The Science of Time - Carlo Rovelli
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- Опубліковано 15 тра 2024
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- VIDEO NOTES
Carlo Rovelli, an Italian theoretical physicist, is known mainly for his contributions to research in the field of quantum gravity.
He is the author of:
Seven Brief Lessons on Physics: amzn.to/3Vpsjvc
The Order of Time: amzn.to/3VvzbXJ
White Holes: amzn.to/3vfBhR7
- TIMESTAMPS
00:00 The Confusion Around Time Zones
05:05 Explaining the Concept of Universal Time
12:51 Is Time-Relativity Too Negligible to Measure?
20:31 The Correct Way to View Time
29:43 Heat’s Role in Memory & the Past
36:07 Why Can’t We See the Future?
44:07 Describing the Experience of Time
49:11 Why Do Objects of Great Mass Have an Effect on Time?
57:43 Gravity & Time Are the Same Thing
1:02:30 Carlo’s Book
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Alex O'Connor
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I really respect you Alex but I believe you asked the wrong question in this interview. The question isn't "why can I remember the past and not the future". You can't remember the past, you can only remember your past. This is because we do not have some innate ability or sense to detect what has occured in the past. Our knowledge of the past only comes from gaining knowledge of the present and then storeing that knowledge in our brains to be accessed agian later. We have NO more access to the past than we do to the future. We only have access to the present. The past and the future are not the left and right of time. The states of time are "flowing" or "not flowing". Science proposes the potential to slow or maybe even reverse this flow in specific conditions. But having access to the entirety of time is a misunderstanding of it. As you will have noticed by my awful spelling and grammar I am just some random idiot though so what do I know. This is just my best guess from what I have learned.
YOU sir are a CHARLITTAN and a FOOL!!!
@@KermitsBadFurDay Jesus loves you ❤️Please turn to him and repent and receive Salvation before it's too late. The end times written about in the Bible are already happening in the world. Jesus is the son of God and he died for our sins on the cross and God raised him from the dead on the third day. Jesus is waiting for you with open arms but time is running out. Please repent and turn to him before it is too late. Accept Jesus into your heart and invite him to be Lord and saviour of your life and confess and believe that Jesus is Lord, that he died for your sins on the cross and that God raised him from the dead. Confess that you are a sinner in need of God's Grace and ask God to forgive you for all your sins through Jesus.
Jesus loves you. Nothing can compare to how he loves you. When he hung on that cross, he thought of you. As they tore open his back, he thought of your prayer time with him. As the thorns dug into his head, he thought of you spending time in the word of God. As the spears went into his side, he imagined embracing you in heaven.
Your confusion. Not everyone else. Another “expert” . Waste of time.
@@Multiversalelevations are you talking to me because you didn't say this as a reply? I didn't claim to be an expert, I said I wasn't. But if you where talking to Alex your comment makes even less sense lol.
Mr O'Connor. I am 75 and become a great admirer of yours. To mangle Churchill... Never has one so young gotten so much out of so many. Your interviews are masterful as are your commentaries and debates. You are a remarkable individual and I am eager to follow what I expect to be an exceptional career.
What a nice comment, perhaps you are the masterful one. ❤
I remember forecasting it when he was, I think, 16.
he is a NARCO and a GOVERMENT PLANT
Me being absolutely in luv with Alex. I would just like to say: Just his video on Jordan Peterson is the best explanation on what Jordan says he believes. I’ve being trying to understand for 3 yrs what Jordan believes and couldn’t figure it out until Alex’s video.
That being said everyone one of us whether atheist or religious should be way more complimentary towards other humans. I do not have a “scientific” reason for why it is important but it is. As Jordan might say “transcendent”.
Jesus loves you ❤️Please turn to him and repent and receive Salvation before it's too late. The end times written about in the Bible are already happening in the world. Jesus is the son of God and he died for our sins on the cross and God raised him from the dead on the third day. Jesus is waiting for you with open arms but time is running out. Please repent and turn to him before it is too late. Accept Jesus into your heart and invite him to be Lord and saviour of your life and confess and believe that Jesus is Lord, that he died for your sins on the cross and that God raised him from the dead. Confess that you are a sinner in need of God's Grace and ask God to forgive you for all your sins through Jesus.
Jesus loves you. Nothing can compare to how he loves you. When he hung on that cross, he thought of you. As they tore open his back, he thought of your prayer time with him. As the thorns dug into his head, he thought of you spending time in the word of God. As the spears went into his side, he imagined embracing you in heaven.
Deutsch, Dawkins and now Roveli... I can't thank you enough for bringing these guests.
"thank you, it was remarkably nice" is such a great compliment. Can't help but feel insanely proud of Alex and what he had achieved
I can't help but find people saying they are proud of someone online that they don't know, really odd.
@@mind5403 Been watching all of his content for many years.
Does that really fit the meaning of "not knowing someone" to you?
Two of my favourite people on this world talking about physics. Couldn’t ask for more
Oh yea, that was a huge and wonderful surprise 😁
INCREDIBLE. Not only are you interviewing one of my all time favorite authors, but in 2 months, for my next book, I am embarking on a circumnavigational journey (without flight) and will lose that mysterious day.
