> You can prove the shape of the Earth using thousand year old techniques.
This is a popularly taught misunderstanding.
You can ESTIMATE the diameter of the world ASSUMING it is spherical (only in conjunction with further assumptions) like the ancient Greeks did. But you can’t in any way “prove the shape of the earth” by merely assuming its shape…
You can prove the shape of the Earth using thousand year old techniques.
If you can't, you need to learn some math.
This is a popularly taught misunderstanding.
You can ESTIMATE the diameter of the world ASSUMING it is spherical (only in conjunction with further assumptions) like the ancient Greeks did. But you can’t in any way “prove the shape of the earth” by merely assuming its shape…