[chris (OP)]

I've just been doing this week's science radio phone-in programme, Ask! The Naked Scientists for Talk Radio 702 in South Africa.

Many times people have called in to claim that the Earth is flat. Where on Earth is this gibberish coming from?

I vented my spleen on Twitter, to which one person replied "There are flat-Earthers all around the globe..."

[alancalverd]

Why do people claim the earth is flat? Because it is, Chris.

Use your eyes! Look out of any window in Cambridge and what do you see? Flat, flat, flat, from Norfolk to Essex. Now either Cambridge is the centre of the scientific universe, in which case it is all flat, or it is wholly unexceptional, so by Bayesian statistics, it is efficiently representative of the rest of the world.

[jeffreyH]

I bet their baking skills leave a lot to be desired.

[chris (OP)]

I don't believe it! I come here looking for sympathy and all I get is referred to my window and a culinary joke. Bah. Humbug!

[chiralSPO]

Well, weak jokes are more comfortable than acknowledging the scope and depth of the problems that have lead to unprecedented levels of the rejection of scientifically established fact.

Surprising numbers of otherwise reasonably educated people are willing to ignore or reject what is generally accepted as true, in favor of old disproven theories (like the flat Earth, or the aether, or the geocentric universe, etc.) or new conspiracy theories (chemtrails, vaccines, etc.). I think that what has changed is that now people are able to form or find their own online communities and reinforce each others misconceptions.

[evan_au]

To some degree, everyone believes they are the center of their universe.
To some degree, everyone else is out of sight and out of mind.

It really freaks out people who have lived their whole lives in the Northern Hemisphere when they suddenly come to the realization that to people on the other side of the world (eg Australia or South Africa), Christmas is actually the middle of summer.

It's fun to drop hints and watch it slowly sink in. For some reason, it seems to have the biggest impact on people from the continental USA.

Maybe for people in South Africa, you could drop hints that for yourself, on the other side of the world, Summer is past, and winter is approaching...

[kazbert]

I'm very much inclined to believe that 99% of flat-earthers are just trolls enjoying the attention and enjoying watching people who are taking them too seriously become apoplectic.  The remaining 1% were just never taught critical thinking or geometry.

[chris (OP)]

Maybe for people in South Africa, you could drop hints that for yourself, on the other side of the world, Summer is past, and winter is approaching...

That's a really good point; I'd not thought of highlighting that; brilliant suggestion.

[Janus]

I'm very much inclined to believe that 99% of flat-earthers are just trolls enjoying the attention and enjoying watching people who are taking them too seriously become apoplectic.  The remaining 1% were just never taught critical thinking or geometry.

Sometimes when I run across someone on a discussion board I begin to wonder if they can really be as dense as their posts indicate, and suspect that they are just wanking people's chains.  But some of them just keep at it. Even after the original thread has died off, they come back and try to stat a new thread. I mean, after a while, wouldn't the joke become stale?  The amount and time and effort some of them put into this if they are not earnest in of itself betrays some deep psychological issues.

[Kryptid]

Sometimes when I run across someone on a discussion board I begin to wonder if they can really be as dense as their posts indicate, and suspect that they are just wanking people's chains.  But some of them just keep at it. Even after the original thread has died off, they come back and try to stat a new thread. I mean, after a while, wouldn't the joke become stale?  The amount and time and effort some of them put into this if they are not earnest in of itself betrays some deep psychological issues.

As an ex-troll myself, I have to say that it never did get "old" for me. I found it to be truly hilarious if I was able to make other people angry or flustered by pretending to be stupid. I finally had to convince myself that doing this was genuinely a bad thing so I did manage to stop it. That was back during my college days, many years ago. The best way to deal with a troll is to ignore them. That really does sap all of the fun out of it.

[Bored chemist]

In some cases I'm pretty sure it's just a publicity stunt.
https://www.theguardian.com/music/2016/jan/25/bob-rapper-flat-earth-twitter

[Bogie_smiles]

Clearly they have never seen the moon pass through Earth's shadow. If the Earth was flat, the shadow would give it away, .

[RD]

Clearly they have never seen the moon pass through Earth's shadow. If the Earth was flat, the shadow would give it away, .

If Earth was a giant disc, lunar eclipses wouldn't be much different. 

Pendulums provide proof Earth is not flat : gravity would only act normally in the center of a flat Earth.

[Colin2B]

Clearly they have never seen the moon pass through Earth's shadow. If the Earth was flat, the shadow would give it away, .

Problem is that occurance is quite rare and you would only see a difference if Earth disc seen edge on.
However, if you point to the moon crescent which shows moon is a sphere, you can argue that Earth is most likely a ball.
On the other hand I prefer not to argue with them.

[mrsmith2211]

Next thing ya know, somebody will say flatbread is round, oh the inhumanity of it all.

[evan_au]

If Earth was a giant disc, lunar eclipses wouldn't be much different.

I agree - you can't unambiguously determine the Earth's shape from one eclipse.

But the ancient Greek astronomers pooled knowledge from many eclipses of the Moon. These projected the Earth's shadow from many different directions - and they are all circles.

