Pink Noise - Leonid Korogodski [43]
Not that long ago, if anyone had asked me what was the greatest scientific discovery of the 20th century, I would have been stumped, not knowing which scientific discipline to favor: physics, genetics, computer science? Now, I wouldn’t hesitate a bit before naming Ilya Prigogine (1917–2003) and his discovery of spontaneous self-organization in systems far from equilibrium—because, among other things, it spares me from having to choose between so many worthy scientific disciplines: Prigogine’s discovery concerns them all.
To most people, the term evolution is associated exclusively with Charles Darwin and biology. Prigogine extended the evolutionary approach to many other fields of science.
HE HAD FORERUNNERS. LUDWIG BOLTZMANN (1844–1906) is well known as the father of thermodynamics. But few know that his intent was to do in physics what Darwin did in biology, to explain the formation and development of complex systems. Boltzmann began by studying not individual particles but large populations of them—statistically.
He formulated the concept of entropy, a measure of disorder in a system, and discovered the second law of thermodynamics, by which entropy in a closed (that is, not interacting with anything else) system grows with time. For example, if hot water is mixed with cold water in an isolated vessel, the system (not far from being closed) eventually reaches an internal equilibrium, a uniform state with the same temperature everywhere.
This, however, led to a rather pessimistic scenario for the eventual fate of the universe: the “heat death,” a completely uniform state everywhere. No difference, no distinction. No life. This was completely opposite to what Boltzmann wanted to achieve, which led him into deep depression. He had failed. Where Darwin showed how a new species could appear, evolving from the simple to the more complex, Boltzmann only showed development from the complex back to the simple.
But, in a sense, he had succeeded. However pessimistic the results, he demonstrated the irreversibility of time. After all, all modern physics, classical and quantum alike, describe the trajectories of particles (classical) or wave functions (quantum) as reversible in time. The equations, both Newton’s and Schrödinger’s, are time-symmetric. The wave function collapse, widely cited to demonstrate the irreversibility of quantum systems, does not truly explain anything, because it is found outside the formalism of quantum mechanics, in interaction between a quantum system and a classical observer: the quantum system changes irreversibly once it’s observed. One can say that the wave function collapse is just another formulation of the paradox of time. The equations clearly say that time is reversible. Yet we know well from our life experience that an egg, once broken, never comes back whole.
Some scientists went so far as to claim that time actually is reversible, that we simply don’t live long enough to notice this. Presumably, eventually, after some gazillions of years, somewhere in the universe an egg mysteriously comes back whole from some random motion of particles.
It took Ilya Prigogine to complete what Boltzmann had begun and show why the point of view expressed in the previous paragraph is wrong.
INSTEAD OF STUDYING SIMPLE SYSTEMS CLOSE TO EQUILIB-rium, like everyone else did at the time, Prigogine chose as his subject complex nonlinear systems far from equilibrium.
Simple systems are a natural first step in scientific exploration. They can be exactly solved, expressed in formulas. Their solutions can be taken as an intuitive ballpark, something to expect from a more complex system, at least in a certain approximation. They are well defined, more readily reproduced and, therefore, are more amenable to controlled experiment. Moreover, this is how we tend to design. The vast majority of our technological devices, from antiquity to present day, are simple and as closed as possible, because this makes them manageable, more debuggable—in other words, predictable. For it is