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	Speed of gravity - Wikipedia, the free encyclopedia
		This finite speed of gravitational interaction in general relativity may at first seem to lead to exactly the same sorts of problems with the aberration of gravity that Newton was originally concerned with.
		Kopeikin and Fomalont concluded that the speed of gravity is between 0.8 and 1.2 times the speed of light, which would be fully consistent with the theoretical prediction of general relativity that the speed of gravity is exactly the same as the speed of light.
		"On the Speed of Gravity and the Jupiter/Quasar Measurement".
	en.wikipedia.org /wiki/Speed_of_gravity (1077 words)

	The Speed of Gravity - What the Experiments Say
		If possible waves associated with sources of gravity (those that may induce acceleration in other bodies), and other possible waves induced by targets of gravity (those that result from acceleration), are not distinguished, we are certain to have massive confusion over the meaning of the very concept of “the speed of gravity”.
		The expected aether-drift speed did not put in an appearance in the test results, and the speed of light did indeed seem to be the same in all directions, as SR postulated, even though the observer was obviously moving at high speed in some direction through space.
		That the speed of light is independent of the speed of its source is unremarkable, since that is a property of all wave motion.
	www.metaresearch.org /cosmology/speed_of_gravity.asp (8709 words)

	First speed of gravity measurement revealed - 07 January 2003 - New Scientist
		Isaac Newton thought the influence of gravity was instantaneous, but Einstein assumed it travelled at the speed of light and built this into his 1915 general theory of relativity.
		Gravity could take a short cut through these extra dimensions and so appear to travel faster than the speed of light - without violating the equations of general relativity.
		He reworked the equations of general relativity to express the gravitational field of a moving body in terms of its mass, velocity and the speed of gravity.
	www.newscientist.com /news/news.jsp?id=ns99993232 (624 words)

	The Speed of Gravity: Einstein Was Right! (Site not responding. Last check: 2007-11-02)
		The assumption that gravity also travels at this speed is implicit in Einstein's general theory of relativity, formulated in 1915, which recognizes the universal character of the propagation speed of light and the consequent dependence of space, time, and other mechanical measurements on the motion of the observer performing the measurements.
		Sir Isaac Newton thought that the speed of gravity was instantaneous, and Einstein assumed it traveled at the speed of light.
		So, to find the speed of gravity, all we need is an occasion where Jupiter moves in front of a good strong light source, lensing the rays on their way to Earth.
	www.csa.com /discoveryguides/gravity/overview.php (1948 words)

	Does Gravity Travel at the Speed of Light?
		To begin with, the speed of gravity has not been measured directly in the laboratory--the gravitational interaction is too weak, and such an experiment is beyond present technological capabilities.
		The "speed of gravity" must therefore be deduced from astronomical observations, and the answer depends on what model of gravity one uses to describe those observations.
		The fact that gravitational damping is measured at all is a strong indication that the propagation speed of gravity is not infinite.
	math.ucr.edu /home/baez/physics/Relativity/GR/grav_speed.html (1072 words)

	Speed of gravity - SciForums.com
		In general relativity, on the other hand, gravity propagates at the speed of light; that is, the motion of a massive object creates a distortion in the curvature of spacetime that moves outward at light speed.
		Strictly speaking, gravity is not a "force" in general relativity, and a description in terms of speed and direction can be tricky.
		In general relativity, gravity is a characteristic of spacetime; it is not a force.
	www.sciforums.com /showthread.php?t=59616 (838 words)

	BBC NEWS \| Science/Nature \| Einstein proved right on gravity
		The speed of gravity has been measured for the first time, revealing that it does indeed travel at the speed of light.
		If gravity travelled at the speed of light it would mean that if the Sun suddenly vanished from the Solar System, the Earth would remain in orbit for about eight minutes - the time taken for light to travel from the star to our planet.
		Modern researchers say that knowing the speed of gravity is important in the study of branches of cosmology where the Universe has more spatial dimensions than the usual three.
	news.bbc.co.uk /1/hi/sci/tech/2639043.stm (399 words)

	Curious About Astronomy: What is the speed of gravity?
		In the theory of relativity, the speed of gravity should be equal to the speed of light, since the theoretical "particles" that carry gravity (sometimes called gravitons) are massless particles, just like photons (the particles that carry light).
		The measurements they took then proved that the speed of gravity is the same as that of light, ruling out some of the more bizarre modifications to the laws of gravity which have been proposed, and further backing General Relativity (BBC news article on the experiment).
		However, other astronomers disagree that the experiment is able to measure the speed of gravity, arguing that the effect is much smaller than the scientists claim and that (in effect) they got their arithmatic wrong when they decided that the speed of gravity did come into the equations.
	curious.astro.cornell.edu /question.php?number=573 (509 words)

