The longest soudwaves from a bell can be no longer than the size of the bell. This has also been measured for the universe – how long are the longest waves in it? Turned out that they were pretty long, but there was a limit.
Further on in the article :
“Despite being finite, the Universe would not have any kind of edge. If a spacecraft blasted off in what we’d perceive to be a straight line – the line a beam of light would follow – it would eventually end up back where it started.
Because of this odd wraparound effect, the light from one galaxy could follow two different routes to the Earth, so the same galaxy would appear in two different parts of the sky. Effectively, the Universe would be like a hall of mirrors, with the wraparound effect producing multiple images of everything inside. ”
Cool! Estimated size: 70 billion light years across.
However, another group of scientists could not prove that the Universe was actually finite. I hope they will never figure it out. 🙂