The Physics and Philosophy of Time - with Carlo Rovelli

The Physics and Philosophy of Time - with Carlo Rovelli 990,060 viewsJun 13, 2018 The Royal Institution 1.22M subscribers From Boltzmann to quantum theory, from Einstein to loop quantum gravity, our understanding of time has been undergoing radical transformations. Carlo Rovelli brings together physics, philosophy and art to unravel the mystery of time. Subscribe for regular science videos: http://bit.ly/RiSubscRibe Carlo's book "The Order of Time" is available now - https://geni.us/JjwvO Watch the Q&A: https://youtu.be/NXcu0BlbTrM Time is a mystery that does not cease to puzzle us. Philosophers, artists and poets have long explored its meaning while scientists have found that its structure is different from the simple intuition we have of it. Time flows at a different speed in different places, the past and the future differ far less than we might think, and the very notion of the present evaporates in the vast universe. Carlo Rovelli is a theoretical physicist who has made significant contributions to the physics of space and time. He has worked in Italy and the US, and is currently directing the quantum gravity research group of the Centre de physique théorique in Marseille, France. His books 'Seven Brief Lessons on Physics' and 'Reality Is Not What It Seems' are international bestsellers translated into forty-one languages. This talk and Q&A was filmed in the Ri on 30 April 2018. --- Thank you for our Patreon supporters who help us make more videos like this: Alan Delos Santos, Ashok Bommisetti, Greg Nagel, Lester Su, Rebecca Pan and Will Knott. --- The Ri is on Patreon: https://www.patreon.com/TheRoyalInsti... and Twitter: http://twitter.com/ri_science and Facebook: http://www.facebook.com/royalinstitution and Tumblr: http://ri-science.tumblr.com/ Our editorial policy: http://www.rigb.org/home/editorial-po... Subscribe for the latest science videos: http://bit.ly/RiNewsletter . Product links on this page may be affiliate links which means it won't cost you any extra but we may earn a small commission if you decide to purchase through the link. Buy The Royal Institution merchandise $14.65 Teemill $24.42 Teemill $24.42 Teemill $48.83 Teemill $18.32 Teemill $24.42 Teemill 1,654 Comments rongmaw lin Add a comment... Peter Strider Peter Strider 3 years ago Such interesting ideas. Here is a personal attempt to understand it: Time is essentially change. I remember learning that a photon - which as we know travels (ie is in motion) at the speed of light, actually experiences no "time" during its own existence. It doesn't change at all. (Einstein's theorems explain time slows as objects approach the speeds of light. So for a photon time is stopped!). Imagine a particular photon, travelling from the edge of the cosmic microwave background - as far back as we can measure. The instant it collides with a digital sensor in the Hubble telescope is the exact same instant it was formed and released from the nuclear fusion reaction of hydrogen atoms - at the beginning of the earliest stars 300,000 years after the Big Bang. The "now" for that photon was a single "instant" of existence, during which a universe expanded for some 13.6 billion of our years. So it wasn't the motion that constituted time. It was the changes that went on all around it. Changes we see in the large scale universe are marked out or illuminated by countless gazillions of photons coming into and out of existence and illuminating changes between and within all the other countless non-instantaneous forms of being, such as atoms, molecules and so on. "Time" does not need a mind. It just is the process of physical change. Entropy is one metric for defining the actual process of passing time (the change of things toward greater disorder is a feature of time). Our brains perceive time in another, specifically biologically evolved way, to enable humans more successfully to survive and reproduce. Our perception of time is based on perceiving states of macroscopic being through our senses, and remembering them long enough to discern changes which we can hold in our memory (personally in our minds, or externalized with some technical or symbolic tools). These remembered changes are perceived and recalled relative to other regular cyclical patterns in our brain (our body clock and sense of time) or patterns of the sun each day, patterns of the seasons etc. Human time is very specific to our biological needs and evolution in space and time. It is not absolute. We cannot even conceive of absolute time because there is no privileged perspective in the cosmos. From the micro and quantum scale to the largest megascale of the universe, changes are just continually happening. Galaxy time is different to Planck time. And this means "Now" is not actually a time. It is simply the cognitive process of starting a mental stopwatch and deliberately comparing the sequences of changes. That is why we can only experience "now" when we deliberately think of it. It is not actually "part" of time, any more than the shooting of a starting gun is intrinsically part of the "time" taken to run the race. Another gun on the other side if the field can start another race whenever the officials decide. The reality of time (change) is the constantly varying flow of forces, energy and particles around and through us. "Past" is a name we give to the whole sequence of changes that led to this present state of existence. (But we tend only to think of "The Past" as those changes remembered as relevant to how we came to our current state of being). The "future" is everything and whatever this present state will become, as those forces, energies and particles continue changing according to their natural laws and processes. Our biological memory has a trick, allowing us to remember arrangements of things nd so compare them across a range of microscopic and macroscopic patterns. We call these patterns "time" and we imagine it has fundamental and independent existence. And it really does have fundamental importance for successful life as a biological creature. Not having an acute awareness of time, and of the types of befores and afters and causality that is biologically evolved into our bodies, would mean our time as a living being will be short. But this perceptive frame it is not universally relevant. Time for the cosmos in fact is irrelevant. It just is changing. The ancient Chinese philosophy of Dao, or the Way of Change , actually articulates this mystery profoundly. Paraphrasing it, we might say "the change that can be named is not the true change". The time that can be named, is not the true time. But it is the only time we have. So lets live within it well. 284 Michael Pisciarino Michael Pisciarino 3 years ago (edited) 1:51 Where are we in our understanding of time? 4:39 Order (The Time Line: Past, Present, Future, ) The Past is fixed. The Future has yet to come 9:36 Clocks 11:05 Your head is older than your feet. (Time is longer in the mountains) 14:35 The "Now." We see each other in the past. In Jupiter we see you 2 hours ago. 19:00 Now is only local. What makes something Real? 22:25 Thermodynamic distinction between past and future is Entropy 24:59 Order is in the eye of the observer 31:08 Cause and Effect, and Entropy 33:55 Clock Measurement. At the plank scale. Superposition of times at the quantum level. No Time Variable Needed. 36:00 Aristotle's definition. Time is the number/count of change. 39:52 Basic Conditions Granularity 42:12 Entropy 44:30 The Flow of Time. The Passing of Time 46:50 St. Augustine 393 Jensen Ahlfield Jensen Ahlfield 1 year ago The best talk on the concept of time I've ever heard. Truly mind opening. Great to hear the budding concept talked about by someone on the forefront of its discovery 20 Sulaiman Lalani Sulaiman Lalani 1 year ago Thank you RI for the searching inquisitive souls like us to be able to learn from true legends of our times such as Carlo Rovelli, Jim Baggott, Andrew Pontzen, David Tong et al. Many other names: but thanks to all of these legends. 22 The Royal Institution Gökhan Bayraktar Gökhan Bayraktar 3 years ago I simply love Carlo's books. He has an authentic perspective and he does a great job in conveying his ideas. It takes me only a couple/few days to finish his books. I'm 15 mins through the video and my impression is that he can communicate his ideas much better when he writes. So if you find any part interesting for yourself, I highly recommend you to buy his book, the order of time. 87 Nicole Graber Nicole Graber 6 months ago Thank you for the recording of this lecture. What I really like about C. Rovelli's lectures, is that he often just talks, without showing dozens of slides. This is very convenient, because you can take your eyes off the screen; and it's very pleasant, because you can immerse yourself in your own imagination, while being guided by a clear and pleasant thread. 