The universe is flat. But there's a lot of subtlety packed into that innocent-looking statement.
What does it mean for a 3D object to be "flat"?
How do we measure the shape of the universe anyway? Since the universe is flat, is that…it? Is there anything else interesting to say?
Read all the story here: https://www.space.com/34928-the-universe-is-flat-now-what.html