I have a quandary.

Suppose there is a coin that, when flipped, it lands head’s side up on a table.

Without picking the coin up to confirm the side that is down is tails. Could you ever know that it is tails ?

Assume in this world that the coin has a heads side and tails side when held in your hand.

Assume you cannot view the coin’s two sides in any other way than picking it up.

Is this just a variation of Schrödinger’s Cat ? Or is it more “does a tree make a sound if no one is around to hear it” ?

I am looking for practical ways to prove the Earth is round using materials accessible to the average person. I have zero interest in disproving Flat Earth folks.

I am inspired by Dan Olson's (Folding Ideas) excellent video where he is able to do this measuring the curvature of a lake near his home that has a very specific geography that lends itself to this sort of experiment. I've seen all sorts of ways to prove this measuring shadows and poles, using gyroscopes, etc. and wanted to know if there are any practical guides for proving once and for all that the Earth is round for yourself relying on nothing more than experimentation.

What I'm not looking for:

• Math relying on flight times/charts
• Video/picture evidence
• Deductive proofs built on agreed upon premises
• Expensive tests
• Extremely time consuming projects
• Underwhelming results (relying on a probabilistic argument for a round Earth from the evidence.)

What I am looking for:

• Practical experiments
• Things I could potentially do without spending much money
• Tests that aren't largely comprised of accepting someone else's research
• Potentially math-heavy evidence
• Results that are strong and conclusive

I've thought of finding some easy to test version of Eratosthenes' proof using two poles. I've also thought about using a balloon and sending something to space like what is done in this Tom Scott video. Nothing seems well documented in such a way as for me to be able to follow it at home.

TL;DR: I think it would be a meaningful experience to have the power to prove the Earth is round by myself, for myself. I can only compare this desire to the desire a child with a telescope has when wishing to observe Saturn or Mars themselves for the first time. It's not to prove anything or to settle doubts, but for the personal value of independently observing this astronomical fact oneself.

When I first joined Tildes I posted about weird food combos, with mine being a cheese and tuna omelette (try it! It's protein rich and it works!). Lately I've really been getting into tinned salmon so I thought I'd throw some of that into an omelette along with some chives, wilted spinach and a bit of soft cheese. I figured it'd have an eggs royale vibe to it.

It was... fine? I guess? Not inedible, but not great. Normally I love the soft, chalky bones in tinned salmon because I'm a horrid little goblin but here they were just an unpleasant distraction. 4/10, won't try again. Whether it's something pretty tame and low stakes like mine or a total, unsalvageable disaster, I'd love to hear what didn't work out for you!