How big is the universe?

[Alex K]

One source says it is 46 billion light years across. Another source say it's 23 billion light years across.

I try to do the math and there's no way I can think of that the universe could expand that far in less than 14 billion years. It would require particles to travel faster than light at least until very recently, meaning that the universe is slowing down, not accelerating.

Or maybe I'm missing something.

So the visible universe is more like 2 times 46 billion lightyears= ninetysomething billion lightyears across today.

That's squared with the mere 14 billion years of age since the hot big bang when you remember that cosmic expansion has nothing to do with things moving away from each other *in space* like an explosion, but is rather space itself stretching as a whole. I always employ the analogy of snails on a rubber band. If you have two snails sitting at a distance on a rubber band and if you then stretch the rubber, their distance can grow very quickly simply by the band expanding between them, much faster than it could through their own crawling on the band.