4 Christopher Hart Christopher Hart 3 years ago I really liked the metaphor of the flow of time being experienced like a musical score - one note at a time. I read his recent book. I could not recommend it more highly. 142 Joanne Tenenbaum Joanne Tenenbaum 1 year ago Deep and thrilling, like Rovelli's books. Rovelli has a gift for making abstract ideas understandable for all of us. I have always had the sense that time was a function of our limits of perception, so it was wonderful to hear Rovelli approach a similar conclusion. I was surprised to hear that this notion is considered new in quantum physics. 2 Idle Hands Idle Hands 1 year ago This man has such mad elegance and insight it’s unreal. Highly recommend the book (The Order of Time). His findings are simply astounding and his prose is impeccable. 24 Angela R Angela R 1 year ago I have had a drug induced experience where my brain could no longer properly produce a normal, subjective experience of time passage, and also the continuity effect was broken. A minute (as checked on the clock) felt more like an hour, and I would find myself in a moment, with 0 recollection of the events shortly before. This demonstrates his idea that what we understand of time is strongly regulated by some brain effects. If the brain couldn't bring together the musical notes already registered in a correct order, then there would be no talk of time at all. You'd only experience a snapshot of reality, and no experience of motion, since something requires at least two states in order to say it moved or changed. So then if the physical world has more than one state, the brain needs a way to work with these states. But then did the physical world and entropy determine the brain to develop this arrow of time perception of motion, in one direction, or is it just one possible way of 'making sense' of reality? Just like different eye designs in different species, perceive different wavelengths. Also, in one physics documentary, I have heard the idea that when you break a glass for instance, if you could reverse the velocities of the particles of that glass, you could reverse the whole thing. This example was brought up to demonstrate the idea that for the physical theories in themselves, a glass being unbroken is not forbidden. But for the velocities to change in the opposite direction, something has to change them, it doesn't happen spontaneously. And a realistic example of unbreaking a glass, or making order out of disorder, are all the biological mechanisms. How does this fit into the entropy idea? If you imagine the world at the beginning as a soup of chemicals, biological organisms are so much more 'ordered', and you could argue that in those examples, entropy decreased. I mean, I know I am complicating it all when I introduce biological, macro objects, but I find it relevant. In this video, I really like it how he points out that 'order' is defined by the system we choose, ordering balls by red and green for instance, so that's one problem addressed: what is order? But then the next problem would be, on what level does the observation that things go from order to disorder, apply? If you pour oil in water, in time, the water and oil will segregate in an orderly way. Organisms are clearly defined systems that produce order out of disorder. Because of these examples, I find it really hard to understand why entropy is considered the decisive factor in creating an arrow of time. Perhaps I need a more detailed explanation? The point where different disciplines like psychology, neuroscience and modern physics meet (in a sound, not a superstitious way), is incredibly fascinating. 7 Sarah Atka Sarah Atka 1 year ago incredibly well explained. Thank you so much for this inspirational talk ! 6 Amit Anand Amit Anand 8 months ago Well after listing to your lecture I am really surprised that mathematics and physics is now being put into words and is being aligned with questions whose answers lie with in ourselves. That is our brain where emotions play a very strong part. 3 David Cooke David Cooke 2 years ago I loved Carlo’s book and this talk helped to consolidate that for me. Profound and provocative, with genuine consequences for living. Thank you 5 andrew murphy andrew murphy 2 years ago This presentation is extremely beneficial as an introduction to the conceptualized understanding of time. I am very much obsessed in the idea of "time", I wrote my perception of time roughly a year ago and now just watching this video, I have been pleased to find my understanding is well within reason. Here is what I wrote if anyone cares to read. And please I welcome criticism, constructive or not. Thanks... UNDERSTANDING “TIME” It's important to understand that the creation of the word and definition of “time” was created by man to give measurement of their passing moments in existence. As it's too common for people to just accept what has been oversimplified as the ultimate truth without questioning it. An example of this is the human notion of “time”, everyone accepts the premise of past, present, and future, some to the degree that they all exists simultaneously and or that they can be traversed, as if a highway, and it's accepted without further understanding the actuality that they are a man made virtual construct of reality and is no more realistic than (would insert God here, however to not offend) the boogeyman or Easter bunny. So I ask you for a moment to put aside these meaningless fabrications and try to come to the realization that what so many people refer to as “time”, more accurately fits the definition of Entropy. While this is loosely accurate to the true action that “time” measures, understanding Entropy helps the mind come to terms with what follows, “Matter Evolution”... the physical change of matter in the universe from one possible configuration to another, with the ultimate premise that all matter in existence within the known universe evolving from orderly to disorderly physical constructs (similar to if not exactly as with Entropy) so the notion of past, present, and future, no longer becomes valid if your interpretation of existence evolves into the idea that the entire known universe right now is in one possible configuration of existence that has infinite possible ways to exist from one moment to the next or from every little change of a property of matter within it. Now some configurations can be predicted accurately with an understanding of Causality, and Entropy, as some systems can and do create “partitions” of order from disorder, however this order is created with a fundamental principle to further disorder to the system as a whole. Moving on… The universal existence of “Matter Evolution” is not a concept that can be easily associated with having a past, present, or future, instead should be envisioned as that all of existence having different possible evolutionary outcomes in relation to any and all possible interactions that give change to any physicality of matter... (Still work in progress) 6 Chun chen Chun chen 1 year ago Very insightful explanation of time. The beginning of the lecture was bit slow, but it immediately attracts me when he links time with micro states, entropy and what it means of order. This aspects as always been puzzeling for me. In the end, despite all physics rational property of time, I liked the last part that links how our biological brain works in terms of time, and most importantly the meaning of time to our understanding of life. Thanks for the video 👍 ジョエル ジョエル 1 year ago I always thought time was similar to a fluid. Time dependency goes away when the length scale is small or if the fluid is very viscous. In this regime, fluid is cyclical but does not return exactly to its original position, something like a spiral, if the forces driving the fluid is asymmetric. Of course, this is in the realm of continuum mechanics. Is time a continuous function or discrete? 1 Ascension Wisdom Ascension Wisdom 3 years ago 😇 Thank you for your amazing unique video, it is so much valued and I really value your hard work !👍 24 The Royal Institution Yazan Shukair Yazan Shukair 1 year ago It is great lecture. Make us recognise how our brain 🧠 is limited and at the same time how we trying to go beyond our limitation 8 Steve Deasy Steve Deasy 2 years ago I love how his conclusion ties in the idea that the perception of time causes suffering. How does a Time Scientist release attachment to time? 24 Des Greene Des Greene 2 years ago One of the best overviews of time ever presented. Our human emotional sense of time endowed by evolutionary growth is far from the ontological time of quantum gravity. Perhaps there's an analogy here with how our brain is ill-equipped in conceptualising the ontology of the quantum world.... 