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   Andrew (andrewt@mathstodon.xyz)'s status on Monday, 04-Sep-2023 03:14:18 JST Andrew

   in reply to

   • mixed berry social anxiety disorder 🍓

   @monorail a thing I've found after studying physics is it's often really hard, maybe impossible, to say which thing is "why" — if you start from Newtonian mechanics then yeah, conservation of angular momentum is just a neat by-product you can use as a shortcut in these situations, but if you start from quantum mechanics, then angular momentum is fundamental and Newtonian mechanics is a convenient shortcut that falls out of the maths. To properly understand what's happening, sometimes the important thing is that you find the answer that clicks best for you, whether or not it's the "standard" one — I never intuitively understood the angular momentum explanation of precession (why a spinning top stays up) but the linear explanation works fine for me.

   (I don't think this invalidates the point at all, just thought it was interesting 🙂)

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     mixed berry social anxiety disorder 🍓 (monorail@glaceon.social)'s status on Monday, 04-Sep-2023 03:14:19 JST mixed berry social anxiety disorder 🍓

     i saw a video once that basically said "don't confuse patterns in how things behave with causes of those behaviours"

     the example that was given was the classic "why does a figure skater's spin speed up when they bring their arms in?"

     if you ask that you'll often hear "because the angular momentum of the system has to be conserved" but the video argued that that's not why. it's true but it's not a cause of anything, it's an observation we made about behaviours. and he gave an explanation of an actual mechanism by which bringing their arms in speeds them up, showing afterwards that it conserves angular momentum

     i think about it a lot