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Comment by aunty_helen | Hacker News Reader

https://www.youtube.com/watch?v=MO0r930Sn_8

Richard Feynman explaining magnets is one of the best layman explainers I've seen (in between the ranting). I honestly didn't understand why magnets worked and found this on a late night youtube binge.

(But don't search youtube for anything related to magnets, you end up amongst the perpetual motion nuts)

Edit: Just to be clear with this video (it had been a while since I last watched it), he doesn't 'explain' magnets as much as he hints at the concepts involved. I already knew about the spins being lined up etc but it was the "you can't put your hand through the chair" comment that gave me the eureka moment.

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I don't know, maybe I'm the odd man out, but I've been linked to this video tens of times and always hated it. I find Feynman comes across extremely condescending and wastes time explaining that the interviewer is too dumb to understand in a very roundabout way. One thing I've come to really respect in my CS career are people not only able but willing to distill knowledge down into an approachable way. I've come across so many people with the same attitude as seen in the video, especially in the DNS world for some reason, maybe that's why it strikes a nerve.

I completely agree that his attitude for parts of this video is cringey, but Feynman is famous for (among other things) his ability to simplify and communicate complex ideas. Feynman diagrams are the perfect example of this.

Edit: I guess my point is just that being willing and able to communicate simply and effectively is not necessarily at odds with being a condescending prick.

Except in this case he utterly failed at answering the question and went on an unrelated rant.

“What you feel in the magnet is the same force that keeps my hand from going through the chair, so the question is why does it work at a human-scale distance? The answer is that in an iron magnet all the magnetic forces in each atom are aligned. An individual atoms‘ force is too small to be felt at distance, but the combined effect of all the atoms in a magnet is large enough.”

That wasn’t so hard.

The spin of the atoms in my finger are not aligned at all, why would there be any force?

Also if it's the same force and it is much stronger when aligned, why don't magnets pass through each other? The much stronger aligned magnetic force should easy overwhelm the weaker force that keeps my hand from going through the chair.

Because as the distance becomes smaller, for unaligned magnetic fields, they stop blending into each other and become distinct fields that eventually push away each other.

As for why two magnets don't pass through each other, as they come closer eventually the alignment breaks down because both poles exist for each atom and end up repelling each other.

Of course, Paul's exclusion principle does play a role, but as long as the two objects are rigid enough you can model this mostly well enough with a magnetic dipole at each atom.

Yeah, I understand that people get satisfaction from seeing a scientist dunk on a journalist, but it doesn't seem justified in this case. Feynman's digression about distinctions between proximate and ultimate causes is interesting of course, but it strikes me that the journalist's question isn't ambiguous in this respect, and it's pretty clear what he is asking.

The question is crystal clear, and Feynman even acknowledges that it's an excellent question.

Feynman's detour is to explain to the interviewer that he can't give any satisfactory explanation beyond "the magnetic force exists and behaves like that" given that the interviewer has no advanced knowledge of physics. Trying to do so would invariably involve Feynman cheating the interviewer, causing the interviewer to believe he understood it better until he comes across the flaw in the reasoning.

But in the video he does eventually get to one, that GGGP half-mentions: It's (just about) the same force that prevents you from putting your hand through a chair even though atoms are mostly empty space, but strengthened due to how magnets are made so it works at a much larger distance.

It's a simple, relatively satisfactory explanation a layperson should understand, that provides a hook for finding more in-depth knowledge if the asker wants to.

The whole rest of it was unnecessary.

Saying that it's the same force might provide some additional info but it is not really answering the question about why there is a force.

The idea that atoms are mostly empty space is a great analog to his rubber band example. Our attempts to explain atoms in terms of electrons cleanly orbiting a nucleus gives people the wrong picture. Atoms are not mostly empty space, electrons become standing waves when part of an atom and it's not just that we cannot measure their position with accuracy, their position does not exist. The solar system metaphor for the atom has probably caused more harm than good.

You are not the odd man out, I have also seen this multiple times and had the same reaction. There is always a deeper level to explore, but good teaching both provides enlightenment and hints on where to look further.

He does explain it at around the 5:30 minute mark by saying that it is the aligned spin of the atoms within magnets that give them their peculiar strength.

