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Mass, in Christianity

Mass, religious service of the Roman Catholic Church, which has as its central act the performance of the sacrament of the Eucharist. It is based on the ancient Latin liturgy of the city of Rome, now used in most, but not all, Roman Catholic churches. The term Mass [Lat. missa,=dismissed] probably derives from the practice of dismissing the catechumens—those not yet initiated into the mystery of the Eucharist—before the offertory and from the words Ite, missa est [Go, you are dismissed] spoken to the faithful at the end of the Mass. The term is also used among Anglo-Catholics; in the Eastern churches the Mass is generally called the Holy Liturgy or the Offering. For non-Roman liturgies, see liturgy.

The Role of the Catholic Mass

In the Roman Catholic Church, except for the altogether distinct Ambrosian rite (see Ambrose, Saint) and for some variant forms among religious orders, especially that of the Dominicans, the service is the same everywhere, under regulation of the Holy See. The language of the liturgy is typically terse. The celebrant, who must be a priest, follows a prescribed missal and wears certain vestments. Mass is said at an altar containing relics; two candles must be burning. A congregation is not essential, but solitary Mass is discouraged. A High (solemn) Mass requires a priest, deacon, and choir. Low Mass, much more common, is the same service said by one priest. Normally at Low Mass a server or acolyte, traditionally called an altar boy but now often a girl, helps the celebrant. Most of the text is invariable, or "ordinary," but certain parts, called "proper," change with the occasion or day. Mass may be offered with a special intention, as in thanksgiving or for peace. A requiem is a proper Mass for the dead. Most priests say Mass daily. Sunday Mass is an important sociocultural factor in Roman Catholic life. All members are required to attend Mass on Sunday as a minimum participation in public worship.

The Service

The Mass begins with an entrance hymn, a greeting, and a brief penetential rite that includes the Kyrie eleison, the Gloria in excelsis (not always), a collect or collects, the proper epistle, an anthem and the proper Gospel (usually chanted and with all standing), and a homily on the texts. This ends the part of the Mass known in primitive times as the Mass of the Catechumens.

Mass continues with the creed (sometimes), the offertory (anthem with offering of bread and wine), offering of incense (sometimes), washing of the celebrant's hands, and proper prayers called "secrets." Then there is a chanted or spoken dialogue and proper preface of thanksgiving, ending in the Sanctus. That opens the long eucharistic prayer, or canon. It begins with prayers for the living. The consecration of the bread and wine follows; then the celebrant raises Host and chalice above his head for all to see and adore. The canon ends with prayers for the dead and a doxology, which is the solemn climax of the eucharistic prayer.

After the canon the Mass consists of the Lord's Prayer, a prayer amplifying the supplication "Deliver us from evil," the symbolic breaking of the Host and putting a piece into the cup, the kiss of peace (shared by the members of the congregation), the Agnus Dei, the communion, the ablution of vessels, the communion anthem, postcommunion prayers, the dismissal, and the blessing. There are ceremonial adjuncts such as processions, blessings, censings, and in some places, the ringing of a handbell at the consecration.

Music in the Mass

Of the portions of the Mass that may be sung, some are chanted solo at the altar with choral response; there are also nine hymns for the choir. Four of these are proper and related in theme, with texts usually from the Psalms: introit, anthem after the epistle (alleluia, gradual, tract, or sequence), offertory, and communion. The five ordinary choral pieces are Kyrie eleison, Gloria in excelsis, Credo (see creed), Sanctus, and Agnus Dei. Plainsong is prescribed for all texts, but latitude is permitted the choir. A musical setting for the five ordinary hymns, called a Mass, has been a major musical form. The principal period of Mass composition lasted from 1400 to 1700. It came to an end with shift of interest to instrumental music, although later composers did use the form. Among the many composers who produced Masses are Josquin des Prés, Palestrina, Monteverdi, Bach, Haydn, Mozart, Beethoven, Verdi, and Stravinsky.

