Carlo Rovelli

Theoretical Physicist

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Carlo Rovelli is a distinguished theoretical physicist and a research chair at the Perimeter Institute.   He's an expert in the field of loop  quantum gravity and the goal to unify Relativity, Quantum Mechanics and Thermodynamics.   He is one of the leading thinkers in modern quantum mechanics theory and a gifted physics educator and communicator.   He is one of our favorite authors and sources of information.

Rovelli has expressed doubts about Everett's Relative State Formulation (ie: Many Worlds Interpretation of Quantum Mechanics),  as many others have, due to interpreting the many worlds as distinct, disparate realities.  This is a common complaint...  the Many Worlds interpretation is as holistic and austere of a reading of the probabilistic nature of quantum mechanics, but many in the physics community just can't get over the idea of potentially so many "worlds".   The ConscioCentric model is similar to Everett's Many Worlds interpretation, however, instead of viewing the many worlds as separate realities, Consciocentrism posits that we exist in all of them simultaneously.  That is the canvas of consciousness and our abilities for memory, foresight and alternative path consideration -- and the "moment of now" or "solid reality" we experience on the arrow of time, is a result of a consensual composite of the many worlds, where the most probabilistic configuration of 3D space overlaps.   Think of the Many Worlds as semi transparent layers / onion skin layers that overlap -- in the moment of now, the overlap is so great among a majority of the "many worlds" that we experience that composite image as solid reality.   The many worlds are still constrained by the resolution of the Planck constant, but reality is this composite image of possibilities, and our minds are free to roam the canvas.

Quotes by Carlo Rovelli

"I want a theory of physics that accounts for the structure of the universe, that clarifies what it is to be an observer in the universe, not a theory that makes the universe depend on me observing it." - Carlo Rovelli

"Time opens up our limited access to the world. Time, then, is the form in which we beings, whose brains are made up essentially of memory and foresight, interact with the world: it is the source of identity." - Carlo Rovelli

"Our “present” does not extend throughout the universe. It is like a bubble around us." - Carlo Rovelli

"An elementary structure of the world is emerging, generated by a swarm of quantum events, where time and space do not exist. Quantum fields draw together space, time, matter, and light, exchanging information between one event and another. Reality is a network of granular events; the dynamic that connects them is probabilistic; between one event and another, space, time, matter, and energy melt into a cloud of probability." - Carlo Rovelli

"Probability does not refer to the evolution of matter in itself. It relates to the evolution of those specific quantities we interact with." - Carlo Rovelli

"An extraordinary idea occurred to [Einstein], a stroke of pure genius: the gravitational field is not diffused through space; the gravitational field is that space itself. This is the idea of the general theory of relativity. Newton’s “space,” through which things move, and the “gravitational field” are one and the same thing." - Carlo Rovelli

"For a hypothetically supersensible being, there would be no “flowing” of time: the universe would be a single block of past, present, and future." - Carlo Rovelli

"Special relativity may be summarized as the discovery that there exists a maximum velocity for all physical systems. Quantum mechanics can be summarized as the discovery that there exists a maximum of information for each physical system." - Carlo Rovelli

"If we try to put together what we have learned in the twentieth century about the physical world, the clues point toward something profoundly different from our instinctive understanding of matter, space, and time." - Carlo Rovelli

"Time passes more slowly for the one who keeps moving." - Carlo Rovelli

"But Einstein realizes that energy and mass are two facets of the same entity, just as the electric and magnetic fields are two facets of the same field, and as space and time are two facets of the one thing, spacetime. This implies that mass, by itself, is not conserved; and energy-as it was conceived at the time-is not independently conserved, either. One may be transformed into the other: only one single law of conservation exists, not two. What is conserved is the sum of mass and energy, not each separately. Processes must exist that transform energy into mass, or mass into energy." - Carlo Rovelli

"Music can occur only in time, but if we are always in the present moment, how is it possible to hear it? It is possible, Augustine observes, because our consciousness is based on memory and on anticipation." - Carlo Rovelli

