General relativity
Einstein field equation
In 1915,Einstein founded an equation which relates gravitational field to spacetime geometry. Accurately,it describes gravitational field with geometric language:
where Rμν is the Ricci curvature, R is the scalar curvature, gμν is the metric tensor, and Tμν is the energy-momentum tensor.
Left side of Eistein field equation describes geometric characteristics,and the right side describes motion of matters.This is also the central result of general relativity.
Summary,general relativity is a theory of gravitational interaction,even describes macroscopic physics.
Summary,general relativity is a theory of gravitational interaction,even describes macroscopic physics.
Black hole
When the star becomes senile and unstable,it will collapse and turn into a black hole.
In fact,black holes are also the celestial bodies expected by general relativity. They have huge gravity even can engulf the light, and the residual light around the black hole form "event horizon ". Inside the event horizon,"singularity" is regarded as the end point of spacetime since it can crash everything.
On the other hand,black hole's characteristics of thermodynamics is also important. For instance,black hole entropy have association with black hole information paradox.Moreover,when the black hole to age and become unstable,it will release Hawking radiation and lose lots of mass before it eliminates and vanishes.
It's worth nothing that black hole has both general relativity and quantum mechanics characteristics,so it's an interesting object to build quantum gravity theory.
In fact,black holes are also the celestial bodies expected by general relativity. They have huge gravity even can engulf the light, and the residual light around the black hole form "event horizon ". Inside the event horizon,"singularity" is regarded as the end point of spacetime since it can crash everything.
On the other hand,black hole's characteristics of thermodynamics is also important. For instance,black hole entropy have association with black hole information paradox.Moreover,when the black hole to age and become unstable,it will release Hawking radiation and lose lots of mass before it eliminates and vanishes.
It's worth nothing that black hole has both general relativity and quantum mechanics characteristics,so it's an interesting object to build quantum gravity theory.