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	Einstein's Equivalence Principle
		Little g is also equivalent to the inertial "g" forces of acceleration experienced in sudden starts, stops, and sharp turns (Einstein's "Principle of Equivalence" of gravitational and accelerated reference frames).
		C) (Einstein-Noether) Symmetric - The equivalence of free and bound energy: E = hv (Planck); E = mcc (Einstein); hv = mcc (DeBroglie); - The conservation of the symmetry of free energy: the symmetry as well as the raw energy of light must be conserved (Noether).
		Einstein realized that the gravitational field could be "transformed to rest" in free fall - the basis of his principle of the equivalence of gravity and acceleration.
	www.people.cornell.edu /pages/jag8/equival.html (1991 words)

	Equivalence principle - Wikipedia, the free encyclopedia
		The origins of the equivalence principle begin with Galileo demonstrating in the late 16th century that all objects are accelerated towards the center of the Earth at the same rate.
		The Einstein equivalence principle states that the result of a local non-gravitational experiment in an inertial frame of reference is independent of the velocity or location in the universe of the experiment.
		Einstein's theory of general relativity (including the cosmological constant) is thought to be the only theory of gravity that satisfies the strong equivalence principle.
	en.wikipedia.org /wiki/Equivalence_principle (3178 words)

	Tests of general relativity - Wikipedia, the free encyclopedia
		The gravitational redshift of light, was predicted by Einstein from the equivalence principle in 1907.
		The equivalence principle, in its simplest form, asserts that the trajectories of falling bodies in a gravitational field should be independent of their mass and internal structure, provided they are small enough not to disturb the environment or be affected by tidal forces.
		A version of the equivalence principle, called the strong equivalence principle, asserts that self-gravitation falling bodies, such as stars, planets or fl holes (which are all held together by their gravitational attaction) should follow the same trajectories in a gravitational field, provided the same conditions are satisfied.
	en.wikipedia.org /wiki/Classical_tests_of_general_relativity (4029 words)

	Weak EQuivalence Principle
		Einstein elevated this concept to become the Principle of Equivalence which is the foundation of the General Theory of Relativity.
		The equivalence principle can be stated as "At every spacetime point in an arbitrary gravitational field, it is possible to chose a locally inertial coordinate system such that, within a sufficiently small region of the point in question, the laws of nature take the same form as in unaccelerated Cartesian coordinate systems.
		That is the Weak Equivalence Principle is a restatement of the equality of gravitational and inertial mass.
	aether.lbl.gov /www/science/equiv.html (629 words)

	peoplephysics.com - the laws of physics page 3 (Site not responding. Last check: 2007-10-12)
		Albert Einstein, considering that the free-fall time of bodies in vacuum,subjected to the gravity force,is independent from the mass (this is the Galilean law of the freely-falling bodies),in the context of her theory of the general relativity (the theory of the gravitation), was induced to think that the acceleration
		The Einstein equivalence principle consists in considering the impossibility of distinguishing, by physical experiments, the acceleration given to a body by the gravity from the one produced by an accelerate motion of the reference frame.
		The principle of equivalence can be verified by means of a simple experiment, disposing of a spring balance of the type used to weigh the foods for dietary purposes.
	www.peoplephysics.com /physics-laws3.htm (2303 words)

	Curved Coordinates and Acceleration
		Einstein extrapolated this idea into what is called the "strong equivalence principle", which asserts that gravity is nothing other than the effects of the geometry of spacetime.
		Thus, the equivalence principle relies on our ability to conceptually separate out gravity from the other forces of nature, which are never entirely absent, so this again involves an act of abstraction to isolate the equivalence principle in its pure and exact sense.
		The meaning of the equivalence principle is that the spacetime in a region with a gravitational field is intrinsically the same "stuff" at each point - up to a change of coordinates - as the spacetime in a region without a gravitational field.
	www.mathpages.com /rr/s5-06/5-06.htm (1826 words)

	Incompatibility between Einstein's General Relativity and the Principle of Equivalence
		It is shown that the simple application of that principle to photons moving in the Sun's gravitational potential leads to an equation which is not compatible with the one predicting the deflection of light by the Sun.
		Einstein illustrates his principle of equivalence using a gedanken (thought) experiment in which he compares the trajectory of a particle in a gravitational field (gravitational acceleration g) with its trajectory in the absence of a field, but with respect to an accelerated observer whose acceleration
		Einstein’s general relativity predicts[1] that light passing at a distance r from the center of a star of mass M must be deflected by an angle
	www.newtonphysics.on.ca /Equivalence/Equivalence.html (2073 words)

