This is an excellent book full of inspiring ideas. Jim Al- Khalili is a physicist and a wonderful science popularizer. I'd read a few books written by him already. He tends to explain complex concepts in science in a very lucid and accessible way.
This book is all about physics; why it matters and how it was developed. The first chapter is about the awe of understanding. Why do we have this burning curiosity to learn how things work? Why did we create myths in the beginning? How did science replace these myths? Through rational analysis and careful observation—a painstaking process of testing and building up scientific evidence, rather than accepting stories and explanations with blind faith—we can now claim with a high degree of confidence that we know quite a lot about our universe. We can also now say with confidence that what mysteries remain need not be attributed to the supernatural. They are phenomena we have yet to understand—and which we hopefully will understand one day through reason, rational enquiry, and, yes … physics.
The second chapter is about scales. The world of physics only really came of age in the seventeenth century, thanks to a large extent to the invention of the two most important instruments in all of science: the telescope and the microscope. If we were only able to understand the world we can see with our naked eyes, then physics would not have got very far. once the microscope and the telescope were invented, they opened up windows on the world that dramatically increased our understanding, magnifying the very small and bringing closer the very far away.
Chapter three covers the enigma of space and time. Space and time are the substrates in which all events take place. However, such concepts are slippery. Common sense tells us that space and time should be in place from the start—that space is where events happen and the laws of physics are acted out, while the inexorable passage of time is, well, just is. But, is our commonsense view of space and time right? An important lesson physicists must learn is to not always trust common sense. After all, common sense tells us that the Earth is flat, but even the Ancient Greeks understood that its sheer size meant we could not easily discern its curvature, but that there were simple experiments they could perform to prove that it was in fact a sphere. Similarly, everyday experience tells us that light has the properties of a wave and therefore cannot also behave as though it were made up of a stream of individual particles.
some of the most important breakthroughs in physics have been the results of the logical conclusions drawn not from real experiments or observations, but from ‘thought experiments’, whereby the physicist considers some hypothesis and devises an imaginary experiment that can test its consequences. Some of the most famous thought experiments were conducted by Einstein and helped him develop his theories of relativity. Once his theories were fully developed of course they could be tested in real laboratory experiments.
Chapter four deals with energy and matter. In physics, the concept of energy indicates the capacity to do work; thus, the more energy something has, the more it is able to do, whether that ‘doing’ means moving matter from one place to another, heating it up, or just storing the energy for later use. The law of conservation of energy states that the total amount of energy in the universe is constant. The conservation of energy also tells us that perpetual motion machines are impossible, since energy cannot be continually conjured up from nowhere. In everyday language, mass is often taken to mean the same thing as weight. This is fine on Earth since the two quantities are proportional to each other: if you double a body’s mass you will also double its weight. But out in empty space, a body has no weight, even though its mass stays the same.
In chapter five we enter the weird world of quantum mechanics. An electron is in a superposition. It has a wave function. Based on Heisenberg's uncertainty principle, we cannot measure the velocity and position of a particle at the same time.
Chapter six is about thermodynamics and the arrow of time. when the system reaches equilibrium, its entropy is maximised, and the energy it contains is useless. So, in a sense, it is not energy that is needed to make the world go around, it is low entropy. If everything were in a state of equilibrium, nothing would happen. We need a system to be in a state of low entropy, far from equilibrium, to force energy to change from one form to another—in other words, to do work. Life is an example of a system that can maintain itself in a state of low entropy.
In chapter seven, the author tries to explain the roads to unification. And basically why physicists have this urge to unify different concepts in physics.
Chapter eight is about some of the problems physicists are dealing with and why nothing interesting has happened for a while in physics. We haven't been surprised for a long time. We haven't had revolutionary discoveries like that or Einstein.
Chapter nine is about the usefulness of physics. GPS systems are now such an integral part of our lives that we could not live without them. Not only do we take for granted the fact that we no longer get lost in unfamiliar parts of the world, but GPS has allowed us to see our planet from above and map it with remarkable detail, enabling us to study the way the Earth’s climate is changing, or to predict natural phenomena and help with disaster relief. an understanding of the quantum rules that explain how electrons behave in semiconductor materials like silicon has laid the foundation of our technological world. Without an understanding of semiconductors, we would not have developed the transistor and, later, the microchip and the computer.
And finally, chapter ten teaches you how to think like a physicist. Unlike politicians, physicists have no fear of admitting that they're wrong. Being wrong means there are more interesting things waiting to be discovered. People are often shocked to hear that many physicists—other than those who had dedicated years of their lives to building the Large Hadron Collider—were hoping that the Higgs boson would not be found. You see, not finding the Higgs would have meant that there really was something wrong with the Standard Model, opening the door to exciting new physics. Merely ticking a box to confirm something we already suspect to be true is just not as exciting as finding out that one needs to pursue hitherto unexplored paths of research.