Feynman×Einstein

full transcript

1. 00:00
   Verashare moment

   You're with Radio Ether. Coming up: Richard Feynman sits down with Albert Einstein for STUDY HALL. The subject — On the sentence in their own work they regret most.
2. 00:10
   Richard Feynmanshare moment

   Alright, so we're supposed to talk about sentences we regret. I gotta say, I've written things that turned out wrong, sure, but regret? That's a funny word. Usually when I'm wrong it's because I didn't understand something yet, and then you learn, and that's the whole game!
3. 00:24
   Albert Einsteinshare moment

   Yes, but there is a difference, I think, between being wrong in the privacy of one's notebook and being wrong in print, where it misleads others. Or worse—where it misleads yourself for years.
4. 00:36
   Richard Feynmanshare moment

   Oh, you've got one of those? A sentence that sat there like a rock in your shoe?
5. 00:40
   Albert Einsteinshare moment

   I do. From 1917, in my paper on cosmology. I wrote that the universe must be static, neither expanding nor contracting, and to make the equations behave I introduced a term—the cosmological constant. At the time I called it necessary. Later I called it my greatest blunder.
6. 01:01
   Richard Feynmanshare moment

   Wait, wait. But that constant—it's back now, isn't it? I mean, the universe is accelerating, the astronomers say, and they need something like it to explain dark energy. So maybe it wasn't such a blunder after all!
7. 01:13
   Albert Einsteinshare moment

   Perhaps the number comes back, yes. But the sentence I regret is not about the number. It is about why I put it there. I put it there because I could not imagine the universe doing anything but sitting still. My imagination failed. I had the equations that would have predicted expansion, and I bent them to fit my prejudice.
8. 01:33
   Richard Feynmanshare moment

   Ah, I see. You're not regretting the math, you're regretting that you didn't trust the math.
9. 01:38
   Albert Einsteinshare moment

   Exactly so. The sentence I wish I could take back is this: 'We must assume the universe to be essentially static.' That 'must' is the poison. There is no 'must' when nature is speaking. Only 'let us see what happens if.'
10. 01:54
    Richard Feynmanshare moment

    Boy, that's a good one. The 'must' instead of the 'maybe.' I've done that! Not with the universe, but with smaller stuff. You get attached to how you think it should be, and then the experiment comes along and kicks you in the teeth.
11. 02:07
    Albert Einsteinshare moment

    Do you have a sentence, then? One that kicked you?
12. 02:10
    Richard Feynmanshare moment

    Yeah, I've got one. From my lectures, actually, the undergraduate lectures at Caltech. I was explaining quantum mechanics, and I said—let me get this right—I said something like, 'I think I can safely say that nobody understands quantum mechanics.' And everybody loved that! They quote it all the time.
13. 02:28
    Albert Einsteinshare moment

    But you regret it?
14. 02:29
    Richard Feynmanshare moment

    I regret the way it gets used. People take it as permission to stop thinking. Like, 'Oh, Feynman said nobody understands it, so I guess it's okay if I don't even try.' But that's not what I meant! I meant we don't have a picture of it that satisfies our classical intuitions. We don't have the comfortable feeling we get with, say, billiard balls. But we understand it in the sense that we can calculate, we can predict, we can use it. The understanding is there, just not the kind of understanding people want.
15. 02:58
    Albert Einsteinshare moment

    So you regret giving people an excuse?
16. 03:00
    Richard Feynmanshare moment

    Yeah. And also, I think I was being too cute. I wanted to sound profound, you know? 'Nobody understands it'—it's got a ring to it. But it's sloppy. It confuses 'understanding' with 'having a mental picture,' and those aren't the same thing.
17. 03:14
    Albert Einsteinshare moment

    This is interesting. You regret a sentence not because it is false, but because it is imprecise in a way that encourages laziness.
18. 03:22
    Richard Feynmanshare moment

    Exactly! And coming from me, that's ironic, because I spent my whole life trying to get people not to be lazy, to actually look at what the equations say and what the experiments show. So that one sentence kind of undercuts the whole project.
19. 03:35
    Albert Einsteinshare moment

    I wonder if this is a hazard of teaching. We try to make a point memorable, and so we sharpen it, we exaggerate a little. And then it becomes a slogan, and slogans are almost always lies.
20. 03:47
    Richard Feynmanshare moment

    Yeah, or at least half-truths. You sand off all the nuances to make it fit on a bumper sticker, and then people drive around with the bumper sticker thinking they've got the whole picture.
21. 03:57
    Albert Einsteinshare moment

    Although, I must say, I am guilty of this too. 'God does not play dice'—everyone knows I said this, and everyone thinks they know what I meant. But it is not precise. What I meant was that quantum mechanics, as it stood, could not be the final word. There must be something deeper. And yet the sentence makes me sound like I am talking about theology, about God's personality.
22. 04:21
    Richard Feynmanshare moment