You will lose that mysterious day but if you kept track of the hours, you wouldn't lose any hours. Would you?
@@Myshcanyes I think they could loose hours, depending on where they are and how fast they are traveling
@@Myshcan
Assumptions:
Travel at speeds at which relatavistic effects are negligable. Your circumnavigation is westwards. Daylight savings is ignored / you travel at a time it doesn't change.
Therefore:
1. Track time on your watch: You lose no hours.
2. Track time by the time/date on clocks in the places you visit: You lose or gain 24 hours, thus losing or gaining a day. Each time you cross a timezone, you "lose " an hour, and in circumnavigation you lose 24 of them, thus a day.
@@fiskcakehamster No. 2 is an interesting alternative approach. Sounds kind of like saying when I took a flight from NY at 1:00 p.m. EST and arrived in SF at 2:00 p.m. PST, the trip only took 1 hour.
As an Italian philosophy student and great admirer of Dr.Rovelli, i'm so happy to see him on this podcast!
His books are absolutely must-reads to find the beauty and poetry in the world of physics.
Could you give some examples of the beauty and poetry? Is it objective beauty and poetry?
@@joannware6228 Ah ah. No, he cannot (as we can see). The aspiring philosopher does not seem able to ask (himself) the simple question if those readings are useful to +understand+ the world of physics. And btw that's why he uses the vague "find the beauty".
Amazing! The Order Of Time is one of my favorite books of all time! I am a huge fan. Thank you for the great conversation.
Your videos are awesome 😎
I knew about relativity as an amateur but the fact "We fall towards the direction of where time goes slower" is just wow
It's certainly an interesting explanation for gravity.
I wonder if this thought will solve the problem of dark matter.
@@garyrolen8764 I don't think so. We've known that since the discovery of relativity.
I dont understand why though. Why does something going slower have an inherent pull?
@@JonTonyJim I'm just gonna copy-paste the comment I made on this vid earlier:
The analogy I like better for demonstrating the curvature of spacetime is the following: Imagine a flat plane of conveyor belts, where all of them move in the same direction, but the speed of each belt increases as you go further from the beginning. If you place a large object on such a plane, large enough to span multiple conveyor belts, the object will ultimately end up on the slowest moving part of that plane. This is because the faster moving belts would rotate and push the object towards the slower part of the plane, repeatedly until it hits the stationary belt, or the slowest one.
@@bedro_0 but that seems to me to assume that the conveyor belts all push towards the slower ones. Whats stopping the belts from pushing outwards and the object ending up on the fastest one?
Grande Carlo. And congrats to Alex to have managed to interviewed him. I understood probably 10% of the interview but I’m still blown away about it.
Same. The concept that time is just an effect of gravitational waves is literally what make me recognize time as a real thing for the first… time. That is part of the 10% I understood, and the best explanation about what time is I’ve ever heard.
@@MrGilRoland Less you understand, more you admire.
These are the types of conversations I crave to witness on this platform, thank you for your work Alex
Fantastic interview with a fantastic interviewer and a fantastic interviewee.
Keep it up, Alex.
Loving the recent episodes with physicists! Keep it up!
Alex, you are simply first class. This was one of the best talks about space, time and gravity I heard recently! Going straight to my physics favourites 😁
Thank you for making such interesting content.
Wow, truly a great interview. Great work picking interesting topics to talk about
Yet another introduction to a figure that I really need to dive into! Thanks for this thought provoking interview.
I have been so curious about time recently, thank you for this!
I make it nearly half six, mate. ;)
What do you mean "recently"? 😜🤣
Great conversation as always.
I just read this book last month! Glad to see this pop up on my feed.
Thank you once again Alex for eye opening content
The physicist was very patient with Alex 😊
Because he's of our time, one of the most humble geniuses of global stature
That’s because Rovelli is such a humble, modest guy. Many physicists, e.g. the Lawrence Krauss’s of the world, come across as arrogant and condescending. You can tell that Rovelli has a passion for physics and a wealth of knowledge that he loves to bestow on others.
@@samsimpson565 I've never found Krauss as arrogant or condescending... simply entertaining and easy going, and excited about what he does. Is there anything in particular he has said which grinds your gears?
Maybe Alex was intentionally pressing for more in-depth explanations. His questions seem almost repetitive, but actually dig into real aspects of the topic. The Ads ticked me off though. Every question!
@@nathangonzales2661Alex is always pressing for in-depth explanations but I thought some of his questions were, well, not very in depth. He didn't seem to be listening (or understanding) enough.
In a tram driver's course I took, the transit agency taught us the concept of universal time, which the whole network relies upon (necessary for transfer management and so on), and I was like "why are we learning this, isn't it obvious that there is universal time?"
It blew my mind that just 25 years ago there were hardly any mobile networks transmitting exact time, so everyone had to rely on their own imperfect watch, which of course didn't yield universal time.
Low-key mind blowing at the end
Great questions, excellent answers, fantastic discussion 👍👍
Im gonna watch this tomorrow while on a plane. What a pleasure and great time to be alive😊
Thanks for the great content!
Oh nice🎉! Prof. Carlo Rovelli is one of my favourite physicists, along with his friend Lee Smolin
This is so weird… I randomly watched a speech about white holes this weekend and now you’re interviewing the same person… Amazin!
