3 ms·

By "we", I mean humanity as a whole. Nobody would contest that there are a lot of widespread misconceptions about how an airplane - or, for that matter, anythi

By "we", I mean humanity as a whole. Nobody would contest that there are a lot of widespread misconceptions about how an airplane - or, for that matter, anything - works. A nice blog post on the topic is Sean Carroll's article, "The Laws Underlying The Physics of Everyday Life Are Completely Understood" (http://blogs.discovermagazine.com/cosmicvariance/2010/09/23/the-laws-underlying-the-physics-of-everyday-life-are-completely-understood/#.U-N3cps-uHc http://blogs.discovermagazine.com/cosmicvariance/2010/09/23/...).

DanBC 12y ago
https://www.youtube.com/watch?v=MO0r930Sn_8 https://www.youtube.com/watch?v=MO0r930Sn_8 Feynman: "Magnets repel each other." Interviewer: "What I want to know is what's going on ..." Feynman: "Magnets repel each other." Interviewer: "...between those two bits of metal." Feynman: "Magnets repel each other." Interviewer: "Well then, but what does that mean? Or why are they doing that? Or how are they doing it?" Feynman: "Ah, [pause] uh you're asking ..." Interviewer: "I must say that's a perfectly reasonable question to ask" Feynman: "Of course! It's a perfectly reasonable question." See also his quote about quantum mechanics - "There was a time when the newspapers said that only twelve men understood the theory of relativity. I do not believe there ever was such a time. There might have been a time when only one man did, because he was the only guy who caught on, before he wrote his paper. But after people read the paper a lot of people understood the theory of relativity in some way or other, certainly more than twelve. On the other hand, I think I can safely say that nobody understands quantum mechanics." https://en.wikiquote.org/wiki/Talk:Richard_Feynman#.22If_you_think_you_understand_quantum_mechanics.2C_you_don.27t_understand_quantum_mechanics..22 https://en.wikiquote.org/wiki/Talk:Richard_Feynman#.22If_you...
bane 12y ago
One of the problems with this idea, that we have the physics "perfectly understood", is that even that statement isn't accurate. What we actually have are unbelievably precise models for how things work and people who understand those models at extremely deep levels. But even something we experience literally every moment of every day, like gravity or magnets, we haven't the foggiest idea of how it actually works. We can describe in great depth anything we wish about our models for these things and experiments can reproduce our theories with exquisite precision. But these models are merely complex rituals, we don't actually know, at a deep fundamental level, what happens. The Feynman answer to magnetism, for example, is deeply unsatisfying because he describes all the rituals we've discovered with science about magnetism, but never really answers the question. His answer, in 7.5 minutes are "all the electronics spin in the same direction in iron and that produces a magnified magnetic field large enough we can feel". But why do spinning electrons produce a magnetic field at all? And why does that field work the way it does? We have built beautiful mathematical tools to describe this force, down to elementary particles, but why it exists at all is a completely mystery.
- tobinfricke 12y ago
  All models are wrong. Some are useful. But what is your point, really? By "understand" in physics, we really mean that we can predict what will happen in a given experiment to any desired accuracy based on the established "laws of physics". "But even something we experience literally every moment of every day, like gravity or magnets, we haven't the foggiest idea of how it actually works." I think this does a deep disservice to how much we actually do know about how the universe works.
  - bane 12y ago
    My point is that people often confuse understanding the model with understanding the thing. The model becomes a ritual, it becomes a kind of complex dogma, and when people master the model they claim they understand it. But it's not true, they don't understand the thing, they only understand our description of it. Feynman also addresses this, https://www.youtube.com/watch?v=05WS0WN7zMQ https://www.youtube.com/watch?v=05WS0WN7zMQ The next Monday, when the fathers were all back at work, we kids were playing in a field. One kid says to me, “See that bird? What kind of bird is that?” I said, “I haven’t the slightest idea what kind of a bird it is.” He says, “It’s a brown-throated thrush. Your father doesn’t teach you anything!” But it was the opposite. He had already taught me: “See that bird?” he says. “It’s a Spencer’s warbler.” (I knew he didn’t know the real name.) “Well, in Italian, it’s a Chutto Lapittida. In Portuguese, it’s a Bom da Peida. In Chinese, it’s a Chung-long-tah, and in Japanese, it’s a Katano Tekeda. You can know the name of that bird in all the languages of the world, but when you’re finished, you’ll know absolutely nothing whatever about the bird. You’ll only know about humans in different places, and what they call the bird. So let’s look at the bird and see what it’s doing—that’s what counts.” (I learned very early the difference between knowing the name of something and knowing something.) Models are just a complicated way of calling something, not a way of understanding it. Getting experimental results just means you've used the correct name, not that you understand anything in particular about it. Calling a hot bright thing "fire" doesn't mean you understand it at all -- no matter how many complex tribal dances you do around an open flame. Knowing what fire actually is gave us modern civilization. For many fundamental everyday things like gravity or magnetism, on the scale from "calling an open flame 'fire'" to "rocket ship", we're charitably somewhere around "learning to cook meat".

