Book Review: Reinventing the Sacred, by Stuart A. Kauffman.

Gershenson, C. (2009). Book Review: "Reinventing the Sacred: A New View of Science, Reason, and Religion". Stuart A. Kauffman. Artificial Life 15(4):485-487

Excerpts: One of the main goals of this book is to demonstrate the inadequacy of reductionism in contemporary science. It does not negate its explanatory and predictive powers. It notes its limits, exploring several phenomena that are not predictable due to their complex nature. Thus, Kauffman argues, a shift in science is required if we want to understand these complex phenomena.


People might disagree with the answers that Kauffman puts forward. However, in my opinion the greatest contribution of this book, as with Plato╩╝s works, lies in the questions asked. It points out clearly which problems are currently relevant for science and society, even those that people are not aware of. Different tentative or partial solutions can be debated. However, the most difficult part is to start the discussion, and that is precisely what this book achieves.


I do not see the phenomena Kauffman discusses (evolution, economy, mind) as being “beyond science” just because they are not predictable. In a chaotic system, a future state might also be a “mystery.” However, its consideration is entirely scientific. Indeed, a change in the prevailing scientific assumptions must be made to explore these phenomena, but they can—and must—be studied within science. What we need to give up is the belief that phenomena are completely predictable.


New paper: Modeling self-organizing traffic lights with elementary cellular automata

Carlos Gershenson and David A. Rosenblueth, "Modeling self-organizing traffic lights with elementary cellular automata", C3 Report No. 2009.06.

Abstract: There have been several highway traffic models proposed based on cellular automata. The simplest one is elementary cellular automaton rule 184. We extend this model to city traffic with cellular automata coupled at intersections using only rules 184, 252, and 136. The simplicity of the model offers a clear understanding of the main properties of city traffic and its phase transitions.

We use the proposed model to compare two methods for coordinating traffic lights: a green-wave method that tries to optimize phases according to expected flows and a self-organizing method that adapts to the current traffic conditions. The self-organizing method delivers considerable improvements over the green-wave method. For low densities, the self-organizing method promotes the formation and coordination of platoons that flow freely in four directions, i.e. with a maximum velocity and no stops. For medium densities, the method allows a constant usage of the intersections, exploiting their maximum flux capacity. For high densities, the method prevents gridlocks and promotes the formation and coordination of "free-spaces" that flow in the opposite direction of traffic.

Full paper: http://arxiv.org/abs/0907.1925

Simulation available at: http://turing.iimas.unam.mx/~cgg/NetLogo/trafficCA.html