A review of “Reality Is Not What It Seems” by Carlo Rovelli
Italian theoretical physicist Carlo Rovelli seems to have replaced British academic Stephen Hawking as the foremost exponent of the latest thinking on basic physics in terms which are generally accessible to a non-specialist readership. For those of us who access Rovelli’s work in English, his first popular work was “Seven Brief Lessons On Physics”, but in Italian “Reality Is Not What It Seems” was in fact published first and it is definitely a longer and harder read.
When Hawking wrote his best-selling “A Brief History Of Time”, he was warned by his publisher that every use of an equation would seriously diminish his sales and in the end he only used one (Einstein’s equation on relativity). Rovelli has no such qualms and quotes lots of equations, many of which are not explained but included in case the reader has the mathematics. There is one footnote which runs to a page and a half.
So “Reality” is not an easy read, but Rovelli writes with elegance and enthusiasm and the subject matter is intrinsically fascinating, so everyone will learn something by persisting with the exercise. The Italian scientist presents his work as an historical story, starting with Democritus of Miletus in the sixth century BC, moving on to Isaac Newton, covering Michael Faraday and James Clerk Maxwell, taking in modern giants like Albert Einstein, Niels Bohr and Paul Dirac, and arriving at today’s thinkers such as Hawking and Rovelli himself.
Perhaps the most useful feature of “Reality” is a set of diagrams which summarise the changing orthodox answers to the fundamental question “What is the world made of?” Starting with Newton’s answer of space, time and particles, Rovelli finishes with the single concept of covariant quantum fields. These fields represent what is called quantum gravity which is the latest thinking about how we can synthesise general relativity (which explains the cosmos) and quantum mechanics (which explains the sub-atomic world).
Loop quantum gravity – a theory of which Rovelli is both a leading advocate and developer – has now replaced string theory – which Hawking used to propose – as the best contender for a Theory of Everything (a term used by Hawking and others but not Rovelli).
The Italian concludes: “The world, particles, light, energy, space and time – all of this is nothing but the manifestation of a single type of entity: covariant quantum fields” which are explained as “fields that live on themselves, without the need of a space-time to serve as a substratum, as a support, and which are capable by themselves of generating space time” – so, at the most fundamental level, space and time and infinity do not exist. Indeed the theory raises the possibility that there might have been another universe before the Big Bang and that therefore the Big Bang is actually a Big Bounce – big ideas.
But, as Rovelli concedes, “Am I sure about all this? I am not”.