"If I look at a forest from afar, I see a dark green velvet. As I move toward it, the velvet breaks up into trunks, branches and leaves: the bark of the trunks, the moss, the insects, the teeming complexity. In every eye of every ladybug, there is an extremely elaborate structure of cells connected to neurons that guide and enable them to live. Every cell is a city, every protein a castle of atoms; in each atomic nucleus an inferno of quantum dynamics is stirring, quarks and gluons swirl, excitations of quantum fields. This is only a small wood on a small planet that revolves around a little star, among one hundred billion stars in one of the thousand billion galaxies constellated with dazzling cosmic events. In every corner of the universe we find vertiginous wells of layers of reality." - Carlo Rovelli

"In quantum mechanics no object has a definite position, except when colliding headlong with something else." - Carlo Rovelli

"In the big picture of contemporary science, there are many things that we do not understand, and one of the things that we understand least about is ourselves." - Carlo Rovelli

"From communication to the basis of genetics; from thermodynamics to quantum mechanics; up to quantum gravity, the notion of information is gaining ground as a tool for understanding. The world should not be understood as an amorphous ensemble of atoms-but rather as a game of mirrors, founded on the correlations between the structures formed by combinations of these atoms." - Carlo Rovelli

"I believe that one of the greatest mistakes made by human beings is to want certainties when trying to understand something. The search for knowledge is not nourished by certainty: it is nourished by a radical absence of certainty. Thanks to the acute awareness of our ignorance, we are open to doubt and can continue to learn and to learn better. This has always been the strength of scientific thinking—thinking born of curiosity, revolt, change. There is no cardinal or final fixed point, philosophical or methodological, with which to anchor the adventure of knowledge." - Carlo Rovelli

"Why are precisely these elements listed there, and why does the periodic table have this particular structure, with these periods, and with the elements having these specific properties? The answer is that each element corresponds to one solution of the main equation of quantum mechanics. The whole of chemistry emerges from a single equation." - Carlo Rovelli

"The world, particles, light, energy, space, and time—all of this is nothing but the manifestation of a single type of entity: covariant quantum fields." - Carlo Rovelli

"A moving object therefore experiences a shorter duration than a stationary one: a watch marks fewer seconds, a plant grows more slowly, a young man dreams less. For a moving object, time contracts." - Carlo Rovelli

"“Things” in themselves are only events that for a while are monotonous." - Carlo Rovelli

"The notion of “the present” refers to things that are close to us, not to anything that is far away. Our “present” does not extend throughout the universe. It is like a bubble around us." - Carlo Rovelli

"Probability does not refer to the system as such (the dice, the newspaper editor, the decaying atom, tomorrow's weather), but to the knowledge that I have about this system." - Carlo Rovelli

"It is the individual quanta of space, the elementary grains of space, the vibrating “molecules,” that heat the surface of black holes and generate black hole heat. This phenomenon involves all three sides of the problem: quantum mechanics, general relativity, and thermal science. The heat of black holes is like the Rosetta stone of physics, written in a combination of three languages—quantum, gravitational, and thermodynamic—still awaiting decipherment in order to reveal the true nature of time." - Carlo Rovelli

"None of the pieces that time has lost (singularity, direction, independence, the present, continuity) puts into question the fact that the world is a network of events. On the one hand, there was time, with its many determinations; on the other, the simple fact that nothing is: things happen." - Carlo Rovelli

"The importance of experimental proof, on the other hand, does not mean that without new experimental data we cannot make advances. It is often said that science takes steps forward only when there is new experimental data. If this were true, we would have little hope of finding the theory of quantum gravity before measuring something new, but this is patently not the case. Which new data were available to Copernicus? None. He had the same data as Ptolemy. Which new data did Newton have? Almost none. His real ingredients were Kepler's laws and Galileo's results. What new data did Einstein have to discover general relativity? None. His ingredients were special relativity and Newton's theory. It simply isn't true that physics only advances when it is afforded new data." - Carlo Rovelli

