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Topic: Gravitational collapse

Related Topics

Black hole

Jeans mass

Equivalence principle

Astrophysics

General relativity

Mass

Timeline of black hole physics

Theory of relativity

Neutron star

	Gravitational Contraction and Star Formation
		The source of the energy for star formation is gravitational collapse - this collapse must provide enough energy to heat the gas of the protostar to the ignition point of hydrogen fusion, some 15 million Kelvins.
		A general theorem from the mathematics of physics becomes a useful part of the picture of gravitational collapse.
		As a collection of gas begins the process of gravitational collapse, that collapse is opposed by radiation pressure.
	hyperphysics.phy-astr.gsu.edu /hbase/astro/gravc.html (433 words)

	The Astrophysics Spectator: The Gravitational Collapse of Stars
		Gravitational collapse sets a maximum mass for both the degenerate dwarf and the neutron star.
		And gravitational collapse, whether of a blue giant, degenerate dwarf, or a neutron star, in all cases has the same principal cause—special relativity.
		As the mass increases, the pressure increases, and eventually either the temperature or the density is sufficiently high to cause gravitational collapse.
	www.astrophysicsspectator.com /topics/stars/Collapse.html (656 words)

	Gravitational collapse - Wikipedia, the free encyclopedia
		Gravitational collapse in astronomy is the inward fall of a massive body under the influence of the force of gravity.
		In this sense a star is a "temporary" equilibrium state between a gravitational collapse at stellar birth and a gravitational collapse at stellar death.
		The gravitational collapse of the interior of a star releases so much binding energy that the outer layers are blown away in an explosion.
	en.wikipedia.org /wiki/Gravitational_collapse (1365 words)

	Department of Physics and Astronomy: Gravitational Theory
		Gravitational physics has also developed a solid experimental side with the building of a variety of gravitational wave detectors and with high-precision tests of gravitational effects on Earth and in orbit; it has found practical applications in the GPS system as well as in the guidance of spacecraft.
		Among the classical aspects, of particular interest are the study of the predictions of the theory, with its highly nonlinear dynamics, for the motion of gravitating bodies, the emission of gravitational waves during the gravitational collapse of massive objects, and for the evolution of the early universe.
		Regarding the structure of the gravitating objects themselves, although they involve an infinite number of degrees of freedom, one can study many of their features using simplified models with a high degree of symmetry or lower-dimensional models of gravity, useful for addressing issues in classical gravity that are too difficult to study in four dimensions.
	www.olemiss.edu /depts/physics_and_astronomy/research/gravitation.html (1516 words)

	Gravitational Physics
		Gravitational physics research involves studies of applications of numerical relativity, fl hole dynamics, sources of gravitational radiation, critical phenomena in gravitational collapse, the initial value problem of general relativity, and relativistic astrophysics.
		The two primary purposes of these techniques are to probe the fundamental structure of the theory in circumstances where analytic solution is impossible (for example to study critical phenomena in gravitational collapse) and to model realistic sources of gravitational radiation (for example the merger of binary fl holes).
		Current activities of the UNC gravitational physics group include using a formulation of the initial value problem of general relativity to fashion sequences of quasi-equilibrium fl hole binaries, studying outgoing wave solutions in the presence of spacetime curvature and developing radiative boundary conditions, and developing numerical methods for modeling hyperbolic systems.
	www.physics.unc.edu /research/theory/gravity.php (270 words)

	General Relativistic Core Collapse
		A successful direct detection of gravitational waves, which can be envisaged within the next 5 years, will not only unequivocally prove Einstein's bold prediction (which today is not seriously doubted anymore), but even more interestingly, will open a completely new "window" onto the universe.
		One example of a promising source of gravitational waves is the gravitational collapse of the rapidly rotating core of a massive star to a neutron star and the subsequent explosion of the star as a supernova.
		The gravitational wave signals produced typically consist of a strong short burst with a complicated temporal structure, and they depend crucially on many aspects of the complicated physics involved in this powerful event.
	www.mpa-garching.mpg.de /rel_hydro/axi_core_collapse/index.shtml (911 words)

	blackhole
		The mass of a star after gravitational collapse is less after the compression, which must lead to an explosion with the removal of the surpluses of material from the star.
		With the gravitational collapse the substance of star is compressed to Schwarzschild's radius, which is considerably less than a radius of the atomic nucleus of that formed by the same substance.
		The gravitational collapse of star must end either by the formation of neutron star with the ejection of the surpluses of material, or hole in the space-time which does not contain in itself material.
	www.holetheory.com /blackhole.html (2453 words)

	LSU Gravitational Wave Experiment
		The force that a gravitational wave exerts on the bar depends on both the density of the bar's material as well as the bar's length.
		One candidate is the gravitational collapse of a massive star to form a neutron star.
		The burst of gravitational waves will cover a large frequency bandwidth, however the newly created neutron star is expected to have quadrupole modes that resonate on the order of 2 kHz, creating gravitational waves at that frequency.
	sam.phys.lsu.edu /Overview/waves.html (715 words)

