Binding energy is the mechanical energy required to disassemble a whole into separate parts.

The Einstein field equations (EFE) or Einstein's equations are a set of 10 equations in Albert Einstein's general theory of relativity which describe the fundamental interaction of gravitation as a result of spacetime being curved by matter and energy

The equivalence principle deals with the equivalence of gravitational and inertial mass, and to Albert Einstein's assertion that the gravitational "force" as experienced locally while standing on a massive body (such as the Earth) is actually the same as the pseudo-force experienced by an observer in a non-inertial (accelerated) frame of reference.

Free fall is any motion of a body where its weight is the only force acting upon it. These conditions produce an inertial trajectory so long as gravity remains the only force.

In the Standard Model of particle physics, the Higgs boson or Higgs particle is a hypothetical elementary particle, a boson, that is the quantum of the Higgs field.

The term inert is used to describe a substance that is not chemically reactive.

Mass change (decrease) in bound systems, particularly atomic nuclei, has also been termed mass defect

Nuclear reprocessing technology was developed to chemically separate and recover fissionable plutonium from irradiated nuclear fuel.

Redshift happens when observed light coming from an object that is moving away is proportionally increased in wavelength, or shifted to the red end of the spectrum. Blueshift occurs when an object is moving towards the observer, and light is then shifted to the blue end of the spectrum.

A frame of reference refers to a coordinate system or set of axes within which to measure the position, orientation, and other properties of objects in it. It may also refer to an observational reference frame tied to the state of motion of an observer.