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Topic:
General relativity question
Replies:
4
Last Post:
Nov 7, 2012 8:01 AM




General relativity question
Posted:
Nov 4, 2012 12:28 PM


I can't say I fully understand general relativity, however, one question keeps bothering me . Consider a four dimensional pseudoriemanian manifold . It has a unique Einstein tensor ,that is divergenceless, therefore can be equivalated to a stressenergy tensor . All well and good . However , I keep hearing about this "block universe" concept . At least in Newtonian mechanics , one infinitesimal "slice" of space time is sufficient to determine both the future and past evolution of the space time . However , one threedimensional (infinitesimally 'thick' in the fourth dimension as to contain momentum information) slice of an arbitrary four dimensional manifold is certainly not sufficient to determine the whole manifold . And it is the whole manifold that determines the matterenergy content . It seems to me, the Einstein field equations leave way to many degrees of freedom for a 'block universe' ) . Is there something I'm missing? Some misinterpretation , or some extra constrains on the "universe manifold" or the StressEnergy tensor?