	Extended Definitions: Gravitational Constant, "g"
		Conventional theories would define the gravitational constant as determining the amount of gravity produced between two masses a given distance apart.
		The greater the gravitational constant, the greater the gravitational pull.
		The C-R theory proposes that, instead of the gravitational constant, it is the amount of de-activation of real time which affects the gravitational pull.
	www.geocities.com /recycling_universe/ed_gravitationalconstant.htm (167 words)

	General Considerations
		Baade and Zwicky were first to connect supernova explosions with neutron star formation in 1934 [#!baade!#], and the theory that describes neutrino bursts implicated by supernovae and neutron stars has been developed especially during the last four decades.
		The explosion mechanism of a supernova develops in different stages, from the progenitor star formation to the collapse phase triggering the supernova onset and liberating the emergent neutrino burst, which precedes the emission of the light.
		The gravitational energy liberated by core collapse is estimated to be
	www.ps.uci.edu /~silvestr/thesis/THESIS/node12.html (257 words)

	Extended Definitions: Black Holes (C-R theory obeying type)
		The C-R theory predicts that the gravitational field-strength outside of the newly-formed Black-Hole, measured immediately after the gravitational collapse must be totally unchanged from the gravitational-field strength of the same mass, before the collapse.
		Here is why a total collapse cannot occur: As any (time-active) mass proceeds into greater gravitational curvature, it becomes less time-active, and gains (by exchange) an equivalent amount of kinetic energy in the process.
		Before any further collapse of this collapsed shell of matter is possible, the matter inside this zone would need to collapse.
	www.geocities.com /recycling_universe/ed_blackholes2.htm (1039 words)

	Critical phenomena in gravitational collapse (Site not responding. Last check: 2007-10-19)
		As the scalar field obeys a wave equation, the initial data for this system are the initial value phi(r) of the scalar field as a function of radius, and its time derivative dphi/dt(r).
		There is now a competition between two effects: the scalar field tends to disperse as any wave does, while the gravitational field generated by its own mass-energy tends to focus it and make it stronger.
		Unfortunately, the study of rotating collapse is extremely difficult numerically, and the fl hole threshold has not yet been studied with any precision.
	www.maths.soton.ac.uk /~cg/critphen/critphen.html (1790 words)

	Astrophysicists put kibosh on alternative theory of star formation
		These cores, less than a light year across, collapse under their own gravity and compete for gas in the surrounding clump, often gaining 10 to 100 times their original mass from the clump.
		The competitive accretion model was hatched in the late 1990s in response to problems with the gravitational collapse model, which seemed to have trouble explaining how large stars form.
		The model used by Krumholz, McKee and Klein is a supercomputer simulation of the complicated dynamics of gas inside a swirling, turbulent cloud of molecular hydrogen as it accretes onto a star.
	www.eurekalert.org /pub_releases/2005-11/uoc--apk111605.php (1159 words)

	Garfinkle (Site not responding. Last check: 2007-10-19)
		Critical gravitational collapse refers to the scaling properties of gravitational collapse at and near the threshold of fl hole formation.
		Cosmic censorship is the question of whether the singularities that form in gravitational collapse are hidden inside fl holes.
		Recently Garfinkle performed numerical simulations of the gravitational collapse of a scalar field with negative potential energy.
	www.oakland.edu /physics/physics_people/faculty/Garfinkle.htm (365 words)

	gravitational collapse
		The process by which material is drawn together as a result of its mutual gravitational attraction.
		Each particle of the in-falling mass is accelerated toward the center of collapse and so gains kinetic energy which is generally manifested as pressure.
		Gravitational collapse is the essential precursor to the formation of stars from interstellar clouds and is also the dominant process in the closing stages of stellar evolution when white dwarfs, neutron stars, and fl holes form.
	www.daviddarling.info /encyclopedia/G/gravcoll.html (173 words)

	Gravitational collapse!
		But thanks to Einstein we learned that when any velocity in a gravitating system approaches the speed of light, the Newtonian theory of gravity has to be put aside for the relativistically invariance theory of Einstein.
		If the mass of the collapsing star is too large, bigger than twice the mass of our Sun, the fermionic repulsion pressure of either the electrons or the neutrons is not strong enough to prevent the ultimate gravitational collapse into a fl hole.
		Another way that fl holes can be created is the gravitational collapse of the center of a large cluster of stars.
	www.superstringtheory.com /blackh/blackh1a.html (880 words)

	vsevcosmos: High Mass Star Formation by Gravitational Collapse of Massive Cores. [astro-ph/0607429]
		I review models for the evolution of these objects from the observed massive core phase through collapse and into massive star formation, with particular attention to the least well-understood aspects of the problem: fragmentation during collapse, interactions of newborn stars with the gas outside their parent core, and the effects of radiation pressure feedback.
		Collapse is only very slightly inhibited by feedback from the massive star, thanks to beaming of the radiation by a combination of protostellar outflows and radiation-hydrodynamic instabilities.
		Based on these findings, I argue that many of the observed properties of young star clusters can be understood as direct translations of the properties of their gas phase progenitors.
	vsevcosmos.livejournal.com /19079677.html (201 words)

