus in spite of the work over last 25 years, there still remain serious gaps in grounding of the Unruh effect, and as of now there is no compelling evidence for the universal behaviour attributrd to all uniformly accelerated detectors [Ref. 17].
		The solution was applied to the analysis of matter ejection effect from relativistic stellar clusters and to the chaotic motion of the shells in relativistic regime.
	www.icra.it /Research_area/research_area1.htm (2433 words)

	Physicists hope to simulate a black hole event horizon in the lab: 6/00
		These technologies can in principle accelerate electrons over 1025 times the acceleration due to the gravity on Earth's surface, or 1028m/sec2, more than two orders of magnitude higher than previous experimental proposals.
		Petawatt-class "table-top" lasers currently under development in various laboratories also might be invoked for such a test.
		It has yet to be seen whether this new approach proposed by Chen can eventually provide insights into the Hawking effect.
	news-service.stanford.edu /news/2000/june7/blackholes-67.html (1176 words)

	Peering Into Black Holes / Physicist creates a plan to simulate the outer terrain of one of the great, cosmic mysteries (Site not responding. Last check: 2007-09-19)
		Its namesake, William Unruh at the University of British Columbia, said he has been waiting since the mid-'70s for somebody to find the fluctuating quantum fields he had in mind.
		Many schemes for measuring the Unruh effect have been proposed, but none has turned out to be a ``completely clean experiment,'' Unruh said.
		But like the Hawking radiation from fl holes, Unruh radiation is very faint and would be masked by stronger, background signals in all of the proposed experiments.
	www.sfgate.com /cgi-bin/article.cgi?file=/c/a/2000/07/17/MNC1076.DTL (1464 words)

	SAN JOSE COUNTRY CLUB APARTMENTS v. COUNTY OF SANTA CLARA
		The trial court considered the ordinance to constitute a "discretionary project proposed to be carried out or approved by [a] public agency" within the meaning of Public Resources Code section 21080, subdivision (a), for which CEQA compliance was required.
		If there is a "possibility that the project may have a significant effect," then the agency undertakes an "initial threshold study," and if that study demonstrates that the project "will not have a significant effect," the agency may so declare in a brief negative declaration.
		The Unruh Civil Rights Act was in effect at that time, and the court's decision in Marina Point has now authoritatively declared the meaning of that statute.
	ceres.ca.gov /ceqa/cases/1982/sj_country_club_072082.html (1546 words)

	Re: Unruh effect (Site not responding. Last check: 2007-09-19)
		David Deak claims that: "Cavitation results from the Unruh effect which is a dynamic generalization of the Casimir effect and predicts radiation by noninertially moving quantum mirrors.
		The more intuitive view is that the zero-point electromagnetic field excites fluctuating dipoles in the (perfect or imperfect) mirror and these dipoles are the source of radiation when the mirror moves nonuniformly.
		The resultant record for the Unruh effect is void, this is understood to be the result of the Unruh temperature being small for commonly achievable accelerations." While I don't agree with him that cavitation is caused by the Unruh effect, the description seems clear enough at my level.
	www.lns.cornell.edu /spr/2000-07/msg0026848.html (253 words)

	Sınırları Aşmak
		This effect is commonly known as “inertia” and per definition also somehow related to the much weaker Davies-Unruh effect.
		In effect, it seems that the fields induced by the superconductor and/or the coils used for levitation, did increase local ZPR, probably by uploading photons from E.M. fields to QV.
		The QV effects, we do know (Casimir effect, etc.) do not reveal the deathly nature of vacuum gamma rays and other radiation of still unknown nature, responsible for those practically insignificant spacetime effects.
	www.zamandayolculuk.com /cetinbal/STARGATELAP.HTM (3862 words)

	Quantum gravity
		Quantum field theory on curved (non-Minkowskian) backgrounds, while not a quantum theory of gravity, has shown that some of the core assumptions of quantum field theory cannot be carried over to curved spacetime, let alone to full-blown quantum gravity.
		In particular, the vacuum, when it exists, is shown to depend on the path of the observer through space-time (see Unruh effect).
		Also, the field concept is seen to be fundamental over the particle concept (which arises as a convenient way to describe localized interactions).
	www.brainyencyclopedia.com /encyclopedia/q/qu/quantum_gravity.html (1274 words)

	Interferometric test of the electron mass shift in a cavity (Site not responding. Last check: 2007-09-19)
		There are measurable vacuum effects that are realized when the vacuum interacts with charged particles as in, for example, the Lamb shift [1] and quantum noise in electronic devices [2], and when physical boundary conditions are altered as in the Casimir effect [3], the Casimir-Polder force [4], and spontaneous emission in cavities [5].
		A further vacuum effect that is, in principle, measurable is the Davies-Unruh effect [8, 9] which is due to an altered physical vacuum as perceived from an accelerated frame of reference.
		Since the plane-wave case includes true QED effects beyond what could be derived classically, it is the more interesting of the two cases to test experimentally.
	www.sif.it /cimento/toca/110.06/02/02.html (1616 words)

	Directory - Science: Physics: Relativity: Black Holes (Site not responding. Last check: 2007-09-19)
		Gravitational Redshift · cached · An overview of the effects on light in the presence of a fl hole.
		The fundamentals of the Unruh effect are reviewed, and then the Hawking effect is explained as a ``gravitational Unruh effect".
		Black Holes: A general introduction · This article presents in a pictorial way the basic concepts of fl hole's theory, as well as a description of the astronomical sites where fl holes are suspected to lie.
	www.incywincy.com /default?p=235319 (668 words)

	[No title] (Site not responding. Last check: 2007-09-19)
		The predicted effect is very small: an observer accelerating at one centimeter per second squared would see flbody radiation with a temperature of 4 x 10^{-23} Kelvin.
		In fact Unruh discovered this effect when trying to better understand Hawking radiation.
		Yet this Unruh radiation is predicted to be seen by an accelerating observer in Minkowski spacetime.
	www.math.niu.edu /~rusin/known-math/00_incoming/unruh (236 words)

	Relativity (Site not responding. Last check: 2007-09-19)
		The equivalence between an accelerated vacuum and a thermal bath, often quoted as the Unruh effect, and the resulting insoluble paradoxes appear to be artefacts due to an inadapted representation of accelerated frames.
		These dissipative effects are indications of a symmetry violation and question the principle of relativity of motion applied to an arbitrary motion.
		A resonance enhancement effect takes place not only when the cavity length is modulated but also when the cavity oscillates as a whole while keeping its mechanical length constant
	arachne.spectro.jussieu.fr /Vacuum/English/Relativite (487 words)

Try your search on: Qwika (all wikis)