Say i wanna do an experiment to prove the earth is flat. I remember when i touched the wires of my fathers piano, i guess that was steel and really tightly stretched. If i want to stretch a wire over a mile long over water. And have it really well stretched… What material would i use? What forces would be necessary? Is this feasible? The plan is to have the wire at the beginning just on the waters surface, and at the end aswell. Now if the earth has curvature then, if the wire is one mile long, …