Carlo Rovelli 2016. Seven brief lessons on physics. Translated by Simon Carnell and Erica Segre. London: Penguin Books, 83 pp.

This almost impossibly short and elegant book is an account of the most fundamental topics in physics; including work currently being debated and the philosophical implications of those theories. The ideas in this book (which was originally published as separate articles in the Sunday supplement of an Italian newspaper) are also covered in the later book by the same author, Reality is not what it seems. Yet this account is shorter and even easier to grasp, I think because the chapters seem somehow to lean on each other more easily, so that this book seems even more unified. Thus, despite some repetition, reading both is still immensely rewarding.

Being about half the length of the (already brief) later book, some material is of course missing. Notably the introductory section on the development of scientific thought from the pre-Socratics to Einstein; also read Reality is not what it seems for that history. Also, there is not much discussion in this shorter book of one hugely significant aspect of quantum gravity theory: there is no such thing as infinity.

The structure of the two books is similar, however: lesson one on general relativity; two on quantum mechanics; three on the structure of the cosmos; four on the elemental particles; five on quantum gravity; six on time as an emergent property of thermodynamics and probability; and the last on what it all means for humans.

There were a few things that I grasped more thoroughly or was even more amazed by in this book:

The extraordinary leap by Werner Heisenberg was to imagine, and then show mathematically, that electrons do not exist in between the quantum interactions they have in the orbit of an atom. They are brought into being by collision.

Thermodynamics has been successfully extended to electro-magnetic fields, and to quantum theory. But not, so far, to gravitational fields.

The fundamental indivisible but interlocking ‘atoms’ of space in quantum gravity theory are not in space, they are themselves that space.

Ludwig Boltzman’s insight was to conceive of heat flow from hot to cold as due to chance (statistical physics and probability).

A couple of quotes from Carlo Rovelli:

Our memory and our consciousness are built on these statistical [thermodynamic] phenomena. … But due to the limitations of our consciousness we only perceive a blurred vision of the world, and live in time.

Scientific thought is fed by the capacity to ‘see’ things differently than they have previously been seen.

And one from his editor:

What’s non-apparent is much vaster than what’s apparent.