In “In a Flight of Starlings: The Wonders of Complex Systems,” Nobel Prize-winning physicist Giorgio Parisi takes readers on an enlightening and personal journey into the science of complex systems, using the mesmerizing flight patterns of starlings as a springboard to explore the intricate workings of the world around us. Based on personal experiences and research he wants to bring the “beauty, importance and cultural value” of modern science to common people.
Parisi begins by delving into the captivating behaviour of starling flocks, describing how these seemingly chaotic swarms exhibit remarkable coordination and adaptability. He explains how the birds’ movements are governed by simple rules and interactions, leading to emergent collective phenomena that far surpass the capabilities of any individual bird.
The finding that collective behaviour was completely different from individual behaviour was a revolution. An increase in the number of components in a system creates a change that is not just quantitative but qualitative.
From there, Parisi extends his analysis to other complex systems, ranging from the behaviour of atoms and molecules to the dynamics of financial markets and the evolution of social structures. He demonstrates that despite their apparent diversity, these systems share common underlying principles, revealing a deep and surprising unity in the natural world.
The November Revolution of 1974 was a turning point in particle physics, triggered by the discovery of a new type of particle called the J/ψ meson. This discovery, made independently by two research groups at Stanford Linear Accelerator Center (SLAC) and Brookhaven National Laboratory, challenged the prevailing understanding of the fundamental building blocks of matter.
Before the November Revolution, physicists believed that the basic building blocks of matter were electrons, protons, and neutrons. However, the discovery of the J/ψ meson revealed that there was a whole new family of particles, called quarks, which were responsible for the structure of protons and neutrons.
Just like the flock of birds, the elementary particles, like strings, governed by scientific rules and interactions, create emergent collective phenomena that make everything that exists in the universe.
In chapter four Parisi describes phase transitions, which is again a collective phenomenon.
He writes, “behaviour of a magnetic system does not depend much on the behaviour of the individual elementary objects of which it is composed.”
Parisi goes on to describe how systems that are made of the same elementary entities display a more predictable and ordered emergent collective behaviour than most disordered systems. A disordered system at low temperature is in a very large number of phases at the same time, while in general an ordered system is in a single phase.
“Disorder is born from the fact that certain elementary entities behave differently from others: some spins try to go in opposite directions; certain atoms are different from most others; certain financial actors sell shares that others are buying; some dinner guests actively dislike others who have been invited and want to sit as far away from them as possible.”
Parisi developed the replica method, a mathematical technique for studying disordered systems. He showed that replica symmetry breaking occurs in spin glasses, which means that the system cannot be described by a single set of order parameters. This breakthrough helped to explain the unusual properties of spin glasses, such as their frustration and aging.
Along the way, Parisi shares his insights into the creative process of scientific discovery, emphasizing the importance of serendipity, collaboration, intuition, micro creativity (small everyday ideas) and a willingness to embrace unconventional approaches. He also reflects on the broader implications of his work, discussing the role of science in addressing global challenges such as climate change and pandemics.
One area where the book disappoints is the lack of details. After reading the title one expects the author to go into more details of complex systems and tell us more about emergence. However, the chapters starts well and then falls short of expectations. That’s the reason I would give it 3.5/5 ⭐.
In his words, “This book is my attempt to convey to a wide readership something of the beauty, importance, and cultural value of modern science. If you have followed me this far, I hope that I have succeeded in my attempt.”
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