[Transcript] Richard Feynman on Why Questions

I thought this video was a re­ally good ques­tion dis­solv­ing by Richard Feyn­man. But it’s in 240p! No­body likes watch­ing 240p videos. So I tran­scribed it. (Edit: That was in jest. The real rea­sons are be­cause I thought I could get more ex­po­sure this way, and be­cause a lot of peo­ple ap­pre­ci­ate tran­scripts. Also, Paul Gra­ham spec­u­lates that the writ­ten word is uni­ver­sally su­pe­rior than the spo­ken word for the pur­pose of ideas.) I was go­ing to post it as a ra­tio­nal­ity quote, but the tran­script was suffi­ciently long that I think it war­rants a dis­cus­sion post in­stead.

Here you go:

In­ter­viewer: If you get hold of two mag­nets, and you push them, you can feel this push­ing be­tween them. Turn them around the other way, and they slam to­gether. Now, what is it, the feel­ing be­tween those two mag­nets?

Feyn­man: What do you mean, “What’s the feel­ing be­tween the two mag­nets?”

In­ter­viewer: There’s some­thing there, isn’t there? The sen­sa­tion is that there’s some­thing there when you push these two mag­nets to­gether.

Feyn­man: Listen to my ques­tion. What is the mean­ing when you say that there’s a feel­ing? Of course you feel it. Now what do you want to know?

In­ter­viewer: What I want to know is what’s go­ing on be­tween these two bits of metal?

Feyn­man: They re­pel each other.

In­ter­viewer: What does that mean, or why are they do­ing that, or how are they do­ing that? I think that’s a perfectly rea­son­able ques­tion.

Feyn­man: Of course, it’s an ex­cel­lent ques­tion. But the prob­lem, you see, when you ask why some­thing hap­pens, how does a per­son an­swer why some­thing hap­pens? For ex­am­ple, Aunt Min­nie is in the hos­pi­tal. Why? Be­cause she went out, slipped on the ice, and broke her hip. That satis­fies peo­ple. It satis­fies, but it wouldn’t satisfy some­one who came from an­other planet and who knew noth­ing about why when you break your hip do you go to the hos­pi­tal. How do you get to the hos­pi­tal when the hip is bro­ken? Well, be­cause her hus­band, see­ing that her hip was bro­ken, called the hos­pi­tal up and sent some­body to get her. All that is un­der­stood by peo­ple. And when you ex­plain a why, you have to be in some frame­work that you al­low some­thing to be true. Other­wise, you’re per­pet­u­ally ask­ing why. Why did the hus­band call up the hos­pi­tal? Be­cause the hus­band is in­ter­ested in his wife’s welfare. Not always, some hus­bands aren’t in­ter­ested in their wives’ welfare when they’re drunk, and they’re an­gry.

And you be­gin to get a very in­ter­est­ing un­der­stand­ing of the world and all its com­pli­ca­tions. If you try to fol­low any­thing up, you go deeper and deeper in var­i­ous di­rec­tions. For ex­am­ple, if you go, “Why did she slip on the ice?” Well, ice is slip­pery. Every­body knows that, no prob­lem. But you ask why is ice slip­pery? That’s kinda cu­ri­ous. Ice is ex­tremely slip­pery. It’s very in­ter­est­ing. You say, how does it work? You could ei­ther say, “I’m satis­fied that you’ve an­swered me. Ice is slip­pery; that ex­plains it,” or you could go on and say, “Why is ice slip­pery?” and then you’re in­volved with some­thing, be­cause there aren’t many things as slip­pery as ice. It’s very hard to get greasy stuff, but that’s sort of wet and slimy. But a solid that’s so slip­pery? Be­cause it is, in the case of ice, when you stand on it (they say) mo­men­tar­ily the pres­sure melts the ice a lit­tle bit so you get a sort of in­stan­ta­neous wa­ter sur­face on which you’re slip­ping. Why on ice and not on other things? Be­cause wa­ter ex­pands when it freezes, so the pres­sure tries to undo the ex­pan­sion and melts it. It’s ca­pa­ble of melt­ing, but other sub­stances get cracked when they’re freez­ing, and when you push them they’re satis­fied to be solid.

