Mason Porter http://www.its.caltech.edu/~mason/wisdom/predrag.txt These come from Predrag Cvitanovic', purveyor of witticisms and acknowledged expert on classical and quantum chaos. The course in which these occurred was Physics 7123 (Statistical Mechanics II: Classical Chaos) taught in Fall 2003 at Georgia Tech and Physics 7224 (Quantum Chaos) taught in Spring 2004 at Georgia Tech. (Note: Predrag's many amusing comments from other venues ordinarily will not be included.) ---Classical Chaos--- 8/19/03: "It's version 10. It's counted like Klenex." "Ryan must have done something." "Who knows what this stuff does?" "Physicists had no clue that this stuff was going on because they were preoccupied with quantum mechanics and building bombs and stuff." "As a physicist, you have to show it for 1, 2, 3, and then you're happy." "Mathematicians care about all this stuff. We're practical people... we don't have to care about it." "There's no way you'll understand quantum mechanics. You just get used to it." "It's very easy to do wrong things in infinite-dimensional settings." "It's just number theory, so it shouldn't be very important." (Slaven Peles lectured on 8/21 and 8/26, so there are no amusing comments to report.) 8/28/03: "Did you receive a mail about the missing student?" (Predrag citing a recent example to illustrate wandering and recurrent trajectories) "There's lots of mathematics that I'll try to avoid." "I can be as sadistic as I want." "You can just do some simulation, publish it, and you're done. You don't have to understand anything." 9/2/03: "So this you'll have to understand yourself." "I remember this with coffee." 9/4/03: "This is a clinic, so you just say where it hurts." "You can spend six months having fun with bras and kets but understanding nothing." "Amazing... what an institution." 9/9/03: "God! There are still people in the class!" "It really looks like quantum mechanics except it's not as beautiful." "Then you stare at this thing and say, 'God, how do I do this?'" "This course has very few ideas, and this is one of them. So please pay attention." "Now, why am I doing this to you? What is good about this?" 9/18/03: "Just as I was talking about the Devil..." "They're basically uncontrollable except the examples in this book." "Number theory is what makes the National Security Agency go." "I don't understand my figure at all." "You'll discover that this is all very pretty, but it's kind of weird." 9/23/03: "You might find that the optional chapter will come to haunt you later." "People kill each other for this, commit suicide, whatever." (on statistical mechanics) "Serious stuff, but now accessible to every man." (the very next sentence) "It's one of those things they show you in high school if you went to a decent high school." (on Cantor sets) "It has a reasonable name. It's not called a conjugacy." 9/25/03: "What I'll do today... we can basically go home. We're done." "I sense I'm failing here." "Let me demystify this nonsense." "Now I have a formula for the trace... which I keep erasing. Too bad." 9/30/03: "As we are physicists, we are fearless." "On Thursday, we will derive a formula which is not divergent." "This I discussed in chapter whatever." "Now I'm just covering the gaping hole in your education left by 300 years of tradition in classical mechanics." 10/07/03: "People don't read. They just publish papers." "I have a problem--not with you because you just sit here and don't tell me anything--but with professionals." "I had a student who refused to understand everything." "He did it right by being dumb and not reading the literature." "Good. There's one dummy who doesn't know." 10/09/03: "This is the end of the first term, so I think we should have a conversation instead of me haranguing you all the time." "I thought about what I could do today. I'll teach you something useless but pretty." "I want you to grill me on whatever you want to grill me on the indignities suffered so far." "You have to abandon mathematics because it's useless." "[He is] one of the important people who started the field of chaos, who is now dead." (on Joe Ford) 10/16/03: "Old historians get better but old physicists--it's tough." "It was such a disaster that it led to Heisenberg and Schrodinger theory." "John Paul just finished 25 years as The Pope, so I felt I needed to give a sermon." "I didn't grow up in the Soviet Union, but I grew up under communism, so when I see an acronym..." (on the use of 'UPO' for 'unstable periodic orbit') "Formulas are just formulas; there's nothing intellectual in them." "It turns out that life doesn't make sense unless you understand linear stability." "We already did the thinking for you, so I might as well just tell you how it works." "I don't care about it, but all _Phys. Rev. Letters_ are full of it, so we have to do it." "It's stupid, so of course it's the most heavily funded." 10/21/03: "How much you can get depends on how powerful you are." "It's a learned theorem that you could never understand if you look at the original papers." "I'll tell you something that's deathly cute." "If nobody volunteers, it will be the Chinese volunteer system." 