	THE GRAVITY (Site not responding. Last check: 2007-11-02)
		A speed greater than the speed of light that deals with on the formulation by the author of several hypotheses against theory of Relativity of Einstein and in individual of the existence in the nature of speeds greater than the speed of light of which it would be the speed of gravity.
		In my theory the speed of gravity belong the family of the super speeds and is one of the speeds greater than the speed of light.
		The gravity field and the other existing fields in the nature, the same as the different states of the substance, are material form differentiated according to its magnitudes; one of them is its speed.
	www.geocities.com /physic1525/gravityspeed.html (6678 words)

	speed of gravity - a definition from Whatis.com (Site not responding. Last check: 2007-11-02)
		Scientists have conducted various experiments and performed calculations in an attempt to determine the speed of gravity, and also to find out whether or not that speed is influenced by conditions such as acceleration, gravitational field intensity, or electromagnetic fields.
		Tom Van Flanders concludes that the speed of gravity is far greater than the speed of light.
		An experiment has recently found that the speed of gravity is the same as the speed of light.
	whatis.techtarget.com /definition/0,,sid9_gci874815,00.html (283 words)

	The Speed of Gravity - Repeal the Speed Limit
		If the field propagation speed were lightspeed, we would be forced to interpret the momentum transfers as applied in a different direction from the direction of travel of the momentum carriers because of aberration.
		The statement that “the speed of gravity equals the speed of light” is manifestly false, and is heard often only because of the confusion with the propagation speed of gravitational waves.
		However, the consequences of a propagation speed of gravitational force variations as slow as lightspeed would be catastrophic for many astrophysical bodies, and are strongly disallowed by physical principles and by all existing experimental evidence.
	metaresearch.org /cosmology/gravity/speed_limit.asp (7427 words)

	Gravity Speed Measured
		"We have determined that gravity's propagation speed is equal to the speed of light within an accuracy of 20 percent," said Ed Fomalont, an astronomer at the National Radio Astronomy Observatory (NRAO) in Charlottesville, VA.
		The once-in-a-decade celestial alignment was the last in a chain of events that made measuring the speed of gravity possible.
		We now know that the speed of gravity is probably equal to the speed of light, and we can confidently exclude any speed for gravity that is over twice that of light," Fomalont said.
	www.nrao.edu /pr/2003/gravity (1023 words)

	THE SPEED OF GRAVITY - WHAT THE EXPERIMENTS SAY
		Recognition of a faster-than-light-speed propagation of gravity, as indicated by all existing experimental evidence, may be the key to taking conventional physics to the next plateau.
		This is usually not mentioned in proximity to the statement that GR reduces to Newtonian gravity in the low-velocity, weak-field limit because of the obvious question it begs about how that can be true if the propagation speed in one model is the speed of light, and in the other model it is infinite.
		Analogous to the Poynting-Robertson effect, the magnitude of that tangential force acting on the Earth would be 0.0001 of the Sun’s radial force, which is the ratio of the Earth’s orbital speed (30 km/sec) to the speed of this hypothetical force of gravity moving at light-speed (300,000 km/sec).
	www.gravitywarpdrive.com /Speed_of_Gravity.htm (8778 words)

	On the Speed of Gravity
		One concludes that, if the speed of gravity is not equal to the speed of light, then measurements of the strength of gravity are reference frame dependent.
		This produces a speed of gravity that differs so minutely from the speed of light as to be not measurable in any of the classic tests of general relativity including the Jupiter/quasar experiment.
		In summary, if a speed of gravity parameter is introduced into general relativity that differs from the speed of light then measurements become observer dependent thereby rendering the theory inconsistent.
	www.jupiterscientific.org /sciinfo/soganalysis.html (1443 words)

	The speed of gravity?
		The assumption of zero mass flow from the assumption that gravity is an infinite distance force.
		Models that show gravity, either by particle or other means propogating at c seem to work better than those that assume a lower speed (although it day to day, this would be unnoticable except for large masses moving a great speeds).
		If gravity propagates at c, the aren't all the arguments about the total mass of the universe and it collapsing irrelevant, because the universe is expanding so fast that gravity couldn't keep up and make it collapse.
	www.physicsforums.com /showthread.php?p=402496 (1230 words)

	Speed of gravity to be measured - 05 September 2002 - New Scientist
		Speed of gravity to be measured - 05 September 2002 - New Scientist
		The answer, says Sergei Kopeikin of the University of Missouri, Columbia, is by watching a distant quasar as the planet Jupiter moves in front of it and its gravity bends radio waves from the quasar.
		The calculations show that if gravity has a finite speed, the ring-like image seen at Earth will be subtly warped compared to the shape expected if the gravitational changes propagate instantaneously.
	www.newscientist.com /article.ns?id=dn2763 (437 words)

