Assertion: black hole's surface | /r/HasProperty | defined
Facets:
value: well
type: DEGREE
Source sentences:
text: A black hole has a defined surface known as the “event horizon” which marks the point of no return.
text: A black hole is therefore bounded by a well-defined surface or edge known as the “event horizon”, within which nothing can be seen and nothing can escape, because the necessary escape velocity would equal or exceed the speed of light (a physical impossibility).