Is the Universe Shaped Like a Doughnut?

A doughnut is better at causing the lack of ripples that they see in c m b. And it's got two different length scales, as you say. It's got like, the one way around and the other way around. Whereas a sphere only has one length, or it's just the radius. Even if the universe is curved, we're talking about something very slightly curved. We can't really confidently extrapolate past what we can see.