DanBC 12y ago

https://www.youtube.com/watch?v=MO0r930Sn_8 https://www.youtube.com/watch?v=MO0r930Sn_8 Feynman: "Magnets repel each other." Interviewer: "What I want to know is what's going on ..." Feynman: "Magnets repel each other." Interviewer: "...between those two bits of metal." Feynman: "Magnets repel each other." Interviewer: "Well then, but what does that mean? Or why are they doing that? Or how are they doing it?" Feynman: "Ah, [pause] uh you're asking ..." Interviewer: "I must say that's a perfectly reasonable question to ask" Feynman: "Of course! It's a perfectly reasonable question." See also his quote about quantum mechanics - "There was a time when the newspapers said that only twelve men understood the theory of relativity. I do not believe there ever was such a time. There might have been a time when only one man did, because he was the only guy who caught on, before he wrote his paper. But after people read the paper a lot of people understood the theory of relativity in some way or other, certainly more than twelve. On the other hand, I think I can safely say that nobody understands quantum mechanics." https://en.wikiquote.org/wiki/Talk:Richard_Feynman#.22If_you_think_you_understand_quantum_mechanics.2C_you_don.27t_understand_quantum_mechanics..22 https://en.wikiquote.org/wiki/Talk:Richard_Feynman#.22If_you...

bane 12y ago

One of the problems with this idea, that we have the physics "perfectly understood", is that even that statement isn't accurate. What we actually have are unbelievably precise models for how things work and people who understand those models at extremely deep levels. But even something we experience literally every moment of every day, like gravity or magnets, we haven't the foggiest idea of how it actually works. We can describe in great depth anything we wish about our models for these things and experiments can reproduce our theories with exquisite precision. But these models are merely complex rituals, we don't actually know, at a deep fundamental level, what happens. The Feynman answer to magnetism, for example, is deeply unsatisfying because he describes all the rituals we've discovered with science about magnetism, but never really answers the question. His answer, in 7.5 minutes are "all the electronics spin in the same direction in iron and that produces a magnified magnetic field large enough we can feel". But why do spinning electrons produce a magnetic field at all? And why does that field work the way it does? We have built beautiful mathematical tools to describe this force, down to elementary particles, but why it exists at all is a completely mystery.

tobinfricke 12y ago
All models are wrong. Some are useful. But what is your point, really? By "understand" in physics, we really mean that we can predict what will happen in a given experiment to any desired accuracy based on the established "laws of physics". "But even something we experience literally every moment of every day, like gravity or magnets, we haven't the foggiest idea of how it actually works." I think this does a deep disservice to how much we actually do know about how the universe works.
- bane 12y ago
  My point is that people often confuse understanding the model with understanding the thing. The model becomes a ritual, it becomes a kind of complex dogma, and when people master the model they claim they understand it. But it's not true, they don't understand the thing, they only understand our description of it. Feynman also addresses this, https://www.youtube.com/watch?v=05WS0WN7zMQ https://www.youtube.com/watch?v=05WS0WN7zMQ The next Monday, when the fathers were all back at work, we kids were playing in a field. One kid says to me, “See that bird? What kind of bird is that?” I said, “I haven’t the slightest idea what kind of a bird it is.” He says, “It’s a brown-throated thrush. Your father doesn’t teach you anything!” But it was the opposite. He had already taught me: “See that bird?” he says. “It’s a Spencer’s warbler.” (I knew he didn’t know the real name.) “Well, in Italian, it’s a Chutto Lapittida. In Portuguese, it’s a Bom da Peida. In Chinese, it’s a Chung-long-tah, and in Japanese, it’s a Katano Tekeda. You can know the name of that bird in all the languages of the world, but when you’re finished, you’ll know absolutely nothing whatever about the bird. You’ll only know about humans in different places, and what they call the bird. So let’s look at the bird and see what it’s doing—that’s what counts.” (I learned very early the difference between knowing the name of something and knowing something.) Models are just a complicated way of calling something, not a way of understanding it. Getting experimental results just means you've used the correct name, not that you understand anything in particular about it. Calling a hot bright thing "fire" doesn't mean you understand it at all -- no matter how many complex tribal dances you do around an open flame. Knowing what fire actually is gave us modern civilization. For many fundamental everyday things like gravity or magnetism, on the scale from "calling an open flame 'fire'" to "rocket ship", we're charitably somewhere around "learning to cook meat".