Changes in the Mass

The basic structure of the Mass is largely unchanged since the 6th cent. In the Counter Reformation the forms were restricted and local variants eliminated. As a result of the Constitution on the Sacred Liturgy of the Second Vatican Council, the Roman Mass liturgy has undergone extensive reformation. The revisions include the use of the vernacular languages in the place of Latin, an emphasis on congregational singing, latitude for modifications that may be introduced by local bishops, additional eucharistic prayers, and communion in both bread and wine.

Bibliography

See J. A. Jungmann, The Mass of the Roman Rite (rev. ed. 1959); F. Amiot, History of the Mass (tr. 1959); H. Daniel-Rops, This Is the Mass (rev. ed. 1965); P. Loret, The Story of the Mass (1983).

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mass, in physics

mass, 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. Under ordinary conditions the mass of a body can be considered to be constant; its weight, however, is not constant, since the force of gravity varies from place to place. There are two ways of referring to mass, depending on the law of physics defining it: gravitational mass and inertial mass. The gravitational mass of a body may be determined by comparing the body on a beam balance with a set of standard masses; in this way the gravitational factor is eliminated. The inertial mass of a body is a measure of the body's resistance to acceleration by some external force. One body has twice as much inertial mass as another body if it offers twice as much force in opposition to the same acceleration. All evidence seems to indicate that the gravitational and inertial masses of a body are equal, as demanded by Einstein's equivalence principle of relativity; so that at the same location equal (inertial) masses have equal weights. Because the numerical value for the mass of a body is the same anywhere in the world, it is used as a basis of reference for many physical measurements, such as density and heat capacity. According to the special theory of relativity, mass is not strictly constant but increases with the speed according to the formula m=m₀/1−v²/c², where m₀ is the rest mass of the body, v is its speed, and c is the speed of light in vacuum. This increase in mass, however, does not become appreciable until very great speeds are reached. The rest mass of a body is its mass at zero velocity. The special theory of relativity also leads to the Einstein mass-energy relation, E=mc², where E is the energy, and m and c are the (relativistic) mass and the speed of light, respectively. Because of this equivalence of mass and energy, the law of conservation of energy was extended to include mass as a form of energy.

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mass

Quantitative measure of inertia, or the resistance of a body to a change in motion. The greater the mass, the smaller is the change produced by an applied force. Unlike weight, the mass of an object remains constant regardless of its location. Thus, as a satellite moves away from the gravitational pull of the Earth, its weight decreases but its mass remains the same. In ordinary, classical chemical reactions, mass can be neither created nor destroyed. The sum of the masses of the reactants is always equal to the sum of the masses of the products. For example, the mass of wood and oxygen that disappears in combustion is equal to the mass of water vapour, carbon dioxide, smoke, and ash that appears. However, Albert Einstein's special theory of relativity shows that mass and energy are equivalent, so mass can be converted into energy and vice versa. Mass is converted into energy in nuclear fusion and nuclear fission. In these instances, conservation of mass is seen as a special case of a more general conservation of mass-energy. See also critical mass.

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mass

Celebration of the Eucharist in the Roman Catholic church. It is considered a sacramental reenactment of the death and resurrection of Jesus as well as a true sacrifice in which the body and blood of Jesus (the bread and wine) are offered to God. It is also seen as a sacred meal that unifies and nourishes the community of believers. The mass includes readings from Scripture, a sermon, an offertory, a eucharistic prayer, and communion. The rite was greatly changed after the Second Vatican Council, notably in the adoption of vernacular languages in place of Latin. See also sacrament, transubstantiation.