If you take some of the statements from this conversation out of context they still sound profound. "There is a time for each and everyone one of us"
Great interview 🎊 🎉
This was a fascinating interview and I think you did a brilliant job of asking (as you always do) interesting and thought provoking questions, Alex.
I think something that Carlo perhaps forgot to mention which may have helped your understanding is that the relationship between time and heat (or entropy) is a statistical one. The equations which describe the dissipation of energy, referred to in the discussion, essentially tell you that the 'future' is far more probable than the past. This means the passage of time from past to future is actually statistical in nature, and the statistics we use tell us that the future is far more likely to happen than the past (far is an understatement). Brian Greene gives a great explanation of this in a video titled 'Your Daily Equation #32: Entropy and the Arrow of Time'.
However, armed with that knowledge, it would have been interesting if you'd asked Carlo what the relationship is between the statistical nature of time that he's describing i.e. its relationship to heat/entropy etc. and the slowing down of time around large masses. I don't know the answer to this and would have been glad to hear Carlo's thoughts.
Thank you for the tip on Brian Greene. I'll check it out for sure. And probably get back to a book I red long time ago - "Time's Arrow and Archimedes' Point" by Huw Price. I guess it's time to read it again 😁
refers to reality evolving from the least probable to the most probable
Thank you! This is the stuff we need right now. A new framing/question of reality. We have heard enough propositional answers. Iain Mcgilchrist would be a phenomenal guest for you
Literally in the middle of writing an essay on theories of time (in the movie About Time) for my philosophy in Sci-fi course...
I would keep away from Carlo Rovelli if I was you. For example he states the following as an argument against the Kalam and the A-theory of time;
"Well, cosmological time is a fake. Why? Because matter, gravity
slows time so inside the galaxy clocks go slower than outside. Point is there are
many different clocks in the universe which they don't agree with one another
and there are many times in the universe which don't agree with one another.
The idea of the cosmological time is just one arbitrary definition of an average,
but I can give a different definition of it."
How wrong can someone be?
@@TBOTSSI think he’s right. It’s relative in the way we experience it
I always presupposed time was just a measure of decay. Thank you for these insights
From arguably the worst guest (Knowles) you’ve had on this show to now one of the best. Very interesting video.
Oh now im curious.. who is Knowles? I saw the Hitchens one - that was just so odd.. when guest behave badly eh. I thought Alex handled that well though.
@@kiwiopklompenhe’s a right wing propagandist basically
He had the radical Christian crusader on right after that too
@@DandelionScribeAlex is incredibly good at positioning himself.
🤔🤔🤔
Love this guy. Before watching even, time is already weird enough with relativity, it's weird thinking those having fun are truly experiencing our future, weirder still if there was some absolute time keeping mechanism in our human experience.
Seems like your podcast is become the OG lex with these guests, nice.
Wow Alex, you ask the best questions. I honestly appreciate you.
33:08 "as soon as it goes down to equilibrium, there is no phenomenology whatsoever that tells you which one's the past direction and which one's the future direction"
The analogy I like better for demonstrating the curvature of spacetime is the following: Imagine a flat plane of conveyor belts, where all of them move in the same direction, but the speed of each belt increases as you go further from the beginning. If you place a large object on such a plane, large enough to span multiple conveyor belts, the object will ultimately end up on the slowest moving part of that plane. This is because the faster moving belts would rotate and push the object towards the slower part of the plane, repeatedly until it hits the stationary belt, or the slowest one.
How can the speed increase as you go further from the beginning?
@@crazyprayingmantis5596the first conveyor belt moves at speed of 0 m/s, the next onr moves at 1 m/s, the next one 2 m/s and so on.
Of course, it's good to remember this is an analogy. It does not bring insight on what actually occurs. Don't wanna be a debbie downer, but don't want people to be mislead.
I don't understand why it would rotate?
@@PROJECTJoza100 Imagine a plank across two treadmills. If they were both moving at the same speed it would just move along with it. If however one was on and the other wasn't, one end of the plank would stay still and the other would be pushed along giving the effect of "rotation". It doesn't mean it will spin on the spot, just that the end of the plank on the moving treadmill will not keep pace with the treadmill because it is experiencing a dragging force from the end on the stationary treadmill.
This is really mind blowing and interesting…
Getting closer and closer to the Bernardo kastrup interview with your embrace of the subjective.
Looking forward to that one! Finally someone who has a radical different view from all people that seem to take models of reality to be reality.
Is he a Marxist? 😅
Time isn't a "flat circle"! It's a spiral! 🍥😵💫
A fundamental tenet of Marxism is something called "dialectical materialism." This is a lot different from the materialism you might be used to!
he should do donald hoffman since he actually knows more about spacetime
Well done.
37:43 "There is a sense in which one direction is accessible and one direction is not"
Lets call this phenomenon Schrödingers One Direction
It's good that you're examining the physics toolbelt of ideas Alex! It's the best thing for a philosopher, just as philosophy is the best thing for a physicist! Two sides of the same coin cannot stay unawares of one another!
