The Physics and Philosophy of Time - with Carlo Rovelli
Why Hacker News recommends it
HN commenters point to it as a lucid, general-audience lecture that shows how wrong common conceptions of time are, often in threads on entropy and the arrow of time.
What it is
Physicist Carlo Rovelli gives a public lecture at the Royal Institution on how our understanding of time has changed, from Boltzmann and Einstein to quantum theory and loop quantum gravity. He blends physics, philosophy and art to argue that time is stranger than everyday intuition suggests.
Recommended by 5 HN commenters across 6 different months, 2018 to 2022.
What Hacker News said
Strong rec danbruc · 2019-09 · on “Exotic Physics Phenomenon Involving Time Reversal Observed for First Time”
Our conception of time is just totally wrong, or at least this is true for 99.9 % of all humans and that is certainly an underestimate. Something like THE time does not exist, we are just all living together in a small bubble in the universe, all of us experiencing more or less the same gravitational field, all of us moving together at more or less the same speed as Earth moves through space, and that is what makes it look like there is THE time. But actually time is more like counting the calories you burn as you walk through the world, it is specific to you and the path you take. There is a great lecture »The Physics and Philosophy of Time« by Carlo Rovelli [1] aimed at the general public
Strong rec crispyambulance · 2022-05 · on “Searching for What Connects Us, Carlo Rovelli Explores Beyond Physics”
Rovelli is an astounding communicator. Here's a wonderful lecture he did for the Royal Institute on the nature of Time: [this video] His communication style is a model of lucidity and kindness that more specialists should emulate when talking or writing to general audiences.
Recommends ballenf · 2018-06 · on “Carlo Rovelli on the ‘greatest remaining mystery’: The nature of time”
Royal Institute presentation that I really enjoyed. Has some visual aspects, but can be mostly listened to while driving: The Physics and Philosophy of Time - with Carlo Rovelli > 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. [this video] Posted 13 June 2018, recorded 30 April 2018.
Recommends zvrba · 2019-04 · on “The discrete-time physics hiding inside our continuous-time world”
Watch this video: [this video] I myself lean to the Aristotelian definition: count of change. After all, all our clocks are built on this definition. If there were a lone particle traveling in an infinite universe, it'd be nonsensical to talk about its speed because there'd be nothing to relate the distance traveled to (and no observer). Indeed, whenever we talk about "time" and related quantities like "speed", we always compare the observed object to some other, existing reference. So I think of the interaction of particles/matter as being something fundamental, whereas "time" is a synthetic human notion.
Recommends danbruc · 2019-06 · on “How to Understand the Universe When You’re Stuck Inside of It”
There is a very good introduction - 20 lectures of 45 minutes - to loop quantum gravity by Carlo Rovelli [1] who worked together with Lee Smolin on that topic. In a nutshell loop quantum gravity is about triangulating space with tetrahedra, then representing this triangulation as a graph - one vertex per tetrahedron, one edge between every two tetrahedra sharing a face - with the edges labeled with SU(2) transformations describing the change in orientation due to spacetime curvature as one moves from one tetrahedron to a neighboring one, and of course the dynamics of this description. I hope I got this right, I am totally not a physicist. There is also a very good talk for the general public
Recommends kergonath · 2020-08 · on “Entropy explained, with sheep (2016)”
We don’t have an answer to this question. I don’t want to discuss metaphysics here, but there is a very interesting discussion on that subject here: [this video]
Cites noiv · 2018-07 · on “Do Our Questions Create the World?”
You may want to exclude language from reality. The dichotomy of questions and answers might not happen in the latter. Or the other way round: As long you have questions you're not there yet. I present you one piece of the puzzle: The Physics and Philosophy of Time - with Carlo Rovelli on Youtube, [this video] In a way he supposes minds as entropy inducing entities.
Cites Supermancho · 2020-10 · on “You don’t have free will, but don’t worry”
> Everyone who has taken a class on complex systems is aware of the phenomenon of emergence. Interactions (any observed results) are side effects of deterministic properties. Not knowing all initial states or the complexity of the intetactions being incomprehensible in aggregate (by humans) is not relevant. Emergence is not incommensurate with determinism. Full stop. Once you figure out that time is an illusion of local shared human memory (if you travel to nonlocal spacetime you will have a divergent memory), the situation becomes clearer. [this video] Wake me up when there's something new to talk about.