Ptolemy and Homer (Simpson)

What Hacker News said

Recommends TheMakeA · 2013-11 · on “Fourier Toy”

These guys are one of the reasons I love mathematics. Check this out too: [this video] Edit: Didn't realize that this was also linked to in another thread on the front page as well.

Recommends JadeNB · 2015-10 · on “Fourier visualised”

I'm only seeing an image, with no explanation, and it took me a while to realise what it was showing; so, in case anyone else is puzzled by it, each image is the sum of the previous one with a new factor (indicated by the "wheels upon wheels"). I think that the reconstruction of Homer Simpson's face (which I think I originally saw thanks to OP ColinWright!) may be a more convincing demonstration of the power of Fourier transforms: [this video] . There's a Nautilus article about it, too: [LINK] (EDIT: and an HN post discussing that: [LINK] ).

Recommends jordigh · 2016-10 · on “Opposition to Galileo was scientific, not just religious”

I tl;dr'ed the article (sorry), but I wanted to say one thing about epicycles. They are not wrong and certainly can be used to explain motion, but the problem with them is that you can keep adding epicycles to fit any continuous orbit at all (this actually is because a Fourier series can converge to any continuous periodic function). This is my favourite visualisation of this fact: [this video]

Cites jordigh · 2015-06 · on “Fourier series”

Huh, so I never though about it this way. The reason you can use epicycles to draw anything is because the trig functions form a complete orthonormal system. Because you can write a Fourier series for any piecewise continuous function, you can also draw Homer Simpson: [this video]

Cites jerf · 2016-06 · on “Why not string theory? Because enough is enough”

The characteristic of metaphorical epicycles is that the make simple, testable predictions that are then wrong , which are fixed with another epicycle. Another more subtle aspect of epicycles, real ones this time, is that they are too powerful and can be used to prove anything. You can predict the motion of the planets with epicycles, it's just that the required series is very long or infinite. And with very long series of cycles, you can "predict" anything: [this video] Thus, one of the problems with epicycles both real and metaphorical is that they are indeed not refutable. Because epicycles can predict anything, they aren't that useful; they exclude far less than meets the eye at first. It isn

Cites mannykannot · 2016-10 · on “Opposition to Galileo was scientific, not just religious”

I cannot edit my post any more , but I can still reply to it, and it seems the answer is yes: [this video] - but you need eccentricity to get the speeds right: [LINK] (10 minutes in.) Furthermore, the result is not equivalent to the heliocentric model because it has many more parameters.

Cites witherk · 2021-03 · on “Intriguing new result from the LHCb experiment at CERN”

If your model has a lot of wiggle room it can be consistent with anything. Maybe the solar system really does move in epicycles [this video]

Cites whatshisface · 2021-10 · on “Is the great neutrino puzzle pointing to multiple missing particles?”

This isn't an elephant but it demonstrates the principle: [this video] Epicycles were originally considered a good idea because it takes exactly two circles to make an ellipse, and Kepler's laws were satisfied by such an ellipse. They were "falsified,", in the two-cycle form, when closer observations revealed that Kepler's laws were not obeyed exactly. At that point, the choice was to either add more epicycles (working your way up to an elephant), or for Newton to discover universal gravitation.