Review:

Reality Is Not What It Seems

by Carlo Rovelli

‘The only true infinite thing is our ignorance.’

Carlo Rovelli is a professional scientist, a theoretical physicist who specialises in the study of quantum gravity. In this book he traces the developments in scientific thought that have led to our present knowledge of the cosmos. Beginning with the philosopher scientists of ancient Greece, he shows how, in many ways, our understanding of reality today is only an extension and development of ideas put forward by Democritus and Ptolemy, and more recently by Copernicus, Kepler and Galilei. Moving on to the more controversial theories of this century, he leaves us in no doubt that the story is incomplete for, as much as we know, there is so much more we do not know.

‘Our life is a combination of atoms, our thoughts …. hopes and emotions are written in a language formed by combination of atoms which bring us images.’

After reviewing the achievements of Newton, Rovelli gives us the electromagnetic fields of Faraday and Maxwell before introducing Special Relativity and the concept of ‘the extended present.’ He moves on to discuss the two major (and apparently conflicting) physical theories of the twentieth century, General Relativity and Quanta.

‘…. every object in the universe has its own time running, at a pace determined by the local gravitational field.’

So far, so good! Fields and Relativity are part of school physics nowadays and anyone with a grounding will be able to appreciate Rovelli’s new approach to the subjects. We learn that not only is spacetime curved but it equates to the gravitational field (and vice versa). Instead of the ‘simplistic’ structure envisaged by Newton of space + time + particles, our new reality consists of particles + electromagnetic and gravitational fields.

‘The world is a swarming of elementary events, immersed in a sea of vast dynamical space which sways like the water of an ocean.’

Quantum Theory is something else, and no one really understands it anyway, so to appreciate it takes a bit more effort. The point we have reached now is no entity is infinitely divisible, ie there is no infinity. The universe, though without borders, is finite and everything in it is granular, composed at the sub-microscopic level of tiny clouds of probability. Both visions of reality work, Relativity Theory at the macroscopic level, Quantum Theory at the microscopic – how else could we make digital computers? The trick now is to combine the two ideas into one universal theory which works at all levels.

The rest of Reality Is Not What It Seems is devoted to doing just that. Modern science offers us two competing theories, respectively string theory and loop quantum gravity. Carlo Rovelli believes the latter to be ‘the most promising’ and in discussing it turns a few more of our cherished idea about ourselves and our world on end. What, for example, are we to make of the statement ‘time does not exist’? What are these loops? What are spinfoam and thermal time?

This book takes us on a fascinating journey on which we meet not only the familiar giants of science like Galilei, Newton, Einstein and Hawking but other, lesser-known but no less brilliant thinkers: Matvei Bronstein, executed by Stalin’s police at the age of thirty for daring to challenge the system; Henrietta Leavit, who devised a way of measuring the distance of other galaxies; George Lemaitre, the Catholic priest who told the Pope he was wrong. Because many of the ideas  presented here are counter-intuitive, they are not always easy to grasp, nevertheless they are always intriguing and make the journey worthwhile.

Reality Is Not What It Seems won’t be a book for everyone, but if you are interested in science, in particular physics at its cutting edge, it’s a stimulating read.

*****