Dictionary of Space Concepts

Short Definition:

The horizon of a black hole is called event horizon and is an astrophysical phenomenon, which describes the “point of no return” where matter and even light can not cross back according to our understandings of physics. The event horizon is a boundary in spacetime, where the gravitational pull becomes absolute.

Detailed Definition:

The astrophysical phenomenon of the event horizon defines the boundary of spacetime, where the ability of mass to deform spacetime is absolute.

Near this event horizon time seems to work differently, because of gravitational time dilation, which appears to slow down clocks near the horizon more than those farther away and the clock would take an infinite amount of time to reach the black hole in itself.

The huge amounts of gravitational pull causes any light to redshift in a process called gravitational redshift. A clock that is falling into a black hole would change from being visible from an outside perspective, to the light of it red shifting and then finally it would disappear from view and all this in a mere minute. On the contrary an indestructible observer that falls into a black hole would experience time normally and it would fall into the black hole in a finite amount of time.

Etymology:

Black hole  term was coined in astronomy in 1964

Horizon Greekhorizon (kyklos) àboundary

Sample Sentence(s):

From an outside perspective an object falling into the black hole horizon would take an infinite amount of time to reach it.