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mass

1. Physics a physical quantity expressing the amount of matter in a body. It is a measure of a body's resistance to changes in velocity (inertial mass) and also of the force experienced in a gravitational field (gravitational mass): according to the theory of relativity, inertial and gravitational masses are equal

2. (in painting, drawing, etc.) an area of unified colour, shade, or intensity, usually denoting a solid form or plane

3. Pharmacol a pastelike composition of drugs from which pills are made

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Mass

1. (in the Roman Catholic Church and certain Protestant Churches) the celebration of the Eucharist

2. a musical setting of those parts of the Eucharistic service sung by choir or congregation

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mass [mas]

(mechanics)

A quantitative measure of a body's resistance to being accelerated; equal to the inverse of the ratio of the body's acceleration to the acceleration of a standard mass under otherwise identical conditions.

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Mass

The quantitative or numerical measure of a body's inertia, that is, of its resistance to being accelerated.

Because it is often necessary to compare masses of such dissimilar bodies as a sample of sugar, a sample of air, an electron, and the Moon, it is necessary to define mass in terms of a property that not only is inherent and permanent but is also universal in that it is possessed by all known forms of matter. All matter possesses two properties, gravitation and inertia. The property of gravitation is that every material body attracts every other material body. The property of inertia is that every material body resists any attempt to change its motion. A body's motion is said to change if the body is accelerated, that is, if it increases or decreases its speed or changes the direction of its motion. Because of its inertia a body cannot be accelerated unless a force is exerted on it. The greater the inertia of a body, the less will be the acceleration produced by a given force. See Gravitation, Inertia

The present definition of mass is in terms of inertia. The masses of two bodies are compared by applying equal forces to the bodies and measuring their accelerations. For example, the two bodies may be allowed to collide. According to Newton's third law, each body will then experience an equally strong force. If there are no external forces, and if a₁ and a₂ are the measured accelerations of the two bodies, the ratio of the masses of the two bodies is by definition given by the equation

This equation gives only ratios of masses; it is therefore necessary to designate the mass of some one body as the standard mass to which the masses of all other bodies can be compared. The body that has been chosen for this purpose is a cylinder of platinum-iridium alloy. It is known as the international standard of mass; its mass is called 1 kilogram (kg), and it is kept at the International Bureau of Weights and Measures near Paris, France. Replicas of the standard mass, kept at various national laboratories, are periodically compared with this standard.

Einstein's special theory of relativity predicts that the inertia of a body should increase if the energy of the body increases. This prediction has been conclusively verified experimentally. It follows that the mass of a body will increase if, for example, the body gains speed (addition of kinetic energy), or its temperature rises (addition of heat energy), or the body is compressed (addition of elastic energy). See Conservation of mass

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Mass 

a physical quantity; a fundamental characteristic of matter that defines its inertial and gravitational properties. A corresponding distinction is made between inertial and gravitational mass.

The concept of mass was introduced in mechanics by I. Newton. In Newtonian classical mechanics, mass is part of the definition of the momentum of a body: the momentum P is proportional to the velocity of motion v of the body,

(1) p = mv

The proportionality factor—the quantity m, which is constant for a given body—is the mass of the body. An equivalent definition of mass can be obtained from the equation of motion of classical mechanics:

(2) f = ma

Here the mass is the proportionality factor between the force f acting on a body and the acceleration of the body a that it causes. The mass defined by equations (1) and (2) is called the inertial mass, or inert mass; it characterizes the dynamic properties of a body and is a measure of the body’s inertia. The greater the mass of a body, the smaller the acceleration it acquires upon application of a constant force—that is, the more slowly its state of motion changes (the greater its inertia).

The mass ratio of various bodies may be determined by applying a given force to them and measuring their acceleration: m₁ : m₂ : m₃,… = a₁ : a₂ : a₃.… If one of the masses is taken as the unit of measurement, then the masses of the other bodies can be found.

In the Newtonian theory of gravitation, mass assumes a different form—it is the source of the gravitational field. Each body creates a gravitational field proportional to its mass and experiences the effect of the gravitational field generated by other bodies, whose force is also proportional to the masses of the bodies. This field causes the attraction of any other body to the given body with a force that is defined by Newton’s law of gravitation:

where r is the distance between the bodies, G is the universal constant of gravitation, and m₁ and m₂ are the masses of the attracting bodies. A formula for the weight P of a body of mass m in the earth’s gravitational field may be easily obtained from formula (3):

(4) P = m · g

Here g = G·M/r² is the free-fall acceleration in the earth’s gravitational field and r ≈ R is the radius of the earth. The mass defined by equations (3) and (4) is called the gravitational mass of the body.

