# Condensed Matter Physicist Leo Kadanoff Passes Away

I was sad to learn from Jason Chin that eminent condensed matter physicist Leo Kadanoff recently passed away. He was definitely among the smartest people around. Although I never met him personally, he influenced my life in profound ways. In 1967, he wrote a ‘throw away’ book explaining non-equilibrium Green functions, and that book (discovered by my adviser) became the starting material for my graduate research. Thanks to Kadanoff’s excellent maths, my first paper using his theory turned out to be among the most cited theoretical papers in molecular electronics (aka nanotechnology).

I use the word ‘throw away’, because Kadanoff’s real research in those years was on scaling and criticality, and his contributions were no less in that field. Kenneth Wilson built on Kadanoff’s theory to go on to receive Nobel prize in physics in 1982, whereas the physics community was surprised that Kadanoff was not included for the award. Taking from Kadanoff’s obituary published in NY Times -

Dr. Kadanoff turned to a simple model of another second-order phase transition, ferromagnetism. In some materials, atoms, like tiny bar magnets, line up to produce a magnetic field. As the temperature rises, the atoms become jumbled, and the magnetic field diminishes; above a certain temperature, the magnetic field disappears.

…..

At Cornell, another physicist, Kenneth G. Wilson, took Dr. Kadanoffs work and came up with a more general mathematical theory.

The approach proved useful in understanding not only phase transitions but also a wide range of phenomena, including the interactions of elementary particles and how a drop of water breaks in two.

In 1980, Dr. Kadanoff shared a prestigious physics prize from the Wolf Foundation in Israel with Dr. Wilson and Michael Fisher, one of Dr. Wilsons collaborators.

Two years later, the Nobel Prize in Physics honored the same advances, but only Dr. Wilson received the prize. At the time, Dr. Wilson said he would have expected the Nobel committee to honor Dr. Fisher and Dr. Kadanoff as well.

I came across an excellent blog post about Kadanoff by Lubo Motl Pilsen, where he wrote -

During the funeral, his daughter modestly pointed out that when he was in his 50s, his switched from making discoveries to making great new people.

That reminds me that years later I was introduced to bioinformatics by one of Kadanoff’s very smart student, who worked with him during those years of ‘making great new people’.