Black Hole
A region of spacetime where gravitational acceleration is so intense that nothing, including light, can escape beyond its event horizon.
Governing formula
R_s = 2 G M / c²
SI unit
Solar Masses (M_☉) or Kilograms
In depth
Formed when massive stars undergo gravitational collapse at the end of their nuclear burning lifecycle, compressing mass beyond the Schwarzschild radius. General relativity models black holes as pure spacetime curvature terminating at a central gravitational singularity.
Examples in the real world
Sagittarius A*, the 4-million-solar-mass supermassive black hole at the center of the Milky Way galaxy.