Lev Landau's “Theoretical Minimum” | Hacker News Reader

Lev Landau's “Theoretical Minimum”

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It’s a strange feeling reading Ioffe’s memoir.

When I was a physics undergraduate, I understood the mentality. The high-maintenance asshole professor was exactly who I’d be drawn towards. I learned how unhealthy that was, and many of those who didn’t ended up burning out HARD.

Landau was the rare asshole whose ability to hone students was worth the abuse. And reading this, I found myself in the frame of mind of “yeah, in that scenario, I’d absolutely work my ass off just to be in that guy’s favour”.

Years training myself out of that unhealthy mentality and boom, a few pages of memoir and I’m back in that naive frame of mind.

We are seduced and captivated by raw genius. I’m sure Landau was one of the highest caliber. To pass his examination, to be well regarded by him, to be part of such a select group, who wouldn’t want to? Don’t be hard on yourself.

I don't even know that it's even raw genius - our brains are full of 'ape shit' which at times includes close attention to hierarchy. Seems likely to be a combination of charisma, ape-dominance, and enough smarts to be a good physics researcher.

Many groups that select people for arbitrary reasons exist. Sure, here we see external cause and zealous dedication, but those things don't automatically make anything good. We then have to decide whether “advancement of scientific knowledge” should be seen as some kind of royal mantle (and by whom). And so on, and so forth.

It is easier to compare it to professional sport. Not only athletes have natural talents, they also participate in training that would be useless or harmful for everyone else. Only then they can reach the record setting zone.

What memoir you're referring to? A.Ioffe didn't write one as far as my research shows.

My bad... Boris Ioffe (not related to A. Ioffe) has indeed written a memoir:

Иоффе Б. Л. Без ретуши. Портреты физиков на фоне эпохи. —М.: ФАЗИС, 2004; 160 с. ISBN 5-7036-0088-Х

Landau's Theoretical Minimum, Landau's Seminar, ITEP in the Beginning of the 1950's - https://arxiv.org/abs/hep-ph/0204295v1

"...In the worst cases, when the speaker failed a few times, he was ostracized — excluded from the list of the seminar participants, and Landau would refuse to have discussions with him, but, of course, he (the ostracized person) could attend seminars. (I remember two such cases — in one case the speaker was a famous physicist, V.G. Levich, who eventually became a Member of the Academy of Sciences). Only after a long time, a year or more, and after being advocated by the most respected seminar participants, could such a person be pardoned by Landau..."

Time in GULag makes people grumpy.

He was arrested, but never went to a labour camp.

He was quite a bit of an asshole before he was arrested.

Fairly comprehensive, highly technical but hardly inspiring or insightful. Old-fashioned, austere (The classical theory of fields has like a handful of diagrams).

The polar opposite of the "Pleasure of finding things out" of Feynman. Or the incongruous visual orgy and outright speculation of Gravitation.

Of-course the interesting question is which educational / pedagogical approach works "best". Alas that is almost impossible to define, let alone prove on the basis of the highly idiosyncratic development of physics in the 20th century.

It makes me wonder of the 43 students who passed, how many achieved significant breakthroughs or Nobel prizes?

His students were successful enough that nine of them have their own articles on English Wikipedia. Many more (>20) have articles on Russian Wikipedia.

Amongst the nine students who have English Wikipedia articles, one won a Nobel [0]. The others have all won highly prestigious physics prizes, and all appear to be major contributors to their subfields. One even has a class of subatomic particles named after him [1].

Was Landau's pedagogical approach optimal? Impossible to say. Was it extremely successful? Objectively, yes, without a doubt.

[0] https://en.wikipedia.org/wiki/Alexei_Abrikosov_(physicist)

[1] https://en.wikipedia.org/wiki/Pomeron

Is that not just selection bias? Makes sense that the most gifted students at the most prestigious school over a span of 30 years went on to have great careers.

OP was questioning whether Landau’s method of identifying the most gifted students actually selected for successful physicists:

“It makes me wonder of the 43 students who passed, how many achieved significant breakthroughs or Nobel prizes?”

So yes, it is selection bias by definition, but the point is that the method of selection worked. Most other professors at the most prestigious schools in the world could only dream of advising anything close to Landau’s academic descendants.

