Fifty years ago today, a whole lot of light bulbs went on

September 26, 2011 8:31 AM

Fifty years ago today, Richard Feynman gave the first of his famous lectures at Caltech.

Feynman, well covered on the blue, set the bar high with these freshman lectures on physics.

You can watch some of them online at YouTube, read the textbook (first published in 1964), enjoy some related stories, or watch some entertaining Feynman videos.

You can watch similar lectures he gave subsequently at Cornell in 1964 online over at Project Tuva (Silverlight required).

The lectures are enjoyable even for those without a physics background. Feynman lifts back the veil like none other, and gives you glimpses into the workings of our world that are breathtaking. His demonstrated ability to analyze, synthesize, and convey information is as much a part of the experience as is the content he is delivering. These lectures are a window into the way Feynman thought, and it is a beautiful thing to see that mind at work.

"If you can't explain something to a first year student, then you haven't really understood it."

posted by SNACKeR (55 comments total)

When I was an undergraduate physics student they showed Feynman lectures on Thursday and Friday nights on 8mm black-and-white movie reels. I went as often as I could and took any of my friends who were willing to go with me, including ones who knew next to no physics. Almost everybody liked them. It was the biggest lecture hall in the building and there were always a hundred people in there.

This man was an inspiration. If he were French they would have his picture on the ten franc note.

(Do they even have franc notes any more?)
posted by bukvich at 8:48 AM on September 26, 2011 [2 favorites]

If he were French they would have his picture on the ten franc note.

(Do they even have franc notes any more?)

No, they have euros.

Cliff Stoll, who sells Klein bottles, markets 10 Deutsche Mark notes as portraits of Gauss.
posted by madcaptenor at 9:03 AM on September 26, 2011 [2 favorites]

"If you can't explain something to a first year student, then you haven't really understood it."

Where are you getting this quote from?
posted by empath at 9:05 AM on September 26, 2011

"If you can't explain something to a first year student, then you haven't really understood it."

This quote is nowhere to be found on the wikiquote page it links to.
posted by Tomorrowful at 9:12 AM on September 26, 2011

empath, it seems like variants of that quote have existed from different people. I seem to recall reading that as well, possibly in Surely You're Joking Mr Feynman.

The quote was removed, check the talk page on the wiki...
posted by ryanfou at 9:13 AM on September 26, 2011

Yeah, i checked it because it didn't sound like something that anybody who knew what they were talking about would say.
posted by empath at 9:14 AM on September 26, 2011

Yeah that quote is bullshit, I could explain why but you wouldnt understand.
posted by villanelles at dawn at 9:15 AM on September 26, 2011 [11 favorites]

Looks like it's an unsourced Quotation no longer considered WikiQuote-worthy. So probably it was made up for someone's blog.

Oops. On preview, others beat me to it.
posted by saulgoodman at 9:15 AM on September 26, 2011

@empath - It is all over the web, but may be unsourced, my bad. The link was just meant to provide more quotes, not act as a reference. That was bad form on my part.
posted by SNACKeR at 9:23 AM on September 26, 2011

I could see Feynman making a statement like this. He was the first to admit he didn't actually understand quantum mechanics, they just came with some rules that seemed to work.

I just did a bunch of googling and a lot of people seem to agree that he made some kind of statement like this. So why does it seem like bs? Have you seen him answer the question of why magnets repel?
posted by ryanfou at 9:24 AM on September 26, 2011 [1 favorite]

See "Teaching quote" here for some substantiation of a similar quote: "You know, I couldn't do it. I couldn't reduce it to the freshman level. That means we really don't understand it."
posted by SNACKeR at 9:28 AM on September 26, 2011

This is a fantastic post. Don't wait another nine years for the next one!
posted by longsleeves at 9:30 AM on September 26, 2011 [3 favorites]

FEYNMAN SQUEEEEE
posted by JHarris at 9:31 AM on September 26, 2011 [2 favorites]

@longsleeves - (you outed me) Thanks!
posted by SNACKeR at 9:39 AM on September 26, 2011

Yeah, i checked it because it didn't sound like something that anybody who knew what they were talking about would say.

Feynman explained quantum electro-dynamics in ways this less-than-freshman could understand, so I'm not sure I agree with you.
posted by neuromodulator at 9:41 AM on September 26, 2011 [2 favorites]

@ryanfou, jeez, now I am inspired AGAIN after watching that! I gotta go for a walk or something...
posted by SNACKeR at 9:41 AM on September 26, 2011

I had a fanTAStic astrophysics-for-humanities-majors class in college. One of the most brilliantly enlightening and entertaining profs I've ever had (and probably the hardest class I took in undergrad). He turned me on to Feynman and the Cosmos and other neat things. I thank him every night when I look up at the sky and know a wee bit about all those flaming balls of gas.
posted by smirkette at 9:41 AM on September 26, 2011 [1 favorite]

Yeah, i checked it because it didn't sound like something that anybody who knew what they were talking about would say.