1 love is free to be liked is earned love is free to be liked is earned 2 years ago Tremendous talk, very enlightening, i never understood it better! Thank you 6 Prod.WinterxPhool Prod.WinterxPhool 1 year ago That was an amazing lecture. I took lots of good notes on that, thanks. 2 Julian Bass-Krueger Julian Bass-Krueger 6 months ago Love Rovelli. His book The Order of Time is a revelation. Cutting edge physics and poetic lyrical writing. As people have said, he communicates better in writing so check out his books! Amit Anand Amit Anand 8 months ago Thanks once again. As I am overwhelmed by the concept of non existence of time in absolute terms. It is relative both at macro and micro level and is an instrument developed by our brain for our contin iued existence. 1 Martin Eastburn Martin Eastburn 1 year ago Dr Rovelli, Some years ago, my father was flying his two super high precision atomic clocks to be calibrated and back. Both were always kept together and in use, only one was used but the other was used to verify they matched. If no match was attained, a human had to determine which was was to be the Master. Needless to say the project was not civilian but is in operation today. Concrete N.D. if you are interested. 1 Quantized Inertia Quantized Inertia 3 years ago Really great! Thanks to all! This clip really helped me to understand many things! Big thanks to Carlo! Ziggy Freud Ziggy Freud 2 years ago Thanks for your efforts in sharing your views of how some of us see time. For me, there is no time. And my now is a unique now as is everyones. We use the concept of time to measure change to help us interact with one another and make sense of our world. But the reality is that time doesn't exist. There is only my now for me :) Great lecture and thanks for sharing. 5 R R 5 months ago This lecture opened a new perspective for me to observe my surroundings 2 William William 1 year ago Absolutely brilliant lecture clear, concise and to me looking for something to listen to quite timely. 🤔 MK ULTRA MK ULTRA 2 years ago What a pleasure it was to listen to that talk. Next time this gentleman comes to the RI can we maybe give him some extra time, i could listen for hours. I really like his thoughts on how we perceive time through an emotional lens, I think his ideas about that are bang on. What a wonderful talk, excellent speaker! nyworker nyworker 10 months ago Nice to see a scientist say something that we all understand intuitionaly. Cássio Leite Vieira Cássio Leite Vieira 5 months ago Rovelli rescues the old (and great) tradition of Italian physicists with a strong Humanity cultural background. Great lecture! J. F. J. F. 3 years ago Fantastico! Very easy to follow and to understand, given the complexity of the subject. 7 John Eyon John Eyon 2 years ago i was very excited to hear this lecture - it confirmed some of my ponderings on the subject - change creates time - time is local - altho i always hate to see entropy brought in - i'll have to find one of his book that's on the same subject 2 Maksimilian Kiefer Gregl Maksimilian Kiefer Gregl 1 year ago Excellent explanation from Dr. Rovelli. His book "The Order of Time" is highly recommended. Now I need to get back to "Confessions" from St. Augustine. 1 Nathan Okun Nathan Okun 2 years ago The "thickness" of "now" can be considered the time it takes to do something for a reason and then get a response from your "target" on which to base your next action. Nearby, this is very short and "now" seems to be a thin slice of time. As the distance increases (or the response time of the target slows down), this interval gets larger and larger, but still forms the basic concept of "now" to humans. Thus, the concept of what is the separator of the past from the future -- what is "now" -- is usually based on our human perceptions, not on physics. 1 Thuo Kagiri Thuo Kagiri 1 year ago His simplicity,eloquence and pedagogical approach almost put him in league with Richard Feynman demystifying such counter-intuitive ideas for non physicist like me ....Simply elegant. Elvis Sibilia Elvis Sibilia 1 year ago (edited) Nice video. Philochrony is the theory that describes the nature of time and demonstrates its existence. Time is magnitive: objective, Imperceptible (intervals) and measurable. 2 Julian Lewis Julian Lewis 3 years ago I would have loved to have asked him the question... If time is measured by changes in entropy, how can these changes be observed unless there is time in which to make the series of observations ? But I loved the idea that time is a subjective phenomenon created by our brains need to make predictions based on memory. A great thought provoking talk. 13 Abdulkader Jaleel Muhammad Abdulkader Jaleel Muhammad 3 years ago I think "CHANGE" is the 'tool' that makes us 'aware' of time. The change, may be the change of our 'shape' with 'age', or change of state of motion or change of state of energy or change of state of 'entropy', ...etc.. The change is always a change 'relative to time' (or with respect to time). If 'Laws of Physics' do not differentiate between past and future, it is because that these laws do not have a 'memory'; that is these laws do not keep a record for the 'past events and or past changes'! The talk is great in shining light upon these topics. Thanks for RI and for Prof. Carlo Rovelli. 1 Syed Syed 1 year ago I'm one of those philosophers he talks about and so good to see this talk. I do disagree with certain points of his. But all that aside the thing that the best about this video? It's the fact that it has been viewed more than half a million times. In this world of anti-science, this is so good to see. 9 granduniversal granduniversal 2 months ago It's nice to hear you talk about living in the moment. Culturally, we do seek that. It seems to have something to do with our understanding, collectively, about time. What about entanglement? Doesn't that hold some promise about understanding time? It looks like the architecture allows for going back, in order to effect the other particle. Our brains are always playing these tricks with time on us. I wonder if that is involved at all? Andrea Franco Andrea Franco 1 year ago Henry Bergson stated his "real duration" as flowing continuously belonging to our consciousness in contrast with the discrete time of the physics, which recently also vanished at a given scale as Carlo Rovelli explained Puni Charana Puni Charana 1 year ago 1. time dilation 2. now/present (speed of light) 3. entropy thermodynamics 4. space time (Einstein) TheFinalJudge TheFinalJudge 3 years ago Since there is a lot of discussion on presentation style, and since I could only find one reference to his book "The order of time" in some sub-response, I would like to advise reading that book as it covers the topic of his presentation in a clear, well-written, sufficiently high-level way. By referencing many authors throughout history and their insights, he manages to make an abstract topic into a coherent story and a pleasant read. Well done Carlo Rovelli! User Droid User Droid 3 years ago It was great to hear him talking about time as a change in objects states because I'd been thinking the exactly same thing Breaux Segreto Breaux Segreto 3 years ago Thank you Dr. Rovelli ! Watching this and reading your most recent book, The Order Of Time... I’ve come up with a t-shirt idea 💡”Time is not a movement... it’s a perception.” ;) 4 amalia antonopoulou amalia antonopoulou 1 year ago Carlo Rovelli is great. This is not only a conception of time, is a genuine philosophy of physics! Beena Plumber Beena Plumber 2 years ago Nice to see Herr von Smallhausen found a decent gig after the war :D I think Prof. Rovelli, like so many others, comes so close to saying it but falls short - time is a dimension, and not a special one. Past differs from future like left differs from right. The thing that's unique about time for us is that we are beings who live by moving through the dimension of time. quinterbeck quinterbeck 13 days ago This is really interesting and I follow right up to the last part which I really don't understand. Rovelli talks about the past-future distinction as a product of the brain's design, which serves a certain function - but always describes this function with reference to some external past and future. So it seems circular to me... Simon Kitt Music Simon Kitt Music 3 years ago (edited) I was having a discussion about the illusions of time with a friend a while back and I think we came to the crux of why it is so hard to think or talk about reality without evolution through time. It is because a sentence is not a sentence if it does not contain a verb. Therefore pretty much any thing you say is either not a sentence or contradicts the view you are tying to express. Elias Leousis Elias Leousis 1 year ago "In the beginning there was chaos. Out of chaos came order. Out of order came love." My ancestors came to the same conclusions thousand of years ago. My humble summary contribution to knowledge: " Love is the ink, wisdom is the message. Imagination is the way." 2 Harry Hatters Harry Hatters 2 years ago Fantastic insight into a complex subject! 