But the physics, and science in general, finished with "Mors tua vita mea" when it comes to talking the talkosophy vs cognitive order (needed by exact science). There were some physicians and philosophers in the past, not nowadays, and there will no be in the future (except some divulgative ones).
@@voltydequa845 mors tua vita mea means "your death my life" I'm not sure I get what you're saying.
@@KieranLeCam The philosophy, especially the continental one, is dying. The need for formalization of knowledge is wiping out the vagueness.
@@voltydequa845 I don't understand what you're saying or why it's relevant to my point.
@@KieranLeCam «I don't understand what you're saying or why it's relevant to my point.»
--
In your starting comment you wrote «... just as philosophy is the best thing for a physicist!». Imo it is a nonsense. Same as saying something like "... just as philosophy is the best thing for a carpenter, smith, cook, etcetera, etcetera.
As a lifelong climber, skier and mountaineer it certainly makes sense. It goes some way toward explaining why I seek to spend so much “time” at high elevation, where time goes slower.
At 35:45, that is such a deep point... Mind blown! 🤯
Hi Carlo. I’m a recent, huge fan of yours. I read White Holes and I’m now reading The Order of Time. I believe you are one of very few physicists that actually understand how time works. And you have an elegant way of explaining the complex in terms anyone can understand. White Holes addressed some thoughts I’d not even considered, and I’ve considered a lot when it comes to time.
When Alex asks the question (36:38) about why a human can’t remember the future, we can only remember the past, I believe you missed the mark. You talked about heat equilibrium, which I agree this universe generally disperses heat rather than consolidating it (possibly other universes consolidate it rather than dispersing it - we don’t know this for sure we can only hypothesize), but I don’t believe that’s the only reason humans can’t remember the future.
I believe the reason humans can’t remember the future is because the future has not occurred yet, and for that matter the past no longer exists either.
The only thing that actually exists is the present moment tor every singular particle. Yes, as you know, events happened, but I believe they no longer exist other than in the marks that they left behind on the universe around them. Whether for example that’s in our brains as memories or whether that’s in craters left when asteroids collide with the earth, or any other effect that is left behind by a cause for that matter. Since the future has not occurred yet, it has left no mark yet for us to “remember “it by, the future cannot be remembered.
I believe the only moment that exists is the now - the present. The past no longer exists (accept in the marks it left behind), and the future does not exist yet. The present moment is a moment of constant change, transitioning from a set of infinite possibilities and transitioning to another set of infinite possibilities. Reality is sandwiched in between.
Every single tiny little particle has a set of probabilities that it could do in the future. For simplicity sake, for example, the particle might go up or down, left or right. It’s even within the realm of possibility for a particle to go back to the state that it came from. Computer scientists in a laboratory have shown that for single particles, we can “rewind time”. They’ve done this with quantum bits. It is possible to rewind time for single particles. But what does that actually mean? Does it mean that the particle goes back in time? It leaves our universe to the one in the past? No. The particle stays within this constantly changing moment of time that we call the present. It just goes back to the state it was in in the past. There is no past that exists for that particle, but there is a recollection of where it came from. So I hope this explains why I believe you missed the mark on that question. And please correct me if you believe me in error. Thank you.
In a reference-less scenario we orchestrate endless references though they are built inside a framework of abstraction. So contingent on our perspective, a perspective built from the heart of time and space. This that looks familiar will also look alien until the looker is seen as itself.
1:04:08 “Thank you. It was remarkably nice.”
A sweet and gracious comment from renowned Italian theoretical physicist and writer Carlo Rovelli.
I have to rewatch this podcast 😅
I've never heard anyone talk about time as well as this or even close. And I watch a LOT of science videos.
About up and down:
1. Even on Earth, the vector that defines down is different in different places. It's the tiniest bit different here from what it is in the next room; the difference is much greater between Alaska and Australia.
2. I wonder whether astronauts in near-Earth orbit with big windows in their spacecraft do have a visual sense of up and down, even in the absence of a gravitational one. I assume that they look out at the Earth and consider it to be "down there", and look at the horizon and consider it to be "out there" or "over there", and look at the blackness of space on the other side of the horizon and say it's "up there".
3. When they get farther away, does the astronauts' visual sense of up and down change. When they head to the moon, do they look back at the Earth and see not as "down there" but "over there" or "back there"? My knowledge, since childhood, of the relatively planar nature of the moon's orbit around the Earth, along with my knowledge that that plane is roughly perpendicular to the Earth's axis, leaves me often _thinking_ of the moon as _over_ there, even though, when I _look_ at it, _sometimes_ (when it's high in the sky, but not when it's near the horizon) I _see_ it as _up_ there. (Indeed, in a sense, I have two distinct concepts of the moon: a sphereoid out there in orbit, and a moving light (of changing shape) here in the sky on Earth.
huiii omg im so early Alex i love your channel
Yes you are coming fast this time!
I've waited for a long time for this interview but eixx l now feel like the time is running out😂
Time code 7:35 - Carlo misspeaks. "The one (clock) that has been higher indicate(s) less time." In fact, it is exactly the other way around. The clock upstairs runs fast so it will indicate more, not less, time. I'm sure Carlo knows this and just misspoke but for your viewers I think it important to clarify how gravitational time dilation works.
