Concept
Mass
Overview
In physics, mass is an intrinsic positive physical quantity of a body, which measures its resistance to acceleration. In modern physics, it is generally defined as the strength of an object's gravitational attraction to other bodies — as measured by an observer moving along at the same speed. The unit of mass in the International System of Units (SI) is the kilogram (kg). Since 1905, mass can also be understood as a measure of the energy content of a body (see E=mc²).
Mass can be experimentally defined as a measure of the body's inertia, meaning the resistance to acceleration (change of velocity) when a net force is applied.
In physics, mass is not the same as weight, even though mass is often determined by measuring the object's weight using a spring scale, rather than balance scale comparing it directly with known masses. An object on the Moon would weigh less than it does on Earth because of the lower gravity, but it would still have the same mass. This is because weight is a force, while mass is the property that (along with gravity) determines the strength of this force.
In the Standard Model of physics, the mass of elementary particles is believed to be a result of their coupling with the Higgs boson in what is known as the Brout–Englert–Higgs mechanism.
Overview adapted from Wikipedia (CC BY-SA 4.0; see the article history for authors).
In the original texts
Passages from public-domain books where Mass is discussed.
In addition to all this, this dragon's tail, [I mean] the Mass, has begotten a numerous vermin-brood of manifold idolatries. First, purgatory. Here they carried their trade into purgatory by masses for souls, and vigils, and weekly, monthly, and yearly celebrations of obsequies, and finally by the Common Week and All Souls Day, by soul-baths so that the Mass is used almost alone for the dead, although Christ has…
Martin Luther, The Smalcald Articles
names the idea; a chapter is titled for it; states what it is; opens on it
For theoretical purposes, a mass is defined as being determined by the amount of force required to produce a given acceleration: The more massive a body is, the greater will be the force required to alter its velocity by a given amount in a given time. It takes a more powerful engine to make a long train attain a speed of ten miles an hour at the end of the first half-minute, than it does to make a short train do so.
Bertrand Russell, The A B C of Relativity
names the idea; a chapter is titled for it; states what it is; opens on it
[Sidenote: The Testament ignored] 18. I fear, therefore, that there is at present more idolatry in Christendom through the masses than ever occurred among the Jews. For we hear nowhere that the mass is directed toward the feeding and strengthening of faith, for which alone it was ordained by Christ, but is only used as a sacrament without the testament.
Martin Luther, Works of Martin Luther, with Introductions and Notes
names the idea; states what it is; opens on it
The rich cannot feel it, either as a support to dignity or as security to fortune: for the aristocratic mass is generated from purely democratic principles; and the prevalence given to it in the general representation has no sort of reference to or connection with the persons upon account of whose property this superiority of the mass is established. If the contrivers of this scheme meant any sort of favor to the…
Edmund Burke, The Works of the Right Honourable Edmund Burke, Vol. 03
names the idea; states what it is; opens on it
We might even suppose that apart from electrons of the two signs, there are neutral atoms which have only their real mass. In this case, mechanics is not affected; there is no need of touching its laws; the real mass is constant; simply, motions are deranged by the effects of self-induction, as has always been known; moreover, these perturbations are almost negligible, except for the negative electrons which, not…
Henri Poincaré, The Foundations of Science
names the idea; states what it is; opens on it
Philosophers who discussed Mass
Related ideas
- Force
- Elementary particle
- General relativity
- Imaginary number
- Isaac Newton
- If and only if
- Johannes Kepler
- Gravitational field
- Moon
- Classical mechanics
- Theoretical physics
- Maxwell's equations
- Momentum
- Velocity
- Quantum
- Real number
- Physics
- Particle physics
- Newton's law of universal gravitation
- Quantum field theory
- Sun
- Solar System
- Special relativity
- Galileo Galilei
Place in the tradition
Part of Naturalism (philosophy).