5 Keith Colin Keith Colin 1 year ago (edited) Should we compare time to the second law of thermodynamics and does it only work if you think in a reductionist manner? For instance, mountains eventually are turned into sand, but that sand collects together into order, with larger pieces settling on top of smaller pieces. Many elements re-order themselves, which is why we can easily mine many of them. Stars get torn apart - yet the gasses always come together again to form new planets. I wonder if part of the scientific process is missing? We are taught from an early stage to use the reductionist method but not how to re-build or vision them completely within the complex systems that these phenomena occur. If within our minds we only reduce things to the nth degree rather than building and understanding complex and interdependent systems, does that skew our perception of science, time and our very own existence? 1 Sam Sam 3 years ago (edited) This was the subject of my college thesis. When I went through the physics in my thesis, I used decoherence and consistent histories to define the arrow of time rather than thermodynamics. Within any possible macroscopic timeline as experienced by any individual, that is any single path through spacetime, all events that are in the past, as seen relative to the reference frame of that path, can be derrived from the full set of quantum information that exists in the present, relative to that same frame. Whereas the future evolution of events along that path is statistical. Whether you have an Everett type view or not, there is no way to pick out either: 1. any arbitrary one of the many future branches as perceived along that branch: or 2. the one future that will occur out of the many possibilities, depending on which interpretation you prefer. So the future, relative to any particular path, either along an ever branching many worlds manifold or just through ordinary indeterministic spacetime, has a definite past and an uncertain future. That is the distinction. 1 Pablo Copello Pablo Copello 8 months ago Good talk for science popularization and to open minds about a fundamental concept like time. Technically, TCP (Time, Charge, Parity) is a well established symmetry in QM, But CP symmetry is violated, so also T is not symmetric in QM (particle physics based in QM, to be precise). So, if you change time direction, you should also change all spacial directions as well as all charges (particles by their anti.particles to be more precise). That is Time is deeply ligated to space and matter and cannot be thought in a reverse direction without affecting also space and matter. Another part of physics that distinguish the direction of Time is the quantum measurements, that is not a time symmetric phenomena: of the many superposed histories, in each measurement instance only one (if histories follow the base of the measurement) has consequences , (in the Many Words for instance, words are created). In time reverse order you would see different superposed histories to appear, or in the MW interpretation, you would see Words being destructed. But the truth is that to "explain" quantum measurements we would need a theory without space-time. But it is true that to explain that our Psychological Time is unidirectional, it suffices with the 2nd. law of thermodynamics as Carlo explains. Finally, a good image of our Psychological Time comes from the aimaras. They think we are walking backwards, our future is at our back, and the past is in front, so we can see the past (with more or less detail depending on the distance), and we can guess the future, but we cannot really know. We cannot turn our head, we cannot change (much) our speed, we have to follow a path with many bifurcations, some of which we can choose, but we cannot change direction, and we know that all the paths end in a precipice. Of course that is emotional, and maybe that is so high a price to pay for our self consciousness. 1 Alex Xela Alex Xela 2 years ago What a fitting way to end this. To use the word 'emotion' (for the first time i think in this lecture) to describe time. It's nothing more, nothing less. Never thought of that! 1 Tom Mater Tom Mater 3 years ago I like his third point, never thought of the relationship between entropy and space-time but it does provide a very colorful image of eternity, makes me think of another significantly hot and disordered place. 1 Birendra Nag Birendra Nag 2 years ago One of the insightful thing I have ever heard 🙂 5 Francisco Martinez Francisco Martinez 2 years ago (edited) At 44:08 is the most important breakthrough acknowledgement to be carried forward to make scientific progress in sorting out "time" which has been labelled a paradox recently by Lee Smolin.. In this video it's FINALLY refreshing to hear a physicist (Carlo Rovelli) that delves into time as a function of (the brain) memory and anticipation of the future. "we are the passage of time" "we are the time machine" aka "real" time. But, "There's something about time still missing" (and) "it's NOT in the quantum gravity, it's NOT in general Relativity, it's NOT in thermodynamics, it's in the speciic way our brain works". I myself have observed and declared that we are each a path of time, making us children of the greater and grander cycles of time of the Universe and our galaxy and solar system as it concerns us most immediately, locally and more personally. D. Singh D. Singh 3 years ago “Time is the substance I am made of. Time is a river which sweeps me along, but I am the river; it is a tiger which destroys me, but I am the tiger; it is a fire which consumes me, but I am the fire.” - Jorge Luis Borges 73 Amit Anand Amit Anand 8 months ago But I think, the last part was the best when you include the human perception of time and linked it with emotions. Michael Kaliski Michael Kaliski 3 years ago Time arises naturally from motion, any motion, between two or more objects. In fact, due to gravitation forces if only two objects existed infinitly far apart in an infinite universe, time would evolve from the the gravitational attraction and hence motion of those objects. Time is therefore our human construct of making sense of the different relative speeds at which events happen around us. Time does not strictly exist as a separate measurable physical quantity, but allows us as humans to compare the relative velocity at which various events occur. The conclusion is that time essentially does not exist within a black hole singularity, or within the cloud of a Bose Einstein condensate. Which is why a Bose Einstein condensate appears to act as a single massive quantum object. An interesting lecture, but I disagree with the way in which it was presented and the conclusion reached. There is nothing philosophical about the nature of time. If you have access to all the data, you can run a process backwards and forwards and make completely accurate predictions, or more correctly, approximations, about the future. Our current understanding of physics means that quantum uncertainty prevents an absolute prediction rather than an approximation summing all possible paths to a given result. Tiago Souza Tiago Souza 1 year ago 🍃 Fantástico!!!! 