>>3205729 (lb)

FWIW, the problem with the horizon "proof" is that you can only see a certain distance, say 25m. You see that 25m in a curve, not in a flat line, i.e., if the coastline were straight, you're not seeing 25m offshore at every point; you're seeing 25m from your point of origin. When you trace that curve on a globe you get... a straight line.