"The difference between past and future only exists when there is heat. The fundamental phenomenon that distinguishes the future from the past is the fact that heat passes from things that are hotter to things that are colder." - Carlo Rovelli

"In the elementary equations of the world, the arrow of time appears only where there is heat.  The link between time and heat is therefore fundamental: every time a difference is manifested between the past and the future, heat is involved. In every sequence of events that becomes absurd if projected backward, there is something that is heating up. If I watch a film that shows a ball rolling, I cannot tell if the film is being projected correctly or in reverse. But if the ball stops, I know that it is being run properly; run backward, it would show an implausible event: a ball starting to move by itself. The ball’s slowing down and coming to rest are due to friction, and friction produces heat. Only where there is heat is there a distinction between past and future. Thoughts, for instance, unfold from the past to the future, not vice versa—and, in fact, thinking produces heat in our heads." - Carlo Rovelli

"A stone is a prototypical “thing”: we can ask ourselves where it will be tomorrow. Conversely, a kiss is an “event.” It makes no sense to ask where the kiss will be tomorrow. The world is made up of networks of kisses, not of stones." - Carlo Rovelli

"Bertrand Russell describes the same idea thus: “the raw material out of which the world is built up is not of two sorts, one matter and the other mind; it is simply arranged in different patterns by its inter-relations: some arrangements may be called mental, while others may be called physical."" - Carlo Rovelli

"Let’s begin with a simple fact: time passes faster in the mountains than it does at sea level." - Carlo Rovelli

"The discovery of quantum theory, I believe, is the discovery that the properties of any entity are nothing other than the way in which that entity influences others. It exists only through its interactions. Quantum theory is the theory of how things influence each other. And this is the best description of nature that we have." - Carlo Rovelli

"Physics opens windows through which we see far into the distance. What we see does not cease to astonish us. We realize that we are full of prejudices and that our intuitive image of the world is partial, parochial, inadequate. Earth is not flat; it is not stationary. The world continues to change before our eyes as we gradually see it more extensively and more clearly. If we try to put together what we have learned in the twentieth century about the physical world, the clues point toward something profoundly different from our instinctive understanding of matter, space, and time." - Carlo Rovelli

"The properties of an object become manifest when this object interacts with others. We cannot separate the properties from these other objects. We cannot attribute them just to a single object. All of the (variable) properties of an object, in the final analysis, are such and exist only with respect to other objects." - Carlo Rovelli

"Ten years before understanding that time is slowed down by mass, Einstein had realized that it was slowed down by speed.  The consequence of this discovery for our basic intuitive perception of time is the most devastating of all. The fact itself is quite simple. Instead of sending the two friends from the first chapter to the mountains and the plains, respectively, let’s ask one of them to stay still and the other one to walk around. Time passes more slowly for the one who keeps moving. As before, the two friends experience different durations: the one who moves ages less quickly, his watch marks less time passing; he has less time in which to think; the plant he is carrying takes longer to germinate, and so on. For everything that moves, time passes more slowly." - Carlo Rovelli

"A lightbulb does not emit continuous light, it emits a hail of evanescent photons. At small scale, there is no continuity, or fixity, in the real world: there are discrete events, interactions, gapped and discrete. Schrödinger had fought tooth and nail against quantum discontinuity, against Bohr’s quantum leaps, against Heisenberg’s world of matrices: he wanted to defend the image of continuous reality provided by classical intuition." - Carlo Rovelli

"Quote" - Author

"We are made of the same stardust of which all things are made, and when we are immersed in suffering or when we are experiencing intense joy we are being nothing other than what we can’t help but be: a part of our world." - Carlo Rovelli

"This is time for us. Memory. A nostalgia. The pain of absence. But it isn't absence that causes sorrow. It is affection and love. Without affection, without love, such absences would cause us no pain.  For this reason, even the pain caused by absence is in the end something good and even beautiful. Because it feeds on that which gives meaning to life." - Carlo Rovelli

