Monday, May 2, 2016


SEVEN BRIEF LESSONS ON PHYSICS by Carlo Rovelli is a book about the most challenging theories of today’s scientific world. I opened this book and on reading the first line, instantly selected it for review, for it says, ‘These lessons were written for those who know little or nothing about modern science’. True, these lessons cover the fascinating aspects of the great revolution that has occurred in physics in the twentieth century, and of the questions and mysteries which this revolution has opened up.
The first lesson is dedicated to a beauty, Albert Einstein’s general theory of relativity. Einstein's major breakthrough in realizing Newton's gravitational field is not a field at all but is spacetime itself is explained here. The extraordinary idea, a stroke of pure genius that the gravitational field is not diffused through space; the gravitational field is that space itself. This is the idea of the theory of general relativity. Newton’s ‘space’, through which things move, and the ‘gravitational field’ are identified now one and the same thing.
The second one is about quantum mechanics, which opens to us, some of the most baffling aspects of modern physics. Unlike relativity, the basic tenets of which are easy to understand, quantum theory - wave particle duality, entanglement, the uncertainty principle - have left even the theory's great founders uncertain. Rovelli zeroes in on one of the essential qualities of quantum mechanics and elaborates how, its laws "do not describe what happens to a physical system but only how one physical system affects another". I find it an illuminating thought that the same emphasis on the philosophy of interactions which lies at the heart of quantum theory also underlies the science of emergent complex systems like the weather, the stock market, biochemical networks and social networks.
The third is dedicated to the cosmos, which talks about the Big Bang theory and the architecture of the cosmos, but for gravitational waves. What all contributed to the present idea of cosmos like radio telescopes, particle detectors and other means of foray into space is discussed here.
The fourth is dedicated to elementary particles. Quarks and electrons, Higgs bosons and neutrinos find mention here. How all this culminated in the Standard Model of particle physics, and how it remains incomplete and the opportunities of further discoveries are detailed here. How we have arrived very far from the mechanical world of Newton and Laplace, a world of long precise trajectories in geometrically immutable space, to one of continuous, restless swarming of things.
The fifth deals with quantum gravity. The fifth lesson tackles the marriage of general relativity with quantum mechanics, which so far could not be solemnized. Universe contracting into a nutshell, time and space disappearing altogether, and the world dissolving into a swarming cloud of probability are some of the esoteric topics discussed here.
The sixth is on probability and the heat of black holes. The sixth lesson takes us on a journey into one of the most exciting frontiers of modern physics: the union of thermodynamics, quantum mechanics and relativity, posing questions like why time seems to flow only in one direction. As Rovelli explains, the arrow of time seems to be inextricably linked with the flow of heat. Time, thermodynamics, quantum mechanics, relativity, statistics; it's all here, and it's all tantalizing.
The final section of the book returns to ourselves, and asks how it is possible to think about our existence in the light of the strange world described by physics. The lesson ties it all up together as Rovelli talks about the ultimate entity that allows us to figure all this out - the human brain. He ponders the delectable paradox that an entity which is composed of particles and fields and quanta can also decipher its own mysteries. (I used to have a similar question, how can we know about life when we are in it? We should able to see life from the outside, to understand it better!)
What touched me most is the total absence of mathematics. The author has taken an intrepid step in answering the problems of our existence without the help of mathematical formulae. And that has paid of well. This remarkable book will go a long way in making clear, the reigning issues of physics, that too, some of the most complex ones.