Montgomery Fellow and Nobel Prize-winning theoretical physicist Murray Gell-Mann challenged his audience to comprehend "complexity" and its relationship to life in a packed 105 Dartmouth yesterday afternoon.
Gell-Mann's speech, titled "The Quark and the Jaguar, From Simplicity to Complexity," was so well-attended a closed-circuit television link was set up in 217 Dartmouth Hall to allow space for additional viewers.
"Plectics" was the term Gell-Mann used to explain the linking of simple interactions -- like those of one elementary particle to another elementary particle -- and the complex interactions of life, all of which are symbolized in the jaguar.
Gell-Mann asked the audience to consider why systems occurring in nature tend to get increasingly complex as time passes.
He spent the first half-hour of his speech defining three different kinds of complexity and then used these definitions to describe how life operates.
Compression of complex data means describing it more simply -- such as through simplification using algebra. Effective complexity is the best way to compress data.
Complex adaptive systems receive data about themselves and their surroundings, he said. By compressing the information, the system can determine a "schema" -- a plan of action to predict and respond to the outside world.
Different "schemata" compete under real-world consequences which results in the more successful "schemata" surviving.
Gell-Mann also described how different entities act as a single complex adaptive system. Evolution was one such system where data led to schemata which were either selected or eliminated.
Social schemata like traditions, culture, mythology and the operation of business firms were other systems explored by Gell-Mann during the explanation. The immune system was a quick-acting complex adaptive system designed to mimic evolution in just a few hours or days, he said.
Gell-Mann added that learning, thinking humans living in groups and computers are also examples of complex adaptive systems. Complex systems lead to other complex systems, he said. All complex adaptive systems on Earth are linked to life.
"The behavior of a complex adaptive system may be contrasted with simple or direct adaptation" like the response of a thermostat to heat and cold, Gell-Mann said.
Gell-Mann concluded his speech by discussing the dynamic interactions between elementary particles and the condition of the universe before expansion.
The initial condition of the universe leads to a phenomenon everyone deals with -- the forward motion of time, he said.
Even if everything was known about these interactions, nature could still not be duplicated because of probability, Gell-Mann said.
Accidents lead to the way things are, and any attempt to re-create the past is bound to fail because of chaos theory -- the dependence of an outcome on chance details, he said.
Gell-Mann said accidents led to the formation of our galaxy, to the creation of the solar system, to life on Earth and to us. Increasingly complex organization -- whether in life, construction or computer software -- is the direction of nature.
The appearance of life, a complex adaptive system, on Earth is not special, Gell-Mann said. Neither is the appearance of the "vaunted human self-awareness and intelligence," he said.
Gell-Mann concluded by quoting a Pogo comic strip which asked whether another planet might have more intelligent species or whether we were the most intelligent species on the planet.
"Either way, it's a mightily sobering thought," he said.
Gell-Mann is a theoretical physicist and won the 1969 Nobel Prize in physics for his work on nuclear particles and their interactions. He is this term's second Montgomery Fellow.
