spacetimeenergy

Spacetimeenergy is a term used in some theoretical discussions and in science fiction to denote a proposed quantity that measures the energy content associated with the structure of spacetime itself, as distinct from the energy of matter and radiation. In these discussions, spacetimeenergy aims to quantify the energy stored in spacetime curvature and the dynamical gravitational field, and may be treated as a scalar field or as a contribution in a broader energy budget of a system.

In mainstream physics, energy and momentum are described by the stress-energy tensor in general relativity, which sources spacetime curvature via the Einstein field equations. Gravitational energy, however, is notoriously difficult to localize in a coordinate-independent way; global notions such as ADM energy or Bondi energy define the total energy of an isolated system but depend on asymptotic structure. Consequently, a universal local spacetime energy density is not generally accepted in standard theory.

Some speculative approaches or speculative fiction handwaves treat spacetimeenergy as a property of spacetime itself, sometimes linked to vacuum energy, the quantum structure of spacetime, or emergent gravity scenarios. In cosmology, related ideas appear in discussions of dark energy and vacuum energy, which couple to spacetime geometry through the field equations.

Practically, if spacetimeenergy is used, its meaning must be explicitly defined, including how it is computed, its units, and its relation to established quantities like the stress-energy tensor, curvature invariants, or quasi-local energy measures.

See also: stress-energy tensor, Einstein field equations, ADM energy, Bondi energy, gravitational energy, vacuum energy, dark energy, emergent gravity.