What is Schwarzschild radius?
The '''Schwarzschild radius''' (sometimes erroneously referred to as the '''gravitational radius'''), is the [[radius]] of a [[sphere]] that has certain properties: If all the [[mass]] of an object is compressed within this sphere, the [[escape velocity|escape speed]] from the surface of the sphere would equal the [[speed of light]]. An example of an object smaller than its Schwarzschild radius is a [[black hole]]. Once a [[compact star|stellar remnant]] collapses below this radius, light can no longer escape and the object is no longer visible.<ref>Chaisson, Eric, and S. McMillan. Astronomy Today. San Francisco, CA: Pearson / Addison Wesley, 2008. Print.</ref> It is a characteristic radius associated with every quantity of mass. The ''Schwarzschild radius'' was named after the [[Germany|German]] astronomer [[Karl Schwarzschild]] who calculated this exact solution for the theory of [[general relativity]] in 1916. This radius can be calculated using the equation: <math>r_{s} = rac{2 G M}{c^2}</math> where the [[gravitational constant]] G is {{val|6.67430|e=-11}} N⋅m<sup>2</sup>/kg<sup>2</sup>, M is the mass of the object, and c is the [[speed of light]] which is 299,792,458 m/s. == Derivation == The Schwarzschild radius<ref>https://vixra.org/pdf/1512.0496v1.pdf</ref> is found within the [[Schwarzschild metric]], and originally was used to describe the gravitational field around a black hole, given the assumptions that it is [[spherical]], non-[[rotating]], without a [[magnetic field]], and that the [[cosmological constant]] is zero; (it describes the path of a particle moving through this [[spacetime]]) however, this radius can be calculated for any object. ==References== {{reflist}} ==Relatted pages== *[[Event horizon]] [[Category:Relativity]] [[Category:Astrophysics]] {{physics-stub}}