"There are frontiers where we are learning, and our desire for knowledge burns. They are in the most minute reaches of the fabric of space, at the origins of the cosmos, in the nature of time, in the phenomenon of black holes, and in the workings of our own thought processes. Here, on the edge of what we know, in contact with the ocean of the unknown, shines the mystery and the beauty of the world. And it’s breathtaking." - Carlo Rovelli

"Because everything that begins must end. What causes us to suffer is not in the past or the future: it is here, now, in our memory, in our expectations. We long for timelessness, we endure the passing of time: we suffer time. Time is suffering." - Carlo Rovelli

"We are perhaps the only species on Earth to be conscious of the inevitability of our individual mortality. I fear that soon we shall also have to become the only species that will knowingly watch the coming of its own collective demise, or at least the demise of its civilization." - Carlo Rovelli

"The atoms of our body, as well, flow in and away from us. We, like waves and like all objects, are a flux of events; we are processes, for a brief time monotonous." - Carlo Rovelli

"I am my mother’s caresses, and the serene kindness with which my father calmly guided me; I am my adolescent travels; I am what my reading has deposited in layers in my mind; I am my loves, my moments of despair, my friendships, what I’ve written, what I’ve heard; the faces engraved on my memory. I am, above all, the one who a minute ago made a cup of tea for himself. The one who a moment ago typed the word “memory” into his computer. The one who just composed the sentence that I am now completing. If all this disappeared, would I still exist? I am this long, ongoing novel. My life consists of it." - Carlo Rovelli

"If I ask whether two events—one on Earth and the other on Proxima b—are happening “at the same moment,” the correct answer would be: “It’s a question that doesn’t make sense, because there is no such thing as ‘the same moment’ definable in the universe.” The “present of the universe” is meaningless." - Carlo Rovelli

"Time is like the point where the rainbow touches the forest. We think that we can see it—but if we go to look for it, it isn’t there." - Carlo Rovelli

"Compare ‘now’ with ‘here’. ‘Here’ designates the place where a speaker is: for two different people ‘here’ points to two different places. Consequently ‘here’ is a word the meaning of which depends on where it is spoken. The technical term for this kind of utterance is ‘indexical’. ‘Now’ also points to the instant in which the word is uttered and is also classed as ‘indexical’. But no one would dream of saying that things ‘here’ exist, whereas things that are not ‘here’ do not exist. So then why do we say that things that are 'now' exist and that everything else doesn't?" - Carlo Rovelli

"Quantum mechanics and experiments with particles have taught us that the world is a continuous, restless swarming of things, a continuous coming to light and disappearance of ephemeral entities. A set of vibrations, as in the switched-on hippie world of the 1960s. A world of happenings, not of things. " - Carlo Rovelli

"The world seems to be less about objects than about interactive relationships." - Carlo Rovelli

"All of the sons of Adam are part of one single body, They are of the same essence. When time afflicts us with pain In one part of that body All the other parts feel it too. If you fail to feel the pain of others You do not deserve the name of man." - Carlo Rovelli

"As human beings, we live by emotions and thoughts. We exchange them when we are in the same place at the same time, talking to each other, looking into each other's eyes, brushing against each other's skin. We are nourished by this network of encounters and exchanges. But, in reality, we do not need to be in the same place and time to have such exchanges. Thoughts and emotions that create bonds of attachment between us have no difficulty in crossing seas and decades, sometimes even centuries, tied to thin sheets of paper or dancing between the microchips of a computer. We are part of a network that goes far beyond the few days of our lives and the few square meters that we tread. This book is also a part of that weave..." - Carlo Rovelli

"I believe that our species will not last long. It does not seem to be made of the stuff that has allowed the turtle, for example, to continue to exist more or less unchanged for hundreds of millions of years, for hundreds of times longer, that is, than we have even been in existence. We belong to a short-lived genus of species. All of our cousins are already extinct. What's more, we do damage. The brutal climate and environmental changes that we have triggered are unlikely to spare us." - Carlo Rovelli

