Outdoor World

Carlo Rovelli: Time travel is just what we do every day

The theoretical physicist and bestselling author answers questions from famous devotees and Observer readers

Author and activist

Theoretical physicists and mathematicians are fond of describing their assumptions and equations as beautiful but very few novelists are able to bring this elegance to life for the general public. The Italian physicist Carlo Rovelli has proved himself to be one of those rare figures. His first endeavor at writing a book for a mainstream audience, Seven Brief Lessons on Physics ( 2014 ), outsold Fifty Shades of Grey in his home country, has been translated into 41 languages and sold more than 1m photocopies. His second, The Order of Time , is an appreciation and lucid deconstruction of a quality we take for granted-” We occupy time as fish live in sea ,” he writes.

Like other popular scientists such as Stephen Hawking, Carl Sagan and Brian Cox, Rovelli feeds our fascination with the fundamental armies that construct our universe tick. Here, famous devotees and Observer readers question him further.

Questions from famous fans

Ian McEwan


Can you imagine a future in which relativity and quantum mechanics could be so well and generally understood that time, as mediated by relative motion and the strength of the local gravitational battleground, becomes part of our immediate and common sense appreciation of the world? Could we experience in the every period space and time patently and sensuously inseparable? Or are we bound by our very nature and our evolutionary past, and living between the very large and very small, to remain within the sensory limits we experience now?
I think that we will learn, and gradually counterintuitive ideas will become intuitive. It has happened with the facts of the case that the Earth is a sphere( clarified two millennia ago) and the facts of the case that it spins( clarified a few centuries ago ). At first these were extremely counterintuitive suggestions; nowadays we accept them as comprehensible. But it takes time. I suppose, for example, that the working day when we will have spaceships travelling very fast, and we experience immediately things like gratifying our children older than us on our return home … when we experience this, the elasticity of hour will become obvious to us. Of course, all this is assuming our civilization survives long enough and we do not destroy ourselves with conflicts and stupidity, which is something we humen seem to be very good at and not ready to move away from.

Es Devlin

Artist and decorator known for her kinetic stage statues

Es Devlin with her installing The Singing Tree at the V& A in 2017. Photo: Nils Jorgensen/ Rex/ Shutterstock

The course of events often feels cyclical; in architecture, intend and style, styles and propensities seem to echo and recur . Could there be folds in the fabric of hour that wrap around and touch one another, inducing imprints and echoes?
Oh, Es! If your extraordinarily creative artist’s thinker can induce something out of these folds, wrappings, imprints and echoes, I am the last one willing to tune this idea down! The fabric of hour is multilayered, stratified; that is exactly the main idea of my last book. At some degree, my reply would probably be negative, but at another level- the one thread by the recollections and anticipations of our brain- the answer is certainly yes; this is the level we actually mean, when we concretely think about what time is for us.

John Grant


How, if at all, has music helped you on your path of knowledge and understanding about the route things job?
I do not know. Like most people, I listen to a lot of music and in writing my volume on time I have guessed much about the relation between music and our appreciation of hour flowing. The reality that so much meaning is transmitted in such an apparently meaningless arrangement as a sequence of audios has always mystified me.

Robin Ince

Comedian and co-host of The Infinite Monkey Cage

Does dealing with the reality of atomic and subatomic behaviour help take your brain off the surrealism of human political behaviour in these strange days?
I do not think that these times are particularly strange. Humen have massacred one another and had a hard time collaborating for ever. What changes is who the[ short-term] wins are. As for me , no, dealing with physics does not help in taking my thinker off humans’ continuous self-inflicted pain.

James Lovelock

Scientist best known for proposing the Gaia hypothesis

What is the best way to view time?
What we call time, and usually perceived as a very simple elementary notion, is actually a complex experience grounded on different levels. There is a basic physical degree of” things happening”, but this is very far from our common notion of day, because it absence all the rich the specific characteristics of what we call time. Then there are approximations due to our specific scale. There is the effect of the large number( myriads) of microscopic degrees of liberty we interact with. There is the very peculiar behaviour in which our brains interact with the nations of the world, based on remembrance and tentative anticipation of the future.

Finally, there is a thick emotional layer, which is what dedicates us the sense of the “flow” of time. The difficulty of understanding period is the problem of untangling this complex tangle of structures and consequences. Your wonderful realisation of the notion of Gaia was based on viewing unity beyond apparent intricacy. Understanding hour is the opposite: viewing the complexity beyond apparent unity.