Why does wa­ter ex­pand when it freezes and other sub­stances don’t? I’m not an­swer­ing your ques­tion, but I’m tel­ling you how difficult the why ques­tion is. You have to know what it is that you’re per­mit­ted to un­der­stand and al­low to be un­der­stood and known, and what it is you’re not. You’ll no­tice, in this ex­am­ple, that the more I ask why, the deeper a thing is, the more in­ter­est­ing it gets. We could even go fur­ther and say, “Why did she fall down when she slipped?” It has to do with grav­ity, in­volves all the planets and ev­ery­thing else. Nev­er­mind! It goes on and on. And when you’re asked, for ex­am­ple, why two mag­nets re­pel, there are many differ­ent lev­els. It de­pends on whether you’re a stu­dent of physics, or an or­di­nary per­son who doesn’t know any­thing. If you’re some­body who doesn’t know any­thing at all about it, all I can say is the mag­netic force makes them re­pel, and that you’re feel­ing that force.

You say, “That’s very strange, be­cause I don’t feel kind of force like that in other cir­cum­stances.” When you turn them the other way, they at­tract. There’s a very analo­gous force, elec­tri­cal force, which is the same kind of a ques­tion, that’s also very weird. But you’re not at all dis­turbed by the fact that when you put your hand on a chair, it pushes you back. But we found out by look­ing at it that that’s the same force, as a mat­ter of fact (an elec­tri­cal force, not mag­netic ex­actly, in that case). But it’s the same elec­tric re­pul­sions that are in­volved in keep­ing your finger away from the chair be­cause it’s elec­tri­cal forces in minor and micro­scopic de­tails. There’s other forces in­volved, con­nected to elec­tri­cal forces. It turns out that the mag­netic and elec­tri­cal force with which I wish to ex­plain this re­pul­sion in the first place is what ul­ti­mately is the deeper thing that we have to start with to ex­plain many other things that ev­ery­body would just ac­cept. You know you can’t put your hand through the chair; that’s taken for granted. But that you can’t put your hand through the chair, when looked at more closely, why, in­volves the same re­pul­sive forces that ap­pear in mag­nets. The situ­a­tion you then have to ex­plain is why, in mag­nets, it goes over a big­ger dis­tance than or­di­nar­ily. There it has to do with the fact that in iron all the elec­trons are spin­ning in the same di­rec­tion, they all get lined up, and they mag­nify the effect of the force ’til it’s large enough, at a dis­tance, that you can feel it. But it’s a force which is pre­sent all the time and very com­mon and is a ba­sic force of al­most—I mean, I could go a lit­tle fur­ther back if I went more tech­ni­cal—but on an early level I’ve just got to tell you that’s go­ing to be one of the things you’ll just have to take as an el­e­ment of the world: the ex­is­tence of mag­netic re­pul­sion, or elec­tri­cal at­trac­tion, mag­netic at­trac­tion.

I can’t ex­plain that at­trac­tion in terms of any­thing else that’s fa­mil­iar to you. For ex­am­ple, if we said the mag­nets at­tract like if rub­ber bands, I would be cheat­ing you. Be­cause they’re not con­nected by rub­ber bands. I’d soon be in trou­ble. And sec­ondly, if you were cu­ri­ous enough, you’d ask me why rub­ber bands tend to pull back to­gether again, and I would end up ex­plain­ing that in terms of elec­tri­cal forces, which are the very things that I’m try­ing to use the rub­ber bands to ex­plain. So I have cheated very badly, you see. So I am not go­ing to be able to give you an an­swer to why mag­nets at­tract each other ex­cept to tell you that they do. And to tell you that that’s one of the el­e­ments in the world—there are elec­tri­cal forces, mag­netic forces, grav­i­ta­tional forces, and oth­ers, and those are some of the parts. If you were a stu­dent, I could go fur­ther. I could tell you that the mag­netic forces are re­lated to the elec­tri­cal forces very in­ti­mately, that the re­la­tion­ship be­tween the grav­ity forces and elec­tri­cal forces re­mains un­known, and so on. But I re­ally can’t do a good job, any job, of ex­plain­ing mag­netic force in terms of some­thing else you’re more fa­mil­iar with, be­cause I don’t un­der­stand it in terms of any­thing else that you’re more fa­mil­iar with.