I think that his leadup is an attempt to get a couple points across:

1) That we typically can explain things in terms of more basic or more 'fundamental' concepts. This does not work with magnetism since magnetism itself is a fundamental force. Attempts to explain via analogy should be avoided.

2) Even the spin explanation probably does more harm than good. A non-physicist will think of atoms spinning like a top, which is wrong and misleading.

I think he's internally dissatisfied with his own answer to the question. He's certainly a man who wanted to know more than he could ever hope to achieve. I think things like this irked him at a deep level.

You come up to him. "Hey, so magnets, these trivial things that children play with, can you explain it to me?"

His real answer would be "no. not to my satisfaction, I can't"

That isn't it, though. Feynman explains magnetism perfectly well in his lectures, he's just saying that he can't give a decent math-free answer in a few minutes to an interviewer with no science background. Any answer that short would not functionally be any better than "magnets work because of magic".

I agree with this. I found it very off putting and not what I'd expected from someone lauded as an amazing teacher.

Having said that, there is a lot to think about in his irritation. For example: the mysteries of magnets are no more mysterious than lots of other things that we take for granted and treat as entirely unmysterious. To priviledge magnets with an almost magical respect when we haven't spotted that gravity is at least as mysterious is a failure of imagination.

There's also the question 'what kind of answer would you accept'? When we can only express bafflement about a phenomenon, we're still in the prescientific myths and magic world. You can't really get to the scientific world until you can formulate some kind of question. The passage from Hitchikers about the Ultimate Question touches on something pretty profound.

Still, I think an honest expression of bafflement is an excellent beginning (or at least it's where I often find myself), and I think there may have been more sympathetic ways Feynmann could have expressed his thoughts on the topic.

I understood that differently:

https://news.ycombinator.com/item?id=22816968

Hint, the questions were:

"Now, what is it, the feeling between those two magnets?"

"There's something there, isn't there?"

"what's going on between these two bits of metal"

"What does that mean, or why are they doing that, or how are they doing that?"

I don't know what phenomena you study, but I assure you that "magnets" aren't the only topic for which the "feeling" and "what does that mean" and "why" questions would warrant the same answer.

And where answering "how" would be cheating if the answer would use some false analogy.

Wow, I think this is a problem with you. Feynman is smiling through most of his answer. His diversion at the start is just to explain to his interviewer how wide and deep the question “why” can go.

> Feynman is smiling through most of his answer.

I don't think smiling and being condescending are mutually exclusive are they?

I think the lesson of Feynman’s rant has eluded you. I’d keep studying it.

I learned the lesson of explanations going into a 'why?' rabbit hole 2 years ago. It was taught to me by my then 6 year old daughter.

That isn’t the lesson.

If a watcher doesn't understand the lesson, was it a good session? As an acolyte, why not enlighten us? Or should I just keep watching a condescending asshole avoid a question until I understand something that makes you happy?

What is the lesson?

The confusion comes from the wrong expectation: whoever called the Feynman's answer "Magnets" missed the point. I'm quite sure Feynman would not name his answer so.

One has to carefully to listen to the question he was asked and he then answers.

I wrote about that before and I link to that this time too in my other answer.

People are also missing the complete video, its not just about magnets, it’s about why imagination can be fun. Here he just demonstrates why you can’t always turn to similarities in the classical world:

https://www.youtube.com/watch?v=P1ww1IXRfTA

A reasonable perspective for sure. But I don't see it. Asked a question about the nature of magnetic force by a lay person, he saw fit to launch into a lecture about causation. He was a lecturer by trade.

Socrates, as we receive him, opened peoples' eyes about causation, too. If anyone did it like a jerk it was him. Leading you down the path of your own ideas into a contradiction, just to show you what you don't know? That's embarrassing and unhelpful. I'd rather be lectured.

Is he the friendliest explainer? Surely not. Who cares? His gifts in communicating deep ideas in science to lay people were beyond compare.

The video is great. If you feel offended by it, think about why.

I feel like the people put off by this video somehow take it personally that he didn't answer the question in a manner which they found satisfactory like he owed them a better answer. I didn't feel like he was being a jerk in the slightest. The answer he did give was rather interesting.

