I realize that some people go to extreme lengths to make themselves believe an unlikely theory, here the flat earth theory.
I have to ask how can nature support a flat slab of mass in space? Simple geophysics proves that this can not be, astronomy shows that objects with a mass like Earth's are all spherical.
Second, at night, you can look up and see the international space station. They have taken many photos of the Earth from up there that show it's spherical. You can claim that NASA is part of some crazy conspiracy but you can look up at night and see the station pass by. That alone should be good enough physical evidence.
Also, if the Earth was really flat, then why are there horizons? If it was flat we should be able to see for hundreds of miles, but we can only see for about 20 because of the curvature of the Earth.