This little book was, with some caveats, a pleasure to read. Rovelli’s prose is beautiful, and he covers a few major topics in physics in quick succession: relativity, quantum mechanics, the cosmos, subatomic particles, gravity, time, and consciousness.

The first four chapters were breezy, and I have little issue with it. The latter three chapters are the Wild West, and the topics are really quite contentious. Readers should not go into this book with the assumption that it’s settled science. The fact of the matter is that we have little idea about what gravity, time, or consciousness are—we barely even have a starting point.

With that in mind, I can’t say that I can evaluate Rovelli’s claims. I don’t know what the competing arguments are. But, I can outline Rovelli’s own views.

Gravity is challenging, because it’s the point on which quantum mechanics and general relativity become irreconcilable. To make it work, physicists have to fudge the numbers. Rovelli finds loop quantum gravity to be a way to reconcile the two theories. If I understand right, this argument suggests that neither space nor time are “out there.” Like subatomic particles, they, too, are quanta distributed unevenly throughout the universe. This perspective likely has a lot of limitations, and I haven’t the slightest idea what they are.

Rovelli finds that time as we experience it isn’t out there either. Instead, our best understanding of time is that it’s intimately connected to heat. Time happens when heat is transferred from a set of atoms to another. Maybe, but also maybe not. We might be wired to understand time as an evolutionary benefit, but that doesn’t mean it’s something “out there.”

Finally, I found Rovelli’s commentary on consciousness wholly unconvincing. Like everything else, he doesn’t look at what “is,” but relationships between things, as that’s all we can do in the wake of quantum mechanics. Great! That’s fair. But he also falls back on the idea that consciousness is merely an emergent property of interactions between neurons. It could be true, but there is 0 evidence, at all whatsoever, that describes how we go from electrical signals to complex thought. Until we have some sort of evidence to that nature, the argument that consciousness comes out of neural interactions is untenable. So what is consciousness? I haven’t the slightest damned idea, but my intuition pushes me away from physicalist arguments until some sort of evidence can be furnished. I’d be happy to change my mind when confronted with evidence, but the argument for consciousness as neural mechanism is—at this point—equally strong as arguments for the soul. That’s to say, there is none either way. We have to run on vibes.

Still, Rovelli’s writing is charming, and it was a delight to read.