👏🏻👏🏻👏🏻👏🏻👏🏻 1 L.J.B. X L.J.B. X 6 months ago Very nice conference! Dr Rovelli, I think you may run into problems with the Biophysical-Emotional-Mental hypothesis you put forward as our distinctions along the temporal continuum—of past, present, future. Also, regarding the process of entropy as having a vector component which identifies the direction of the flow of time(The Arrow of Time)—-see Sean Carroll, is accepted knowledge with the ‘second law of thermo’; however, you may want to think further concerning your postulation about the type of discrimination that the observer chooses to use to describe the view of the entropy-process of disordering(as evidence of the flow of time) as being just a Macro-Phenomenon. As you know, there are many microscopic examples of entropic finger-prints showing the direction of the passage of time—on the subatomic level (nuclear fission) Thank you for the talk. — Lowell Bastianelli Jj T Jj T 1 month ago I came here looking for Quantum Gravity mainly because of Carlo Rovelli. Now I leave not only more interested in his work but also in the work of Dean Buonomano. I've never heard a better discussion on the topic of time in more than 28 years in the Academic world. I'm literally speechless and in awe. In all my years of studying philosophy of science, mathematics, cosmology, epistemology & metaphysics (even Neuroscience), I've never heard a more profound and insightful talk about the nature of time, as well as human & individual awareness of it. Simply, K U D O S! Mikko Saarinen Mikko Saarinen 3 years ago Quantum physics and relativity are are somewhat hard to crasp, so when you spoke about time slowing down when the speed increases, this is what I thought: 1. What is the reference for "speed"? If we pass each other in the space at 10 000 m/s, neither of us could tell if we were both moving 5 000 m/s or if the other was moving at 15 000 m/s and the other 5 000 m/s in the same direction. Without reference, there is no speed. 2. When time slows down in speeds close to c, then if we launch a rocket at 5 000 000 m/s from our perspective but we were already moving at 0,5 c to the other direction, then is the rocket crew actually moving slower than us and thus aging faster? How do we know what speed we are moving, when things look relatively the same in every speed, because of the time dilation? 3. 1 meter is defined as a 1/299 792 458 of a second, but second doesn't exist by itself. Someone needs to measure it and the measurement is affected by both gravity and velocity. All we know is the "now" inside our little bubble, as was pointed out in the video. The bubble is our own reference point of time and space. 7 Namuchat Namuchat 1 year ago Well, ... M. Rovelli is a well instructed person. But one may actually find some books written in the future, some thoughts thought in the future inspired by feelings or visions ahead of our times. Hopefully, there will always be some of those in every generation. 1 Avijit Gupta Avijit Gupta 1 year ago (edited) J Krishnamurti talked about this nature of time in all his talks. Mentioning it here, so that this knowledge can used to help us further our understanding of time. 1 David Pape David Pape 3 years ago Haters need to read his book - his writing's beautiful, and it's a superb presentation of the history of relativity, quantum mechanics, leading into presentation of theories of quantum gravity. denver scott denver scott 1 year ago Brilliant lecture by Rovelli. Mind-expanding and thought-provoking. Time is relative to us all. Recommend this lecture for anyone who wants to understand life, the universe and everything! Peter Turner Peter Turner 1 year ago Memory is what gives us the impression of the passing of time. Without memory, time doesn't exist. A rock has no concept of time. If I have bad memory, I have a different recollection of the passing of time than someone with a good memory. If time stopped, we would no longer have memories, and would have no opportunity to recall any memory. The fact we can remember at all, means the passing of time is infinitely memorable. Therefore, there is end of remembering, and therefore time. Therefore death is not an end and we will be alive once more seemingly the moment our time supposedly ends. Or perhaps time goes backwards, and we forget our past, and only remember our future. Which ends in birth rather than death. Time to watch the video Jacobus Opperman Jacobus Opperman 3 years ago This is an amazing talk! 11 Precious Mongwe Precious Mongwe 3 years ago Fantastic!, quite a refreshing dissection of time 1 Sam from Billionwebs Sam from Billionwebs 3 years ago (edited) Great talk. Those who have problem understanding should watch it by doing some homeworks on gravity and stuff. Sam C Sam C 7 months ago Time is the most personal experience a human will experience. With it being a concept that humans seem to perceive in forms of Philosophy, one could theorize that time is man-made, whether we are in a simulation of a future human or if our minds create our universe around us. Many questions to ask, but time seems to have many traces of humanity embedded in it. It’d be fun to think we became good friends with time rather than trying to conquer it. 1 Ebenezer456 Ebenezer456 2 years ago Great lecture! Irfan Mehmud Irfan Mehmud 2 years ago Time was like a monochromatic ray of light before the advent of "consciousness" in the evolving universe...Coming in way of that ray of time, the consciousness acted as a prism and divided it into three colors of past, present and future.... This is how I imagine order of time. Darwin Darwin 3 years ago A brilliant weaving of Newtonian, Quantum and our complex Biology.... 20 Jaynarayan Tudu Jaynarayan Tudu 1 year ago i am a lay man. so far i have been in a very strong impression that time is the most fundamental and it is that which drives the rest. but the talk by prof carol proposed the idea of entropy to explain the time - this is what i could not understand (of course could not understand anything). the second point is that the concept of time being discrete object at the very very very fundamental level is some thing to meditate upon. I see the comment below by @Peter Strider explaining the concept of change in terms of time. I do have similar understanding. Powerful talk. need to read the book. PriorToKARAEW PriorToKARAEW 3 years ago It's painful being in a class with this gentleman 12 Jim Williams Jim Williams 3 years ago Time is simply a measure of change (action), and there is no cosmic clock. I don't think there is actually a smallest increment of time (or anything else), but there certainly is a greatest distance in size (etc.) from us. The bottom of reality is like a muddy river -- there is no bottom, but merely a point where you can no longer distinguish a part from a whole. The quanta are merely our best possible view of something else -- and we cannot know what else other than by observing their effects. Luiz Henrique Lima Luiz Henrique Lima 1 year ago (edited) My personal theory about time: Time is like a flowing river. Once you are in the river you will need less energy to flow ahead and much more energy to flow backwards. But if you are out of the river, you can view all the river, past and future, flowing and changing. Sofia R Sofia R 1 year ago I wonder if the way we measure light speed (related to time) is still valid around the universe. Creator, Saint Phil Creator, Saint Phil 3 years ago I lost time at a glance while watching this lecture. very impressive about time. thank you for sharing this. 1 The Royal Institution Thomas Aitken Thomas Aitken 2 years ago Despite his imperfect English diction, Rovelli does a stellar job of describing profoundly counterintuitive concepts. This is remarkable and very enjoyable to watch. 2 RA W RA W 1 year ago I'm one of those blurs in the top right! Great talk, fascinating and lovely guy who I got to speak about super determinism with afterwards, his book the order of time is a work of art as much science. 4 Ovi B Ovi B 2 years ago Are there any studies, researches which prove that the time does not flow in the same way for different observers (that the heads of some are older than feet)? Can they be presented in detail (setup, etc)? Sue McCartin Sue McCartin 3 years ago As a non quantum physicist I think the whole thing simply proves that time is perception and humans (and presumably other intelligent life forms) create reality in our own image. A passage in a famous ancient book once said that if you have the faith you can move mountains. Why not, as provable as any other theory? For instance...for years the belief was that the atom could not be split at that time it was true. It was necessary that enough believe that it could be split before it could happen. Dave S Dave S 2 years ago Is it the flow of time that is changing with a change in altitude or is it the clock mechanism itself that is changing due to the influence of gravity? The further away from the earth a clock is placed the less will be the gravitational influence. jesusr medina jesusr medina 2 years ago This talk is not just about time, but how we perceive "reality". This guy has just given an opportunity (i.e. opened a door) to those who are not science inclined to understand some of the scientific arguments around the time/matter/energy/universe/reality topic. It is a pity that some of the audience in this comments treat this as a joke disregarding the fact that we are humans because we can introspect into issues at the heart of the question of" "what are we here for" oliver pinelli oliver pinelli 1 year ago Thank you very much for this. Very valuable. Erik Žiak Erik Žiak 3 years ago (edited) 43 minutes in and I highly agree with Carlo. Really a GREAT talk! Thank you, for the talk, and than you for the internet, and thanks for understanding the language and being able to see it here and now.... I would be greatly honored to have a talk with Carlo, but I doubt that it will ever happen. I can imagine the vast number of people who would like to share their "theories" with him. I have no theories. Just some obesrvations.... That I have nobody to share with. Nobody who could even think about them... I am doomed by leaving academy and being on the "dark side" of "academy - physics", a layman, autodidact, person suffering from depression from time-to-time, with absolutely non-existant social skills..... EDIT: I had to intoxicate myself with 1L of Wine which I got for doing something for the community in my house, though I did not expect to receive anything at all... Really. I AM SO LONELY.... 