Monday, September 15, 2014

quantum field theory - Is space-time a special form of energy?


I know space-time can be influenced by matter and energy, so it must be somehow mingled in with the mix of it all, but does space-time have a fundamental particle? Can we make a little bit of space-time with enough energy? Might the Planck length & time quantize space-time?




Answer



The Einstein field equations relate matter to the deformation of spacetime, i.e.


Rμν12gμνRgeometry=8πGTμνmatter


However, Tμν=0 does not imply a trivial solution. A non-trivial solution such as the Schwarzschild metric which describes a spherical body, e.g. a black hole is a solution for a totally vanishing stress-energy tensor. However, as indicated in another answer, we may associate a mass to the solution,


M=R2G


in natural untis where R is the Schwarzschild radius (distance from the center to the event horizon) and G is the four-dimensional gravitational constant. As expected, in the limit M0 gμν reduces to,


ds2=dt2dx2dy2dz2


which is flat (Rabcd=0) Minkowski spacetime, as expected.






Does spacetime have a fundamental particle?



Spacetime itself is a manifold, and we do not associate a particle which literally comprises spacetime. However, the graviton is a gauge boson of spin 2 which is believed to act as the mediator of gravitation which is represented or interpreted as the deformation of spacetime.


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