The observable universe is larger than you might expect. Much larger.

The observable universe is larger than you might expect.  Much  larger.

The age of the universe is about 13.8 billion years old.  Since nothing can travel through space faster than light, most people would think the universe has a radius of 13.8 billion light years.  But this is not so.

Einstein's speed limit does not apply to the expansion of space itself because space does not possess mass.  Space is expanding faster and faster and it carries the matter contained within it at a rate faster than the speed of light as well because those galaxies are not moving through space but, instead, are riding in it.

The rate of expansion is higher for objects that are farther away from us.  What we call the visible universe is the part of space around us that is expanding more slowly than light speed, but only in relation to us.  That region does appear to have a radius of 13.8 billion light years.  But that's not the whole story.

The matter that looks to be that far is in reality much further now because the expansion of the observable universe has continued while the light was travelling to reach us.

Some might think this means that matter at the visible horizon is disappearing as the space around it breaks light speed and that the light from these distant places can never reach us, ever.  Eventually, all the galaxies we can see now will forever disappear from view.  Space will appear empty. But this is also not true.

Actually, the expansion has always been faster than lightspeed and what we can see is more and more over time. Weird!  Einsteinian cosmology is just as strange as quantum physics.  Watch this video if you dare.

Calculations based on the increasing expansion rate tell us our observable universe is currently about 46.5 billion light years in radius.  Remember that I am describing the observable universe.  The whole universe may well be infinite.

The Big Bang was not like a single explosion.  The Big Bang occurred EVERYWHERE at the same time.  As far as any point in space is concerned, it is the center of the universe because the universe is the expansion of a singularity.  That's right---an infinite and expanding singularity.  Hmm!

EDIT-- Physicists do not think of spatial expansion in terms of the speed of light, but it is convenient here to illustrate the behavior in a way that is easily understood.