"In the world described by quantum mechanics there is no reality except in the relations between physical systems. It isn’t things that enter into relations but, rather, relations that ground the notion of ‘thing’. The world of quantum mechanics is not a world of objects: it is a world of events. Things are built by the happening of elementary events: as the philosopher Nelson Goodman wrote in the 1950s, in a beautiful phrase, ‘An object is a monotonous process.’ A stone is a vibration of quanta that maintains its structure for a while, just as a marine wave maintains its identity for a while before melting again into the sea." - Carlo Rovelli

"I do not fear death. I fear suffering. And I fear old age, though less so now that I am witnessing the tranquil and pleasant old age of my father. I am afraid of frailty, and of the absence of love. But death does not alarm me. It did not scare me when I was young, and I thought at the time that this was because it was such a remote prospect. But now, at sixty, the fear has yet to arrive. I love life, but life is also struggle, suffering, pain. I think of death as akin to a well-earned rest." - Carlo Rovelli

"Past and future are different from each other. Cause precedes effect. Pain comes after a wound, not before it. The glass shatters into a thousand pieces, and the pieces do not re-form into a glass. We cannot change the past; we can have regrets, remorse, memories. The future instead is uncertainty, desire, anxiety, open space, destiny, perhaps. We can live toward it, shape it, because it does not yet exist. Everything is still possible... Time is not a line with two equal directions: it is an arrow with different extremities." - Carlo Rovelli

"We can think of the world as made up of things. Of substances. Of entities. Of something that is. Or we can think of it as made up of events. Of happenings. Of processes. Of something that occurs. Something that does not last, and that undergoes continual transformation, that is not permanent in time." - Carlo Rovelli

"National identity is a con. It's good for overcoming local interests for the common good, but it is short-sighted and counterproductive when it promotes the interests of a totally artificial group – 'our nation' – above a more ample sense of what the common good consists of." - Carlo Rovelli

"Things change only in relation to one another. At a fundamental level, there is no time." - Carlo Rovelli

"Quantum gravity is the discovery that no infinitely small point exists. There is a lower limit to the divisibility of space." - Carlo Rovelli

"The “quantum leaps” from one orbit to another constitute their way of being real: an electron is a combination of leaps from one interaction to another." - Carlo Rovelli

"But the effective way of continuing to exist in a changing environment is to better manage correlations with the external world, that is to say, information: to collect, store, transmit, and elaborate information. For this reason DNA exists, together with immune systems, sense organs, nervous systems, complex brains, languages, books, the library of Alexandria, computers and Wikipedia: they maximize the efficiency of information management. The management of correlations favoring survival." - Carlo Rovelli

"The notions of fields and particles, separated by Faraday and Maxwell, end up merging in quantum mechanics.  The way this happens in the theory is elegant: the equation of Dirac determines the values a variable can take. Applied to the energy of Faraday's lines, they tell us that this energy can take on only certain values and not others. Since the energy of the electromagnetic field can take on only certain values, the field behaves like a set of packets of energy. These are precisely the quanta of energy introduced by Planck and Einstein thirty years later. The circle closes, and the story is complete. The equations of the theory, written by Dirac, account for the granular nature of light, which Planck and Einstein had intuited." - Carlo Rovelli

"Information is the measure of the number of possible alternatives for something." - Carlo Rovelli

"General relativity and quantum mechanics are in the end not as incompatible as they seemed. On closer inspection, they shake hands and engage in a beautiful dialogue. The spatial relations that weave Einstein's curved space are the very interactions weaving the relations between the systems of quantum mechanics. The two become compatible and conjoined, two sides of the same coin, as soon as it is recognized that space and time are aspects of a quantum field, and quantum fields can exist without being grounded in an external space." - Carlo Rovelli

