The definition of mass as a measurement of the quantity of matter goes back to Newton's Principia, which was enough for a long time. It underwent a long sequence of modifications as classical mechanics evolved, but also to cope with the conceptual changes introduced by Special Relativity firstly and Quantum Mechanics after. The concept of mass is firmly bound to the theory we use for the dynamics. The cited definition mixes in an uncontrolled way different concepts. So, staying at small velocities with a body, its constant $m$ plays the same role as in classical physics in the law used to define it. It turns out that there is a positive constant $m$, called the mass of the body, associated to our body and a second positive constant $m'$ associated to the other body interacting with the former, such that the vector Let us consider first the case of two-body interactions, assuming that the two bodies do not interact with anything except possibly each other. We consider a body and we make it interact with other bodies, describing what happens with respect to an inertial reference frame. Let us refer to bodies whose interactions are local (essentially contact interactions with some generalisation). What it is really necessary is just the law of conservation if total momentum. I will explicitly avoid to introduce the notion of force because, in my view, it makes the discussion even more complicated and it is by no means necessary (the notion of force is quite subtle and its use would open a number of related issues really unnecessary). Mach when replacing velocities with accelerations. There, in classical mechanics, the mass can be defined as follows, with an argument which can be traced back to E. More at mission.The issue is a bit tangled because the notion of mass in relativity historically relies upon the notion of mass in classical physics. Compare Dutch mis (“mass"), German Messe (“mass"), Danish messe (“mass"), Icelandic messa (“mass"). The scientific sense is from 1687 (as Latin massa) in the works of Isaac Newton, with the first English use (as mass) occurring in 1704.įrom Middle English masse, from Old English mæsse (“the mass, church festival"), from Vulgar Latin * messa, from Late Latin missa, noun use of feminine past participle of classical Latin mittere (“to send"). The sense of "a large number or quantity" arises circa 1580. The Greek noun is derived from the verb μάσσω (mássō, “to knead"), ultimately from a Proto-Indo-European *mag'- (“to oil, knead"). In late Middle English (circa 1400) as masse in the sense of "lump, quantity of matter", from Anglo-Norman masse, in Old French attested from the 11th century, via late Latin massa (“lump, dough"), from Ancient Greek μᾶζα (maza, “barley-cake, lump (of dough)"). Compare Christmas, Lammas, Mess a dish, Missal So the word gave the name of Mass to the sacrifice in the Catholic Church. At its close the same words were said to those who remained. Then they were dismissed with these words: "Ite, missa est", the congregation is dismissed. In the ancient churches, the public services at which the catechumens were permitted to be present were called missa catechumenorum, ending with the reading of the Gospel. Late Latin missa, from Latin mittere, missum, to send, dismiss: compare French messe. From Old English masse, messe, Old English mæsse.
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