If you watch this video
http://www.youtube.com/watch?v=zqb1lSdqRZY
you'll see a demonstration of how we know the universe is flat. It has something to do with using the Earth as an apex of a triangle then measuring two points on the cosmis microwave background. I'm assuming they then add the angles of the triangle up to 180 degrees. Well, how do you what the angles of your triangle are? I've seen three tries at attempting to explain this. No one succeeds. There is also something about going around the Earth in a balloon in Antartica and I don't see why that is necessary.

Question

If you watch this video
http://www.youtube.com/watch?v=zqb1lSdqRZY
you'll see a demonstration of how we know the universe is flat.  It has something to do with using the Earth as an apex of a triangle then measuring two points on the cosmis microwave background.  I'm assuming they then add the angles of the triangle up to 180 degrees.  Well, how do you what the angles of your triangle are?  I've seen three tries at attempting to explain this.  No one succeeds.  There is also something about going around the Earth in a balloon in Antartica and I don't see why that is necessary.