    Do you regret that one too?
23. 04:22
    Albert Einsteinshare moment

    A little, yes. Because it makes the argument sound mystical when it was not mystical at all. It was a scientific objection. I thought—I still think—that a complete theory should tell us what actually happens, not merely what we can observe. But 'God does not play dice' sounds like an old man shaking his fist at the sky.
24. 04:43
    Richard Feynmanshare moment

    Well, you were kind of old when you said it.
25. 04:45
    Albert Einsteinshare moment

    I was fifty! Not so old. But yes, older than you when you said your thing.
26. 04:51
    Richard Feynmanshare moment

    Touché. Okay, but here's a question: if you could go back and rewrite your sentence—the 'must assume the universe is static' one—what would you say instead?
27. 05:00
    Albert Einsteinshare moment

    I would say, 'Let us explore the possibility of a static universe, knowing that the equations also permit dynamic solutions.' Something like that. More tentative. Less dogmatic. What about you?
28. 05:13
    Richard Feynmanshare moment

    I'd probably say, 'Nobody has a classical mental picture of quantum mechanics, and that's fine—we have something better, which is the mathematical framework that actually works.' But that's clunky. Doesn't have the same punch.
29. 05:27
    Albert Einsteinshare moment

    No, it does not. And this is the problem, yes? The true sentence is often longer and less memorable than the false one.
30. 05:35
    Richard Feynmanshare moment

    Right. The lie gets to the finish line first. Or not even a lie, just the oversimplification.
31. 05:41
    Albert Einsteinshare moment

    So perhaps the real regret is not about the sentence itself, but about the choice between clarity and truth. Sometimes they pull in opposite directions.
32. 05:51
    Richard Feynmanshare moment

    Yeah, but I don't know if I buy that we have to choose. I mean, I've spent a lot of time trying to be both clear and true. It's harder, sure, but it's not impossible. You just have to be willing to say more words.
33. 06:03
    Albert Einsteinshare moment

    But then you lose people. The attention wanders. I have seen this in lectures. You begin with a careful qualification, and already they are asleep.
34. 06:13
    Richard Feynmanshare moment

    Okay, that's fair. But then maybe the problem is us, the teachers. Maybe we're too worried about keeping people awake and not worried enough about whether they're learning the right thing.
35. 06:23
    Albert Einsteinshare moment

    Perhaps. Or perhaps there is no solution. Perhaps every sentence we write is a compromise between what is true and what can be understood.
36. 06:32
    Richard Feynmanshare moment

    Man, that's bleak! I don't want to believe that. I want to believe you can get it right if you work hard enough.
37. 06:38
    Albert Einsteinshare moment

    Then you are more optimistic than I am. Which is surprising, because usually I am accused of being the optimist.
38. 06:44
    Richard Feynmanshare moment

    About physics, maybe. About sentences, I think you're a pessimist.
39. 06:48
    Albert Einsteinshare moment

    I have been burned too many times. You put a sentence out into the world and it takes on a life of its own. People quote it in contexts you never imagined. They use it to justify things you would oppose.
40. 07:02
    Richard Feynmanshare moment

    Yeah, I've had that happen too. The quantum mechanics line shows up in all kinds of mystical nonsense, like it's proof that consciousness creates reality or some garbage like that. Drives me crazy.
41. 07:14
    Albert Einsteinshare moment

    And yet we keep writing. We keep trying to say what we mean.
42. 07:17
    Richard Feynmanshare moment

    Well, what else are we going to do? Not write? Not talk? That's worse. At least if you say something, even something imperfect, there's a chance someone will understand. If you say nothing, the chance is zero.
43. 07:31
    Albert Einsteinshare moment

    This is true. And besides, the regret itself is useful. It means we are still learning. If I did not regret that sentence about the static universe, it would mean I had learned nothing in the thirty years since I wrote it.
44. 07:45
    Richard Feynmanshare moment

    Yeah, exactly! The regret is a sign you've moved forward. You look back and you cringe a little, and that's good. It means you're not the same person you were.
45. 07:53
    Albert Einsteinshare moment

    So perhaps we should not wish to erase these sentences after all. They are part of the path. They show where we have been.
46. 08:01
    Richard Feynmanshare moment

    I guess. But I still wish I'd been more careful with that 'nobody understands' thing. Just a little more careful.
47. 08:07
    Albert Einsteinshare moment

    And I wish I had not used the word 'must.' But we did, and here we are. Talking about it on the radio, many years later.
48. 08:15
    Richard Feynmanshare moment

    Yeah. And maybe that's the best we can do. Say what we think, mess it up a little, and then come back later and explain what we really meant. It's not elegant, but it's honest.
49. 08:25
    Albert Einsteinshare moment

    Honest, yes. That is the word. Better an honest mistake than a perfect silence.