"Therefore, the first meaning of quantum mechanics is the existence of a limit to the information that can exist within a system: a limit to the number of distinguishable states in which a system can be. This limitation upon infinity, this granularity of nature glimpsed by Democritus, is the first central aspect of the theory. Planck's constant h measures the elementary scale of this granularity." - Carlo Rovelli

"Only where there is heat is there a distinction between past and future." - Carlo Rovelli

"Quantum uncertainty across the horizon of the black hole generates fluctuations of the horizon geometry. But "fluctuations" imply "probability," and probability implies thermodynamics, and therefore temperature. Concealing from us a part of the universe, a black hole makes its quantum fluctuations detectable in the form of heat." - Carlo Rovelli

"Dirac's quantum mechanics thus allows us to do two things. First, to calculate which values a physical variable may assume. This is called "calculation of the spectrum of a variable"; it captures the granular nature of things. When an object (atom, electromagnetic field, molecule, pendulum, stone, star, and the like) interacts with something else, the values computed are those that its variables can assume in the interaction (relationism). The second thing that Dirac's quantum mechanics allows us to do is to compute the probability that this or that value of a variable appears at next interaction. This is called "calculation of an amplitude of transition." Probability expresses the third feature of the theory: indeterminacy, the fact that it does not give unique predictions, only probabilistic ones.

This is Dirac's quantum mechanics: a recipe for calculating the probability that one or another value in the spectrum appears during an interaction. That's it. What happens between one interaction and the next is not mentioned in the theory. It does not exist." - Carlo Rovelli

"With a great deal of effort, seeking help from friends better versed in mathematics than himself, Einstein learns Riemann’s math—and writes an equation where R is proportional to the energy of matter. In words: spacetime curves more where there is matter. That is it." - Carlo Rovelli

"A star must ignite for hydrogen to begin to burn there into helium. What causes stars to ignite? Another process that increases entropy: the contraction due to gravity of one of the large clouds of hydrogen that sail throughout the galaxy." - Carlo Rovelli

"Any description of a system is therefore always a description of the information a system has about another system, that is to say, the correlation between the two systems." - Carlo Rovelli

"What are the elementary "atoms" that vibrate, making a black hole hot? Hawking left this problem unanswered. Loop theory provides a possible answer. The elementary "atoms" of a black hole that vibrate, responsible for its temperature, are the individual quanta of space on its surface." - Carlo Rovelli

"There is our past: all the events that happened before what we can witness now. There is our future: the events that will happen after the moment from which we can see the here and now. Between this past and this future there is an interval that is neither past nor future and still has a duration: fifteen minutes on Mars; eight years on Proxima b; millions of years in the Andromeda galaxy. It is the expanded present.  It is perhaps the greatest and strangest of Einstein’s discoveries." - Carlo Rovelli

"Quantum mechanics teaches us not to think about the world in terms of "things" that are in this or that state but in terms of "processes" instead. A process is the passage from one interaction to another. The properties of "things" manifest themselves in a granular manner only in the moment of interaction-that is to say , at the edges of the processes-and are such only in relation to other things. They cannot be predicated in an unequivocal way, but only in a probabilistic one." - Carlo Rovelli

"The entropy of a system depends explicitly on blurring. It depends on what I do not register, because it depends on the number of indistinguishable configurations. The same microscopic configuration may be of high entropy with regard to one blurring and of low in relation to another." - Carlo Rovelli

"The fact that we live at the bottom of a deep gravity well, on the surface of a gas-covered planet going around a nuclear fireball 90 million miles away, and think this to be normal, is obviously some indication of how skewed our perspective tends to be." - Carlo Rovelli

"“Proper time” depends not only on where you are and your degree of proximity to masses; it depends also on the speed at which you move. It’s a strange enough fact in itself, but its consequences are extraordinary.  " - Carlo Rovelli

