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I read a book a long time ago (Poetry of the Universe: A Mathematical Exploration of the Cosmos, by Robert Osserman) about the shape of the universe. In it he

I read a book a long time ago (Poetry of the Universe: A Mathematical Exploration of the Cosmos, by Robert Osserman) about the shape of the universe. In it he talks about quasars. If you observe 2 of them in opposite directions, each 13 billions light years from earth, then they must be 26 billion light years from each other. But the universe is only a little less than 14 billion years old so how can this be? He argues that the universe must be a hypersphere. I read this more than 20 years ago, and I'm no cosmologist, so forgive me if I butchered that summary.

YayamiOmate 7y ago
But that's not the only explanation. If you strech space in each direction you get the same effect. If you have a baloon with a band attached to two opposite points on it's surface and blow the ballon, the distance between points (the band length) on the surface will change 2 times as the distance from the middle. Moreover, if you place some markers on the band the distance between them will also strech. You get that effect in plain Euclidean 3d space. It's not that surprising even for nice orthogonal geometry.