Problems from Lev Landau's "Theoretical Minimum"

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Discussion Overview

The discussion revolves around the challenging problems posed by Lev Landau in his entry exam for students, particularly focusing on problems related to electrodynamics and quantum mechanics. Participants express interest in finding more such problems for practice, especially in the context of graduate qualifying exams.

Discussion Character

  • Exploratory
  • Homework-related

Main Points Raised

  • One participant shares four specific problems from Landau's exam, covering topics in electrodynamics and quantum mechanics.
  • Another participant suggests consulting Landau's books for additional problems, referencing a discussion on Physics Stack Exchange.
  • A third participant confirms that they found quantum mechanics problems from the same Stack Exchange discussion but expresses uncertainty about which problems from Landau's books were included in the exam.
  • One participant reflects on the difficulty of Landau's problems, noting their own struggles with solving them and suggesting that the last few problems in each chapter are likely the hardest.

Areas of Agreement / Disagreement

Participants generally agree on the difficulty of Landau's problems and the value of solving them, but there is no consensus on the availability of a comprehensive collection of such problems.

Contextual Notes

Participants express uncertainty regarding the specific problems from Landau's books that may have appeared on the exam and the challenges in proving the correctness of their solutions.

Who May Find This Useful

This discussion may be useful for graduate students preparing for qualifying exams, educators seeking challenging problems for their curriculum, and anyone interested in the works of Lev Landau in theoretical physics.

JoePhysics
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It seems Lev Landau created an entry exam to test his students, and the exam was known to be ridiculously hard. To get an idea as to how hard the test really was, I've been scouring the Internet for problems Landau proposed... so far I've managed to find only four.

Electrodynamics
  1. A dielectric sphere with the electric and magnetic susceptibilities ##\varepsilon_1## and ##\mu_1## is rotating with angular frequency ##\omega## in a constant electric field ##\mathbf{E}## in a medium, characterized by the parameters ##\varepsilon_2## and ##\mu_2##. The angle between the rotation axis and the direction of ##\mathbf{E}## is ##\alpha##. Find the electric and magnetic fields inside the sphere and in the medium.
Quantum mechanics
  1. The electron enters a straight pipe of circular cross section (radius ##r##). The tube is bent at a radius ##R \gg r## by the angle ##\alpha## and then is aligned back again. Find the probability that the electron will jump out.
  2. A hemisphere lies on an infinite two-dimensional plane. The electron falls on the hemisphere, determine the scattering cross section in the Born approximation.
  3. The electron "sits" in the ground state in the cone-shaped "bag" under the influence of gravity. The lower end of the plastic bag is cut with scissors. Find the time for the electron to fall out (in the semi-classical approximation).
Does anyone know where to find more problems? These should be entertaining and good practice for the graduate qualifying exam. :oldbiggrin:
 
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jedishrfu said:
You might try reading his books for the problems as per this physics stackexchange discussion:

http://physics.stackexchange.com/questions/13861/lev-landaus-theoretical-minimum
Yes, that PSE is exactly where I got the quantum mechanics problems from. It does seem to mention his books, though I'm not sure which problems in his books showed up in the exam later on. I was hoping there was a compendium of some sort somewhere.
 
Any Lev problem is worthy of solving. They were all so difficult and I didn't have the patience to solve them or if I did I'd get stuck and couldn't prove my answer was correct. It takes a certain level of knowledge and brilliance which I have yet to attain to get through his stuff.

Look through each chapter and assume the last few problems are the toughest ones.
 
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