And that's exactly what makes Feynman special.
posted by SNACKeR at 9:49 AM on September 26, 2011 [2 favorites]

F*cking Magnets - How do they work? In this brief excerpt from an interview Feynman does briefly talk about it having to due with the mechanics of the iron atom magnifying the effect of the force but then he oddly backs off and says he's unable to tell us.
posted by longsleeves at 9:52 AM on September 26, 2011

Still have my old "Feynmann Lectures" books from when I bought them for Uni, way back in 1977. Must dig 'em out again to confirm that I've forgotten more physics than I can even remember knowing.

The man had a good head on his shoulders. This is almost a creed for sanity, for me.
posted by Decani at 9:53 AM on September 26, 2011 [2 favorites]

My uncle studied with him.
posted by brujita at 10:18 AM on September 26, 2011

"If you can't explain something to a first year student, then you haven't really understood it."

Actually that video of Feynman talking about magnetism is a perfect example of what's wrong with that quote.

Feynman understands the mathematics and physics involved in what is known about magnetism. But a first-year student probably doesn't have enough math to follow an overview he might give of that knowledge.

In the video, Feynman is pointing out is that any attempt to explain magnetism using analogies to everyday experience instead of math is a cheat. Because any of the everyday things you might use to try to explain magnetism are themselves examples of magnetism.

"How do magnets work?"

"Well, they're sort of like rubber bands..."

"But how do rubber bands work?"

"Well, actually, they're made up of lots of tiny magnets..."
posted by straight at 10:22 AM on September 26, 2011 [5 favorites]

Another illustration of the breadth of the Feynman appeal just came to me. The one professor in my department with whom I shared the greatest antipathy, i. e. we practically hated one another, told us at the start of lecture on the first day of class that the single best resource for any professional physicist wanting a quick broad review in a few sittings was Feynman's lectures; they are probably not a good resource for an amateur wanting to pick up skill, but that is the the closest thing to a criticism you are likely to hear.

How long will Feynman have to be dead before they are in public domain? We really ought to be able to get a Dover edition for ten bucks.
posted by bukvich at 10:33 AM on September 26, 2011 [5 favorites]

(Silverlight required)

Eurgh.
posted by alby at 10:51 AM on September 26, 2011 [1 favorite]

We really ought to be able to get a Dover edition for ten bucks

**cough cough cough bit torrent cough cough cough**
posted by Chekhovian at 11:09 AM on September 26, 2011 [1 favorite]

apropos
posted by idiopath at 11:22 AM on September 26, 2011 [2 favorites]

Have you ever read a quote and thought: My God, that applies to every possible case I can think of in the history of the world!

Quotes are useful at quickly and concisely illuminating something. As far as I know, most people do not regard them as strict logical statements about the universe.

When attempting to understand or explain something, it is worthwhile to ask, can this be any simpler? And if not, why? The whole point about the magnets is that we can't explain the underlying principle behind magnetism, so we say there is a force, which it turns out is just handwaving, because we don't understand in everyday terms what those forces are. You can go pretty deep into explaining what we know about magnetism and electric forces, but at the end of all these complex answers, there isn't a good understanding of it, aside from complex and incredibly precise predictions.

Nobody would claim that you should be able to explain quantum electrodynamics in 3 sentences or less. I couldn't explain shit to a 100 year old toilet, so I am as guilty as anybody, but I wish this thread wasn't derailed by a throw-in quote, but rather focus on the fact that Richard Feynman was rarely gifted at explaining very difficult concepts in easy to understand terms. And that simplicity and clarity can be a sign of greater understanding.
posted by ryanfou at 11:29 AM on September 26, 2011 [6 favorites]

I could not help but to read ryanfou's comment in Feynman's voice.
posted by Fraxas at 11:59 AM on September 26, 2011 [3 favorites]

I love this guy so much.

One of the many, many things I love about him is his honesty in being willing to say "I don't know!" Truly an amazing intellect.
posted by odinsdream at 12:02 PM on September 26, 2011

In the video, Feynman is pointing out is that any attempt to explain magnetism using analogies to everyday experience instead of math is a cheat. Because any of the everyday things you might use to try to explain magnetism are themselves examples of magnetism.

