tl;dr This is the result of a thought experiment regarding the "Flat Earth Conspiracy" theory. Is it possible to confirm this, oneself, without a lot of traveling or expensive equipment. (There *is* some expense, but it's not ridiculous.) One of the features of our modern world is the Global Positioning System. (You flat Earthers may object to the name but that's what it's called.) I'm sure anyone with a cell phone will concede that GPS exists; even if you've no idea how it works, it can clearly locate your position on a map with a high degree of accuracy. This is - supposedly - done by receiving radio signals from satellites about 11,000 miles high in the sky, traveling in circular orbits around the sphere that is Earth. This wouldn't work with a flat Earth. If you built your own GPS receiver, you'd be able to interpret these signals yourself. You'd need to understand how both the hardware and software work, which is a bit complicated; but you'd see that the radio sources the receiver is listening to have to be certain distances away from you, and moving according to the model of the orbits in the software used to interpret the radio signal. This could possibly be faked - for one position - but move a few dozen yards away and you're essentially triangulating the distance to those transmitters. (You'd need two recievers, and run them both simultaneously, to be *abolutely* sure, but you might not consider that necessary.) ------------------------------- Here is information on how to build a GPS receiver, the pattern for the FPGA and the software to interpret the output: http://www.aholme.co.uk/GPS/Main.htm - [archive link](https://archive.ph/WQ3ok)