Carl Sagan: How the circumference of the Earth was calculated using only sticks, eyes, feet, and brains

Originally published at: Carl Sagan: How the circumference of the Earth was calculated using only sticks, eyes, feet, and brains | Boing Boing


Waiting for the flat-earthers to show up on the comments.

Awkward Season 4 GIF by The Office



One of my guilty pleasures on YouTube is flat earth debunkers (e.g. SciManDan, MC Toon, Wolfie6020, Dave McKeegan and his chill AF springer spaniel, et al). I get to see all the absolutely nutso flat earth “proofs” without actually giving them any monetized views, AND I get to see those “proofs” expertly and often humourously dismantled.

I’ve legitimately learned a bunch about optics, gravity, orbital mechanics, tidal locking, etc.

For example, did you know it’s possible to prove the Earth is an oblate spheroid from 19th century survey data? Well, it is: each of the thousands of triangles surveyed have internal angles that sum to a little more than 180°, which is only possible with geometry on a sphere.


But the pyramids totally HAD to be built by aliens because ancient people could only be smart if their skin was light enough…:thinking:


I’m getting old. Cosmos was one of my favorite TV series growing up. This particular sequence is still engraved in my memory.


This is a great reminder that our ancient ancestors were fucking smart, just like us. We all have the same brains (not nearly enough time separates us for any evolutionary pressures to have acted there). The only reason we know more than them is because we’re standing on their shoulders, and the many giants who came after them.


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Missing a turtle and a few elephants there

:elephant: :elephant: :elephant: :elephant:



Well of course it’s flat, how else would it balanced on the back of a turtle?


Ahhh, Sir Terence of Pratchett, so sorely missed. Met him a number of times at book signings; at the first one, in WHSmith in my home town, I took a rucksack full of his books, mostly hardcover copies, and his shoulders visibly slumped as I was taking them out. Bless him, he personalised all of them apart from the first three that were paperbacks. I’m also lucky enough to have a first edition of Good Omens, signed by Neil and Sir Terry; inside, Terry wrote ‘Neil made me do it!’, which made Neil laugh out loud.
The world is a lesser place without him.


I started re-watching Cosmos again (thanks youtube), and unlock SO MANY core memories.

It’s really, really good. Still.


I think Maestro taught me that a long time ago.


This is why, when I ran conventions, we had a very hard and fast “you get 3 books signed then you got to the back of the queue” rule. The authors loved it as more people got books signed that way.


Completely Off-Topic:

I wonder if Hugo Weaving was channeling Carl Sagan when he played Agent Smith in ‘The Matrix’? Agent Smith’s speech patterns in that movie really sounds like Carl Sagan’s delivery in this video.

The main thing to take away is that our ancestor would start this experiments like this:
“I believe X to be true/false, can I find out which one it really is?”

Now a lot of people today start these experiments with:
“I believe X to be true and will try my hardest to find ways to convince other people that it is so”

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Sadly most people have always been this way. It’s a lower-effort pattern of thought so it’s the one we all default to most of the time. Now we have social media to make the worst of those people louder, but they were always there.


I don’t exactly believe that’s a valid assumption.

For every Eratosthenes there were likely hundreds of people who would work the other way.

i think social media of the day was probably church.

extra time spent trying to look good, check. amplification of fringe voices, check. public posts shaming ne’er-do-wells… and heck their posts were made of wood :smiley_cat: