Assertion: photon sphere | /r/HasProperty | possible
Facets:
value: within a photon sphere
type: LOCATION
value: to imagine a photon
type: PURPOSE
Source sentences:
text: Within a photon sphere, it is possible to imagine a photon that's emitted from the back of one's head, orbiting the black hole, only then to be intercepted by the person's eyes, allowing one to see the back of the head.