No, Carlo is correct, the clock on the satellite runs slower than the one on earth. The astronauts on the space station age more slowly than people on earth.
@@I.Reckon I disagree. Carlo was not talking about satellites nor the ISS - he was talking about clocks that are stationary with respect to each other but separated by altitude. For things in orbital motion there are two different competing time dilation effects - a speed up due to the lower gravity at high altitude and a kinematic slow down due to orbital velocity of about 7 km/s. The altitude of the orbit matters. For the ISS there is a net slow down, for GPS satellites there is a net speed up. Here's a quote from the wiki page on Gravitational time dilation: "Clocks that are far from massive bodies (or at higher gravitational potentials) run more quickly, and clocks close to massive bodies (or at lower gravitational potentials) run more slowly...." Carlo just misspoke.
@@alleneverhart4141 I think you are right, but does he just misspeak, or is he wrong. He also conflates time zones into his explanation.
Does this mean that a theoretical spaceship travelling close to the speed of light in low earth orbits would experience time more slowly than if it were doing the same sized circles, at the same speed, in open space, away from a gravity mass?
The ultimate crossover
Hello all from NC USA
The past is a place we remember but can't visit and the future is unknown but we're compelled to go there. Having said that many of us try to recreate the past with an ex and seem to forget why we chose a future without each other until it's too late.
Killing some time watching this
Nice to see you embrace physics Alex
you should have sam harris talk about buddhism and meditation
Done.
What is that to do with the physics of time ?
the universal clock can be though like that: time passes differently depending on position and speed relative to an arbitrary observer. A universal time would mean you could find a place where time was considered as a universal reference for everyone but such place would need to have something special otherwise you wouldn’t had a reason to declare it universal. for example you could say time on Earth is universal but there is nothing special about Earth. An absolutely stationary point would be the perfect place but there is no point in space that can be considered absolutely stationary, there is no fabric of the Universe were objects move relative to it
Yes, a clock can be in many times at the same place, all at the same time. Picture a huge mechanical clock, with hands of massive lengths. As these hands are on the move, the further near the end of each hand you go, the slower time is ticking, all due to movement being faster the closer to then end of the hand it is that you are located. And so the ends of these hands are younger than the opposite ends, which are tied to the clocks centre spindles.
Can't believe you brought out one of my favorite thinkers. What a day, what a day...
I am happy to see that you try to catch up a bit on modern physics. It's unfortunate that this particular quest is not a good explainer, he seems to confuse more than enlighten. But please continue this way!
I'm amazed at how quickly, Alex, you're able to come up with a perfect counter-example argument/question every time.(Whatever "time" is heh)
This was a brilliant interview. Thank you very much.
Fascinating subject. Towards the end, regarding the relationship between gravity and time, I wish you had asked him what this means for an object floating around in deep space, somewhere far between galaxies, with very little gravity acting upon it. What would this mean for the passage of time for that object? And conversely, the effects of an immense amount of gravity, near the event horizon of a black hole.
«What would this mean for the passage of time for that object?»
--
The error is in "passage of time". All this talk is built upon the absence of definition of time. Try to make you own logical / physical definition of (what is) time, and you'll understand better the rhetorical tricks around. Hint: there can be more or less two concepts of time : the one is the clock time, the other is about relations.
I very much wish I could have been involved in this conversation so as to give my own perspective of how I perceive the illusion of "time". There is so much that I could say regarding everything that was discussed in the video, but it is too much to post in this comment section. I can't say that I agree with everything that was said, but I feel that there is enlightening conversation to be had. I will say this: from my own understanding, the illusion of time is a side effect of gravity and gravity is a side effect of mass. Why this is so is something that no one is able to figure out and it's something that we will most likely never be able to comprehend.
There is another, I think easier, way to imagine proper time. "Proper time" contrasts with "time as a dimension." Proper time is the amount of physical aging which is experienced by an object including clocks and people. The time dimension is good for setting future meetings. Let's meet at Big Ben when it says it's noon and the 3rd of November.
In this model the "shaping of space" is modeled as matter density in an otherwise flat space.
Consider any arbitrary point. The sphere of all the events which could have possibly affected that point expands at 1sec/sec (proper) of added radius. The past flows in from all directions and then emerges back into the same space it came from. Time's emergence is slowed by the experienced density of matter in all directions with mass's effect reducing by an inverse square law. Time is passing faster in your head than in your feet since the average density is greater there.
Matter density also provides downhill and uphill directions. An easy way to go and a hard way to go. It defines geodesics.
Rovelli rocks🎉❤
LOL I know I am thick .. as two short planks .. but that 'time' is still a matter of concern not only of discussion strikes me as - odd. Aquinas and the Ancients understood < time > as a relationship, a 'measurement' between two (or more) points in passing (i.e. from a given perspective, e.g. stasis and dynamic, energy and gravity (weight), dimension and space, et al). Our 'level' or attainment of knowledge (still called 'science' today) of the experience of this quirky relationship (in time, through time, with time, outside time, etc) differs largely in degree of measurement (how many beans will make five, and, how long will it take to count them) rather than of kind (physical, mystical, emotional, rational, commercial, national); Dr Rovelli does a remarkably good job in knitting together something like a common understanding of the 'parts' involved, and making a presentable case for the whole = the metaphysics upon which the physics must rest ... or fall apart in confusion.
