[abhashanand1501]

>In spherical geometry, the interior angles of a triangle add up to more than π. And in fact you can determine the area of a spherical triangle by how much the angle sum exceeds π. On a sphere of radius 1, the area equals the triangle excess

To all the flat earthers out there, this property can be used to find out earth is not flat, just by drawing a giant triangle on the surface, without leaving the earth. Historically, to prove the earth is round, people have relied on the sun shining directly overhead on wells in different cities. But this approach proves it without the need to refer the sun.

[lwansbrough]

Once you internalize that flat-Earther-ism isn’t about the Earth being flat you realize that rational arguments are pointless.

To expand on that, it’s about community and finding people who share your interests. The movie Behind The Curve explores this idea and it’s quite revealing.

[thomasahle]

A bunch of flat-earthers went to Antarctica to see if the midnight sun was real. Turns out it was.

Jeran from Behind The Curve was one of the ones to flip, and since then, he's been making videos on how the earth is actually round.

He has a lot of thoughts on what it actually takes to convince other flat-earthers. I found it somewhat interesting: https://www.youtube.com/watch?v=1grMf17PeEk

[QuadrupleA]

And the ego boost of it all - being one of the special few who sees "the truth" that others are too brainwashed/dumb/whatever to see. Makes one feel quite important.

[lordnacho]

Indeed, this might be why religion seems so odd to outsiders.

It's implausible, yet that's what stimulates the tribal feelings among the believers.

[kakacik]

Those are the simple cows to be milked, but numerous 'gurus' in these communities are very well aware of the bullshit they propagate to the weak and gullible, but its just such an easy noncritical prey. You can always just go deeper in paranoia.

Makes me think that mr trump switched from being democrat to republican and pushed for magaesque folks who often love him to the death due to very similar principle - just spit out some populist crap that stirs core emotions - the worse the better, make them feel victim, find easy target to blame which can't defend themselves well (immigrants), add some conspiracy (of which he is actually part of as wall street billionaire).

Extreme left wouldn't swallow easily that ridiculous mix from nepotic billionaire who managed to bankrupt casinos and avoided military duty (on top of some proper hebephilia with his close friend mr E and who knows what else).

But what do I know, just an outside observer, but nobody around the world has umbrella thick enough that this crap doesn't eventually fall on them too.

[immibis]

I think Trump's just been running a simple popularity-seeking loop for a while. Do a thing; if his people like it, do it more; otherwise do it less.

I've heard that even Hitler was like this: that he didn't start out hating Jews, but repeatedly reacted to the fact that he got louder cheers whenever he blamed things on Jews. But I don't know how to verify if this is true.

[theoreticalmal]

The feedback response post is true, but specifically about Jews is not true. He hated Jews long before he rose anywhere near power

[dnemmers]

Hitler was enthralled by Henry Ford, and copied what he learned about anti-semitism.

https://www.thehistoryreader.com/historical-figures/hitlers-...

[zahlman]

What could be expected to be the "shared interests" of a community of people organized around supposedly believing something that they aren't actually about believing?

[teiferer]

It's since being replaced by similar isms like climate change hoax-ism. Very similar way of arguing, dealing with contradicting evidence and seeing a conspiracy whenever a large body of scientists has a consensus.

Unfortunately, the climate change deniers in all their forms have made it much further by having support in politics and having a real impact on people's lives. In contrast to flat earthers.

Just the mere fact that my post here could be interpreted as political (which it really isn't) is evidence of this.

[fooker]

It's more about discrediting conspiracy theories to shift the Overton window so the real ones with the flavor of 'the government is spying on you' also seems crazy to most people.

[fluoridation]

>Historically, to prove the earth is round, people have relied on the sun shining directly overhead on wells in different cities.

That wasn't to prove the Earth is round (and it doesn't prove it). Eratosthenes assumed two things when he performed his experiment: 1) the Earth is round, and 2) the Sun is an infinite distance away. By just this experiment he would have been unable to distinguish between this situation and the Earth being flat while the Sun being only a finite distance overhead (and in fact a fair bit closer than it actually is). Eratosthenes and his contemporaries were already convinced of the roundness of the planet, and he simply wanted to measure it.

>But this approach proves it without the need to refer the sun.

A flat-earther would just tell you that you're not able to maintain a straight path over such long distances without relying on external guides that would definitely put you on curved paths. If the Earth is flat and you stand at 0 N 0 E, how do you move in a straight line East of there? I.e. continuously moving towards the South because the polar coordinates curve towards your left as you progress.

[roywiggins]

>the Earth is flat and you stand at 0 N 0 E, how do you move in a straight line East of there?

This is something that was more or less solved a long time ago with surveying instruments. You don't have to move in a straight line, you build triangles out of sight lines.

[fluoridation]

I can kinda see how that would work, but it presents the challenge that whatever route you plan, it cannot go over water for more than a few kilometers.

[roywiggins]

I don't think it would be that different than the arc measurements that were actually done, you triangulate a bunch of points to work out distances and angle sufficiently precisely:

https://en.wikipedia.org/wiki/Arc_measurement

[fluoridation]

That doesn't help you if you're moving West to East, though.

EDIT: Also, that's to measure distance, not direction.

[roywiggins]

You can survey West to East just as well:

https://www.noaa.gov/digital-collections/collections/4774/it...

https://amerisurv.com/2012/10/27/the-longest-line/

And measurements of, say, very precise equilateral triangles, necessarily imply certain interior angles, which you can compare to the actual angles they make. For instance, on a flat plane, you can fit six equilateral triangles sharing one point to make a hexagon. On a sphere if you make them big enough you'll find that they don't quite fit.

[teo_zero]

> A flat-earther would just tell you that you're not able to maintain a straight path over such long distances without relying on external guides that would definitely put you on curved paths.

Do flat-earther reject the existence of LASER, too?

[fluoridation]

Flat-earthers don't accept that a flat plane implies infinite line of sight (especially at sea), so who knows.

[themafia]

> relied on the sun shining directly overhead on wells in different cities.

It was just one city actually. The critical piece is that the city's northern latitude was nearly identical to the Earth's angle of axial tilt. Which also means that this shadow phenomenon only occurs during the Summer Solstice.

https://www.khanacademy.org/science/shs-physical-science/x04...

[schobi]

This sounds more like a Matt Parker video idea - get a bunch of people, three theodolites to measure angles accurately, a good location and start measuring angles for line of sight and see how well this determines the earth's radius.

Rough estimate - with an excellent 0.5" angular resolution and 35km triangle this could work.

[Sharlin]

As they say, you can't reason someone out of something they didn't reason themselves into in the first place.

[thaumasiotes]

> But this approach proves it without the need to refer the sun.

Only if you're happy "proving" your argument to an audience that never had any doubts. You can't use this argument to prove the earth is not flat over the objections of your audience because you can never convincingly show that any given line is straight.

[taneq]

It also means that pi could be equal to 3 if you world is small enough.

[amelius]

No, you're talking about a hologram. Everything is flat.

https://en.wikipedia.org/wiki/Holographic_principle