To complete the analysis we should look at the achievements of those who failed the Theoretical Minimum.

Well how many Nobel prize winners did Feynmann bring up?

Arnold Sommerfeld was supposedly a great educator and a likeable teacher.

From Wikipedia: “ He invited collaboration from them, and their ideas often influenced his own views in physics. He entertained them in his home and met with them in cafes before and after seminars and colloquia. Sommerfeld owned an alpine ski hut to which students were often invited for discussions of physics as demanding as the sport.” [1]

Four of his doctoral and three of his post-doctoral students went on to become Nobel prize winners. That’s a lot of Nobel prize winners.

[1] https://en.m.wikipedia.org/wiki/Arnold_Sommerfeld

The important question here is how many went on to become gold medal winter olympians.

At least one has the prize and many others are internationally recognized for their contributions.

One of them was Lex Fridman Father.

Nobel prizes are highly political and random. It’s like judging programming skill by who won the startup lottery.

Say the bitter losers.

Rarely does anybody credible say "It's bullshit that they won the prize. I should have won the prize!"

Much more often people say "So that prize was bullshit... $OTHER should have won it instead."

Lise Meitner is a classic example. Chien-Shiung Wu is another.

There is more work than can win the Nobel then prizes to hand out and some awards are mystifying like the one for the automatic navigation aid light.

I have no doubt that visual is better than text-only and austere, by any metric, except one: filtering out those with less commitment.

Laundau himself didn't have much patience for struggling to understand dense language, according to Ioffe's account:

"Landau knew well all subjects (despite the fact that he almost did not read papers, only listened to their presentations) and put questions which had to be immediately and definitely answered -- general words or statements like “the author claims ...” were not accepted."

That said, Landau's Theoretical Physics textbook is graduate-level. Feynman wrote an undergraduate Physics textbook. And some other things Feynman wrote might have been for even wider audiences.

My hunch is this filter would be particularly bad for true talent but would be quite good to populate the workhorse ranks. Which would not a small feat. Underneath the exalted world of Class I scientists that open new vistas, the bread and butter in any field is the adaptation and application of techniques to "nearby" problems.

Curiously there isnt a complete graduate level physics textbook collection in the modern style. Only individual examples here and there from different authors.

With the heyday of physics and textbooks behind us its unlikely we see that ever happening.

Feynman wrote at least one book aimed at the graduate level, “Quantum Mechanics and Path Integrals”: https://www.amazon.com/Quantum-Mechanics-Path-Integrals-Emen...

Haven’t really read it so don’t know if its lucidity matches his undergraduate series.

It is a good book, have it in hard cover.

Feynman indirectly wrote quite a few graduate level texts such as The Theory of Fundamental Processes, Statistical Mechanics Lecture Notes and Photon-hadron Interactions which are compilations of lecture notes re-written in book form. There is also one on gravitation dating to the early 1960s.

It would be incredible to gain access to the archive of exams, particularly those administered during Landau's era. These must surely exist in paper format somewhere, right?

Anyone read the Livshitz-Landau textbooks? Any thoughts on them and how the compare to the Feynman Lecture series?

P.S. No immediate relation to Landau (and family name is really Livshitz).

The Feynman lectures are definitely easier to understand. I could pick something from them.

And more fun to read.

Course of Theoretical Physics is too "cold". It however seems more comprehensive. As it looks to contain more material.

Feynman was trying to teach the first three years of physics by mixing the splits between topics. It's far less comprehensive than L&L.

They are incredibly dense. Like, it assumes you are already an expert on the topic and you need a high level refresher.

Accurate. I had a immigrant Russian professor in undergrad QM whom provided no notes, I could barely understand anything he said, and he just said to use L&L as the course book when people asked for help. I spent hours trying to read it but it was utterly useless. Worst studying experience I ever had

As the joke goes, one morning Livshitz was riding a tram to work, someone pushed him and he dropped his manuscript into the mud, ruining a few pages. When he arrived at the lab, he complained to Landau that he would have to spend the whole day rewriting the proof of a tricky theorem because the middle part was now gone, but Landau suggested simply to put "from which it is obvious that" there instead.