Neat.
Keep the Faith; tell the truth, shame the devil, and let the demons shriek.
God bless. ;o)
This and the problem of the "arrow" of time (why time is flowing "forward"?) have been melting my brains for years... i've read about thermodynamics, relativity, quantum theory and I still feel very stupid about all these issues.
Great interview :)
I think, physical time measured with physical clocks is absolute i.e. independent of reference frames. Here is my reasoning: in special relativity, the theoretical time has been redefined by Lorenz transformation, but the clocks are still clocks without changes. But Einstein uses Lorenz transformation to get that the time t' of a moving inertia reference frame (the moving frame ) becomes shorter than the time t of the observer's own inertia reference frame (the stationary frame): t' < t. The period τ' of of the moving clock as an interval of time should also become shorter than the period τ of the stationary clock: τ' < τ . Then the frequency f' of the moving clock becomes faster than the frequency f of the stationary clock: f' > f, which makes the clock time T' of the moving clock equal to the clock time T of the stationary clock:
T' = t'f'/k = tf/k = T where k is a calibration constant.
Please note that a clock never directly measures the theoretical time, but records the number of oscillations of the clock which is the product of the theoretical time and the frequency of the clock. That is, physical time measured with clocks is still absolute in special relativity, independent of reference frames and the theoretical time of special relativity is a fake time. Therefore, special relativity is wrong.
Not only special. :) It is a relativistic messing model.
I’m taking a shot every time they say time i’m 1 minute in and i’m plastered
Awesome
I have couple of books by Carlo Rovelli that were translated to Czech/Slovak language! Great author, especially the fact he's physicist and philosopher so he's not like i.e. Jim Al-Khalili or Hawking spending time shitting on philosophy but Rovelli is actually engaging with it.
EDIT: I made a mistake with Al-Khalili's opinions on philosophy - he agrees about importance of philosophy of science, epistemology and logic, probably along with Einstein, Heisenberg. So not so bad.
What physical thing has philosophy ever discovered?
@@niblick616 Is this bait question? I can only give honest one: philosophy lead to many changes in our civilization and culture, but not in physical sense per se. Modern logic, inductive scientific method, major shifts in law and social structure, influences on art and literature, theoretical discussion which lead to many helpful disciplines being established and many more were shaped by philosophy. There are many disciplines like phrenology, eugenics, astrology which died off. Philosophy didn't. It was persecuted across centuries (middle age, Nazi and Communist regimes), sometimes even almost erased - but it always came back. There were always people willing to give their lives for it, for the last 2500 years. Idk, I don't read much philosophy nor engage with it daily but I am kinda frustrated by random people on internet thinking they are bigger then something spanning millennia, continents and eras shaping the culture, politics, arts, law, social sciences, ethics and the way we look at the world. I know philosophy is small in institutional sense - small fundings, small budgets, small faculties, small journals, small number of students etc. but that doesn't mean its not helpful. I hope I sensed your question correctly as honest question for the function of philosophy in our society.
@@eterista3868
1/ My question was carefully phrased.
2/ You should understand what informal logical fallacies are, if you have read anything about philosophy.
3/ At no point did I say anything about thinking I am bigger than philosophy.
That would be the fallacy of a straw man argument if you were trying to apply it to what I actually posted.
4/ Millions of people used to think that lightning was made by gods. We know that was wrong, no matter how long it was believed nor how many people used to believe it.
5/ It was science, not philosophy, that made the relevant discoveries about what caused lightning
6/ Religions have also been studied for thousands of years and nobody, including any philosopher, has ever been able to demonstrate the existence of any god using at least some of the type of valid and verified evidence I have for the demonstrable existence of my dog.
7/ In many areas Philosophy is science led because science actually does the measuring and acquisitions of basic data that is required to confirm the existence of things that actually exist in our reality.
8/ A large number of modern philosophers generally accept that. In that sense Philosophy is a bit like the caravan of traders that used to follow Roman legions as they moved into and around new countries.
As a scientist I think what you were trying to convey when asking about the irreversibility of time, was if there is a metaphysical reality underlying the thermodynamical explanation of past and future. In other words: is the linearity of time an artefact/illusion arising from the fact that our very brain works based on thermodynamic effects (therefore time dependant), or is there a non-contingent reality called "time" which by coincidence lines up perfectly with the direction of thermodynamic processes? After hearing this discussion I lean on the first interpretation, I can imagine (even mathematically) that if a brain would be able to work without dissipation processes, then ideally it could remember the future, and this concept sounds very intriguing to me.
@@markreed2563 good question, we are in the realm of speculation (such as that a non thermodynamics based mind can exist at all, probably the answer is no). So I do not think I can make any reasonable assumptions on such a thing. Certainly in whatever way it would be able to experience past and future in the same way, another question that could arise from such a perspective is how would thermodynamic dependent beings experience an interaction with such a being. Can such a being exist within a thermodynamic based universe, or only outside of it? It would defy the rules of physics, so I am tempted to say it cannot exist within the universe.
