closed trapped surface

closed trapped surface

[¦klōzd ¦trapt ′sər·fəs]
(relativity)
A compact spacelike two-surface in space-time such that outgoing null rays perpendicular to the surface are not expanding.
References in periodicals archive ?
The first key insight was that closed trapped surfaces, discovered by Roger Penrose in the black hole case, would occur in a time reversed sense in cosmology; and the second was that one could show such closed trapped surfaces would exist because of the existence of the cosmic microwave blackbody radiation.