	SparkNotes: Albert Einstein: General Relativity
		Indeed, this was the essence of Einstein's "equivalence principle," which posits the equivalence of physical effects within reference frames at rest within a gravitational field (like the room) and within reference frames accelerating in the absence of any gravitational field (as in the rocket).
		The equivalence principle also posits the equivalence of gravitational mass (the measure of the force a body exerts on another) and inertial mass (the measure of a body's resistance to being accelerated).
		Basically, with his general covariance principle, Einstein applied the equivalence principle to special relativity: given that the laws of physics are the same in all inertial reference frames and that inertial and gravitational masses are equivalent, the laws of physics are the same in all accelerating frames as well.
	www.sparknotes.com /biography/einstein/section7.rhtml (944 words)

	The principle of equivalence
		Einstein noted one other coincidence in Newtonian theory which proved to be of great importance in formulating the principle of equivalence.
		This is the principle of equivalence between gravity and acceleration, and is a corner stone of the theory of General Relativity.
		We shall later use the strong equivalence principle , which says that one can discover how all the laws of physics behave in a gravitational field by postulating that their laws in a freely falling inertial frame are identical to their laws in Special Relativity i.e.
	vishnu.mth.uct.ac.za /omei/gr/chap5/node5.html (844 words)

	Equivalence Principle (Site not responding. Last check: 2007-10-12)
		The Equivalence Principle is the fundamental basis for the theory of general relativity.
		The Weak (or Newtonian) Equivalence Principle is the principle that the laws of mechanics are the same in inertial and freefalling frames of reference.
		The Strong (or Einstein) Equivalence Principle is the principle that all physical laws, not just those of mechanics, are the same in all inertial and freely falling frames of reference.
	www.astro.virginia.edu /~jh8h/glossary/equivalence.htm (97 words)

	Relativity at the centenary (January 2005) - Physics World - PhysicsWeb
		Although Einstein used it to derive general relativity, his equivalence principle implies only that gravitation must be described by a "metric theory" - a theory in which matter responds to the geometry of space-time and nothing else.
		Einstein’s great insight was to realize that gravity and acceleration are equivalent in free fall, and he then went on to show that the laws of physics, such as the equations of electromagnetism, should have built-in local Lorentz and local position invariance.
		In the past it was customary to speak of the three classical tests proposed by Einstein: the deflection of light by a massive body; the advance of the perihelion of Mercury; and the gravitational redshift of light (although this is actually a test of the Einstein equivalence principle rather than general relativity itself).
	physicsweb.org /articles/world/18/1/5 (4326 words)

	The Principle of Equivalence (Site not responding. Last check: 2007-10-12)
		Einstein later recounted that this realization was the "happiest moment in his life", for he understood that this idea was the key to how to extend the Special Theory of Relativity to include the effect of gravitation.
		An equivalent formulation of the Principle of Equivalence is that at any local (that is, sufficiently small) region in spacetime it is possible to formulate the equations governing physical laws such that the effect of gravitation can be neglected.
		For example, by considering the Principle of Equivalence applied to light travelling across a freely falling elevator, it is possible to conclude that light will follow a curved path in a gravitational field.
	csep10.phys.utk.edu /astr162/lect/cosmology/equivalence.html (244 words)

	The Principle of Equivalence
		The principle of equivalence being a postulate, the reasons for which Einstein did not take into account the motion of his own frame were not explained.
		We must conclude again that Einstein's equivalence principle is erroneous which means that the behavior of light is perceived differently by observers subjected to gravitational acceleration and inertial acceleration.
		The principle of equivalence implies the equivalence between the inertially accelerated elevator (figure 10.3A) and the gravitationally accelerated photon on figure 10.3B.
	www.newtonphysics.on.ca /EINSTEIN/Chapter10.html (3088 words)

	gravityhist2
		This is usually interpreted as implying that the two quantities are equivalent measures for a single physical property, the quantity of mass of an object; hence, the term Equivalence Principle.
		A direct consequence of assuming the Equivalence Principle is true, is that all bodies fall with the same acceleration under the influence of gravity.
		The Strong or Einstein Equivalence Principle states that all of the laws of physics (not just the laws of gravity) are the same in all small regions of space, regardless of their relative motion or acceleration.
	einstein.stanford.edu /STEP/information/data/gravityhist2.html (1680 words)

