The physics of finance? 

What this is about

This collection explores modern research that is helping to transform economics and finance, especially through inspiration coming from physics and the other natural sciences. If traditional economics has emphasized self-regulation and market equilibrium, the new perspective emphasizes the myriad positive feed backs that often drive markets away from equilibrium and cause tumultuous crashes and other crises. Much as happens routinely in the atmosphere, as with the storm pictured above. I’ve been writing a blog on this topic for several years; here at Medium I’d like to spread these ideas to a larger and I hope different audience.

I’m a physicist by training and was formerly an editor with the science journal Nature. I also write a twice monthly column on finance for Bloomberg Views. I also wrote a recent book on this topic.

All of our lives are significantly influenced by economics and finance, but most of us know little about the theories that economists use to think about these systems. In the spring of 2009, in the wake of the recent financial crisis, economists gathered at a conference in Dahlem, Germany for five days of discussion on the economic modeling of financial markets. After the meeting, the group issued a joint statement on the economic profession's failure to either see the financial crisis coming or to judge its ultimate severity. The lack of understanding, they suggested in the conference report, is due…

“... to a mis-allocation of research efforts in economics. We trace the deeper roots of this failure to the profession’s insistence on constructing models that, by design, disregard the key elements driving outcomes in real-world markets. The economics profession has failed in communicating the limitations, weaknesses, and even dangers of its preferred models to the public.”

The full report makes good reading. Most importantly, it singles out the lack of realistic market dynamics as the primary failing of the standard models used by economists. These models assume that markets tend to a state of balance or equilibrium (although what economists mean by this term is sometimes confusing), and pay little attention to potential positive feed backs -- among asset prices, investors views, new regulations and so on -- which might drive markets far away from a state of balance. Realistic models would seek to capture such processes from the outset.

My aim is to bring to more peoples’ attention a wide range of new research — much of it in physics, but some elsewhere — which is beginning to fill this gap. The idea is to accept that markets like most other natural systems have rich and complex internal dynamics. As with the weather, terrific storms can brew up out of blue skies through quite ordinary natural processes. If the equilibrium fixation of traditional economics has pushed the study of crises to one side - as the study of those exceptional events that occur when markets fail - the new perspective aims to understand how crises of many kinds emerge quite naturally from market processes. As any glance at history shows, they surely do, and quite routinely.

This work has been developing and growing more sophisticated since early evolutionary models of financial markets first developed in the mid 1990s at the Santa Fe Institute in New Mexico. It has come a long way since then, particularly in the past five years, and a growing number of economists and policy makers are beginning to take it very seriously. Old crude ideas about efficient markets and market equilibrium are rapidly being buried, good riddance, to be replaced by more realistic and useful ideas emerging from the physics of finance.

Follow the Physics of Finance on Twitter: @Mark_Buchanan