The only shape whose shadow is a circle from every direction is: a sphere!

[Bogie_smiles]

I've just been doing this week's science radio phone-in programme, Ask! The Naked Scientists for Talk Radio 702 in South Africa.

Many times people have called in to claim that the Earth is flat. Where on Earth is this gibberish coming from?

I vented my spleen on Twitter, to which one person replied "There are flat-Earthers all around the globe..."

I went to see Neil deGrasse Tyson the other night and he asked the same question. He said there was even a go-fund-me page asking for money to support the effort to prove the Earth is flat. Don't know how much they have collected.

[Janus]

If Earth was a giant disc, lunar eclipses wouldn't be much different.

I agree - you can't unambiguously determine the Earth's shape from one eclipse.

But the ancient Greek astronomers pooled knowledge from many eclipses of the Moon. These projected the Earth's shadow from many different directions - and they are all circles.

The only shape whose shadow is a circle from every direction is: a sphere!

I recently saw an argument that tried to use the recent solar eclipse to "prove" the Earth wasn't round.
It went something like this:
Science says that the light from the Sun travel in parallel lines such as shown in this image explaining the seasons of the Earth:


However, during an eclipse it says that it comes in at angle like shown in this image:


Thus they claim that science contradicts itself.

The problems with this argument are twofold:
1) Science doesn't claim that all the rays of light from the Sun are parallel to each other, just nearly parallel. There is ~1/2 degree difference between rays coming from opposite limbs of the Sun, (which is just too small to show in images like the first one)
2) Images like the second one are never drawn to scale in terms of the sizes of the object with respect to the distances between them.  It is just not practical to do so.  For example, if the Earth were represented by a circle 1 inch across, then the Moon would  be a circle ~5/16 in across and 30 inch away, and the Sun would be a circle ~3 yards across and nearly 1000 ft away.  And with this "to scale" image, you would have the nearly parallel Light rays from the Sun producing a total eclipse shadow on the Earth just like the one we see. 

[PmbPhy]

Where on Earth is this gibberish coming from?

Like many beliefs, there's are different reasons held by different sets of people. Recall how many people think that we never landed on the Moon! In fact the Smithsonian quoted some stats on this which showed that about 25% of people around the age 20-24 think the Moon landing was a hoax. I also recall an irritating set of people in a forum who claimed that rockets can't work in space because there's no air to push on. When I tried to explain how Newton's laws imply that rockets can work in space I was either met with silence or met with a demand for hard experimental facts from a source which I had to provide to them etc. I  was basically flamed off the forum for it. The thread was well over 200 posts long and they expected me to read all of them before discussing the subject. Yeah! Right! Like I was going to read 200 posts f stupidity and ignorance. Nope. Homie don't play that.

I'm kidding of course. The real meaning of "Homie don't play that" is somethin that a true gangsta would never do...

See: https://www.urbandictionary.com/define.php?term=homie%20don%27t%20play%20that

My understanding of members of the Flat Earth Society is that they hold that believing modern astronomy means rejecting the Bible, i.e. the flat earth is what the Bible implies. In a special issue of their periodical from 1930 the head of their society at the time, Wilbur Voliva suggested

... do some original thinking before they accept Modern Astronomy as taught in schools, and reject the Bible, the Inspired Word of God.

I recall a seeing a flat earth believer on TV who said something to the effect that since the Bible says that God is up in heaven it must be true that the earth is flat. It was on TV at the time a certain plane was flying around the earth nonstop.

A often reoccurring reason is that certain folks have claimed to have measure the curvature of earth by measuring the surface of bodies of water which they claimed were flat from their measurements. Of course they don't know what they're talking about. Its quite possible to show that the earth is a sphere merely by measuring the distances between a large set of points on the earths surface to other points. Then the metric can be established which will show that the surface of the earth is spherical. I.e. apply geometry to the situation. I think Riemannian geometry works best for this.

To be a flat earther means to stop thinking. I find such people quite irritating. All one needs to do is get o the phone with people who are in different hemispheres and describe what they see. That never happens.

I almost always go to Wikipedia when discussing things like this. See:
https://en.wikipedia.org/wiki/Flat_Earth

In my philosophy of science course in college we discussed this claim and the flawed reasoning behind it. Some of the flat earth people didn't understand geometry and that was the source of their beliefs. I.e. if you look at a ship with a large sail from a large distance you will see the boat itself start to disappear before the top of the sail does. That's to be expected from observations made on a spherical earth. Yet the flat earth folks hold that the reason they boat disappears is because you're looking at it from a large distance so of course that's what happens. Clearly that was never argued between two people but merely a statement made somewhere. It'd be quite simple to show that such a belief is erroneous.

The book we used and where I read about that is called Science and Unreason by Radner and Radner. Wonderful book!! Everyone should get a copy of it. At the moment Amazon sells a used version for $2.

If anybody would like to read what this books says on the flat earth society then I'd be happy to scan the relevant pages in to a PDF file and post a link to it here.