A new model for defining life across the Universe

It’s pretty easy to see that a rock and a chipmunk are different. The rock doesn’t do much of anything except erode slowly. The chipmunk, on the other hand, is a flurry of activity. It endlessly scans its environment in search of food or danger. And when either one shows up, the chipmunk is quick to react. At a more fundamental level, however, what really is the difference between the inanimate rock and the very animate chipmunk? What’s the difference at the level of mathematical physics and chemistry? 

This question lies at the heart of a three-day workshop on “Information-Driven States of Matter” that I’ll be co-hosting along with Gourab Ghoshal and Artemy Kolchinsky next week at the University of Rochester. I am really looking forward to the meeting, and today I want to give you a preview of some of the topics we’ll be exploring since they are bound to drive future columns.

Information-driven systems

Over the past few decades, physicists have increasingly begun to view life as a unique “state of matter” that requires special consideration. It began 70 years ago when Edwin Schrödinger wrote his seminal work, What Is Life? In that small book, he asked whether living systems might require the development of new laws of physics. Although that remains a contentious 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 contemplating might be describable in terms of information (in, say, the arrangement of its atoms), we are the ones doing the describing. The rock couldn’t care less about information. On the other hand, even a simple amoeba is adept at storing, copying, transmitting, and processing information. Not only are cells adept at using information, but they also depend on it. In this sense they are information-driven: They need to continually gain and use information from their environments to stay alive. It’s also worth noting that some physicists used the term “active matter” to describe living systems, but the active part is really about information.

At the workshop, we will be taking a broad view of our question about information-driven systems. At the largest scale, we want to understand life as an astrobiological phenomenon. To that end, we’ll host a talk by Caleb Scharf, from NASA’s Ames Research Center. Scharf’s work explores the concept of “computational zones.” If life requires information processing, which regions of the Universe have physical conditions that allow computation to occur? Along similar lines but looking in finer detail, Manasvi Lingam of the Florida Institute of Technology will look at constraints (i.e. limits) on the kinds 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 specifics of how life on Earth uses information. Since so much of life’s computational machinery is based in chemistry Juan Perez Mercader of Harvard is going to unpack the links between biochemistry and information processing. For humans at least, brains are the CPU for information use. That’s why Sarah Marzen of the Claremont Colleges will be asking how well nervous systems of any kind (including artificial ones) can make predictions (like the ones needed to stay alive in changing environments). Jordi Pinero, a post-doc in our own collaboration, will be exploring how the needs of information processing can actually limit the growth of organisms. 

No progress, however, can made in this field without the development of new and potent mathematical tools that combine information theory and the physics, chemistry, and biology of complexity science. To that end, David Wolpert from the Sante Fe Institute will do 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 just as important as using it all, Damian Sowinski from our own group at Rochester will be taking the workshop through our studies of semantic information, i.e. the importance of meaning. 

These are just a sampling of the ideas we’ll be learning about, discussing, and arguing over (scientists love to argue). I can’t tell you how excited I am for this workshop. I am hopeful we’re going to come away with a new and better perspective on that potent question Schrödinger asked so long ago: What is life?

By the way, I plan on live-tweeting (or live-X-ing, or whatever it’s called these days) the workshop at @adamfrank4 if you want to follow along (July 10-12). Also, major thanks to the Templeton Foundation for sponsoring the meeting.