Hacker Newsnew | past | comments | ask | show | jobs | submitlogin

Like tides?

What Physics Teachers Get Wrong About Tides! | Space Time | PBS Digital Studios: https://www.youtube.com/watch?v=pwChk4S99i4



Yeah, this is pretty much exactly the kind of thing I am talking about. Except that the guy in question was generally replacing "relatively simple explanation which is more wrong than right" with "relatively simple explanation which is more right that wrong". Meanwhile the guy in the video seems to be adding quite a bit of complexity, even though he says that he's actually presenting a simplified view of the matter.

IIRC, one of the examples from the book thing had to do with the explanation and illustration of how light gets refracted when passing through glass. The overall effect is supposedly explained by the fact that light slows down as it enters glass, and typically a wavefront illustration is used to depict this. He went on to explain how the illustration is wrong and what the correct illustration should be instead, but I don't remember the details. And now that we have meta-materials which can bend light the wrong way, the whole "slowing down causes refraction" idea may be wrong, too. In fact, I remember reading an early potential explanation of this new effect (which as I recall had to do with the notion that the magnetic aspects of light might be affected differently than how the electrical aspects of light are, or vice versa) and thinking to myself "Aha - now that makes perfect sense!" And if that explanation makes sense for meta-materials then it also probably makes sense for regular materials. But once again I don't remember the details.

BTW, I understand the need to often simplify things quite a bit when you're dealing with students, but if we have "simple but incorrect" vs. "simple but correct" then we should be working hard to eliminate the former as soon as possible. If his critique of the situation is valid then it kind of beggars belief that we are still teaching so many things the wrong way!


Seriously? He gets this worked up explaining the difference between "the water is pulled out at the earth moon line" and "the water is pushed from the poles towards the earth moon line"? The net effect is identical.


If I understand his explanation correctly, the math says the effect can't be identical because the difference in gravitional force is much too small to lift the water that much. It has to be squeezed from the poles to raise the water high enough to account for tides.




Guidelines | FAQ | Lists | API | Security | Legal | Apply to YC | Contact

Search: