Theoretical physicist Carlo Rovelli has a hypothesis for why his slim, elegant primer Seven Brief Lessons on Physics has been such a success — a million copies sold; translated into 41 languages — since its publication in late 2014. “It’s small, it’s cheap, it’s readable, and it talks about big things,” says Rovelli with a laugh.
The 60-year-old Italian, one of the founders of the loop quantum gravity theory, is being humble. Seven Brief Lessons — now being followed by a new more expansive book on physics from the ancient Greeks to contemporary quantum mechanics, Reality Is Not What It Seems — is, indeed, everything Rovelli mentioned. But with its warm, enthusiastic language and tone, the book is also deeply humanistic in approach, using words like elegant and beauty about a subject — post-Newtonian physics — that can seem impenetrably dense and abstract.
Reality Is Not What It Seems takes much the same approach, all part of an attempt by Rovelli to entice readers to engage both intellectually and emotionally with physics’ attempts at answering fundamental questions about the universe and the nature of reality. It’s one thing to get a basic conceptual grasp of, say, the theories for why our universe may well be just one of many, or how every object has its own time. It’s another to absorb those ideas in such a way as to change how we might perceive our own lives. And that, the relevance of physics to our day-to-day and why it can matter to laypeople, is what Rovelli spoke with us about — along with his concerns for the status of science in contemporary society and the stupidity of simulation theory — over the phone from his home in Marseille.
Your books are written with such a sense of wonder and amazement about physics. Do you think that, for your readers, those feelings should translate into their daily existence? Or is learning about physics strictly an intellectual pursuit and not really an emotional or philosophical one?
Well, that’s one of those questions where the answer changes depending on what level you approach it. So let me start from the easiest one: Physicists are researching quantum gravity and the grain of space and the deepness of time. And what we find is not going to change what’s happening to you or me today or tomorrow or have any effect on American politics. So from that simple perspective, there’s a clear separation between physics and our lives. That’s level one. Level two involves something that’s said all the time, which is that science has historically had a huge technological impact on society. One could even say that modern life is entirely a result of science.
But those are the two easy answers. The more complex approach is about how physics and science can affect your soul, which I think is a real idea and is completely different from those two levels. Being interested in understanding hypotheses for what time and space are made of or where matter comes from helps to form an attitude. It means you’re interested in the world, in changing your mind, in discovering where our thinking is prejudiced and being aware that issues are complex. The willingness to change your mind about complex subjects in the face of new science is where the greatest philosophical value of an interest in physics comes from.
Do you feel like a willingness to adapt one’s thinking according to new scientific evidence is becoming increasingly rare? I feel like, particularly here in the United States with things like the anti-vaccination movement and climate-change skepticism, there’s this growing idea that for a lot of the public science has almost moved into the realm of opinion.
There is no doubt that’s happening. I used to be much more soft-spoken about this subject but it’s stupidity going wild. It’s not just happening in the United States, either. The United States is still a leader in the scientific world but a large part of the American population is taking ideological positions regarding science, which is frightening. Ideological positions on global warming or evolution are stupid and dangerous and the worst part is that this kind of thinking is increasing. American society in the ‘60s and ‘70s was much more open to rational thinking. There was trust in reason, trust in science, trust in thinking, trust in change — the same things that as I mentioned earlier, an engagement with science can cultivate. In France, where I live, more and more people when their child is ill, instead of taking them to a doctor, are looking at alternatives. And this is when there is no doubt that medical science can help. It’s very upsetting. Science obviously can’t solve all our problems, but it can solve a lot of them.
I wonder if some of the cutting-edge concerns of science have alienated people. It’s a lot easier to think of something like Newton and the apple than it is to wrap your head around thermal time.
No, not at all. In Newton’s time his concepts were difficult; and Copernicus’s concepts were difficult in his time. These ideas have always been difficult to digest. It took people 150 years to accept the Copernican revolution. The idea that nowadays science has gone away from common sense is a perspectival mistake.
Do you think that physicists are more open to changing their minds when it comes to nonscientific areas of thinking than nonscientists are?
I think that intellectuals in general are more open, not necessarily just physicists. Scientists are just as capable as anyone else of falling in love with the wrong person or making stupid mistakes in their life. But as a group, I think they’re aware of the limitations of first impressions and the value of rational thinking.
Speaking of which, do you know about simulation theory?
Do you want to know what I think of it? It’s bullshit.
Of all the infinite possibilities I can’t believe such as simple-minded, silly possibility should be true. Reality has more imagination than that! Why should we be in somebody’s computer simulation? This is so incredibly naïve. Reality might be very different than what we think, but not in such a childish way.
But at the risk of offending our AI overlords, why is simulation theory so childish?
I know it’s very popular right now. I go to conferences with otherwise very intelligent people who mention it, and I find it childish. Each generation of humans has a new technological discovery, gets completely fascinated by this discovery, and then tries to interpret the world in terms of this discovery. We have computers that are remarkably advanced. My little iPhone can perform so well and do so many things in spite of being a little piece of plastic and metal. But to then think of these technological inventions and go Ah! This is how the universe must be! No. There’s nothing about the simulation idea that helps me to understand the world or myself any better. When I was a child, I learned that the universe is expanding and contracting, so I rolled around in my bed and thought that since my heart is expanding and contracting when it beats, maybe the universe is the heart of a huge giant. It’s a nice story. Can we prove it wrong? No. Is there any reason to take it seriously? Zero. This is how I feel about the simulation theory. Just because we don’t understand everything about our brains or the universe doesn’t mean we have to start dreaming up psychotic scenarios.
This is, I hope, more neurotic than psychotic, but there are times I find reading about physics extremely unsettling. The idea that our experience of time is just a construct of our brains to help us achieve some mental coherence, or I’ll be sitting on the subway on the way to work and thinking that I could exist in multiple universes — it makes me want to freak out a bit. Does physics ever cause you to wrestle with existential issues like that?
Yes, yes. I know what you mean. We don’t know if there are universes besides ours; we just don’t know. We ultimately know very little, but we should think of that as a challenge, as a reason for thinking, and not as a conclusion. How can I put it? Yes, there’s something deeply confusing and destabilizing about how much we don’t really know. But we don’t have an obligation to face all of that every day. Instead, we have the privilege of thinking about that. David Hume, the great philosopher, concluded that he doesn’t believe any of the things that we think we believe. And at the end of the day, he said, “Good, I’ve reached that conclusion, but now I go down to the bar with my friend and drink ale.” Life continues. In a sense, I think this experience of doubting the tissue of our reality can be enriching. It leads to more thinking.
In your new book, you write about how Lucretius’s conception of atoms invites a less hierarchical view of thinking about the universe than what was common before. You also talk about how the work of people like Galileo and Newton led to the Enlightenment and widespread changes in popular thinking and ideology. Does contemporary physics have the potential to incur similar widespread change?
Yes, I think so. Let me mention two things; one is more complicated. There’s an increasing scientific understanding that relations matters more than things. This is another way that, to go back to your earlier question, physics can affect your life. Learning to think in terms of relations with one another, more than entities, is a good thing. If you take that to heart, it suggests that collaboration works better than competition. It’s not either the lion or the lamb — it’s both or none. So recognizing that we live in a complex interconnected net might positively affect the way we think about society and organize things.
What’s the second thing?
The second example is simpler. It seems to me that there’s been a transition in cosmology, one that’s very humbling, which is this: We’re not special in any way. Humans are just an accident, and we are fragile. In this moment, widespread recognition of our fragility is essential. I hope people understand this.