Yet our discussion here has given me an idea (which is so simple, I’m sure it’s been done).
A right angle triange can be drawn on a sphere (like a globe), and it can have 3 90° angles, when the interior angles of a triangle add up to 180° when depicted on a flat surface.
So, if we have a very large right angle triange, will we see angles that add up to more than 180°? If space is curved?
So, does measuring the angles of a very large triangle tell us if space is flat or curved, and–if curved–how large the Universe actually is?
Like determining the size of a globe by measuring the length of the sides and interior angles of the triangle that’s drawn on it?
Assuming that the Universe is a hypersphere, and not elipsoid or saddle-shaped?