Portrait of Carlo Rovelli on balcony

Interview: Carlo Rovelli, theoretical physicist and author of ‘The Order of Time’

Image credit: Jamie Stoker

Carlo Rovelli is a leading figure in the field of loop quantum gravity. His popular science book, Seven Brief Lessons on Physics, sold more than a million copies worldwide and his most recent book, The Order of Time – which describes the bizarre nature of time as understood by physicists – has been met with critical acclaim.

How did you approach writing The Order of Time (Penguin, £12.99, ISBN 9780735216105) following the success of Seven Brief Lessons on Physics?

Having discovered all these readers, I felt a sort of pressure and I didn’t want to repeat a formula, so I hesitated before I started writing again. I decided that the thing I wanted to use was the fact that I had so many readers looking forward to a book […]. I said: “Alright, if people want to listen, I don’t have to compromise, I’m happy to take a risk and try to write a story about what has been for me the most fascinating problem and all that I understand and don’t understand about it”. Once I got into the spirit, then it came easily. Essentially, I wanted to update the reader like I would update a friend.

In The Order of Time, you deconstruct the familiar human experience of time. In doing so, did you feel restrained by language?

Definitely, yes. In physics we use mathematics and so one gets over the language. Language is good for talking about reality, but it’s also blinding because one risks using it without thinking what it is actually saying. When you try to talk about time, everything goes well as long as you’re talking about our common experience of time. But as soon as you try to talk about the different temporal structure of the universe, the language is just not there […] so a lot of the book was struggling with language.

Do you have to sacrifice mathematical precision when writing books about physics?

You cannot do [physics] without mathematics; mathematics allows us to derive quantitative results and make predictions and we cannot do that in words - or we could, but it becomes horrendously more complicated. The books of Galileo do not have really explicit mathematics, it’s all words, but now we [can] transform a page of Galileo into a line of mathematics. So you lose [precision] but you gain poetry and visual things. 

I could tell you that the earth is like an orange: you can walk around it and come back to the same point. The content is the same as [going] to the blackboard and writing an equation: x2+y2+z2=1. But you look at that equation and do you really see a sphere? It takes a lot of visual intuition. I think words and language completes and explains what’s hidden in equations.

Is there such a thing as boring physics or is there only physics presented in a boring way?

If I have to be honest, yes, there is such a thing as boring physics, certainly! But of course some things which are horrendously boring for somebody are not boring for somebody else, so it’s a matter of taste. I’ve [got] colleagues who are totally enchanted and passionate about things which I find boring and maybe it is also [true for my work] as well.

Unusually for a physics book, The Order of Time is lively and poetic with lots of your personality in it. Is there something about physicists in particular which makes them averse to taking creative approaches to their writing?

Yes. We are told in science that we must learn to be precise, we must learn to be rational, we have to keep out imprecision, emotion, and the result is that one feels we have to be dry otherwise it is not scientific.

I think there’s a big misunderstanding; some texts by Galileo are incredibly lively and full of emotion. It’s not that physicists don’t feel emotion [about] what they do. They do of course, otherwise they wouldn’t spend the night without sleeping because they want to do their calculations and their experiments. But we come from a culture that tells us rationality needs to be cold, which is true in the sense that we shouldn’t be misled by emotion. But it’s false in the sense that it’s not by hiding the emotional part that things become more comprehensible. In fact, it’s the other way around.

Feynman was a fantastic teacher; when he was teaching something he was just bubbling with enthusiasm - his enthusiasm, his joy, his fury because he doesn’t understand. Communication is completely at the emotional level because that’s the way we communicate best, especially on difficult topics. On difficult topics we [also] have to use metaphors, we have to use visuals; that’s how we learn.

Has the division between arts and sciences softened during your lifetime?

Maybe there has been a growing understanding that the division is artificial. The division is there because there are different techniques and that’s fine of course […] everybody has their own tools. But the goal [of arts and sciences] is common; to develop conceptual tools for understanding the world and how best we can make sense of what’s around us.

There was a strong separation especially in the ’50s […] then in the ’60s and ’70s people started to say we cannot understand the world with separate pieces, we need to have a global understanding, otherwise the separate pieces are profoundly non-satisfactory. It is profoundly non-satisfactory having equations about the world which leave out things important to us and it’s also profoundly non-satisfactory reading poetry or thinking about our psychology and believing that this is unrelated to the physical. It’s a common world and we have different tools for relating to it.

What could we learn about ourselves by understanding the concepts described in The Order of Time?

We’re increasingly understanding that what we call time is very much related to ourselves. So I think the physical quest – the physical research into the nature of time – and the effort to understand consciousness are getting close to one another. That’s the reason [why] in the closure of my book I get to talk about us and our fear of death. Time is close to us; we live in time, but time is the source of our joy and sorrow.

Of course, it’s not that a book of physics gives us a sense of life or a good way of being less sad and more serene. But I think we have to bring all the pieces together and include what science tells us and it tells us that we are made of this temporality and time is made by us.

Read our review of The Order of Time here.

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