10/23/03 (Slaven Peles lecturing and providing quotes): "It wouldn't be fun if I don't give you homework." "This is optional homework, so you don't have to do it if you really don't want to, but it's so simple that it's really a matter of honor to do it." 10/28/03 (Slaven Peles lecturing and providing quotes): "Let's put vector signs here to make it a little more complicated." "Official disclaimer: Studying from these lecture notes may cause you to fail the exam, so use them carefully." 10/30/03: "I should tell you about killer apps of nonlinear dynamics." "One half is like quantum mechanics, which means you know it but don't understand it." "It's like going from a graduate student's salary to a postdoc's salary.You can't go back." "I don't know how to write it in a human language." "If you feel ready to talk about your project, let us know. Otherwise, an e-mail will arrive." "I wash my hands from this." "You shouldn't trust anything in the book." 11/4/03: "The book is not bad in this chapter, so I think it's readable." "If you start here, you go to the other side---to the dark side." "Then it's like quantum mechanics because you have to write character tables and that kind of nonsense." "I've already forgotten this stuff two or three times." "This is sort of how we discovered this nonsense." "So you have to scratch your head and understand what this means." 11/6/03: "Maybe you don't want to do it, but are you man enough to do it?" "We don't have much time left in the class, so maybe next week we'll have an orgy of presentations." "I'm a failed artist. I'll do this." "I can count the number of times in my life that a program just worked. It's a miraculous event, so you remember it." "You rescale things, etc. Have you read the book?" 11/9/03: (Sorry, I missed that lecture.) 11/11/03: "It becomes mathematics when you do this stuff. It's not worth it." "I have a very respectable colleague--Pierre Gaspard--who thinks it cannot be done, but I don't believe him." "Don't worry that English is not your native tongue. You have to learn how to scream at people in English." 11/16/03: (Sorry, I missed that lecture.) 11/18/03: "Now comes the miracle of cycle expansions." "I don't know how to write it in a way that doesn't sound stupid." "Don't worry about the dimensions. I think it's garbage." 11/23/03: (Sorry, I wasn't there on this day either.) 11/25/03: "I find this theory much more sophisticated than you would do by guessing." "Statistical mechanics is a subject where lots of people have very strong opinions." "It could be worked out as a problem set, but I've given up doing this." "Things are just magically converging like a ton of bricks." "I've never seen graduate students isolated like the ones here. You need to either stand together or hang together." "Unfortunately, the theory is still kind of unpresentable." 12/02/03: "There are covers of all types of coffee table books having to do with this function." "He's never had to deal with lower forms of life." (on David Ruelle never having advised any students) "He spent an hour talking, and nobody understood a single word he said." (on Ruelle's talk at GA Tech the previous day) "Hopefully, it will get obvious later." "You can't appreciate it until it hits you in the head." 12/04/03: "It's endlessly painful, but such is life." "So what are you going to do?" ---Quantum Chaos--- 1/8/04: I was out of town that day. Sorry. 1/13/04: "That's why mathematicians are sometimes useful." 1/15/04: "I'll regret this. What's done is done." "The most idiotic answer is correct." "Later on, it becomes horrible." 1/20/04: "It's a little like popular science writing. The more you know, the less accessible it becomes." "When it comes up next time, it's going to be painful and wrenching." "Mine doesn't make any sense either." "If you're willing to swallow this, we're in business." "I used it in my thesis. I didn't say I derived it." (yours truly) "You have to work a bit to really believe yourself." "This is surprising. Nobody ordered this." 1/22/04: "There is a problem with quantum mechanics---that is, none of us understand it." "He has a Nobel prize, so he's not a total dummy." "I'm writing a stupid thing, right?" "This is very popular in some currently occupied countries." "I'm a specialist in chaos, so I always ignore the integrable problems." 1/27/04: "The whole thing is a totally dark art." "This is going to be slightly circular." "Trust me it's true, and it's trivial, and we'll do it." 1/29/04: I was out of town today, so I missed lecture. Sorry. 2/3/04: (lecture titled: 'The Fog of Algebra') "I'm allowed to choose any dq and dt that makes my day." "This minus sign shows up. Nobody asked for it." "The intellectual content of all this is rather small." "This might help or might distract, but I'll do it anyhow and see how it works."" "It was written by a very unreliable colleague and myself, so there could be errors of 2 all over the place." 