In principle it does not follow that a mass that creates a gravitational field also defines the inertia of the same body. However, experiment has shown that inertial and gravitational mass are proportional to each other (and, with the choice of ordinary units of measurement, are numerically equal). This fundamental natural law is called the principle of equivalence. Its discovery is associated with Galileo, who established that all bodies on earth fall with identical acceleration. Einstein, who was the first to formulate this principle, made it the basis for the general theory of relativity. The principle of equivalence has been established experimentally with very high accuracy. A precise test of the equality of inertial and gravitational masses was first made (1890-1906) by L. Eötvös, who found that the masses coincide with an error of ˜ 10^’8. The error was reduced to 10^-11 by the American physicists R. Dicke, R. Krotkov, and P. Roll in 1959-64 and to 10^-12 by the Soviet physicists V. B. Braginskii and V. I. Panov in 1971.

The principle of equivalence makes possible the most natural determination of the mass of a body, by weighing.

Mass was originally considered (by Newton, for example) to be a measure of the quantity of matter. This definition has clear meaning only for comparison of homogeneous bodies that are constructed of the same material. It emphasizes the additivity of mass—the mass of a body is equal to the sum of the mass of its parts. The mass of a homogeneous body is proportional to its volume; therefore, the concept of density—the mass per unit volume of a body—may be introduced.

In classical physics it was believed that the mass of a body does not change in any processes. The law of conservation of mass (matter), which was discovered by M. V. Lomonosov and A. L. Lavoisier, corresponded to this. In particular, the law asserted that in any chemical reaction the sum of the masses of the initial components is equal to the sum of the masses of the final components.

The concept of mass acquired deeper meaning in the mechanics of Einstein’s special theory of relativity, which considers the motion of bodies (or particles) with very great velocity to be comparable to the speed of light, c ≈ 3 × 10¹⁰ cm/sec. In the new mechanics, which is called relativistic mechanics, the relation between the momentum and velocity of a particle is given by the equation

For low velocities (v « c) this equation becomes the Newtonian relation p = mv. Therefore, the quantity mo is called the rest mass, and the mass m of a moving particle is defined as the proportionality factor between p and v, which is dependent on the velocity:

Keeping in mind this formula in particular, we say that the mass of a particle (body) increases as its velocity. This relativistic increase in the mass of a particle with increased velocity must be taken into account in the design of high-energy particle accelerators. The rest mass m₀ (the mass in a frame of reference that is connected with the particle) is the most important intrinsic characteristic of a particle. All elementary particles have strictly defined values of m₀ that are inherent in the given type of particle.

It should be noted that in relativistic mechanics the definition of mass from equation of motion (2) is not equivalent to the definition of mass as the proportionality factor between the momentum and velocity of a particle, since its acceleration ceases to be parallel to the force that causes it, and the mass is found to be dependent on the direction of the particle’s velocity.

According to the theory of relativity, the mass m of a particle is related to its energy E by the equation

The rest mass determines the internal energy of a particle—its rest energy, E₀ ×m₀c². Thus, energy is always related to mass (and vice versa). Therefore, the laws of conservation of mass and energy do not exist separately (in contrast to classical physics) but are fused into the unified law of conservation of total energy (that is, including the rest energy of the particles). Its approximate division into the law of conservation of energy and the law of conservation of mass is possible only in classical physics, when the particle velocities are low (v « c) and processes of conversion of particles do not take place.

