3 ms·
“Just like the "explanation" of seasons by the Earth's changing distance to the Sun, or textbook pseudo-explanations of history, like the "crisis" over the disc
by dr_dshiv 2y ago
“Just like the "explanation" of seasons by the Earth's changing distance to the Sun, or textbook pseudo-explanations of history, like the "crisis" over the discovery of irrationals, or Maxwell's "mathematical" reason for adding an extra term to Ampere's equation.”
Love it! Anyone have any others?
- topspin 2y agoSimplified explanations of how electrical current flows in conductors comes to mind. Water analogies, for example.
- IshKebab 2y agoThe water analogy is great. Not only are the basic equations exactly the same but it's easy to visualise. I don't see why you wouldn't like it. The basic equations are actually identical for a lot of domains, including rotational motion which gave rise to the Spintronics game.
- zokier 2y agoI agree that water analogy doesn't belong in this category because technically it works, but disagree on it being easy to visualize or pedagogically useful. Unless you have really solid understanding of hydraulics/fluid mechanics you are just trading one poorly understood subject for another.
- zihotki 2y agoIt's quite easy to get the solid enough understanding of hydraulics/fluid mechanics since it's something you can see/touch and easy to visualize. Kids love to play with water, a few experiments at school/home and they quickly understand it.
- IshKebab 2y agoYou can feel pressure and see flow rate. They're way easier to understand than voltage and current. Hydraulic accumulators are a real thing. There's even a freaking hydraulic equivalent of a boost converter! It's an amazing analogy. I'd say even calling it an analogy sells it short - it's not "like" electricity; it's exactly the same but in a different domain.
- nandomrumber 2y agoProblem is electricity is kinda three different things, as far as models go. 1) DC; 2) low frequency AC; 3) Radio frequency circuits With DC, the water in pipes analogy is close enough to be useful. With low frequency AC, like mains electricity at around household voltages, there are additional considerations to make the water in pipes analogy to be useless enough we generally require people to be licensed to work with it. Radio frequency electronics is indistinguishable from magic.
- tlb 2y agoThe pipes analogy gives people a wildly unrealistic idea of the speed of electron movement in a wire. They only move a few mm/s at max current in copper wire. Electrons take minutes to go down the power cable from your PSU to your GPU. At GHz frequencies, they move less than an atom diameter.
- nandomrumber 2y agoAll models are wrong, some are useful. If you go on to study electronics / electricity beyond junior schooling level, you’re going to be exposed to progressively less wrong models. Or watch three YouTube videos, there was some action from the big guns a couple years ago.
- km6GEwiQqsyEKQH 2y agoHow come? It seems it is very analogous to water in a pipe. Let's say I have a 30 m long garden hose. The water in it moves (in the order of magnitude of) 10 m/s in it. If the water is turned off, and I hold my thumb at the end of the hose and turn the tap on, I feel the water pressure almost immediately (the speed of mechanical waves in water). So it is obvious that there are two speeds. One is the speed of propagation and one is the speed of the medium, and they are way different.
- exitb 2y agoThere's a discussion on why ice is slippery that has similar vibes to the origin of lift.
- blueflow 2y ago"/usr stands for UNIX System Resources" And less technical: "The rainbow has 7 colors" "Sun is the day, moon is the night" So many things, i wish i had a name for these kind of traditional beliefs.
- Kim_Bruning 2y agohttps://en.wikipedia.org/wiki/Lie-to-children https://en.wikipedia.org/wiki/Lie-to-children short version: https://en.wikipedia.org/w/index.php?title=Lie-to-children&oldid=7502195 https://en.wikipedia.org/w/index.php?title=Lie-to-children&o...
- dr_dshiv 2y agoLove this Sussman quote: “ In fact, this is an engineering model, in the same way that, [for an] electrical resistor, we write down a model V = IR—it's approximately true, but it's not really true; if I put enough current through the resistor, it goes boom, so the voltage is not always proportional to the current, but for some purposes the model is appropriate”
- blueflow 2y agoThis is only sensible for models that are useful for something.
- jobigoud 2y agoThey are called "Common misconceptions" Wikipedia has a full page of them: https://en.wikipedia.org/wiki/List_of_common_misconceptions https://en.wikipedia.org/wiki/List_of_common_misconceptions