One of my co-workers is a FLAT Earth believer. I have tried all kinds of logic and facts to disprove his belief. He is not the sharpest knife in the drawer so trying to explain Gravity, atmosphere moving with Earth, etc is difficult. I have read the threads trying to explain if pilots make adjustments for curvature. Answers/explanations are all over the place...

What I need is a very uncomplicated explanation as to how a plane tracks along with the curvature of the Earth WITHOUT pilot making adjustments.

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    $\begingroup$ Could you try and prove it to him in a different way? For example, if you have the sea close to you with bigger ships visible, you can quite literally see the bigger ships "sink" into the horizon due to the curvature of the earth. $\endgroup$ – JustSid Oct 26 '16 at 16:31
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    $\begingroup$ You might have better luck with the answers over here: What is the simplest way to prove the Earth is round? $\endgroup$ – voretaq7 Oct 26 '16 at 16:50
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    $\begingroup$ Related $\endgroup$ – Pondlife Oct 26 '16 at 16:55
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    $\begingroup$ @Pondlife I would almost consider that a duplicate, but a flat-Earther would reject the premise of the 8-inch-per-mile drop because they reject the premise that the surface of the Earth is, in fact, the curved surface of a spheroid. $\endgroup$ – voretaq7 Oct 26 '16 at 16:59
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    $\begingroup$ Give up. I have come across these people before. They make moon-landing deniers look smart. Never argue with an idiot. They will drag you down to their level then beat you with experience. Nothing you say, do, experiment with or draw, will change this persons mind. Even if you could somehow put them into orbit so they can see with their own eyes, they would twitter on about fisheye distortion in the windows, mind altering drugs pumped into the air etc. They will invent a new explanation for why anything you say is wrong. Voting to close. $\endgroup$ – Simon Oct 26 '16 at 18:25

Nothing you say can convince this person that the Earth is round. You need to show him.

Find a hill that is a few hundred feet high. One of you stands at the top, the other at the bottom and observe the sunset. You will, of course, be accompanied by a trusted flat-earth friend of his to validate your observations.

Each person will note the time that the sun disappears below the horizon. Your times will be different. You can even use math to calculate the expected time delta if you really want to drive your point home. The higher the mountain, the greater the time delta. Also, if you're at the top, you can flash him with a mirror to prove that you can still view the sun. Be careful though...this might blow his mind.

This is a direct observation of the curvature of the Earth. A rational person will accept this as proof of a curved surface. An irrational bozo will continue to offer absurd theories. Please let us know how your friend responds.

  • $\begingroup$ "the sun disappears below the horizon", it just proves the Sun orbits around the Earth. $\endgroup$ – mins Oct 26 '16 at 20:31
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    $\begingroup$ If you can predict the time delta based on a calculation predicated on the known curvature of the earth, a person can't conclude anything other than that the earth is indeed round. If a person wants to start questioning the particulars like our distance from the sun or speed of rotation then all bets are off. At some point you have to just let stupid people be stupid. $\endgroup$ – acpilot Oct 26 '16 at 20:38

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