‘ The world is made up of networks of kisses , not of stones ,’ Rovelli argues in The Order of Time. Photo: Tony French/ Alamy

Nick Hornby


I desired The Order of Time . It made my head spin, while your writing is clear and beautiful. Nonetheless, I have decided to ignore you and I am going to think about time the old-fashioned behavior for the rest of my life- in a line, with a now, a yesterday and a next year. To think of it to its implementation of kiss and crowds of Italians jostling is too disorienting. What am I missing out on?
If you prefer to keep thinking about time in the old-fashioned lane, what you are missing out on is of great fun and an opportunity to learn more in depth about how the universe truly operates. Not much more than this. I envision one can merrily continue living thinking that the Earth is flat or is at the center of the universe; in daily life, it does not matter much, if at all. And of course I understand that crowds of Italians jostling is disorienting; but still, do you really feel that a world made of stone is more hospitable than a world made of kisses?

Hans Ulrich Obrist

Artistic director of the Serpentine Galler ies, London

I am curious to know more about your unrealised programmes. We know a great deal about architects’ unrealised programmes as they publish them, but we don’t know much about those of artists and scientists , which is why I’m mapping them. What is your dreaming?
I suppose most scientists have unrealised projects. My drawers are full of unfinished studies. My dreaming programme is between physics and biology. There is a common idea that a living organism is a sort of fight against entropy: it retains entropy locally low. I think that this common suggestion is wrong and misleading. Rather, a living organism is a place where entropy grows especially fast, like a burning fire. Life is a channel for entropy to grow , not a route to keep it low. My dreaming is to be able to articulated this properly and quantitatively. I do not know if I will ever be able to. I have to study.

Monica Grady

Space scientist

In The Order of Time , you write: “< strong> The characteristic features of time have proved to be approximations, missteps determined by our perspective …” How does this affect your ability to read a bus timetable and get at an appointment on time?
Not at all, of course. Does knowing that in Sydney people live upside down make it harder for you to distinguish the floor from the ceiling? Realising that we use approximate notions, and that it is a mistake to assume that they have universal legality, does not prevent us from using them. If anything, we understand them better, because we now know the limits of their validity.

The Milky way system over Alberta, Canada. If you want to travel far into the future, says Rovelli,’ it is sufficient to build a fast starship, travel fast enough backward and forward, and in a few days( of yours) you can be back on Earth a millennium in the future .’ Photograph: Alamy Stock Photo

Michael Pollan

Author and activist

I have three questions: do you think that quantum mechanics has any relevance for our understanding of consciousness? Do the quantum influences find at the level of particles scale up to its own experience of the nations of the world or do the effects wash out as you move up? Ultimately, y ou have said that your youthful experience of psychedelics opened you up to the non intuitive ideas of theoretical physics. What specifically happened during those trips to change your psyche?
I do not believing that quantum theory play-acts any major role in an improved understanding of consciousness. However, I suspect that perhaps better understanding quantum theory could free us from some prejudices about the structure of reality, racisms that obstruct us in[ our] understanding of what consciousness is, whatever that word signifies. Quantum theory was indicated that reality is more interdependent than it is in the picture classical physics paints.

The reason I think that quantum results are more or less irrelevant for consciousness is precisely since they are do not scale up to its own experience of the world; they wash out as we move up in dimension. This is why the world looks so “non-quantum” to us, well provide a description of classical mechanics.

Your question about my own experience of psychedelics and its relation to the nonintuitive ideas of theoretical physics is delicate. Let me set it this way: I get so confused about the basic structure of reality that when, 10 several years later, I had to dive into fundamental theoretical physics, I wasn’t scared of losing my bearings. You ask what specifically happened during those trip-ups. The psychedelic experience is notoriously very strong and at the same day very hard to talk about. A drastic loss of the usual personal, emotional and intellectual coordinates. Overwhelming emotions, a sudden sense of seeing everything profoundly differently. The colorful visual theater is nice and fun, but less significant, at the end. In the working day after my first experience, I wrote frenetically in a notebook about it. I filled an entire notebook. A few months later, my mother saw the notebook and burned it.

Albert Einstein at work in his study. Photo: Eric Schaal/ Time Life Pictures/ Getty Images

Neil G aiman


‘< strong> I’m haunted by the idea of Einstein telling a colleague that his dead wife was still alive and it is simply a failing in our perception to see all of hour as existing at once.( I may have completely misunderstood what you and/ or he were saying .) So are we flatlanders, is inadequate to perceive a much richer universe around us, deluded by the idea of sequential hour?
You haven’t misunderstood. We are flatlanders, failing to perceive a much richer world around us, deluded by the idea of sequential period. But perhaps not in the simple-minded appreciation of our loved ones still being alive … The reason for the failure of our perception to see all of hour as existing at once is deeply grounded in the physics of environmental matters and ourselves, but we still have the intelligence and imagination to allow us to see beyond those limits. And to see plural worlds, as you know well, I would say…

Helen Czerski

Physicist, broadcaster and novelist

Time and gravitation are grand concepts that can seem very remote from the practicalities of being human. What are the small things in life that bring you joy and what are your favourite ways to spend time with family members or friends? Do you separate the small exuberances and the grand supposes or are they all woven together?
I think that they are pretty much woven together, because I have difficulty compartmentalising my life. The small things that bring me joy are things like waking up in the morning and going out to watch the sea( I live near the sea) or simply doing nothing with my friend. I like a lot hiking and travelling. I have a small, very old barge and as soon as I can, I just go out to sea, maybe even to eat bread and cheese while the sunshine sets.

Jim Al-Khalili

Theoretical physicist and host of Radio 4′ s The Life Scientific

Despite all its success as a beautiful hypothesi of the building blocks of the universe, quantum mechanics still leaves even those of us physicists who work with it daily both disappointed and bemused. Would you agree that maybe Einstein was right after all and that quantum mechanics is not yet complete?
Yes, I agree that maybe quantum theory is incomplete. Because how could we ever be assured that anything is “complete”? But only “maybe”, because I do not realise compelling reasons to conclude that quantum theory can only be viewed as an incomplete assumption. The reason is that any possible “completion” of quantum theory requirements that we accept strangenesses that are even less plausible than those implied by quantum theory as it is. With certain differences that the strangenesses of quantum theory as it is are empirically demonstrated, while the strangeness of its completion are arbitrary guess. I think that quantum theory can make sense as it is: we just have to give up some cherished metaphysical prejudices and accept the deep relational aspect of nature that the success of the theory has revealed.

Back in the working day: Carlo Rovelli as a student. Photograph: Courtesy Carlo Rovelli

Questions from readers

I read recently that you take enormous pleasure in rinsing up heaps of dishes. Why is this? And any tips-off for removing stubborn stains from pans? What other household chores do you enjoy ?
Jane via email

I have no special tips. In fact, I do not suppose I am particularly good or effective at washing bowls. I just like doing it. The reason is that it is one of those( rare) human activities where you start with a disgusting mess, you immerse yourself in an easy duty that relaxes your mind and you end up with everything nice and clean and glittering and neat. Wouldn’t it be great if life was all like that? Usually, it is the opposite: you start with something so-so, you struggle and get nervous and at the end it is all a mess. My habit of clean bowls comes from my youth when I used to live with messy pals. Nobody ever want to get do the dishes and cohabitation tended to raise tensions. I discovered that if I did the dishes for everyone then everybody adoration me and living together became a pleasure. So I got a lot for a inexpensive cost. In reality, in exchange, my room-mates routinely did the groceries and cooked wonderfully for me. Definitely worthwhile.

Do you believe in free will?
Celso Antonio via Twitter

Free will is an equivocal expres. In the commonsense meaning of” being free to decide “, of course there is free will: we decide. If, instead, by free will you mean that in deciding we infringe known laws of physics and their standard causal relations, then no, there is no free will in this appreciation; the evidence is now overwhelming. What happens in a “decision” is a very complex network of microevents in the brain, which is too complicated to predict. As help clarify Spinoza, free will is real: it is the epithet we give to our own inner complexity, which is too rich for us to extricate or predict.

The physicist Erwin Schrodinger makes a lecturing, circa 1950. Photograph: SSPL via Getty Images

Is [ Schrodinger’s] goddamn feline dead or not?
Afristotle via Twitter

I envision the cat is never” dead and likewise alive”, as quantum theory is sometimes said to claim. The feline is either dead or alive. The subtle point, in my opinion, is that all contingent aspects of reality are relative to other physical systems and are realised in interactions. Therefore in principle a feline could be neither dead nor alive as long as it was not interacting with anything. But a macroscopic entity such as a feline is constantly interacting heavily with the rest of the nations of the world- therefore it is effectively always either alive or dead. Cats behave. The discussion on the explanation given by quantum theory is wide open, nonetheless. I think that different perspectives are possible. It may be a mistake to pretend to choose one. Perhaps the various reads of quantum theory that are discussed are all interesting and the future will tell us better.