	Interactions between galaxies
		Here we consider the collapse of two spherical mass distributions (representing the collision of two galaxies), observing the systems' behaviour qualitatively if not quantitatively.
		The distribution of the `stars' is by the final frame indistinguishable from the distribution resulting from the collapse of a single galaxy.
		The bitmaps can then be glued together either as a montage (Figure 15) or as an animated GIF file, showing the collapse in much greater detail.
	compsoc.dur.ac.uk /~tw/nbody/report/node4.html (473 words)

	21st-CONSCIOUSNESS MEDIATED QUANTUM GRAVITATIONAL COLLAPSE VIA GENERATED WORMHOLES
		From the point of view of General theory of relativity, physical processes in accelerated reference frame outside gravitational field and in that one inside gravitational field with equal (gravitational) acceleration - are identical (so-called Principle of equivalence, being one of the fundamentals of EinsteinÂ¹s theory of gravitation).
		Furthermore, as the EM field is only one out of four manifestations (electromagnetic, gravitational, weak and strong nuclear forces) of the unified physical field, it can be tentatively generalized that the unified field itself may be internal conscious display for various physical processes at different structural levels, from macroscopic cosmic to microscopic subnuclear ones.
		The problem of the wave function reduction (collapse) in an act of measurement is "orthodoxly" interpreted in quantum theory of measurement as the discontinues change induced by the observation of a quantity with eigenstates Y
	www.vxm.com /Link.DejanWormholes.html (2845 words)

	Science Bag Video: No Exit! Black Holes, Neutron Stars, and Gravitational Collapse
		Modifying an idea of Galileo's, Friedman illustrates the use of a laser beam to measure the speed of light, "the speed limit of the universe," He goes on to explain how this upper limit on the speed of atoms is the determining factor in the creation of fl holes.
		He further transforms the universe into manageable proportions by graphic references to a baseball stadium and by "collapsing" a large star to the size of the city of Milwaukee.
		He presents a series of pertinent video clips, of student Joselyn Bell's discovery of the ticking "like a clock" of a rotating neutron star, a simulation of a fl hole bending the light near Orion, and neutron stars spiraling about each other before merging in a bright explosion to form a fl hole.
	www.blueskyassociates.com /sbvideos/BLA130.html (351 words)

	A Brief History of The Concept of Gravitational Collapse (Site not responding. Last check: 2007-10-19)
		Using a numerical model, Israel shows that when small lumps are present in slightly aspherical gravitational collapse, the resulting perturbations of the Schwarzschild vacuum are radiated away via gravitational radiation, with the waveforms showing a characteristic ringdown followed by a powerlaw decay.
		The connection with gravitational collapse is that in the same year, Aichelburg and Sexl prove that the ultrarelativistic boost of the Schwarzschild vacuum results in an impulsive gravitational plane wave.
		This chart represents a gravitational wave moving in the d/dZ direction, with a two dimensional isometry group, generated by the null Killing vector field d/dZ (translations along the null geodesic ``rays'' of the plane wave) and the spacelike Killing vector field d/dU (rotations around R = 0).
	math.ucr.edu /home/baez/RelWWW/history.html (7117 words)

	Collapse - Wikipedia, the free encyclopedia
		Collapse, a fictional event in the computer game Dreamfall.
		The Collapse (Deus Ex), another fictional event within the plot of the computer game Deus Ex and its sequel Deus Ex: Invisible War.
		"Collapse," a song by Sparta from their 2002 album Wiretap Scars.
	en.wikipedia.org /wiki/Collapse (112 words)

	[No title]
		These clouds are supported against gravitational collapse by their thermal pressure, but if the clouds get too big massive, gravity wins and they can start to collapse.
		For a particle of mass m on the edge of the cloud, the force on it depends whether it is on the rotation pole or the equator:
		Recall that the proto-Sun is undergoing gravitational collapse as it forms, and that gravitational collapse produces a lot of heat.
	burro.astr.cwru.edu /Academics/Astr221/SolarSys/Formation/starform.html (532 words)

	ESA - Space Science - Black holes
		The gravitational field of a fl hole is so strong that the escape velocity needed is greater than the speed of light.
		Black holes are created by the gravitational collapse of supermassive stars (stars that, before collapse, are about eight times larger than the mass of our Sun).
		As a body is crushed into a smaller and smaller volume, the gravitational attraction increases, and hence the escape velocity becomes larger.
	www.esa.int /esaSC/SEMDJ71P4HD_index_0.html (473 words)

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