# Einstein's mass-energy relation

Einstein's mass-energy relation
Relationship between mass (m) and energy (E) in Albert Einstein's special theory of relativity, expressed E = mc2, where c equals 186,000 mi/second (300,000 km/second), the speed of light.

Whereas mass and energy were viewed as distinct in earlier physical theories, in special relativity a body's mass can be converted into energy in accordance with Einstein's formula. Such a release of energy decreases the body's mass (see conservation law).

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relationship between mass (m) and energy (E) in the special theory of relativity (relativity) of Albert Einstein (Einstein, Albert), embodied by the formula E = mc2, where c equals 300,000 km (186,000 miles) per second—i.e., the speed of light.

In physical theories prior to that of special relativity, mass and energy were viewed as distinct entities. Furthermore, the energy of a body at rest could be assigned an arbitrary value. In special relativity, however, the energy of a body at rest is determined to be mc2. Thus, each body of rest mass m possesses mc2 of “rest energy,” which potentially is available for conversion to other forms of energy. The mass-energy relation, moreover, implies that if energy is released from the body as a result of such a conversion, then the rest mass of the body will decrease. Such a conversion of rest energy to other forms of energy occurs in ordinary chemical reactions, but much larger conversions occur in nuclear reactions (nuclear reaction). This is particularly true in the case of nuclear-fusion reactions that transform hydrogen to helium, in which 0.7 percent of the original rest energy of the hydrogen is converted to other forms of energy.

Although the atomic bomb proved that vast amounts of energy could be liberated from the atom, it did not demonstrate the precision of Einstein's equation. As knowledge of the atom developed in the 20th century, it was discovered that the protons (proton) and neutrons (neutron) that form its nucleus are themselves formed from the more elementary subatomic particles (subatomic particle) known as quarks (quark), bound together by massless gluons (gluon), in the theory of quantum chromodynamics. However, quarks account for only about 5 percent of an atom's mass (atomic mass), leaving the vast remainder of its mass to be explained. In 2008, following intense computations led by Laurent Lellouch of France's Centre for Theoretical Physics on various supercomputers (supercomputer), the missing mass was shown to reside in the energy associated with the subatomic particles' motions and interactions—in other words, Einstein's equation was verified at the subatomic scale.

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Universalium. 2010.

### См. также в других словарях:

• Mass–energy equivalence — E=MC2 redirects here. For other uses, see E=MC2 (disambiguation). 4 meter tall sculpture of Einstein s 1905 E = mc2 formula at the 2006 Walk of Ideas, Berlin, Germany In physics, mass–energy equivalence is the concept that the …   Wikipedia

• mass — massedly /mas id lee, mast lee/, adv. /mas/, n. 1. a body of coherent matter, usually of indefinite shape and often of considerable size: a mass of dough. 2. a collection of incoherent particles, parts, or objects regarded as forming one body: a… …   Universalium

• Mass — /mas/, n. 1. the celebration of the Eucharist. Cf. High Mass, Low Mass. 2. (sometimes l.c.) a musical setting of certain parts of this service, as the Kyrie eleison, Gloria, Credo, Sanctus, Benedictus, and Agnus Dei. [bef. 900; ME masse, OE… …   Universalium

• mass, conservation of — ▪ physics       principle that the mass of an object or collection of objects never changes, no matter how the constituent parts rearrange themselves. Mass has been viewed in physics in two compatible ways. On the one hand, it is seen as a… …   Universalium

• Einstein — /uyn stuyn/; Ger. /uyn shtuyn /, n. 1. Albert /al beuhrt/; Ger. /ahl berddt/, 1879 1955, German physicist, U.S. citizen from 1940: formulator of the theory of relativity; Nobel prize 1921. 2. Alfred /al frid/; Ger. /ahl frddet/, 1880 1952, German …   Universalium

• energy — /en euhr jee/, n., pl. energies. 1. the capacity for vigorous activity; available power: I eat chocolate to get quick energy. 2. an adequate or abundant amount of such power: I seem to have no energy these days. 3. Often, energies. a feeling of… …   Universalium

• relation — relationless, adj. /ri lay sheuhn/, n. 1. an existing connection; a significant association between or among things: the relation between cause and effect. 2. relations, a. the various connections between peoples, countries, etc.: foreign… …   Universalium

• Mass number — The mass number (A), also called atomic mass number or nucleon number, is the total number of protons and neutrons (together known as nucleons) in an atomic nucleus. Because protons and neutrons both are baryons, the mass number A is identical… …   Wikipedia

• Mass in special relativity — incorporates the general understandings from the concept of mass energy equivalence. Added to this concept is an additional complication resulting from the fact that mass is defined in two different ways in special relativity: one way defines… …   Wikipedia

• mass-en|er|gy equation — «MAS EHN uhr jee», an equation expressing the relation of mass and energy, formulated by Albert Einstein in 1905: E = mc2; Einstein equation. E = the energy in ergs; m = the mass in grams; c = the velocity of light in centimeters per second.… …   Useful english dictionary

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