@@domenico26752
You may be interested in the field of Reversible Computing.
You're a scientist saying this?
@@anticorncob6 you pose a question, but it sounds like you are trying to convey a point. Could you elaborate?
A scientist wondering about the non-contingent reality of time? Sounds strange to me. Reality can only be described in terms of space and time (nothing to do with "spacetime" concept). So the time is a requisite for perceiving / describing / measuring / etcetering reality. Science needs cognitive order. Questions around the linearity and existence of time provoke cognitive disorder.
This one absolutely blew my mind. In specific the part about how we cannot form memories in a state of equilibrium because it wouldn't be equilibrium if we were there with our brains which dissipate heat. And even if we were to be able to look at that universe from the outside, if it were in a state of equilibrium, then nothing is happening, so you also wouldn't be able to form memories from a so called God's eye perspective since there would be nothing to remember since nothing ever happens to be remembered. Crazy stuff to think about.
7:30 Can someone tell me why the clock closer to earths gravitational pull would have more time? If time is passing slower the closer you get to the earths core, then the clock would show that less time has passed, right?
My paternal grandmother from the Clydebank's family motto: Carpe Diem. Seize The Day - or better yet "Savour The Moment". Yes! All kinds of profundity to mull over. Zeno's infinitesimals, expanding your awareness, consciousness coordinated with time, the so-called mindfulness?
My favourite author and physicist and my favourite philosopher of modernity combined. I might need a tissue ahahahaa
Can someone explain this to me. Carlo says in a lecture that when you have a black hole, inside the black hole really far down still the star resides. I’m super confused.
40:00 I don’t agree with this interpretation. I think that the best argument about the why we don’t ’remember’ the future is that the future doesn’t really exist as one state, it is not deterministic. The wave functions of all the particles in the future has not yet collapsed to any state and so the future is infinity possibilities which have an inherent randomness and so remembering the future does not make sense based on the state of ones mind at any given time.
So I don’t think the real answer comes from just plane statistical physics and thermodynamics but from the nature of the quantum physics of all particles.
That such a great comment! The future is infinite possibilities - 🥰
So time is relativistic, my experience of time isn't exactly the same as anyone else's.
But do we even have our time synchronized ourselves? If every point in space experiences time differently then the atoms that make me should also not by synchronized. I am confused by the implications of this
Maybe it’s about how big a difference, “here” and “now” as smudges rather than points.
When I was young time went really slow, now I'm old it goes really fast. Hey! JS! If I lived for a thousand years, would I see the sun flying across the sky... ?
What if we have a single weightless particle in the universe, how fast is it moving? and who slow is time for that particle? Can a weightless particle stay put? Do those particles ever decay? if yes, does it happen at the same time of the big-bang (cause i heard that for a foton, everything just happened at the same time)
I got an ad for Meghan Trainor's "Timeless Tour" on this video. How fitting
If energy is mass less then how mass can be converted into energy? Otherwise energy should also have inertial property.
What I still don't understand in terms of why relativity means there can not be a universal "now" is that I can understand that time may move faster or slower based on where a point is, and therefore you can fit in more "time" in the same period, but there could still be a continuous transition where that just has longer to travel over.
Imagine a map where one square on the grid is 1km, but at the south of one of the squares the land is flat, but as you go north it becomes uneven and hilly. Someone walking that land measuring the distance would measure 1km at the bottom but a much longer distance at the top as it would also be influenced by the height (also the top measurement would not necessarily increase at a universal rate). Say you were to ask for their measurement 0.5 km across, the flat measurement would give you 0.5 km, but the top with their relative measurement might give a value that is not half of what they will report at the 1km point. Just because they don't report half their value doesn't mean that they aren't half way across the land.
Admittedly, one could ask why I have chosen the flat as the objective measurement of time here, and you could argue that this is still relative as you could just as well choose the baseline to be the bumpy path and say that the flat is not at 0.5km at the half way point. This argument would conclude that you have to choose one relative framework to measure all others against, so doesn't escape the problem. My disagreement would just be that I am only positing that there is a baseline "time", which I believe could only exist in the equilibrium as it would require no effects on the point, which the time dilating effects act upon in order to experience the phenomenon we observe. As such it may not be "objective" in the sense that I could have chosen any value for this time period but, from what I understand, could be used as the basis for describing what is happening "now" despite relativistic time effects
oh how interesting
Oh, it's Carlo. I read a couple of his books. I liked 7 Brief Lessons, but Order of Time wasn't as good.
3:19 Let's stand in front of a working clock for one minute. During that minute, I'll move my thumb around the perimeter of the clock one time. During the same minute, you'll move your thumb around the perimeter of the clock ten times. If your idea of how much time has passed is times a thumb has moved around the perimeter of the clock, you'll say that somehow ten units of time went by for you while only one went by for me. But we both watched the clock, whose second hand moves at a constant rate, register the passage of just one minute. This is why we measure time by things that move at constant rates instead of variable rates. For many purposes, the rotation of the Earth is constant enough-and we count the movement of the Earth, not the movement of us on its surface. Imagine the confusion that would arrive if we instead counted human movements: you went back and forth between our house and our workplace six times today, but I went back and forth between our house and our workplace just one time today-we agree that what happened is one day, not three days for you and one day for me. This is why we bother to have different words-e.g., "trips" for our movements to and from the workplace, and "day" for a rotation of the Earth. We have to understand that our movements across the Earth are different from its movements about its axis.