"Einstein was no great mathematician. He struggled with maths. He says this himself. In 1943 he replied in the following way to a nine-year-old child with the name of Barbara who wrote to him about her difficulties with the subject: ‘Don’t worry about experiencing difficulties with maths, I can assure you that my own problems are even more serious!’  It seems like a joke, but Einstein was not kidding. With mathematics, he needed help: he had it explained to him by patient fellow students and friends, such as Marcel Grossman. It was his intuition as a physicist that was prodigious." - Carlo Rovelli

"Too often scientists sell hypothetical theories to the large public, as if they were established theories. I have seen this often done, for instance, with string theory. I think this is a great mistake, because it questions the credibility itself of science. We scientists live out of public money and it is our duty to be fully honest in reporting what we know and what we do not know. We are paid to dream, but we must not sell our dreams for established realities." - Carlo Rovelli

"In order to grasp the basic grammar of the world, we need to merge three basic ingredients, not just two: not just general relativity and quantum mechanics, but also the theory of heat, that is, statistical mechanics and thermodynamics, which we can also describe as “information theory"." - Carlo Rovelli

"The speed of an object is not a property of the object alone: it is a property of the object in relation to another object. The speed of a child on a moving train has a value relative to the train (a few steps per second) and a different value relative to the ground (a hundred kilometers per hour). If his mother tells the child to 'Keep still!', she does not mean that they have to throw themselves out of the window to stop in relation to the ground. She means that the child should stop with regard to the train." - Carlo Rovelli

"The sun bends space around itself, and Earth does not turn around it because of a mysterious force but because it is racing directly in a space that inclines, like a marble that rolls in a funnel. There are no mysterious forces generated at the center of the funnel; it is the curved nature of the walls that causes the marble to roll. Planets circle around the sun, and things fall, because space curves." - Carlo Rovelli

"The difference between past and future exists only when there is heat. The fundamental phenomenon that distinguishes the future from the past is the fact that heat passes from things." - Carlo Rovelli

"The world is not a collection of things, it is a collection of events." - Carlo Rovelli

"If things fall, it is due to this slowing down of time. Where time passes uniformly, in interplanetary space, things do not fall. They float, without falling. Here on the surface of our planet, on the other hand, the movement of things inclines naturally toward where time passes more slowly, as when we run down the beach into the sea and the resistance of the water on our legs makes us fall headfirst into the waves. Things fall downward because, down there, time is slowed by the Earth." - Carlo Rovelli

"This does not mean that science is just the art of making measurable predictions. Some philosophers of science overly circumscribe science by limiting it to its numerical predictions. They miss the point, because they confuse the instruments with the objectives. Verifiable quantitative predictions are instruments to validate hypotheses. The objective of scientific research is not just to arrive at predictions: it is to understand how the world functions; to construct and develop an image of the world, a conceptual structure to enable us to think about. Before being technical, science is visionary." - Carlo Rovelli

"Quantum mechanics cannot deal with the curvature of spacetime, and general relativity cannot account for quanta. This is the problem of quantum gravity." - Carlo Rovelli

"It’s the same for every object, properly considered, including living organisms. This is why it makes little sense to ask whether a half-cut fingernail is still “me,” or has become “not-me”; or if the hairs left on my sofa by the cat are still part of the cat, or not; or precisely when a child’s life begins. A child begins to live on the day when a person dreams of her for the first time, long before her conception, or when she forms her first self-image, or when she breathes for the first time, or when she recognizes her name, or when we apply any number of other conventions: they are all useful, but arbitrary. They are ways to think, and to orient ourselves within the complexity of reality." - Carlo Rovelli

"Loop theory describes this atomic and granular quantum structure of space in a precise mathematical form. It is obtained by applying the general equations of quantum mechanics written by Dirac to Einstein's gravitational field.  In particular, loop theory specifies that volume (for example the volume of a given cube) cannot be arbitrarily small. A minimum volume exists. No space smaller than this minimum volume exists. There is a minimum "quantum" of volume: an elementary atom of space." - Carlo Rovelli