How Nature Works: The Science of Self-organized Criticality First Edition

This book is a great attempt at finding some universality based on systems in a "critical" state, with departures from such state taking place in a manner that follows power laws. The sandpile is a great baby model for that.Some people are critical of Bak's approach, some even suggesting that we may not get power laws in these "sandpile" effects, but something less scalable in the tails. The point is :so what? The man has vision.I looked at the reviews of this book. Clearly a few narrow-minded scientists do not seem to like it (many did not like Per Bak's ego). But the book is remarkably intuitive and the presentation is so clear that he takes you by the hand. It is even entertaining. If you are looking to find flaws in his argument his pedagogy allows it (it is immediately obvious to us who dabble with simulations of these processes that you need an infinite sandpile to get a pure power law).Another problem. I have been ordering the book on Amazon for ages. Copernicus books does not respond to emails. I got my copy at the NYU library. Bak passed away 2 years ago and nobody seems to be pushing for his interest and that of us his readers (for used books to sell for 99 implies some demand). This convinces me NEVER to publish with Springer.

Very personal account of a new science... irreverent... entertaining and understandable.

I felt that the book was well written given that many of the concepts detailed were rather complex and advanced. I enjoyed the read because the author made a convincing case in addressing my doubts about a purely 'Darwinian' or 'Religious' explanation for evolution as we know it.

Per Bak, sadly now deceased, in How Nature Works wrote a book of considerable intellectual strength, but one quite accessible to the general reader. The basic notion of the book, that self-organized criticality underlies the world we live in and does so at multiple levels of organization, is clearly developed and supported with examples from geophysics, from evolution, from brain science, and the list goes on, and this is done with clarity and force.For me, personally, what is most effective about this book is the ability it gives thereader to make comparisons between such disparate natural events as earthquake occurrences and the occurrences of extinction events of differing magnitudes; they both obey simple power law relationships. Further, Bak is masterful in the way in which he approached an explanation of 1/f noise. Finally, the book is well referenced so that readers who are equipped with some math and scientific insight may pursue chosen concepts in more depth.In closing, for the reader who might be a bit math-phobic, Bak is one of those researcher/authors who empowers his readers to take risks, go beyond their perceived limitations, and enter a new world of knowledge and inquirey. If you are one of those, take a leap of faith, buy the book, and open your eyes and mind to a new world.With respect and gratitude to a great scientist, Per Bak,Tony Harper

Per Bak's 1996 book "How Nature Works: the science of self-organized criticality" is a foundational work in the popularization of complexity, and is still widely read and cited over 20 years after its publication. It is engagingly written, interesting, and persuasive, suggesting that many if not all natural phenomena--from sandpiles to earthquakes, forest fires, extinction events, solar flares, and the human brain--share the characteristics of self-organized criticality. Bak claims that non-periodic catastrophic events, not gradual change, are the main drivers of these phenomena, and that the distribution of these catastrophes (called "avalanches" after his experimental and theoretical studies of sandpiles) follow a power law, reveal a fractal (self-similar) pattern in time and/or space, and form the "basis for emergent phenomena." The idea is that an open, energy-dissipative system with slow energy inputs (like a sandpile with a slow drip of sand onto it) inevitably evolves over a long period of time to become critical, i.e. susceptible to sudden large avalanches. "If this picture is correct, then we must accept instability and catastrophes as inevitable in biology, history, and economics" (p.32).I agree that Bak's work has identified an interesting paradigm that provides a theoretical description of certain classes of natural phenomena, but it really doesn't EXPLAIN much in terms of causation. Bak uses as an illustration the fossil record of extinction events in the last 600 million years, which has many small extinction events and a few very large events. He claims, "Large catastrophic events occur as a consequence of the same dynamics that produces small ordinary everyday events. This observation runs counter to the usual way of thinking about large events, which looks for specific reasons (for instance, a falling meteorite causing the extinction of dinosaurs) to explain large cataclysmic events...Self-organized criticality can be viewed as the theoretical justification for catastrophism" (p.32). But wait a minute! Is he claiming that the meteorite impact was NOT the cause of dinosaur extinction? A huge meteorite crashing into the Caribbean could hardly be called a "small ordinary everyday event"! For the dinosaur extinction to be an example of a catastrophe resulting from a system organizing itself towards criticality one must expand the system to include the Asteroid belt and the Oort cloud and not just the planet Earth. Where does it end?Elsewhere in the book Bak claims that, because long-term records of temperature fluctuations follow a power law distribution, "the apparent increase in temperature might well be a statistical fluctuation rather than an indication of global warming generated by human activity" (p.22). Is the documented great increase in atmospheric CO2 irrelevant, and the atmosphere just happens to be poised for a spike in temperature like a critical sandpile? These kinds of claims for the causative power of SOC are not plausible to me. To explain "how nature works" requires more than a description of a long-term statistical pattern, intriguing though it is. Another objection is that, because self-organized critical systems must evolve for very long times to become critical, they necessarily spend a lot of time in sub-critical states, in which the small inputs do not have cascading catastrophic effects. How do we know whether or not most systems are in such transitional states?Over 20 years of research inspired by Bak's ideas has been reviewed and critiqued recently by scientists largely sympathetic to the paradigm*. They provide a list of the necessary and sufficient conditions for self-organized criticality (SOC), including power law correlations, self-tuning to a continuous phase transition, non-linearity, and presence of "avalanches." In conclusion they state, "There are few systems that display SOC in all its glory, but they do exist and they provide evidence that it works in precisely the way originally envisioned. SOC may be at work in some natural phenomena, such as earthquakes, solar flares and precipitation, but SOC is almost certainly not ubiquitous...it has provided the very fruitful paradigm for a much deeper understanding of the phenomena concerned, as researchers became aware of the distinct possibility that some very simple interactions on a microscopic scale carry over to and evolve across many different time and length scales, effectively providing the same basic physics in rescaled form across many scales" (p.38).I recommend the book, but please read it with critical skepticism...* Watkins, N.W., Pruessner, G., Chapman, S.C. et al. (2016) 25 Years of Self-organized Criticality: Concepts and Controversies. Space Sci Rev 198: 3-44.