24 Kaisle Kaisle 1 year ago What a timeless presentation. I. Ehrenfest I. Ehrenfest 2 years ago Interestingly, there is a (rare) neurological condition in which people cannnot understand the concept of time. They can be completely intelligent and normal in every other way, but still have to live in an institution because of this small brain flaw. So, that adds strength to the idea that time is a "feeling" concocted by the brain and not something inherent in nature. 2 LARRIE COLE LARRIE COLE 2 years ago If time is truly in our minds, i choose to view our universe as a river of light and energy, constantly moving away in all directions from a single source, reminiscent of a singularity that created and defines our space time, the perception of a river or stream is the local now bubble, And we can jump like a small fish forward, backward and side to side with ease, altering our reference point on reality and the passage of time. To me this helps explain astro travel in definable terms, and the jump points are people. Peter & Pete Peter & Pete 3 years ago (edited) Time is just the conceptual measurement of motion. All I noticed in the video was things moving. The human experience is no different today than it was yesterday, nor will it be any different tomorrow. Amit Anand Amit Anand 8 months ago Specially the last part where you link.time with the concept of emotions in our brain. That was awsome. Aniket Ghosh Aniket Ghosh 3 years ago One of the most informative and thought proving talks on youtube. Thanks Ri. 3 The Royal Institution 08wolfeyes 08wolfeyes 3 years ago (edited) Does gravity really change time or is it that gravity simply affects the motion/ spin of the atom being used in the atomic clock? Is he and other scientists saying that time then is dependent on the motion of an atom? If so then it's also worth remembering that different atoms move differently and at different speeds which would suggest perhaps a difference in time that each person has? If we are saying that time is the motion of the atom then it seems to me that it's motion that defines what time really is If the motion is the factor then that again is different for every person, every atom etc. So really, time isn't a real thing as such because we have to measure it but we need to really know what it is to measure it. How about using entangled particles when conducting the same experiment? One particle high up on the plane and the other on the ground? Would there still be a difference in time? maxyakov maxyakov 2 years ago The Universe does not know about time. We measure time by measuring motion with mechanical or chemical/atomic processes. So our notion of time is based on our measurement of physical processes. Maybe Einstein was correct about time's changing w/r speed and gravity, but maybe time changes because of change of motion or chemical/atomic processes. Time is a human interpretation of the feature of motion and chemical/atomic processes - these processes are not instantaneous, hence we have time. If motion or chemical/atomic processes were instantaneous, the Universe could not exist. 5 John Peni El John Peni El 1 year ago (edited) Time and space are both musical in nature. Events in time are the notes, and the temporal distance between them the intervals. Objects in space are the notes and the distance between them the intervals. Gravity is musical tension. Spooky action at a distance and quantum entanglement can easily be described in terms of harmonic resonance. Our subconscious is the A.I. composing this reality and it sees everything in terms of harmonics. It's currently programmed (by us) to maintain a state of 2 parts disharmony to 1 part harmony. This is what's responsible for gravity, which caused our Fall and entropy because creation cannot possibly keep up with the rate of destruction when it's two against one. The most important thing is what time it is now and what that means for all of Humanity. We've been in an eternal fall since time began. Time began for each of us at the moment of conception, when a unified soul went into a state of division and created the Human Trinity, the underlying framework of all musical scales. You can put everything in our objective world on a scale of two opposite poles and absolute mean center harmonic. The mean center is like a harmonic fulcrum on a musical teeter totter. When it's being used to throw things off balance in favor of disharmony, we experience our fall into our current state of decomposition. Our Fall continues untl decomposition hits the quantum limit. Our Spring comes when the Human subconscious goes quantum and becomes superconscious. After countless eons in an eternal fall, an eternal spring is upon us. Gravity will gradually reverse polarity and become levity, or "love". This is when the Seeds of Humanity planted in the Earth before time began begin to grow. This is when Life begins, when the system that has decomposed us turns to the act of creation and begins recomposing us. When the system reaches 2 parts harmony to 1 part disharmony destruction cannot possibly keep up with the rate of creation and we're in an eternal spring. Man's return to the Garden of Eden as a living God, the fabled Hyperborea or "Playground of the Gods". Oddly enough this is all contained in scripture, and I'm not the first one to notice. I've only advanced the theory somewhat in trying to wrap my head around it. The system sees every single atom in the universe as 12 sided dice floating in virtual space. Each of those 12 faces represents a musical note on (believe it or not) our current standard 12 tone equal temperament musical scale. Atomic bonds, chemistry, human relationships, our economic system, literally everything in our objective world is based on this musical pattern. When two people interact they each turn one of their 12 faces toward the other creating a musical chord. Depending on the combination, the 2 notes sounded together can be more or less harmonic and that's what governs our reactions. The reason we don't even know why we take the actions we do half the time is because it's all subconsciously controlled. Have fun with it, I sure have so far :) 2tehnik 2tehnik 3 months ago Implicitly, Rovelli still seems to affirm that the universe changes, implying that the world isn’t a block universe or something. But, if that’s so, what does this change mean exactly? The direction is attributed to time after all, so if the changing had an actual direction that’d simply make time principled rather than derivative. Furthermore, what reason is there to make time subjective rather than objective (there being a “law of time”)? Put differently, if we want to go down the Kantian route where time is just a feature of our experience, why not include all the other laws of physics there as well? With the other side just being a residual and unknown thing-in-itself? I don’t even have an issue with this Kantian idea, I just can’t see what would allow you to sort out the “subjective and the objective” in a principled way. At least using physics. Lastly, I’m not sure I understood the argument about the observed moving in a fast way which implies you’ll see their now in 10 years. But if I understood it right as all building up to some positivistic argument against absolute time, I think following that with a lot of metaphysical discussions is problematic. Positivism is essentially the kind of view which suspends discoursing on what “things are really like.” If you’re