Did we watch the same video? I'm not in the least bit offended, I just feel like he wasted my time. If he'd just explained it, it's then up to me to research the underlying bits. Not up to him to tell me I'm too uneducated to do so.

I don't agree. I suspect you may have been put off by the beginning (before the 0:57 mark), where he may sound annoyed by the question. Personally, I don't think he was; he does agree that it's an excellent question, and continues happily from there.

His roundabout analogy about the seemingly infinite rabbit holes of "why"s makes an important point that some phenomena are not explainable in a satisfactory way without a considerable theoretical framework, and any layman-friendly analogy is ultimately going to be inaccurate.

I rewatch this video constantly. It's not just about magnets, it's about epistemology and it's also the greatest masterclass on science education in my opinion. It's also one of the best distillations of the thirst for finding out that drives humans (at least some of us apparently). Flawed man, it turns out, but am thankful for at least this video if nothing else.

All humans are flawed.

Amen

Everything in the universe is flawed. (Also, what if it's our "flaws" that define who we are?)

According to my professor, when I was taking quantum mechanics a few years back, the view that Feynman is prevented from falling through his chair by electromagnetic repulsion is somewhat antiquated. She told us that a more modern perspective puts a greater focus on the Pauli Exclusion Principle.

Of course that line of explanation falls to similar loop, re: why do fermions resist sharing state?

I would like to mention the possibility of tunneling through the chair (however small).

Indeed, and Freeman Dyson demonstrated this:

In 1966, independently of Elliott H. Lieb and Walter Thirring, Dyson and Andrew Lenard published a paper proving that the Pauli exclusion principle plays the main role in the stability of bulk matter.

https://en.wikipedia.org/wiki/Freeman_Dyson

Why does he seem so irritated at the question?

A personality quirk. Nothing sinister here.

For what it's worth, we still don't really know how magnets work; at best we can predict some of their behaviours.

What? No. This is not true. We understand 100% the physics of how magnets work.

I guess, depends on who 'we' is. (Besides, do "we" really understand quantum electrodynamics, or we just understand the math?)

Yes, speaking as a physicist, QED is perfectly understandable.

Not entirely true (that we understand magnetism). We get some things about it. But not everything.

The nature of physics is such that we never really have 100% confidence in our theories. We are always looking for things the theory under test doesn't predict correctly in the form of an observation. Which means we have to understand what we are measuring. And how we are measuring it.

All of this impacts magnetism. For example, many explanations here discuss electron "spin". Electron "spin" likely doesn't mean the electron is physically spinning.

So what is "spin" and how does it actually contribute to magnetism? And then you have a number of interesting QM properties, such as spin-orbit coupling. Remember, the original model of electrons orbiting nuclei was discarded as the electron accelerating around the nucleus would radiate all of its energy away. So classical orbital "motion" of electrons, literally a current, that should generate a magnetic field, which could couple with the spin of the electron, is not really a classical thing. It is quantum mechanical in nature.

And we really don't fully grasp QM. Some parts we think we understand and can provide some interpretation to. Other parts ... not so clear.

Again, this is why 99 years after Einstein won the Nobel prize, people are still testing relativity, and still testing fundamental/foundational QM. Look at all the work on delayed choice slit experiments[1][2], and many others.

Basically we think we have some level of understanding of QM. And we need a strong understanding of QM to understand QM phenomenon. Like magnetism.

Its not at 100% understanding yet. May never be. But there is so much more interesting science out there, that this is a good thing.

[1] https://www.popularmechanics.com/science/a22280/double-slit-...

[2] http://www.preposterousuniverse.com/blog/2019/09/21/the-noto...

My understanding is delayed slit experiments have more to do with a common folk explanation of uncertainty principle being flawed (e.g. the notion of collapse) rather that the fundamental math of QM. The later gives correct prediction.

So if you take QM math, AFAIK, it can explain all known electromagnetic phenomena.

Love the first comment on the youtube video:

"RIchard Feyman's wife: "WHY did you not take the trash out yet?!"

Richard proceeds to go on a long tirade about electromagnetic forces, gravity, string theory etc. until the wife sighs in despair and takes out the garbage herself. Again."

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