2/5/04: "I'm actually not sure about anything at the moment." "Again I have a wrong sign, but that's life." "Right bow we're doing quantum mechanics, so we can't even think the way you're thinking." "In quantum mechanics, we can't do anything, so it's much simpler." "The problem in statistical mechanics is that every time they reinvent the Gaussian, they give it a different name." "It doesn't occur to them that they should also think. It's like an extra prize. (...) But I guess they're getting an education." "They seem to be not as fundamental as they seem." "You already learned that a Gaussian turned 90 degrees is called somebody's integral." "Again, I didn't sleep very much." "The book is probably wrong most of the time." "There is a stable version, which is the holy version until next August." 2/9/04 (Predrag commenting during Matthew Bennett's talk): "I mean, I don't find this remark very helpful." 2/10/04 (my N'th birthday!): "Anybody who can't read this needs new glasses." (Editor's Note: Did I ever mention how much I like the movie Spaceballs?) "For some reason, I have to do some work." "This is only the beginning of our troubles." "Why did I do this here?" "Any objections from the floor?" "This has disgusted me my entire quantum chaotic life." 2/12/04: "The only problem with this answer is that we don't actually care about this thing." "I truly think I'm telling you something wrong." "I don't know how to think about these things very well." "We have to discuss what it means to be explicit." "Let us discuss this derivative for a second, and then we'll decide if we understand it." "You were awake at the wrong time." "You find out... I don't know what you find out." "Anyway, screw it. What you have to do is verify the usual stuff." 2/17/04: "Since Thomas Bartsch has been sitting in on this course, things have been rough." "America was like... I don't know... Afghanistan as far as science was concerned 120 years ago." "That brings us to where we were last time." "Trust me on signs. I'll fix them as we go along." "I got it! ... I think..." "I get a -1. Then it's even better." "We take a thinking pause right here." "It looks like it's diverging, so I don't know what I'm doing. It's kind of obvious." "When we take a trace, everything is going to go away, and we're going to get a totally sensible classical answer." "It's ok to cheat on the blackboard, but it's not ok to cheat on the Web." 2/19/04: (For some reason, I have no record of this day.) 2/24/04: "Many other things happened, so I don't know what to say." "There is a bonanza of various \pi's, etc." "I won't be here next Tuesday, but some form of entertainment will be provided." 2/26/04: (Luz Vela-Arevalo is lecturing today.) 3/2/04: (Luz is still lecturing + a student discussed her project a bit.) 3/4/04: "How you do it is your private business." "Don't ask, don't tell." (my response to the above comment) "In practice, it works well for everybody except for Slaven." "I'm reluctant to state this as a religion because it turns out that in every problem you have to rethink this." "As a mathematical problem, it's certainly almost always unstable." "Remember, thinking is extra cost." 3/9/04 and 3/11/04: No lectures due to Spring Break. 3/16/04: "Quantum mechanics is the square root of classical mechanics." "There's no way in the world you can write this formula down without the pain that we went through." "In a trivial case, it reduces to the Riemann conjecture." "The useful idea comes from Poincare, but they usually teach it in a useless way." "Some people like to stare at Lorentz attractors for sentimental reasons." (paraphrased slightly) "None of you saved me, but at least some signs are now correct." 3/18/04, 3/23/04, and 3/25/04: Sorry, I missed these lectures. 4/1/04: (Note: Predrag misses out on my wonderfully written April Fools' prank because of my hard drive's implosion. Wait 'til next year...) "I really want us to see one spectrum before the semester is over." "They lost the war, so you don't hear about him." "He just cleaned it out for us... like a tank." "1 is very interesting. It tells you how to find submarines and stuff like that." 4/6/04: "They're not so horrible, but they're horrible enough that you want to do it all in privacy." "OK, I will now write another horrifying formula." "Now I'll do this very carefully." (Predrag) "How did you go from there [indicates spot on the board] to there [indicates another spot]?" (a student) "Yeah, that's a good question. [a delay] It's a simple exercise in the notes. [another delay] I really don't remember; I'm sorry. [another delay] Apologies... I assure you, it's trivial." (Predrag's response to this student) "If you want to be a real mensch, you can produce thousands of eigenvalues with 10-15 cycles." "I'm only half guilty. Most of the guilt is yours." [Editor's note: Apparently, Predrag has been learning arithmetic from Yogi Berra.] 4/8/04 "It's kind of trivial, but it's too disgusting to do on the blackboard."