Nobel prize-winning physicist Murray Gell-Mann used his tie to explain effective complexity during his keynote address at the Embedded Systems Conference in San Francisco this week.

Using the patterns on his own tie and others he brought (one notably a brand favored by Monica Lewinsky), Gell-Mann, the man who first identified and named the elementary particle known as the quark, demonstrated the difference between simplicity and complexity, defining complexity, known as "effective complexity" in scientific discourse, as the length of a compressed description of a subject's regularities as opposed to its random or incidental features. The regularities on complex-patterned ties take longer to describe than those on simple striped ties. Randomness versus regularity, however, is subjective, depending on who is judging and in what context. For instance, he does not look at the coffee stains on his tie when he's describing its regularities, whereas to his drycleaner the stains are the only regularities.

You wouldn't believe it, he said, but the two fundamental laws of physics (1) unified quantum theory of elementary particles and (2) the initial condition of the universe are not complex, but simple. And yet we can't ever predict the behavior of the universe using quantum mechanics, because quantum mechanics only provides the probability of something happening. Instead, frozen accidents and chaos creep in, spoiling everything.

Gell-Mann defined frozen accidents as arbitrary occurrences and chaos as sensitivity in certain nonlinear systems to outcomes of minuscule changes in input. Using the example of a radioactive atomic nucleus, he said we know the probability of when it will decay, but not exactly when or in which direction it will decay. Therefore, what actually happens in history derives from an arbitrary path an event takes. All science, except for theoretical physics, depends on these frozen accidents, he said.

Born in 1929 on New York's Lower East Side, Gell-Man was considered a child prodigy, entering Yale at 15. He has a PhD from MIT and has worked with Enrico Fermi at the University of Chicago. In 1953 he published the first of the papers honored with a 1969 Nobel prize for physics, in which he described strangeness and eightfold way theory dealing with quarks. He spent most of his career as a professor at the California Institute of Technology and helped found the Santa Fe Institute.

He's been called irascible, a precocious polymath, and the only man who could get colleague Richard Feynman's goat. He showed his charming irascibility during the question and answer period by refusing to answer questions about the existence of God or those that asked for a time prediction (especially in regards to quantum computers). "I don't make predictions of time intervals," Gell-Mann said. It's not impossible to predict if something will happen," he explained, "but assigning time is very difficult." One project manager, agreeing with him, said he wished his boss would stop asking for time predictions. Gell-Mann asked if his boss was "that pointy haired fellow," referring to Dilbert's boss.

For more information about Gell-Mann:
Visit Murray Gell-Man's home page on Sante Fe Institute web site: http://www.santafe.edu/sfi/People/mgm/
Read his biography: Strange Beauty: Murray Gell-Mann and the Revolution in Twentieth-Century Physics by George Johnson.
Read his book on effective complexity: The Quark and the Jaguar, Adventures in the Simple and the Complex.