Overview
Carlo Rovelli dismantles our intuitive understanding of time, showing that nearly everything we think we know about it is wrong.
Rovelli is an Italian theoretical physicist and one of the founders of loop quantum gravity. The Order of Time, published in 2017, is his reflection on time as understood by contemporary physics — as something far stranger than our everyday experience suggests. The book is short (under 200 pages) and unusual for popular physics in being written in lyrical, almost poetic prose.
Key Ideas
Time passes at different rates
Time moves faster at higher altitudes and slower near massive objects.
The arrow of time is entropic
The difference between past and future emerges from entropy.
Time may not exist fundamentally
Our experience of time may be an emergent phenomenon.
Who should read this
Readers who found Hawking hard going and want physics in a gentler, more philosophical register. Rovelli's prose is shaped by his love of classical literature — Horace and Proust both appear — and the book rewards slow, meditative reading rather than a sprint through the ideas.
Who might skip it
Skip if you want a rigorous technical treatment — Rovelli is deliberately working in a space between physics and philosophy, and specialists will find the physics elliptical. Also skip if you need clear answers; Rovelli is honest that physics does not yet understand what time is, and the book doesn't pretend otherwise.
The verdict
One of the most beautiful physics books I have read. Rovelli's argument — that time as we experience it is largely an artefact of our scale and our thermodynamic situation — is unsettling in a way that stays with you. The final chapter, on how physicists should relate to human time, is the kind of writing this genre rarely allows itself.
"Time is not a line with two equal directions: it is an arrow with different extremities."
— Carlo Rovelli, The Order of Time
If you liked this
Seven Brief Lessons on Physics, Rovelli's earlier and shorter book. Helgoland for his later work on quantum mechanics.