We were sat having a picnic in the thin band of trees on the edge of Glasson Moss. I realised that although the band of trees is quite thin, I couldn't see through. In every direction , there was a tree trunk. This is really the opposite of Olber's Paradox, which asks why the sky is black at night. It was based on the idea that the Universe is static and infinite in size. If that were so, says the reasoning, then you'd be able to see a star in any direction you looked. That's like me seeing a tree in any given direction. But of course there isn't a star in any given direction. One explanation now is that the Universe is not infinite in time, so light from more distant galaxies has not had time to reach us yet.
