I have always recoiled at the concept of the Hubble radius, even though I have accepted the idea that space is expanding. This is because like the electromagnetic field it is seeming more possible by the day the gravitational field is comprised of two components as well, spatial curvature and spatial expansion.

After all how Einstein jumped from Newton was first realizing the force of gravity can be completely replaced by an accelerated reference frame for a small distance and time. Spatial expansion is by definition an accelerated reference frame, expanding slower closer to any large mass and faster the further away from it you go.

There is mounting evidence for the duality of the gravitational field, it can be found in the known duality of the electromagnetic field, the only other similar energy field we know of. Arguably it can be found in galactic rotation curves if you get tired of waiting for magic beans to be discovered, but that’s another story.

For me the Hubble radius has never made sense because somewhere beyond our Hubble radius is another point of view in an infinite universe, and our space isn’t expanding faster than light. Our space looks just like their space. We can say that’s in the future but that’s a weak argument because it’s fundamental assumptions lay on yet unproven theories. Leading theories yes, good theories sure, but unproven none the less.

The symmetry between time and space cannot be overstated, they are, quite literally, the same thing. To say that space is infinite but time is finite is counterintuitive and decidedly a human point of view when considered in this context, but ours is to follow where the evidence leads not where we think it should lead.

The best studies show space consistent with either static expansion or accelerated expansion, and the evidence is both circumstantial and hypothetical, I sometimes wonder if we shouldn’t explain these concepts simply as concepts rather than as reality, because we don’t know yet for certain if we are right…