No one who is familiar with my posting history will be surprised that I have thought quite a bit about the idea of an infinite multiverse. For example, I ask myself if, in an infinite multiverse, there would be a universe at an infinite distance from ours.

My answer has to be “yes”. In fact there must be an infinite number of them.

I then ask if, in principle, I could travel to such a universe. Yes, if it’s there I must, in principle, be able to go there. Unless, of course, the other universes occupy “dimensions” to which we have no access; but, in that case, in what sense can this be considered a multiverse?

If I go there, will I have reached infinity? No, because there will still be universes beyond that, on the same straight line; at least one of which will be infinitely far away.

There’s more!

Not only do we perceive our Universe as being at the centre of this infinite lot of universes; we must physically be at the centre, because universes go to infinity in every direction. The trouble is that every other universe is at the centre.

When, some time ago, we talked of a similar situation involving an infinity of nothing, it was simpler because there is no movement relative to nothing. Now, we have movement relative to universes. However, this is still not motion relative to the infinite multiverse. Where ever we go, we are still at the centre.

Does this begin to sound ridiculous? I think it does. Undoubtedly one could resort to mathematical infinities to find a way round this, but I feel that’s just papering over the cracks.

One could always argue that, outside of maths, infinity is a philosophical concept, and that may well be true, but that must call into question the validity of using the infinite multiverse in physical arguments.