Lev Landau

Major contributions

• Developed the theoretical explanation for superfluidity in liquid helium-4 (1941), a state of matter with exactly zero viscosity, discovered experimentally by Pyotr Kapitsa in 1937 — Landau's theory correctly predicted several distinctive superfluid phenomena, including a novel type of sound wave ("second sound") later experimentally confirmed
• Developed Landau's theory of second-order phase transitions (1937), introducing the concept of an "order parameter" to describe continuous phase transitions in a unified mathematical framework applicable well beyond superfluidity, including magnetism and superconductivity
• Predicted quantised electron energy levels (now called Landau levels) for charged particles moving in a magnetic field (1930), foundational to later understanding of the quantum Hall effect discovered decades afterward
• Co-authored, with Evgeny Lifshitz, the influential multi-volume Course of Theoretical Physics, an exceptionally rigorous and comprehensive textbook series that trained generations of physicists, particularly throughout the Soviet Union and beyond
• Made significant additional contributions to nuclear physics, quantum electrodynamics, and the theory of Fermi liquids (a general framework for understanding strongly interacting fermion systems)

Named concepts

Concept	Statement	Codex page
Landau Theory of Superfluidity	Two-fluid model explaining zero-viscosity flow	View entry
Landau Levels	Quantised electron energies in a magnetic field	View entry

Career

A remarkable child prodigy, Landau entered Leningrad State University at age 14 and had largely completed his physics education by his early twenties, subsequently working and studying at several leading European institutes (including with Niels Bohr in Copenhagen) before returning to the Soviet Union, where he eventually settled at the Institute for Physical Problems in Moscow, working closely with experimentalist Pyotr Kapitsa. Landau was known for his exceptionally demanding standards for students and collaborators, maintaining a famous informal ranking system ("Landau's scale") on which he placed himself and other physicists, with only a select handful of historical figures (including Einstein) placed in his very top tier.

Landau's career was seriously disrupted by his 1938 arrest during Stalin's purges, on politically motivated charges; he spent a year imprisoned before being released, reportedly following direct intervention by Kapitsa, who personally vouched for Landau's necessity to ongoing Soviet physics research. Landau's later career was further affected by a severe 1962 car accident that left him with permanent injuries significantly limiting his subsequent scientific output, despite surviving for several more years.

Key publications

• Landau, L.D. (1941). "Theory of the Superfluidity of Helium II." Physical Review, 60(4), 356–358.

Nobel Prize

Lev Landau won the Nobel Prize in Physics for 1962 "for his pioneering theories for condensed matter, especially liquid helium" — awarded the same year as his car accident, requiring the prize to be presented to him in a Moscow hospital rather than at the usual Stockholm ceremony.

Historical context

Landau's close working partnership with experimental physicist Pyotr Kapitsa (who first discovered superfluidity experimentally in 1937, and who separately received his own 1978 Nobel Prize in Physics for that discovery) exemplifies a productive and historically significant theory-experiment collaboration, spanning both the initial experimental discovery and its subsequent theoretical explanation. Landau's imprisonment and eventual release also stand as a notable historical episode illustrating the difficult conditions under which Soviet-era scientists, even those of major international stature, sometimes worked.