Adam Frank writes:

On October 8, 2024, the field of physics was plunged into controversy. That day, the Nobel Prize in Physics was awarded for discoveries not involving black holes, cosmology, or strange new subatomic particles, but about AI. How could the discipline’s highest award go to research about machines designed to mimic human brains? Where was the physics in that?

For most of the 20th century, physicists largely ignored living systems. They understood living things as machines, albeit ones made of gooey parts. A subfield called biophysics uncovered specific physical mechanisms behind those molecular machines. Organisms as a whole, however, were not a major concern.

But today, many of my colleagues in physics no longer agree with such dismissals. Instead, we have come to believe that a mystery is unfolding in every microbe, animal, and human—one that challenges basic assumptions physicists have held for centuries, and could answer essential questions about AI. It may even help redefine the field for the next generation.

The central hubris of physics has long been the idea that it is the most “fundamental” of all sciences. Physics students learn about the basic stuff of reality—space and time, energy and matter—and are told that all other scientific disciplines must reduce back down to the fundamental particles and laws that physics has generated. This philosophy, called “reductionism,” worked pretty well from Newton’s laws through much of the 20th century as physicists discovered electrons, quarks, the theory of relativity, and so on. But over the past few decades, progress in the most reductionist branches of physics has slowed. For example, long-promised “theories of everything,” such as string theory, have not borne significant fruit.

There are, however, ways other than reductionism to think about what’s fundamental in the universe. Beginning in the 1980s, physicists (along with researchers in other fields) began developing new mathematical tools to study what’s called “complexity”—systems in which the whole is far more than the sum of its parts. The end goal of reductionism was to explain everything in the universe as the result of particles and their interactions. Complexity, by contrast, recognizes that once lots of particles come together to produce macroscopic things—such as organisms—knowing everything about particles isn’t enough to understand reality. An early pioneer of this approach was the physicist Philip W. Anderson, who succinctly framed the nascent anti-reductionist perspective with the phrase “More is different.” Complex-systems science has grown rapidly in the 21st century, and researchers in the field won the Nobel Prize for Physics in 2021.

From a physicist’s perspective, no complex system is weirder or more challenging than life. For one thing, the organization of living matter defies physicists’ usual expectations about the universe. Your body is made of matter, just like everything else. But the atoms you’re built from today won’t be the atoms you’re built from in a year. That means you and every other living thing aren’t an inert object, like a rock, but a dynamic pattern playing out over time. The real challenge for physics, however, is that the patterns that make up life are self-organized. Living systems both create and maintain themselves in a strange kind of loop that no existing machine can replicate. [Continue reading…]