In relativistic mechanics, mass is not an additive characteristic of a body. When two particles are combined, forming a composite stable state, an energy excess ΔE (equal to the binding energy), which corresponds to the mass Δm = ΔE/c², is released in the process. Therefore, the mass of a composite particle is less by the quantity ΔE/c² than the sum of the masses of the particles that form it (the mass defect). This effect is particularly strongly manifested in nuclear reactions. For example, the mass of a deuteron (d) is less than the sum of the mass of a proton (p) and a neutron (n); the mass defect Δm is related to the energy E_γ of the gamma quantum (y) that is produced during the formation of a deuteron: p + n → d + γ, E_y + Δm·c². The mass defect that arises during the formation of a composite particle reflects the natural relation between mass and energy.

The gram is the unit of mass in the cgs system of units and the kilogram in the International System of Units. The mass of atoms and molecules is usually measured in atomic mass units. The mass of elementary particles is commonly expressed either in units of mass of the electron m_e or in energy units, by indicating the rest energy of the corresponding particles. For example, the mass of the electron is 0.511 mega electron volt (MeV); the mass of the proton is 1,836.1 m_e, or 938.2 MeV.

The nature of mass is one of the most important unsolved problems of modern physics. It is commonly assumed that the mass of an elementary particle is determined by the fields associated with it (such as electromagnetic and nuclear fields). However, a quantitative theory of mass has not been developed, nor are there theories that would explain why the masses of elementary particles form a discrete spectrum of values or possible determination of the spectrum.

In astrophysics, the mass of a body that generates a gravitational field determines the gravitational radius of the body, R_g = 2GM/c². Because of gravitational attraction no radiation, including light, can emerge from the surface of a body having a radius R≦R_g. Stars of such dimensions would be invisible; therefore, they are called black holes. Such celestial bodies should play an important role in the universe.

REFERENCES

Jammer, M. Poniatie massy v klassicheskoi i sovremennoifizike. Moscow, 1967. (Translated from English.)
Khaikin, S. E. Fizicheskie osnovy mekhaniki. Moscow, 1963.
Elementarnyi uchebnik fiziki, 7th ed., vol. 1. Edited by G. S. Landsberg. Moscow, 1971.

IA. A. SMORODINSKII

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Mass 

the name of the liturgy used by the Catholic Church.

The components and the order of conducting the mass took shape over the course of many centuries. They became essentially fixed at the Council of Trent (1545–63). The Second Vatican Council (1962–65) made changes in the mass (for example, permitting the service to be conducted in local languages as well as in Latin). The liturgical songs forming an invariable part of a given service make up what is called the ordinary of the mass. They are named after the initial word of each text: Kyrie, Gloria, Credo, Sanctus and Benedictus, and Agnus Dei. Originally, the liturgical songs of the mass were monophonic, based on the Gregorian chant. Later, with the development of polyphony, there appeared polyphonic arrangements of the liturgical music of the mass as well as entire ordinaries of the mass written for the traditional text by just one composer. There was also a distinction made between the high mass (missa solemnis) and the low mass (missa brevis), which consisted as a rule of the first two or three liturgical parts of the ordinary of the mass.

In the Renaissance era the mass was the most monumental of musical genres. Masses were written by J. Dunstable (England), G. Dufay, J. Ockeghem, J. Obrecht, Josquin Depres, and O. de Lassus (the Netherlands), Palestrina, A. Willaert, and G. Gabrieli (Italy), and T. L. de Victoria (Spain). At a later period, classical versions of the mass were composed by J. S. Bach (Mass in B minor), Mozart, Beethoven (two masses, including the Missa Solemnis), L. Cherubini, F. Schubert, F. Liszt, and A. Bruckner. The funeral mass is known as a requiem.

REFERENCES

Bobrovnitskii, I. O proiskhozhdenii i sostave rimsko-katolicheskoi liturgii i otlichii ee ot pravoslavnoi, 4th ed. Kiev, 1873.
Ivanov-Boretskii, M. V. Ocherk istorii messy. Moscow, 1910.
Wagner, P. Geschichte der Messe. Leipzig, 1913.

B. V. LEVIK