Curvature of Space

ELI5 - How do we measure the curvature of space?

If space is flat there are 180 degrees in the interior angles of a triangle. Just like if you drew a triangle on a flat sheet of paper.

If space is curved, there will be more or fewer degrees in it like if you drew a triangle on a globe (like two meridians and a line of latitude).

So we need to draw big triangles. We can do that with huge space based lasers. But we can do even better with natural points of light like the cosmic microwave background.

So far, we know the universe is flat to within 0.4%.

By Alex 1 year ago