Response to ‘Local and global definitions of time: Cosmology and quantum theory’

I will discuss the notion of time and spatial finiteness from the perspective of observational cosmology. Our observed universe is well described at early times by small fluctuations in the spatial gravitational field, distributed homogeneously and isotropically on an otherwise smooth background spacetime. The dominant paradigm for an even earlier phase of the evolution of our universe typically generates a space similar to what we observe but with vastly larger spatial extent. Even in a classical theory, the fact that we observe only a finite volume of space and time means that there are statistical uncertainties in testing and constraining the theory. In the absence of evidence that our observable universe is all there is, the cosmological principle suggests that we should consider ourselves to be a typical region of a vastly larger space. I will consider the problems of time and largest spatial scale of the universe from the perspective of accepting an imperfect and incomplete theory on scales currently out of reach of our necessarily imperfect and incomplete observations. The question then is how to work in incremental steps to push for a broader range of understanding.