Mach's principle


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Mach's principle

(mäks) [for E. MachMach, Ernst
, 1838–1916, Austrian physicist and philosopher, b. Moravia. He taught (1864–67) mathematics at Graz and later, until his retirement in 1901, was professor of physics at Prague and Vienna.
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], assertion that the inertial effects of massmass,
in physics, the quantity of matter in a body regardless of its volume or of any forces acting on it. The term should not be confused with weight, which is the measure of the force of gravity (see gravitation) acting on a body.
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 are not innate in a body, but arise from its relation to the totality of all other masses, i.e., to the universe as a whole. Thus, the inertial forces experienced by a body in accelerated motion have the same physical origin as the gravitational forces it experiences near mass concentrations, namely the mass-energy fieldfield,
in physics, region throughout which a force may be exerted; examples are the gravitational, electric, and magnetic fields that surround, respectively, masses, electric charges, and magnets. The field concept was developed by M.
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 described by the general theory of relativityrelativity,
physical theory, introduced by Albert Einstein, that discards the concept of absolute motion and instead treats only relative motion between two systems or frames of reference.
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. Inertial forces have a much longer range than gravitational forces, so the role of very distant matter becomes preponderant. According to Mach's principle, a body experiences no inertial forces when it is at rest or in uniform motion with respect to the center of masscenter of mass,
the point at which all the mass of a body may be considered to be concentrated in analyzing its motion. The center of mass of a sphere of uniform density coincides with the center of the sphere.
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 of the entire universe. When its motion is nonuniform (accelerated) with respect to the total mass of the universe, it experiences forces such as centrifugal force (see centripetal force and centrifugal forcecentripetal force and centrifugal force,
action-reaction force pair associated with circular motion. According to Newton's first law of motion, a moving body travels along a straight path with constant speed (i.e.
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) and the Coriolis effectCoriolis effect
[for G.-G. de Coriolis, a French mathematician], tendency for any moving body on or above the earth's surface, e.g., an ocean current or an artillery round, to drift sideways from its course because of the earth's rotation.
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. Hence, the "local" behavior of matter is influenced by the "global" properties of the universe, i.e., those properties that describe the universe as a whole, which are studied in cosmologycosmology,
area of science that aims at a comprehensive theory of the structure and evolution of the entire physical universe. Modern Cosmological Theories
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.
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References in periodicals archive ?
One of Einstein's leading ideas in formulating general relativity was the Mach's principle that local physical laws must incorporate gravitational interaction with matter in the whole universe (Einstein, 1916a, 1916b).
If we properly instantiate Mach's principle therein we should get a nice correction, because by definition it should includes all effects.
Einstein used the "Mach's principle" terminology when discussing "...
Equation (20) is an explicit form of Mach's principle: planetary movements are determined by the mass distribution of the universe, with gravity as interaction.
Another attempt to account for inertia and its activities is known as Mach's Principle and originated with the physicist and philosopher Ernst Mach and, to a lesser extent, the philosopher Berkeley.
Mach's Principle, in a mathematical form, has become Principle II of the Wave Structure of Matter where inertia is an interaction with the universal medium space, not with the distant stars.
A primer in black holes, Mach's principle and gravitational energy.
-- [1982]: "Mach's principle and the Structure of Dynamical Theories".
I prepared a list of a dozen venerable and obvious subjects and found that seven have no entry: Cosmic Background Explorer (COBE), cosmological principle (but there is an entry for perfect cosmological principle), homogeneity, Mach's principle, Olbers's paradox, space-time, and the tired-light theory.
Even though Earman acknowledges that 'the industry surrounding Mach's Principle has made a significant contribution to our understanding of the foundations of GTR', he gives little credit to Mach's overall strategy on the question of absolute space.
During the years in which Einstein was working up his theories of relativity, Ernst March, who was both a theoretical physicist and a philosopher of science, worked out what became known as Mach's Principle. As Mach was a philosopher, different commentators differ as to what it was he actually said, but in the most general sense Mach's Principle proposes that the mass of any body is related to the masses of all the other bodies in the universe.
The Einstein equations of general relativity have been tentatively modified in the spirit of Mach's principle, multiplying a new cosmological coefficient by the ratio of total retarding gravitational potential of matter in the universe to [c.sup.2].