(SIMPLE, MEASURABLE, REPEATABLE, OBSERVABLE EXPERIMENT)
71% of the earth is made out of water, and the natural physics of water is to find it's level and remain flat, no matter where you go, regardless of your altitude. Especially when it is contained. The water will always follow the flat horizon, it is called horizon because it is horizontal, not curverizon because there's no curvature. You can create an equation for everything, but if you can't prove it in reality that's called pseudoscience, but if something can be proven easily by any observable, repeatable and measurable evidence, then it's real science.
"The horizon always appears perfectly flat 360° degrees around the observer regardless of altitude. All amateur balloon, rocket, plane and drone footage show a completely flat horizon over 20+ miles high. Only NASA and other government “space agencies” show curvature in their fake CGI photos/videos. The horizon always rises to the eye level of the observer as altitude is gained, so you never have to look down to see it. If Earth were in fact a globe, no matter how large, as you ascended the horizon would stay fixed and the observer / camera would have to tilt looking down further and further to see it.
The natural physics of water is to find and maintain its level. If Earth were a giant sphere tilted, wobbling and hurdling through infinite space then truly flat, consistently level surfaces would not exist here. But since Earth is in fact an extended flat plane, this fundamental physical property of fluids finding and remaining level is consistent with experience and common sense." - Eric Dubay