Whenever I see that bit, I think he's simply exasperated at the interviewer (who is pretty annoying). It seems like he's about had enough, and he's decided to dig in his heels and say: no mister interviewer, I can't explain magnets to you.
posted by fleacircus at 12:19 PM on September 26, 2011

haha Fraxas. Much like idiopath's link, I too am a huge hit at parties.
posted by ryanfou at 12:32 PM on September 26, 2011

he's decided to dig in his heels

Exasperated or not, he gives a perfectly clear explanation of this particular obstacle in communication. It's like he couldn't help himself from making clear explanations, like he just produced them without effort, as a side-effect of his thinking.
posted by stebulus at 12:59 PM on September 26, 2011

Whenever I see that bit, I think he's simply exasperated at the interviewer (who is pretty annoying).

My take is that he just saw it as a chance to give the lecture that he did. I'm sure that he dealt with many similar questions from laymen; simple questions whose answers get into complex physics very quickly.

He could simply have left it at the explanation of the structure of iron that he alludes to. This would have technically answered the question but left the interviewer less than enlightened. I think that this would have left Feynmann equally unsatisfied, so he chose another path.
posted by CaseyB at 1:02 PM on September 26, 2011

Whenever I see that bit, I think he's simply exasperated at the interviewer (who is pretty annoying). It seems like he's about had enough, and he's decided to dig in his heels and say: no mister interviewer, I can't explain magnets to you.

I don't see that at all. He seems pretty excited and pleased. He's seems to be enjoying the opportunity to say, "You asked how do magnets work when you really should have asked how do magnets make everything else work?"
posted by straight at 7:10 PM on September 26, 2011

Vaguely related: the comic book autobiography of Feynman came out pretty recently. I'm just a few pages in but it's pretty neat so far.
posted by NoraReed at 10:09 PM on September 26, 2011

I'm not sure that Feynman is annoyed, but I do think I see why one could form that impression from the first 45 seconds of the video. (After that, when he gets going in the explanation, he's having fun.)

First, in the first ten seconds, when the interviewer is explaining what magnets do, when Feynman idly rubs his eye, slowly lowers his arm, and tilts his head, he seems bored. The interviewer is really belaboring his question here.

Second, at 0:26–0:28, when Feynman says, "Of course you feel it, now what do you want to know?": the tone and phrasing here is a bit brusque. Also, he's being Socratic, which is a noncooperative stance; it's easy to think that he's not cooperating because he refuses to, out of annoyance. (But maybe it's just the stance he's used to adopting with students who ask him half-formed questions.)

Third, when the interviewer finally asks, "why are [the magnets] doing that, or how are they doing it?", at 0:40, Feynman glances down, then glances back up at the interviewer under his brows for a moment, then takes a deep breath, starts resetting himself in his chair — this is conventional body language for "you've surprised me and now I have to reassess you and how to proceed in this conversation", and here it could be interpreted as, "I can't believe you asked me such a stupid question". (The interviewer seems to read it that way, because he immediately defends: "I must say, I think that's a perfectly reasonable question." Feynman then tries to correct the misapprehension: "Of course it's a reas— it's an excellent question. Okay?")
posted by stebulus at 8:34 AM on September 27, 2011

"If you can't explain something to a first year student, then you haven't really understood it."

ryanfou: it seems like variants of that quote have existed from different people.

CS Lewis, 1945: 'I have come to the conviction that if you cannot translate your thoughts into uneducated language, then your thoughts were confused. Power to translate is the test of having really understood one’s own meaning.'

This Lewis quote is from his talk 'Christian Apologetics' in God in the Dock.
posted by paleyellowwithorange at 8:51 PM on September 27, 2011 [1 favorite]

Biography, I mean. Crap! Sorry!
posted by NoraReed at 10:36 PM on September 27, 2011

From the Einstein wikiquote page:

You do not really understand something unless you can explain it to your grandmother.

        variant: If you can't explain something to a six-year-old, you really don't understand it yourself.
        variant: If you can't explain it simply, you don't understand it well enough.
        Frequently attributed to Richard Feynman
        Probably based on a similar quote about explaining physics to a "barmaid" by Ernest Rutherford

        P. 418 of Einstein: His Life and Times by Ronald W. Clark says that Louis de Broglie did attribute a
        similar statement to Einstein:

         To de Broglie, Einstein revealed an instinctive reason for his inability to accept the purely statistical
         interpretation of wave mechanics. It was a reason which linked him with Rutherford, who used to state
         that "it should be possible to explain the laws of physics to a barmaid." Einstein, having a final 
         discussion with de Broglie on the platform of the Gare du Nord in Paris, whence they had traveled 
         from Brussels to attend the Fresnel centenary celebrations, said "that all physical theories, their 
         mathematical expressions apart ought to lend themselves to so simple a description 'that even a 
         child could understand them.' "

        Clark's book does not give a reference for this specific statement by de Broglie, but it follows a quote 
        by de Broglie in the previous paragraph which is attributed to de Broglie's book New Perspectives in 
        Physics, so this may come from the same source.

