It’s pretty easy to see that a rock and a chipmunk are different. The rock doesn’t do much except slowly erode. The chipmunk, on the other hand, is a whirlwind of activity. He endlessly scans his environment for food or danger. And when either shows up, the chipmunk reacts quickly. On a more fundamental level, however, what really is the difference between the lifeless rock and the very much alive chipmunk? What is the difference at the level of mathematical physics and chemistry?
This question is at the heart of a three-day workshop on “Information-Driven States of Matter” that I’ll be co-hosting with Gourab Ghoshal and Artemy Kolchinsky at the University of Rochester next week. I’m really looking forward to the meeting, and today I want to give you a sneak peek at some of the topics we’ll be exploring, as they’ll undoubtedly form the basis for future columns.
Information-driven systems
In recent decades, physicists have increasingly come to view life as a unique “state of matter” that requires special attention. It began 70 years ago when Edwin Schrödinger wrote his seminal work, What is life? In that little book, he asked whether living systems might require the development of new laws of nature. While that remains a controversial question, many scientists who study life as a “complex system” have come to believe that living systems are unique in at least one remarkable way: they use information.
While the rock we were just thinking about might be described in terms of information (in, say, the arrangement of its atoms), we are the ones doing the describing. The rock doesn’t give a damn about information. On the other hand, even a simple amoeba is adept at storing, copying, transmitting, and processing information. Cells are not only adept at using information, they are also dependent on it. In this sense, they are information-driven: they must constantly obtain and use information from their environment in order to stay alive. It’s also worth noting that some physicists have used the term “active matter” to describe living systems, but the active part is really about information.
During the workshop, we will take a broad view of our question about information-driven systems. On the largest scale, we want to understand life as an astrobiological phenomenon. To that end, we will have a talk by Caleb Scharf, of NASA’s Ames Research Center. Scharf’s work explores the concept of “computational zones.” If life requires information processing, what regions of the universe have physical conditions that allow computation? Along similar lines, but in greater detail, Manasvi Lingam of the Florida Institute of Technology will look at constraints (i.e., limits) on the types of information processing that can occur in different planetary environments (e.g., hydrocarbon lakes on Titan, Saturn’s largest moon).
We’ll also explore the details of how life on Earth uses information. Because so many of life’s computational machines are based on chemistry, Harvard’s Juan Perez Mercader will tease out the connections between biochemistry and information processing. For humans, at least, the brain is the CPU for information processing. That’s why Sarah Marzen of Claremont College will investigate how well nervous systems of any kind (including artificial ones) can make predictions (such as those needed to survive in changing environments). Jordi Pinero, a postdoc in our own collaboration, will investigate how the demands of information processing can actually limit the growth of organisms.
However, no progress can be made in this area without the development of new and powerful mathematical tools that combine information theory and the physics, chemistry, and biology of complexity science. To that end, David Wolpert of the Sante Fe Institute will take a deep dive into the non-equilibrium statistical physics of computation and communication. His work pushes the boundaries of what we mean when we talk about physics and information together. And because the kind of information you use is as important as how you use it, Damian Sowinski of our own group in Rochester will lead the workshop through our studies of semantic information, i.e., the importance of meaning.
These are just a few examples of the ideas we will learn about, discuss, and argue about (scientists love to argue). I can’t tell you how excited I am about this workshop. I hope we will all go home with a new and better perspective on that powerful question Schrödinger asked so long ago: What is life?
By the way, I plan on live tweeting (or live-Xing, or whatever it’s called these days) the workshop at @adamfrank4 if you’d like to join me (July 10-12). And also a big thank you to the Templeton Foundation for sponsoring the event.