	Speed of Gravity
		I know that over the centuries we have found equations which mathematically relate most of the natural forces, but gravity is one that has resisted all such efforts.
		Since gravity is apparently so different perhaps it is not constrained like electricity and magnetism to a maximum speed - light speed.
		Gravitons travel at the speed of light, in the theory of general relativity (at least to the extent that the theory recognizes the existence of quantum mechanics).
	www.newton.dep.anl.gov /askasci/phy99/phy99004.htm (367 words)

	MU SCIENTIST MEASURES SPEED OF GRAVITY (Site not responding. Last check: 2007-11-02)
		Led by Sergei Kopeikin, a physicist at the University of Missouri-Columbia, a team of scientists took advantage of a rare cosmic alignment on Sept. 8 to test Einstein’s assumption that gravity moves at the speed of light.
		“We have determined that gravity’s propagation speed is equal to the speed of light within an accuracy of 20 percent,” Fomalont said.
		Prior to this study, no one had tried to measure the speed of gravity because most physicists had assumed that the only way to do so was to detect gravitational waves, Kopeikin said.
	www.missouri.edu /~news/releases/decjan03/gravitymeasuring.html (493 words)

	Berkeley Lab Physicist Challenges Speed of Gravity Claim
		His calculations appeared to show that the speed at which gravity was being propagated from Jupiter matched the speed of light to within 20 percent.
		If, on the other hand, the speed of gravity were finite, then the strength of gravity would be determined by the position of Jupiter at a slightly earlier time so as to allow for the propagation of gravitational effects."
		Samuel was able to simplify the calculations of the velocity-dependent effects by shifting from a reference frame in which Jupiter is moving, as was used by Kopeikin, to a reference frame in which Jupiter is stationary and Earth is moving.
	www.spacedaily.com /news/gravity-03d.html (788 words)

	Speed of Gravity Measured for First Time (Site not responding. Last check: 2007-11-02)
		SEATTLE - The first accurate measurement ever taken of the speed with which gravity propagates shows that it is equal to the speed of light, agreeing nicely with the General Theory of Relativity.
		That gravity works instantaneously is almost impossible, according to the study.
		Craig Hogan, an astronomer and physicist at the University of Washington, was not involved in the new research.
	www.ufoarea.com /physics_cosmology_speed_of_gravity_measured.html (480 words)

	Cosmology ... the speed of gravity
		"Gravity" is thus the result of the restructuring and is NOT a "separate force".
		So my conclusion about the "speed of gravity': the membrane is the essence of everything and has does not have speed, it 'IS'.
		"Speed" is only a human definition of a repeatable or unique observation between two or more "units" which interact, and thus question: "with what velocity they interfere given a certain observed location".
	www.mu6.com /Q_3_speed_of_gravity.html (1054 words)

	Speed of Gravity (Site not responding. Last check: 2007-11-02)
		In 2002, Sergei Kopeikin suggested that measurement of the deflection of light from a quasar by the planet Jupiter could be used to measure the speed of the gravitational interaction.
		According to his calculations, there should be a small correction to the normal general relativistic formula for the deflection, which depends on the velocity of Jupiter and on the velocity of gravity (technically, it's an extra term in the ``Shapiro'' delay in arrival of waves at a radio telescope).
		By comparing the arrival of a gravitational-wave signal with that of an electromagnetic signal from an astrophysical source, one could compare the speed of gravity to that of light to parts in 10^(17).
	wugrav.wustl.edu /people/CMW/SpeedofGravity.html (936 words)

	Straight Dope Staff Report: What is the speed of gravity?
		To put it in technical terms, general relativity is only self-consistent if the speed of gravity is Lorentz invariant (that is, the same for all observers), and the only speed for which that works is c.
		Since the beads are attracted to one another by gravity, they'll settle into a position such that they're as close together as they can get, right next to each other on the wires.
		This is all very well theoretically, of course, but it's not practical because gravity is an extremely weak force, and variations of the magnitude necessary to prove the existence of gravitational waves are undetectable except at planetary (or larger) scale.
	www.straightdope.com /mailbag/mgravityspeed.html (782 words)

	Speed of Gravity - Advanced Physics Forums
		It\'s generally accepted that the gravity travels at the speed of light.
		To paraphrase what Hawkins said, the speed of light is a constant, time and space are the variables.
		is the speed of gravity = to c
	www.advancedphysics.org /forum/showthread.php?t=591 (687 words)

	BBC NEWS \| Science/Nature \| Test for Einstein's gravity speed theory
		Scientists hope this will enable them to test one of Einstein's assumptions, that the speed of gravity is equal to the speed of light (300,000 km/s or 186,000 mps).
		Jupiter's gravity should nudge the light coming from the quasar, causing it to appear to shift a little in the sky.
		Astronomers hope to be able to measure this displacement, which depends on the speed of gravity.
	news.bbc.co.uk /2/hi/science/nature/2238452.stm (793 words)

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