If you unironically have fallen for the flat earth CIA psyop, there is one easy experiment you can do to prove yourselves wrong.
Step 1: buy GPS enabled go-pro
Step 2: buy high altitude capable balloon
Combine the two, watch the balloon go up, track where it lands, watch the footage for yourself and free yourself from Mockingbird bondage.
For a little extra, you can configure a live feed system and watch everything in real time all under your control! Yes, it really is that simple!!!
While funny... That's not really an experiment.
I know... my comments here are in a way simply supportive of you, and making fun of the fact that you even need to post it. Carry on!