Renowned American Physicist Professor Paul Chaikin gives a Lecture on `Experimental Geometry: Experiments with Candies, Dice and Colloids’

Sep 12, 2012

Renowned American physicist Professor Paul Chaikin recently gave a public lecture which was part of the International Workshop on Packing Problems that took place in the School of Physics, Trinity College Dublin earlier this month.

A guilty pleasure led to a significant insight into an age-old problem after Professor Paul Chaikin’s students gave the M&M-munching academic a 55-gallon drum of the chocolate treats he was in the habit of having at lunchtime.  

Professor Chaikin, who teaches physics at New York University, was lecturing in Princeton when his students decided to indulge his sweet tooth. Some years later, Chaikin and his colleague Salvatore Torquato decided to use M&Ms to examine the physical and mathematical principles that come into play when particles are poured into a vessel. They found that oblate spheroids, such as M&Ms, pack more densely than regular spheres when poured randomly and then shaken. The small change from sphere to spheroid produced a major change in the random packing density.

How particles pack has implications for fields such as the design of high-density ceramic materials for use in aerospace or other applications. Packing problems – ie how densely objects can fill a volume --  are among the oldest and most persistent problems in mathematics and science. The question has been studied since the 1600s when physicist and mathematician Johannes Kepler investigated ordered arrangements of spheres. He believed the most efficient way to pack spheres was the way that greengrocers stack oranges.  His theory was proved only in recent years. The packing of randomly assembled particles is less well understood however. 

Professor Chaikin and his team have shown that randomly packed ellipsoids – which look elliptical from the top as well as the side like almond M&Ms – can pack more efficiently than spheres. They have also conducted similar experiments with tetrahedral dice; in this case, the densest packing arrangement is still unknown. Such packing problems provide insights into a variety of physical phenomena such as granular materials, rigidity, jamming, and why amorphous glasses don't flow.

A graduate of Caltech, Professor Chaikin is renowned in the field of soft condensed matter physics. With TC Lubensky, he co-wrote  Principles of Condensed Matter Physics, which has been the definitive textbook on the structure and dynamics of soft condensed matter  for the past 15 years. (It has even featured in British sitcom Keeping Up Appearances, when Onslow was shown reading it in bed).

While professor of physics at Princeton, he worked on organic conductors and superconductors. He also started collaborations with Bill Russell on colloids, which led to experiments on the space shuttle, and with Rick Register on block copolymer thin films for nanofabrication. 

Among Professor Chaikin’s major awards are a Sloan Fellowship (1979-81), a Guggenheim Fellowship (1997), and election to both the American Academy of Arts and Sciences (2003) and the National Academy of Sciences (2004). In 2009, he won the World Technology Award for individual contribution in materials research.