> Anyone read the Livshitz-Landau textbooks? Any thoughts on them and how the compare to the Feynman Lecture series?

Landau-Livshitz books are gradual level while Feynman Lectures are undergrad level physics course. They should not be directly compared to each other.

Another one worth mentioning is Theoretical Minimum by Susskind. It's not at the same level as Lev Landau though.

In undergrad I took a graduate class out of Calculus of Variations by Gelfand and Fomin [0] that went deep into the math of classical mechanics but assumed students already knew the relevant physics. I hadn't taken a proper classical mechanics class, and working through Volume 1 of Livshitz-Landau in parallel with the lectures helped to ground the material for me. A brilliant classmate who’s now a successful mathematical physicist had recommended the series.

Later I tried to learn Quantum Mechanics while taking a course on Operator Theory, but gave up on using Volume 3 of Livshitz-Landau because it was just too impenetrable. I ended up going with Sakurai instead.

I found Volume 1 to be beautiful read and felt like I was learning something profound. Volume 3 was beyond me. The only thing I'd say these books have in common with the Feynman Lectures is a dearth of exercises. This wasn't an issue for me reading Volume 1 of LL because that Calculus of Variations course had many exercises which I just wasn't in a position to appreciate without knowing more Physics.

That book was often referred as Landavshitz among students. Fantastic series.

Susskind taught a series of courses at Stanford Continuing Studies called The Theoretical Minimum, in homage to Landau. The lectures are all on YouTube

https://theoreticalminimum.com/

There’s also an excellent series of books by Susskind of the same name.

I've skimmed through the Landau books and while they are technically excellent, they lack a sense of feeling and motivation which makes it hard to self study from. It felt like a slog across random topics with no application

The key is to make sure you're reading books by Landau and Lifshitz. Landau was more the famous as a theoretician, Lifshitz was the better writer.

That said, these are definitely books to read when you're in the mindset of studying for PhD doctoral exams in Physics. I loved them at the time but would definitely have a hard time curling up by the fire with them on a rainy afternoon.

>Landau was more the famous as a theoretician, Lifshitz was the better writer.

As the famous quip goes, "not a word of Landau and not a thought of Lifshitz."

I remember trying to read the first tome of Landau and Lifshitz in my first year of studying at the physics department and instantly bouncing off. The textbooks of Irodov, Savelyev, and Sivukhin were much more approachable.

There's a reason the profs love Landau/Lifshitz. The books have a certain elegance that, once you have a decent understanding of the subject already, is easy to appreciate. But as a first year theory student, that's just not what you need.

Went through the same experience you describe. But enjoyed them when I picked them up again a few years later.

The first volume is "Mechanics" as in Theoretical Mechanics. It's a second or third year Physics course not a first year one. I took it third year, it was mostly fine. The treatment of Hamilton-Jacobi equation lacked motivation but it wasn't super difficult. I also took volume 2, "Classical Theory of Fields". That was much, much harder. Anything after that seemed unreachable.

> I've skimmed through the Landau books and while they are technically excellent, they lack a sense of feeling and motivation which makes it hard to self study from.

A person that I know who has a doctoral degree in pysics and loves the Landau-Lifshitz books said: "If you need such an external motivation (for reading the Landau-Lifshitz books), you simply do not have sufficient inner drive for studying physics. Find another major that better is a better fit for you."

I think this 100% true, you don't read those books for any pleasure, its simply a necessary part of an education in theoretical physics. rigorous and challenging

don't you just love it when people with "doctoral" degrees meme? this is a really bad paraphrasal of the apocryphal story about hilbert:

"There is a much quoted story about David Hilbert, who one day noticed that a certain student had stopped attending class. When told that the student had decided to drop mathematics to become a poet, Hilbert replied, “Good — he did not have enough imagination to become a mathematician.”

— Robert Osserman (US mathematician, 1926 – 2011)"

> don't you just love it when people with "doctoral" degrees meme?

This was not intended as some kind of meme by him. He really is like that. The mention of his doctoral degree in physics has just the relevance that he is not to be considered a crackpot.

I don't like how so many textbooks and university courses teach physics like it's a bunch of theories that popped out of nowhere to be memorized.

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