On Wed, 2 Jan 2019 16:31:45 -0000 (UTC), Mike Collins
wrote:

Every point in spacetime is defined by a single coordinate, (x,y,z,t).
Relativity doesn't change that. There is only one surface; the
interior (that is, space in the past) isn't a surface.


But anything you see us already in the past so you are always seeing the
interior. The photons you see are in the present but the object from which
they originated is in the past.

Right. We see nothing in the past. We see the _effects_ of events in
the past. The observation represents an event on the surface of the
Universe (i.e. now) that was caused by an event below the surface
(i.e. in the past).