• Question: is the universe infinite in spacial extent?

    Asked by maxsmith1 to Arttu, Ceri, James_M, Monica, Philip on 13 Jun 2011. This question was also asked by danniegee, littlebopepe, jenni1, hamzah, rubyvioletbrown.
    • Photo: Arttu Rajantie

      Arttu Rajantie answered on 13 Jun 2011:

      That is an intriguing question, but unfortunately the answer is simply that we do not know. Even if it is infinite, we can only observe a finite part of it, because light moves at a finite speed. When we look at distant objects on the sky, we are also looking into the past. Therefore we cannot see further than roughly 50 billion light years away, because we are already looking at the Big Bang. If the universe is bigger than this (as it seems to be), then we cannot tell whether it is finite or infinite.

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