Is there a layman’s lane of explaining how gravitation varies day, please? Sea -level and up -a -mountain kind of gravity
HarvestingKarma via comment

The straight way of thinking is the opposite: it is not gravity that varies time, rather, it is the alteration of hour that is responsible for gravitation. The point is that a large mass like the Earth slows down time in its proximity( please do not ask why, because I can only answer one question at a time ). And the effect of this slowing down of time in the vicinity of the Earth is that things autumn. A bit like when you run into the sea and your feet are slowed down by the water and your body is drawn downwards…

The Large Hadron Collider at Cern, Switzerland. Photograph: Rex Features

Is a new, more powerful linear[ circular] collider than the LHC really worth it at the moment, given that the beauty years of detecting new elementary particles appear to have ground to a halt ?
bilyou via comment

This is a large and serious discussion, going on currently in the scientific community. There are good statements on both sides. It is never easy to decide where best to allocate resources. Part of the scientific community is digesting the disappointment of not having found at LHC what they were convinced had to be there. For others, such a non-discovery has actually been a confirmation of anticipations. It is good to stop and think sometimes.

How severely should we be taking the recently mooted mind that the universe is a form of hologram? What difference would it construct to doing science? To living life?
palfreyman via comment

I have never been convinced by this vague suggestion. If there is something to it, I have not yet find it realised in a convincing behavior as a hypothesi of our world. On the other hand, I have understood a lot of very free speculations in this direction, which I do not find very plausible. I might be wrong, of course. Others disagree.

Can hour be said to exist if no observer/ participate is there to experience it? How would one know? Could this not attain consciousness a fundamental quality of the universe?
Gary W Kelly, Salinas, California

I definitely don’t think consciousness is an essential quality of the universe. Our subjective awareness experience is the product of the complexities involved in our brain: it is something very specific. The universe is not going to change whether we experience it or not. It is right there and it does what it does. This is what we learn when we are three years old and it’s true. What depends on our consciousness is the way we ourselves perceive period- our experiential period. Discovering that something we perceive depends on the route we are does not be interpreted to mean that the universe depends on us.

Richard Feynman receives word that he is to share the Nobel prize for physics, 1965. Photograph: Bettmann Archive

Do you think that Richard Feynman ‘ s dictum” Shut up and calculate” has done a great disservice to physics? Isn’t physics about trying to understand the root causes behind physical phenomena , not just treating them as “black boxes” we are going to be able never hope to comprehend?
David Mitchell via comment

I imagine the dictum” Shut up and calculate” is misattributed to Feynman. Feynman was a deep thinker, asking subtle and fundamental questions and offering visual interpreting of his figurings: quite the opposite of” Shut up and calculate “. The expres” Shut up and calculate” has been used to characterise a certain excessive pragmatism in the physics of the 1950 s. I believe we have moved out of it. Of course science is about understanding , not about predicting.

Is hour travel a potential? If so, is it restricted in the direction one could travel, forward or back? And would it require a powerful engineered machine or exist in nature?
Sagarmatha1 953 via comment

Time travel is just what we do every day, isn’t it? Every single day we travel one day ahead in time … But “thats just not” what you are asking … You are asking whether we can fast-jump into the future and whether we can go to the past. The answer to the first question is: certainly yes, it is just a question of fund. The answer to the second is that it is improbable in a very technical appreciation. Let me explain: if you want to travel to the next millennium, it is sufficient to build a fast starship, travel fast enough backward and forward, and in a few days( of yours) you can definitely be back here on Earth a millennium in the future. The science of this is completely uncontroversial and clearly. The only difficulty is detecting the money for such a starship. If instead you want to travel to a millennium ago, things are more complicated. The reason is that you have to beat the entropic arrow of time. This is not impossible, because the arrow of day is statistical, therefore it is just a matter of probability and improbability. But the improbability is overwhelming. So in a very technical sense, I think that going to the past is very improbable.

* The Order of Time by Carlo Rovelli is published by Penguin( PS8. 99 ). To order a print go to guardianbookshop.com. Free UK p& p on all online orderings over PS15

Read more: https :// www.theguardian.com/ science/ 2019/ disfigured/ 31/ carlo-rovelli-you-ask-the-questions-time-travel-is-just-what-we-do-every-day-theoretical-physics

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