Abstract Domenico Giulini

Time from Space 

Abstract:
General Relativity is a theory of spacetime and its metric properties in relation to matter. As such, its basic equations need not be in the form of evolution equations; spacetime simply is, it does not evolve. However, the theory allows to be recast into such a form, where evolution takes place in the set of all possible configurations of 'instants'. An 'instant' in spacetime is an entire 3-dimensional hypersurface. Its possible configurations comprise all its geometries. Hence evolution takes place in the space of all 3-dimensional geometries, called Superspace, which is a space that itself carries a geometry imposed on it by the laws of motion according to General Relativity (kinetic-energy metric). The notion of distance on Superpsace relates to the notion of duration (proper time) that a physical system measures in spacetime
in an intriguingly simple fashion. Also, there is a conjecture according to which a single instant (3-geometry) precisely 'knows' its place in spacetime.

I will end my talk by asking what else one could hope for - given that the conjecture were true.