They say the universe is 14 billion years old and is expanding at the speed of light, so the maximum distance from one point to another cannot be greater than 28 billion light years. Is this true?

Cosmology, eh?

From what I’ve read—and I’m a scientist, but not a cosmologist or particularly gifted with math—we don’t really know what the universe is, yet. We have a lot of elegant theories, some more elegant than others… and oddly, the most elegant ones (holarchism, E8) are often not the most popular. Rather, we rely on conceptually impenetrable and less useful postulations, such as string theory.

But here are some points I’ve gleaned that can, at least, challenge the linear concept of space and time and flat expansion rate that you mentioned.

1) Light speed is not really a constant. It is dependent upon the curvature of spacetime (as put forth by Einstein’s relativity theory).

2) The expansion rate of the universe is, most likely, based on the repulsive power of dark energy, which is poorly understood and not to be confused with dark matter.

3) To quote the luminary Slick Willie, “it depends on what the meaning of ‘is’ is.” If what you mean by the universe is what we’ve seen with the Hubble Space Telescope, then yes, roughly… very roughly… it’s a spheroid in the ballpark of 28 billion light years in diameter. But a few centuries ago, we thought the Earth was the universe, and everything else was “firmament” or “heavens”, perhaps crystal ball-like objects in the near distance. Based on several sequential historical reassessments (upgrades) of our estimation of the size of the universe, it’s a good bet that we’ll figure out that A) there’s a lot more to the universe than what we can perceive with our present lenses and B) there are other universes in the multiverse.

4) Using the word “cannot” or speaking in absolutes (guilty as charged, here) is generally a flag for lack of conceptual discipline. If anything, science has taught us that the universe is messy, somewhat unpredictable though orderly, and full of surprises. Once we figure out that one point is 28 billion light years from another, we’re likely to discover some very strange things if we look a little closer: for one, that the points we’re observing are entangled with, or coexist as, others.

That is all assuming that what we perceive is actually reality and physically exists, which the philosopher in me is not prepared to concede.

Actually, as I understand it, the speed limit set by the speed of light within the universe does not necessarily apply to the expansion of the universe. We tend to think of the expanding universe as having some sort of edge, and this edge being part of the universe, but that’s not the way it works.

Example: let’s say you’re blowing up a balloon made out of really strong latex. The “speed limit” for air within the system would be 20 MPH, or whatever you can pump out of your lungs. But the latex is capable of expanding far faster if you hooked it up to a pump.

The problem with the balloon analogy is that it’s a two-dimensional surface. The universe is expanding in three dimensions: everything is moving away from everything else, more or less. And yes, this means that on a daily basis, objects move further away from us than the speed of light will ever bring information about them to us—which means that from our perspective, they might as well not exist. But they’re still there. Wrap your head around that for a while.

The expansion rate of the universe has not been a constant over it’s lifetime. Different stages of expansion occurred at different rates, particularly the early universe – so it may in fact be much bigger. During the early stages of ‘proto’ universe, several rapid bursts of expansion probably occurred which (due to the chaotic/un-uniform nature of the early universe) could have surpassed our current understanding of the speed of light.

In addition, the speed of light is not constant based on some of the most up to date cosmological models/theories.

Using careful calculations, scientists have calculated the age of the universe to be 13.7 billion years old. which means that two particles of light from the “Big Bang” could be as far apart as 27.4 billion light years (and expanding). This is not the same as saying there is a limit to how far apart two points can be. Just because matter doesn’t exist doesn’t mean dimension doesn’t exist.

And this logic is premised on the assumption the universe started with all matter occupying a central location, which is only the currently most widely accepted theory. There are other scientific possibilities than the Big Bang.