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atyy
#2
Nov17-11, 06:25 AM
Sci Advisor
P: 8,394
GR as a 4D geometrical theory involves equations that relate the 4D spacetime metric and matter.

GR can be reformulated as a 3D theory with time evolution, provided spacetime topology isn't weird. The lapse is a function that appears in the 3+1 version. http://arxiv.org/abs/gr-qc/0703035