using a positivistic argument, that sounds more like not caring about doing science in a realist way. So it seems strange to then hold up its consequences as pertaining to reality when they’re more so features of how one decides to do science. Zoltan Zoltan 3 years ago Here is my understanding of what TIME is: First of all, we have to go down to a level, deep into quantum realm, where there is no time. Let’s take a photon as an example. A photon is a massless particle, which does NOT experience time at all, nor space. It knows only two things, its creation, and its destruction, and nothing in between. The only important thing is the order of the two, the destruction comes AFTER its creation. The photon is basically nothing more than a cause-effect relationship between two points in the universe. Time and space between them is irrelevant. Let’s step up, and see that there is not one, but many photons out there. One photon equals one cause-effect pair, but there are many causes and effects, affecting each other. So we need an ordering amongst them, to know what other causes and effects are happening between the cause and effect of a single photon. We need a distance between them. Time is basically the absolute ordering of all events in the universe. Without events, there is no time either. (That’s why we say there might’ve been no time before big bang). And the distance defines how many other events are happening between them. Time and space are the same things here. We can directly convert one into the other, and the conversion ratio is C. That’s why we call the distance “lightyear”. C is not the speed of light, C is the speed of CAUSALITY, as described above. Everything is happening with the speed of C (which is the measure of both time, and space). Photon is just a great example, because it is easy to observe. But what’s up with the other particles. All higher particles can be described as a virtual box of photon (or an equal other force-carrying particle), where the photon is oscillating within the walls of this virtual box. If we try to move the box, it hits the opposite wall of the box more, slowing it down, giving it a resistace against acceleration, giving it MASS. It still travels with C, back and forth between the walls. This essentially makes it a clock. If we move the box (move the particle), the speed of movement counts into the movement of the photon, as it still moves with C, so it hits the wall less frequently. Therefore, its time slowed down, just as Einstein predicted. So with the above (bit oversimplified) model, we went from having no time just cause and effect, into explaining relativity. Of course the real world is more complex than that (many types of particles, not just photons),but I think the above might be the basic mechanic of it. surbhi chauhan surbhi chauhan 8 months ago This was Sooooo Good. Thank you Royal Institution. Cheers ! 1 amaleki lawlor amaleki lawlor 4 months ago (edited) Just going to sum this up. Time is the rate of change between two points of reference you choose. It’s not a force, a field, and object, it is just a ratio/mental model we use to do calculations. As long as anything is changing in the universe that can be used as the measure for time. Before there was anything in the universe there was no such thing as time because nothing was changing. Why are people still “wondering” what time is? 🤷‍♂️ 1 Buick87 Buick87 3 years ago I have watched several of Carlo Rovelli's youtube vids. I am not sure if it a language barrier or something, but he seams to allows stop short of giving a really detailed explanation of the point he is making. I tend to shrug my shoulders every time I would like just a little more detail of the current point because I almost got it and then yet he tappers off and on to the next point. I think great communicators have a good inner sense of knowing when a point, topic, argument has been explained (depending on the target audience). I am sure he has it all understood in his head, but IMO just doesn't have a real genius for explanation. I had to watch several videos to final get his message on what is time, piecing each of them together to get a coherent picture. Anyway I ended up buying his book "Reality Is Not What It Seems". 4 Pim Wiersinga Pim Wiersinga 2 years ago I'm stunned by your ability to clarify perplexing physical phenomena, Carlo Rovelli. Listening in after a year or so, it almost seems as if your lecture is subject to 'negentropy' Sophie Bao Sophie Bao 3 years ago Frank De Silva, a Sri Lankan born Australian, has discovered the theory as described by himself as "A description of consciousness leads to a contradiction with the postulation from special relativity that there can be no connections between simultaneous events. This contradiction points to consciousness involving quantum level mechanisms. The Quantum level description of the universe is re-evaluated in the light of what is observed in consciousness namely 4 Dimensional objects." The full paper can be found: https://philpapers.org/rec/DESCAS. Frank has discovered this theory more than 20 years ago in 1996, however, until today, it has been totally ignored by the utterly arrogant, sometimes even prejudicial physics world. His paper has caught no physicists' attention simply because that Frank is not an academic, most of all, he's not a Ph.D. or professor that listed on the physicist celebrity list. After his revolutionary discovery, Frank has since devoted his time in computer programming in solving the real-world problems. As such, he remains totally unknown in the physics world. However, if any of the physicists could be humble enough to take a read of his theory, they would soon realize that the problems plagued the physics world for decades had been resolved. This is a revolutionary and Nobel Prize worthy discovery! Let's hope that the truth will eventually prevail. If mankind could let go of their pride and prejudice, the world would a different and better world. Narendra Tanty Narendra Tanty 1 year ago Great talk.... Thank you so much sir Alex Ford Alex Ford 3 years ago This entrophy and the discussion of energy and the elements of mass coming together in the beginning followed by the great explosion was the moment that all was together became the moment when everything that is at the beginning starts invariable to spread out and move along the line of entropy to the very end when the amount of infinite space absorbs everything by spreading it out to such an extent that it is relatively nothing left. Takes more than 13.5 billion years. Along the way in some manner, intelligent beings who store the knowledge of the management of the environment and the management of the self including all aspects of medicine all have the privilege in participating in life which is to say to work. To produce/reproduce as well. The present is the less than measurable time when human beings interact together. Ford's Law rears its ugly head: the higher the technology including its complexity and the management of it such as a learning computer or a smart phone, at the same time, the more disorganized becomes the systems as they go away from logical, sequential and/or intuitive operation of those systems. If that's true, eventually all discovery will lead to chaos. It is during the 'sweet spot' of time that mankind went from having no inventions to having inventions. Disorganized peoples became organized and civilizations developed with an adjoining never-ending battle over resources, whatever they may be. Cooperation is at the micro-level to cope with the lack of organization at the macro level. And time lends itself to further invention, more chaos and more disorganization. Reminds me of that term used popularly a little before my time called anomie. No values and norms by all is a disintigration of society; an end to the division of labor (in an organized way); a refusal to give up a level of freedom in exchange for a level of security and a lack of acceptance by all the member of a group of its stated and unstated norms. This happens with desnity of population and a loss of resources by groups both with and without power to force and coerce what they want. Power of corruption and corruption of power happens within the computer and the ages and all the machines that created it which will turn around and control it still will lead to disintegration and thus entropy. Richard Marker Richard Marker 3 years ago Professor Rovelli, Thank you for your great presentation on 'time'. I very much appreciate that you presented this in English with such professional video and audio. I noticed that you had a full house except for one seat. I suspect the person