Resolves once I have the opportunity to view the Earth from space and can confirm the answer directly with my own eyes.
I'll require that we be in orbit or otherwise going "around" the Earth so that I can confirm it's actually a ball and not just a circle. Upper atmosphere or a brief suborbital trajectory is not conclusive.
I'll do my best to ensure that I'm looking through a real window and it couldn't secretly be a TV screen.
If you're in space, all you see is that the earth is round — like a circle, or a pancake. How will you confirm that it is round like a ball?
@Mqrius As we orbit I should be able to see the ball rotate and the continents in my view change as they would on a sphere.
You could also find out by measuring the angles in a large triangle on the Earth's surface.
@tailcalled Infeasible without trusting maps or GPS.
@IsaacKing Just find a mountain that you keep sight of the whole time
@xyz I suspect that triangle would be too small to measure the curvature to a statistically significant level? Not sure though.
Also even with a single reference point, would be challenging to be exact enough.
What if the spaceship has fake windows and shows counterfeit videos of a round Earth instead? Will you require independent auditors to check for that? Or will you leave the spaceship?
@GustavoMafra Hmm. I hadn't considered that! I think if I can inspect the spaceship windows from the outside beforehand, that would be good enough. Leaving it in a spacesuit would be even better though.
In some sense you can confirm the answer with your own eyes today by viewing the Earth from space as captured by various cameras from the past. Though this interpretation would real be torturing the expression.
I presume you mean that you yourself must have the opportunity to be in space.
There’s also a sense in which you do have “the opportunity” to do this today if you’re willing to spend around 20 million, even though you haven’t done it, and that you can confirm the answer with your own eyes by watching ships sail over the horizon
@JimHays Photos can be doctored, and there are other potential explanations for phenomena like objects dissapearing over the horizon. Best to be sure. :)