Flat Earth

Or maybe flattened.


Is the main crux of this topic to jab at Flat-Earthers? Just checking that I’m in the right place.



I have yet to see any flat earthers explain why fiber-optic gyros prove the earth is an oblate spheroid. Other than getting in a rocket and having a look FOG gyros are the definitive test.

I work on guidance systems for things that go “whoosh” and “zoom”. The systems use Fiber-optic gyros, 3-axis systems (xyz, for body-oriented coordinate systems). They use an effect called the sagnac effect to measure rotation with great accuracy. The sagnac effect is independent of any gravity effects, path effects, or external electro-mechanical effects.

If I put the system anywhere on the earth I will detect earth-induced rotation in all three axes. (The exception being that if I put the system with one axis aligned exactly east-west then I dont have rotation in one axis). If I tip the system over by 90 degrees the detected rotations flip accordingly. As you move about the earth the amount of rotation seen by each gyro changes, but the rms value of the rotations equals 15 degrees per hour, or the rotation of the earth. This is unambiguous.

Over the course of a year, one would also notice a subtle shift in the gyro measurements equal to about one degree per day. It’s because these particular systems are sensitive enough to also detect the rotation of the earth around the sun. If you take special care one could detect that the rotation is along an elliptical path. That’s important too as flat earthers seem to be okay with the concept of planets going around the sun (after all, that has been observed, lol).

This shows that 1.The earth revolves around the sun and this rotation can be measured with gyroscopes, which lines up with observations. 2. The earth rotates at 15 degrees per hour 3. The xyz components of the rotation differ across the earths surface which would not be possible for a rotating disc, only a rotating sphere.

If you accept that the earth revolves around the sun, and accept that gyroscopes detect and measure rotation then point 1. must also be true. If point 1. is true, it implies that point 2. is true, and thereby point 2.

The sagnac effect can be duplicated using two volunteers who can walk at the same pace, and a carnival merry-go-round. You dont need any complex apparatus. If you dont accept that the sagnac effect is a real thing, then you just dont believe in physics.


Sadness at the consequences. If there’s a jab here it’s at the toxic delusion that’s cost someone their life. We’ll find no schadenfreude here. Just tragedy. Hence the wrath categorization.


Ah, I see. Up until this event I hadn’t really seen any real hurt caused by flat-eartherism. I don’t see too many (any) of them in the navigation community, for good reason. I always took them to be people having a lark. And now here we are.

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I don’t know… but I’m pretty sure that the main crux of this topic does not have anything to do with congratulating and encouraging people who heedlessly dismiss science.

(Hm. Did I just take a jab at Flat-Earthers? :smiling_imp:)

I’m wondering how long it will take to undo the societal damage caused by anti-intellectualism and the people who embrace and promote it. People with these beliefs are not only harming themselves, but also making decisions that can harm the rest of us. When they enlist sympathetic (or opportunistic) policymakers to take actions on their behalf, it’s more difficult to avoid the fallout.



dude built a homemade spaceship in his backyard, climbed inside, and ignited it

was flat earth really his main mistake

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