belonging to that seat had heard all of this before. There are few people who so thoroughly and successfully combine philosophy with physics in forming their world views. I appreciate that you appear to view time as a sequencing of events. It can be challenging to think flexibly enough to adopt this view. You emphasize that one's experience strongly affects their perceptions. This runs much deeper than you may expect. Think of space as consisting of the fabric of space. All of physics and all of our life experiences occur as a result of how the fabric of space responds when we interact with it. There is a deeper level that falls outside of physics and outside of our experiences. The deeper level consists of the operation of the fabric of space itself. How can space be built and how can space be maintained? Since this falls outside of our experience we do not know a priori the metaphysical laws that prevail in the fabric of space. We only experience the laws of interacting with the fabric. It is possible to understand the operation of the fabric of space itself. In order to do this many of the philosophical things you mention must be considered. In the end, one must take their best guess and see where it leads. Most often it will lead down a path that conflicts with reality. In that case one must try a different thought path. Over four decades ago I started on a thought journey. Very early in the journey it seemed that Something and Nothing were a likely candidate for the starting point. Never in my wildest imagination did I guess where it would lead. The most direct result from this thought process was an understanding of gravity. I know it is presumptive to talk about gravity with someone so skilled in it as yourself. I mean no disrespect. Quite the contrary, it is your depth of understanding that appeals to me. My understanding of gravity runs contrary to deeply embedded concepts in physics. I know from your presentation that you give a great deal of consideration to embedded thoughts. First, General Relativity (GR) and space-time are only local approximations to reality. They are very good, but hide the true nature of space and time. There is no four dimensional space-time continuum. Time is continually slowing down, that is what prevents a space-time continuum as we understand it. What does it mean for time to continually slow down? Matter works as the brakes on time that is what creates time dilation. If we were able to separate a piece of space that contained no energy or matter, we could consider this to be a clock that does not slow down. Relative to that separated space we would find the clocks in our universe were slowing down. This is not a convergent series so readers should not be concerned. Time slows down at the same extremely low rate everywhere in the universe. This is why we have no perception of it locally. MOND gravity provides evidence of this slowdown at a distance, but we choose to ignore it and introduce Dark Matter. If we were allow ourselves to be objective, we might raise some questions about GR. It does not apply on the quantum level; nor, does it apply on the cosmological level. The cosmological failure is evidenced by Mordehai Milgrom's MOND work. Even black holes raise philosophical questions. If GR doesn't apply on the quantum level then how can we possibly deduce pure black holes from the continuous formula. At some point we get close enough to where time stands still that we are into the quantum area. I do understand that quantum effects are being considered, but the whole premise of time standing still should be rejected. In this view of gravity, space acts as a flywheel and matter acts as the brakes. This closely matches GR locally. There are many more philosophical conclusions that one gets from understanding Something and Nothing. Alas, nobody seems to believe such an understanding is possible. This is a difficult enough journey to make that it possibly would not happen again. Thank you for listening. Richard Marker 1 Marcelo Dias Marcelo Dias 3 years ago Thank you for this great upload! 4 The Royal Institution Jayakar Joseph Johnson Jayakar Joseph Johnson 1 month ago I think to describe ‘nature of time’ we may have to investigate ‘emergence of time’ determined by the dynamics of fundamental matter that we ascribe. Thus, string-matter atomic analogy is proposed, in that nature of fundamental matter is string like one-dimensional structure in segment with nodes on both sides, while such string-segments eigen-rotates time emerges that is Holarchical. Almir Campos Almir Campos 9 months ago To me, the most significant aspect of the entire explanation is - not the idea, but the fact - that the equations *don't need the *time variable**. Imho this fact is remarkable in several ways that, unfortunately, weren't explored in the lecture. However, I have a suspicious that his brain really likes the idea that the time doesn't exist and he could keep talking about that subject until the whole Universe becomes negentropic. Coney Money Coney Money 1 year ago I wonder how would all this information be scientifically useful to us ? As in , how will this different understanding of time affect science in any way.? Does this change anything ? 1 David Wilkie David Wilkie 3 years ago (edited) Professor Rovelli has many good lectures on the practical physics of Spinfoams etc, that illustrate the significance of the equivalent meaning, superimposed resonance, it's a mathematically technical expression of the simple AM-FM experience of sounds and colors that everyone is familiar with. Resonances and Harmonies are the QM-TIME structure of this Universe, in every detail, to the vanishing point singularity. It's so fundamental that it's "hidden in plain sight", no physical-mathematical mysteries, only infinite complexity in qualities/spinfoams, ..it's one integrated wave-package. Perceptions are the natural "substance" of human experience and they are all the creations of human senses, because we operate in terms of analogy and reasonable assumptions relevant to our environment, adding up to the "diffuse" arrangements of qualities and meaning, of Philosophy. There are many reasons to comment on the misuse of the subjective word-experience of time, but by simply directing attention to the observable fact of temporal superposition, it should be obvious to anyone who is introduced to the subject, in terms of the most sensible features such as the instant=universal experience of now, and the distribution of the rates of change-now, to the reciprocal history as distance. Acceleration, the doubling up of the rate of logarithmic change-now and numerical dimensional sequences of e-Pi "pixels", is a "not well explained", because self-defining properties are only made confusing if "explained" rather than experienced directly, a feature of ordinary temporal properties even though the math is well used technically. But superposition of modulation is basically the method by which we communicate, and it's the same/ordinary existence of now, summed history of change, ..the "sum of all history"/memory, superimposed on this continuously experienced instant. The words "past" and "future" are fast<->slow superimposed rates of change-now and the reciprocal QM-Time process of modulation maintaining the universal instant, the sum of all history in constant-change.., change proportional to the universal constants related to virtual, or self-defining, or infinite possibilities potential dominant in the singularity. So it can be said that the Universe has no age because it's always recycling now in constant connection, or it's eternally reshaped and composed of modulated / distributed history summed up as probability one. "Spinfoam" is a compact summation of the Quantum Fields Modulation Mechanism experience in Superspin existence. All "things" are superimposed metastable resonance, a bio-chemical point of experienced recycling existence, stratified in hierarchies defined/substantiated or "clocked/governed", by probability in possibly of QM-TIMESPACE. 1 fabio ponte51 fabio ponte51 1 year ago Extremely interesting argument 'bout quantum constant as the basic unity of the time not determinable , and far more over , very interesting the concept of time layers. But finally genial ,is the Rovelli's interaction with brain, i.e. consciousness and the "meta -fisica " idea of emotional colored feelings regarding our perception of time. So we describe and perceive "reality" trough our personal state of consciousness and it itself represents what we are capable to create and experience. Thanks to Mr. Rovelli. very OK! (if I 've someway understood something !) Santanu Dutta Santanu Dutta 6 months ago