Black
Hole
A black hole is a region of spacetime where
gravity prevents anything, including light, from
escaping.The theory of general relativity predicts
that a sufficiently compact mass will deform spacetime to form a black hole.
Around a black hole there is a mathematically defined surface called an event
horizon that marks the point of no return. It is called "black"
because it absorbs all the light that hits the horizon, reflecting nothing,
just like a perfect black
body in thermodynamics. Quantum
mechanics predicts
that black holes emit radiation like a black body with a finite temperature. This
temperature is inversely proportional to the mass of the black hole, making it
difficult to observe this radiation for black holes of stellar mass or greater.
Objects whose gravity
field is too
strong for light to escape were first considered in the 18th century by John
Michell and Pierre-Simon Laplace. The first modern solution of
general relativity that would characterize a black hole was found by Karl Schwarzschild in 1916,
although its interpretation as a region of space from which nothing can escape
was not fully appreciated for another four decades. Long considered a
mathematical curiosity, it was during the 1960s that theoretical work showed
black holes were a generic prediction of general relativity. The discovery of neutron
stars sparked
interest in gravitationally collapsed compact objects as a possible astrophysical
reality.
Source: wikipedia, NASA
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