	The Light Cone: The Principle of Equivalence
		Einstein was looking to extend his Principle of Relativity to more general siutations.
		This led Einstein to predict that light is bent by the gravitational field around the Sun.
		One prediction that Einstein deduced his theory is that starlight will have an angular deflection of 1.75 seconds of arc.
	physics.syr.edu /courses/modules/LIGHTCONE/equivalence.html (293 words)

	Gravitational Time-Dilation
		As was mentioned, Einstein considered that from the point of view of the Principle of Equivalence it is impossible to speak of absolute acceleration just as it is impossible to speak of absolute velocity.
		Galileo's principle of equivalence fails for spinning particles." (Ohanian and Ruffini, 1994, 419.) Actually, it might be better to state that the principle "approximately" fails, in this case, since one can state a certain degree of failure with respect to "free-fall" motion.
		This is another test that uses the equivalence principle relative to the massless photon to measure a predicted alteration of the "apparent speed" of such a photon caused by a gravitational field in a manner somewhat similar to how the apparent speed is altered in a dense but transmitting medium.
	www.serve.com /herrmann/time.htm (4633 words)

	NOVA \| Einstein's Big Idea \| Relativity (Lightman Essay) \| PBS
		Einstein's earlier theory of time and space, special relativity, proposed that distance and time are not absolute.
		The key idea of general relativity, called the equivalence principle, is that gravity pulling in one direction is completely equivalent to an acceleration in the opposite direction.
		Friedmann began with Einstein's equations of general relativity and found a solution to those equations in which the universe began in a state of extremely high density and temperature (the so-called big bang) and then expanded in time, thinning out and cooling as it did so.
	www.pbs.org /wgbh/nova/einstein/relativity (1248 words)

	Questions of the equivalence principle (Site not responding. Last check: 2007-10-12)
		The CoM serves as one of many inertial frames of reference, the principle of relativity is not violated, the equivalence principle isn't invalidated, it's simply irrelevent as the CoM is an inertial reference frame, as previously stated.
		Einstein (and Weinberg) were not sure; in fact Mach's Principle is incompatible with GR because MP singles out a preferred frame of reference, that is locally the Centre of Mass of the system or cosmologically the frame in which the cosmic microwave background radiation is globally isotropic.
		Before dealing the principle of relativity and the equivalence principle, you have to first accept that MP's centre of mass reference point is incorrect, or at the very least not applicable, as Einstein didn't follow this reasoning when formulating his theory, or else it's pointless to try solve the problem.
	www.physicsforums.com /showthread.php?t=32285 (2418 words)

	3 Tests of GR - Equivalence Principle Violations (Site not responding. Last check: 2007-10-12)
		Equivalence principles are fundamental to gravitational theory; for full descriptions, see, e.g.
		The Einstein Equivalence Principle (EEP) includes this concept as well as those of Lorentz invariance (non-existence of preferred reference frames) and positional invariance (non-existence of preferred locations) for non-gravitational experiments.
		This principle leads directly to the conclusion that non-gravitational experiments will have the same outcomes in inertial and in freely-falling reference frames.
	www.univie.ac.at /EMIS/journals/LRG/Articles/lrr-2003-5/node6.html (414 words)

	Einstein's Relativity
		Part of Einstein's genius was his ability to look at ordinary things from a whole new perspective and logically follow through on the consequence of the insights he gained from his new perspective.
		Einstein used this to formulate the equivalence principle that would be the foundation of General Relativity.
		Einstein's theory of General Relativity is a continuation or extension of Newton's law of gravity.
	www.astronomynotes.com /relativity/s3.htm (864 words)

	Einstein equivalence principle (Site not responding. Last check: 2007-10-12)
		Thus, the EEP is a consequence of the
		Nonetheless, for a better understanding of the EEP it seems useful to consider variants of the derivation.
		Thus, we need three assumptions to prove the EEP: the conservation laws, the existence of a Lagrange mechanism, and that the conservation laws are the Euler-Lagrange equations for the preferred coordinates.
	ilja-schmelzer.de /GET/EEP.html (436 words)

	Questions for Module 43
		Einstein's Equivalence Principle states that, local experiments carried out in a sufficiently small laboratory cannot tell the difference between,
		Gravity is equivalent to being accelerated relative to an inertial reference frame.
		Free fall is equivalent to being in an inertial frame.
	www.people.vcu.edu /~rgowdy/mod/r43/qst.htm (239 words)

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