all that dubunkings is... i dont know...
i found only two thinks we can check
1. superzoom photo we can see behind horizon
2. i want to do this, but i need some time and money for this trip.. i can get my Sokkia CX-105 Reflectorless Total station, and do measurment on 5000-6000 miles distance (long trip). On one ocean, from first beach to other, for example San Antonio - Boston, and we will see FLAT or NOT