: the mass of a body exclusive of additional mass the body acquires by its motion according to the theory of relativity
Examples of rest mass in a Sentence
Recent Examples on the WebWhen the temperature of the Universe drops below a certain, critical threshold — a threshold set by the rest mass of each particle — fewer and fewer collisions occur that have enough energy to allow for creation to be a possibility.
Ethan Siegel, Forbes, 2 Sep. 2021 While rest mass energy, gravitational potential energy, and kinetic energy are all concepts that work perfectly well with Newtonian mechanics and gravitation, the idea of gravitation radiation is inherently novel in Einstein’s General Relativity.
Ethan Siegel, Forbes, 5 May 2021 The Higgs symmetry was restored early on, and so none of the Standard Model particles possessed a rest mass prior to that time.
Ethan Siegel, Forbes, 21 Apr. 2021
These example sentences are selected automatically from various online news sources to reflect current usage of the word 'rest mass.' Views expressed in the examples do not represent the opinion of Merriam-Webster or its editors. Send us feedback.