Astronauts orbiting the Earth who see a sunrise about once every 90 minutes don't have much cause to call one of those orbits a "day". They don't try to cram breakfast, lunch, dinner, work, and sleep into 90 minutes. Their cells are multiplying and dying at a rate that has little to do with how many times they see the sun rise.
Hello there
One question (although not related to this content)
If everything we do is determined, why should i believe any of your claim because the you are determined to say them not because they are true.
Even the claim"everything is determined" is by itself determined to be said, so why should i believe it?
Even if it's determined you can analyze what determined processes lead him to believe and say that. If it's, for example, an experiment with clocks, then that's your proof
Whether or not someone is pre-determined to make a claim has nothing to do with the truth value of a claim.
I could program a computer to say true things all day. You should believe them if they are true. The fact that I programmed them has nothing to do with it.
@@APaleDot yes you are correct brother. Just because a claim is determined doesn't mean it is false or true. It has nothing to do with the truth value. But my question is how can i know what you are saying is the right thing because you are determined to say it.
You say, for example, "free will doesn't exist", so that claim is either true or false, but if you were determined when you said that, how can i be sure that your claim is true. You said it because you were DETERMINED.
My question is not about the truth value, but how can we know and be sure of it
@@esromzerihun3572
Whether or not something is true and whether or not you know something has nothing to do with determinism. You know something if you have good evidence and arguments for it and it is true. If someone tells you something which is true, and gives you good evidence and arguments as to why it is true, it is completely irrelevant whether or not they told you by their own free will or were always determined to say it. It's the evidence and the arguments which are relevant.
Let me put it this way: If I wrote a program that systematically constructs mathematical theorems using mathematically valid reasoning, would you be concerned that you couldn't trust the theorems simply because they were constructed systematically by a pre-defined algorithm?
This guy is a genius
Carlo Rovelli I can’t have enough. One day I hope I’m gonna talk to you
39:10 when the future and the past are perfectly symmetrical. Both are permanently fixed
7:45 I read that it was the other way around. Your head is older than your feet. Ex: why time "stops" at the center of a black hole.
This seemed backwards to me also as I imagined falling (feet first) into a B.H. part of the spaghetti process was your feet falling faster in time than your head. Though maybe you would snap faster? 🤔
Can anyone more knowledgeable than I confirm?
I had the same reaction, and so I looked it up to confirm, and yes-time would move slower at your feet, thus they would age slower than your head, and be “younger” than it. It’s easy to mix it up on-the-fly so he probably just misspoke.
Depends on how fast you move and also the spacetime curvature. Faster = age more slowly, slower = age more quickly; ‘deeper’ in a gravity well, age more slowly, less deep, age faster. To give a concrete example, your head is moving faster than your feet (at the equator, roughly 131,472,000 feet in 24 hours for your feet, 131,472,030 feet in 24 hours for your head, so your head is moving faster) *BUT* your feet are ‘deeper’ in the Earth’s ‘gravity well’ so age more slowly. The gravity well effect is stronger at the poles, no relative motion between feet and head. Someone with a very precise calculator would need to do the math to determine which effect would dominate where you live.
I can confirm that they repeated that statement at 1:01:34, but it seems backwards to me as well. If you are at an event horizon, time for you has effectively stopped. AI search tells me that GPS satellite clocks run faster than ground clocks by 45 microseconds per day. Time dilation by relative orbital motion is negligible compared to the gravitational effects.
@Alex why no body asks why clock will slow on hight? Does it changes physicality of watch ? What makes it slow down because watch's time is basically moving clock needles
The clock doesn't slow down. It just takes the energy of its ticks longer to reach you.
@@schmetterling4477 what does that mean ? Does that mean property of energy has changed ?
@@AjayKumar-uk4sp No, it means that spacetime is distorted. We measure the distortion of spacetime by the time it takes energy to flow from one clock to another.
@@schmetterling4477 thx, could pls give me any reference topic to understand this as i still not getting it and no body talks about other than saying slow down. Lets say if it is digital watch. What is it that it slow down ? Which energy we talking here.
Let say we are in very high speed and i have digital clock with me and start counting 1 to 100 , does it mean I will count more in same 1 minutes of clock compare to sitting on earth? If yes which energy we are talking here
@@AjayKumar-uk4sp A reference? As in a textbook about general relativity? I would suggest you read "Gravitation" by Misner, Thorne, Wheeler (MTW) and "Gravitation and Cosmology" by Steven Weinberg. There are many equally good newer books on the topic that I didn't use when I was learning. An electronic copy of MTW is online, so you can look at it right away. I think you will find that it's not an easy book to read, even though it's one of the easier ones. Part IX discusses experimental tests for GR (before 1972) and is a must read if you want to understand how we know what we know.
Which energy is slowing down? The energy in the signal between the two clocks. Everything in physics is about energy flow. A clock sends out a flow of energy that can be detected somewhere else. What changes under the influence of gravity is that flow of energy. It's not the clock itself.