Furthermore, I concur with the "six year old" version of this, having had practice on many six year olds. Mathematics does not explain how magnets work. Mathematics models how magnets work. One level of explanation would be the rubber band. Another level would be "tiny magnets". Another level would be to talk about atoms throwing things at each other, which makes them recoil or...some analogy for the other way that makes them attract. I can't come up with that six-year-old-accessible analogy because -- wait for it -- I don't really understand it myself.
posted by DU at 5:56 AM on September 30, 2011

I can't come up with that six-year-old-accessible analogy because -- wait for it -- I don't really understand it myself.

If you keep asking 'why' about anything, eventually you'll get to the point where you can't explain it, but that doesn't mean you don't understand the general principles. You can completely understand maxwell's equations and how they work and not be able to explain them to a 6 year old, nor even be able to explain WHY they work.

And I don't think the best physicist in the world can explain M-theory, or Lie Algebra, or Supersymmetry to a first year student and definitely not to a 6 year old, at least not in anything but the most superficial way.
posted by empath at 6:47 AM on September 30, 2011

Or hell, General Relativity for that matter. Just thinking about Ricci Tensors and Cristofel symbols makes my head hurt.
posted by empath at 6:47 AM on September 30, 2011

Again, math is not explaining why things work. Balls do not compute equations first and then decide to follow that path. Math models how things work. Why they actually work that way has nothing to do with Ricci Tensors and Cristofel symbols.
posted by DU at 7:08 AM on September 30, 2011

The universe is nothing but math. Particles and waves are mathematical objects. There's nothing there that isn't fundamentally math or an emergent property of math.
posted by empath at 7:13 AM on September 30, 2011

I look forward to the forthcoming proof of this assertion.
posted by DU at 7:17 AM on September 30, 2011 [1 favorite]

Study quantum mechanics, I guess. There's nothing in QM that isn't pure math. You can't explain what anything is in QM without referring to fields (which are just mathematical objects) or particles (which are just mathematical objects) or waves (which are just mathematical objects), or if you want to get into string theory -- strings, which again, are purely mathematical objects.

There's nothing to it that isn't numbers. There's no way of even meaningfully talking about them besides with numbers. Even things like 'color', 'flavor' and 'spin' are really just short hand for numbers. You can't use words to get anything but the vaguest understanding of what's really happening. And all of the rest of physics is just emergent macroscopic properties of these numbers.
posted by empath at 7:45 AM on September 30, 2011

"The only way 20th and 21st century (so far) humans have of talking about the fundamental bits of matter happens to be with a system known as mathematics" != the universe is literally made out of mathematics
posted by DU at 8:27 AM on September 30, 2011

Also "nobody currently living can explain these things to six year olds" != "these things cannot be explained to six year olds". 10,000 years from now, they'll just look back at us and say "they didn't understand it".
posted by DU at 8:46 AM on September 30, 2011

Explaining physics to 6 year olds has gotten harder, not easier in the past 500 years.

You're telling me that explaining General Relativity is easier than explaining Newton?
posted by empath at 8:55 AM on September 30, 2011

Okay, forget physics.

Explain how OSPF works to a 6 year old.
posted by empath at 9:00 AM on September 30, 2011

From the number of errors these arguments contain, maybe I should try explaining basic logic to you.
posted by DU at 9:15 AM on September 30, 2011

Maybe you should. Explain it like I'm a 6 year old.
posted by empath at 10:01 AM on September 30, 2011

Mathematics does not explain how magnets work. Mathematics models how magnets work.
posted by straight at 10:53 AM on September 30, 2011 [1 favorite]

I think someone needs to explain how explaining works.
posted by empath at 10:54 AM on September 30, 2011

(Sorry, that was supposed to be a quote from DU): Mathematics does not explain how magnets work. Mathematics models how magnets work.

You seem to think that using words to explain how magnets work would be somehow more of an explanation than using math. But language is just as much an arbitrary and indirect "model" of the world as math is. Words are not any more directly related to the thing they are describing than mathematical formulas are.
posted by straight at 10:56 AM on September 30, 2011

Right.

Everything you need to know about magnetism is contained within Maxwell's equations (and coulomb's law, etc). They explain huge amounts of phenomena, from the action of magnets to the speed of light in a vacuum, to static electricity, to color, to lenses, to black holes, to red shift, etc, etc, etc.

No amount of explaining with words is every going to match the beauty and simplicity and utility of those equations, and unless you understand how all the math works, you're never going to really understand the phenomena. And you simply can't explain that much math to a 6 year old, or even a first year college student. The most you can give is a gloss. And that doesn't mean you don't understand it. It just means that there is a lot you need to know before you can understand it.
posted by empath at 11:15 AM on September 30, 2011