Hopfield recognized for career in sciences

Professor John Hopfield was awarded the 2005 Albert Einstein World Award of Science last month for his pioneering work in the fields of physics, chemistry and biology.

The World Cultural Council gives out the annual award to "those researchers, which have brought true benefit and wellbeing to mankind," according to its website.

Hopfield was selected to receive the $10,000 prize because of his "ability to think broadly as well as deeply about science ... a characteristic shared by very few scientists in modern times."

The Council also called him "the leading theoretician of biology, both in terms of accomplishment and influence."

Hopfield is best known for the invention of Hopfield networks, computer programs that simulate how the human brain stores memories. Working on unconventional problems that straddle two or more different scientific disciplines is what he likes most about his job.

"Scientists who work in a particular corner or a particular discipline are very secure. But when you are working on the edges of several fields, asking questions that no one asks and wondering if these questions are significant, it's much harder," he said.

Hopfield's work is mainly theoretical, with a focus on computer simulations and mathematics.

"His work was always characterized by a wonderful interplay of theory and experiment," physics professor Bill Bialek said.

Early on, Hopfield learned to look at the world from a scientific standpoint. His parents, who were both physicists, impressed upon him that "any question or phenomena in the world around you was understandable by appropriate experiments," he said.

Using his physics degree from Cornell, he has made fundamental discoveries about the interaction of lights and solids on a molecular level. After a distinguished career in condensed matter physics at Princeton, Hopfield moved to California Institute of Technology, where he studied chemistry and then molecular biology.

"What always interested me about science is the problems which are a mystery, that make you say, 'How can this happen?' When I turned to biology, I found many of these types of problems," he said.

Hopfield views biology as an entirely physical science, believing that true understanding can only come through quantitative predictions. This view wasn't always as prevalent among scientists as it is now, he said.

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"Things are changing now with the genomics era, but biology was much more qualitative," Hopfield said, adding that biological papers often failed to make definitive quantitative conclusions.

His broad scientific background, however, has allowed him to approach the biological problems in new ways.

"Since returning to Princeton, Hopfield has had an enormous influence on the development of a community that crosses the boundaries between physics and biology, and more generally provides the nucleus for the growing effort in quantitative biology," Bialek said.

Drawing from his background in the other sciences, Hopfield has made fundamental discoveries in DNA proofreading, photosynthetic reaction systems and neural networking. For the past 20 years, Hopfield has focused on neurobiology, researching information processing in the nervous system.

While many people today can answer the question of how a heart functions, how the brain works is not so well known, Hopfield said.

Though solutions are sometimes relatively simple, identifying the right questions to ask can be extremely challenging, he said. "To a religious zealot of the 19th century, the animals that roamed the earth were not a problem. However, to Darwin, these species presented a problem," he said.

Hopfield previously received a 1983 MacArthur "genius" award, a 1985 American Physical Society's Prize in Biophysics and the 2001 Dirac Medal from the Abdus Salam International Centre for Theoretical Physics.

He is admired not only by awards committees, but by his colleagues as well.

Molecular biology professor Edward Cox, Hopfield's collaborator in DNA proofreading research, admires Hopfield for the high quality and volume of his work, as well as "his leadership and great abilities as a trainer of graduate students and post docs. Hopfield has very strong moral leadership in setting high standards."

Perhaps Hopfield's most unique talent is his ability to define scientific problems.

"Humans have associative memories, in which all things can be pieced together with a couple of other facts. Unlike computers, human hardware is not based on address, but rather we know things by attaining partial content," Hopfield said.