The Biggest Ideas in the Universe | Q&A 21 - Emergence

[@seancarroll]

Erratum: I bungled the bit about Henrietta Leavitt and parallax. She actually used Cepheids in the Large and Small Magellanic Clouds, which she (correctly) assumed could be treated as being located at approximately the same distance.

[@ivannogolica364]

please talk to David Deutsch :)

[@jayenvaghani4783]

C sq

[@savage22bolt32]

So funny. I thought I heard my neighbor's cat outside my window, so I paused the video and the meowing stopped. I restarted the video, and to meowing did too! (Around 14:00)

[@krzysztofmekwinski8620]

If I saw this video six months, I wouldn’t understand it at all. Thanks to 4 months of watching “big ideas” I could understand it! Amazing! I am a bit proud of myself . But it is not me, it is Sean beeing such an amazing teacher ! Thank You!

[@stepananokhin693]

Sean, THANK YOU SO MUCH! The most thought-provoking series on youtube I've ever seen.

[@alex_madeira]

Fascinating - This is the most interesting episode so far in what I think is the best series on the internet. Sean is a wonderful Nestor!

[@rhondagoodloe3275]

Sean, Thank you again for this series. Going to really miss it when it is over.

[@pizzacrusher4632]

IT MAY NOT BE OVER!!! haha no ending!!!!

[@paulc96]

This arrived a bit too late on Sunday evening here in Wales, so watching on Mon morning instead. And of course, many, many thanks again Professor Carroll, for this truly wonderful series. Please don't stop. Keep them coming. Thank you.

[@GiordanoGaudio]

Hi Sean! I'm an 3rd year undergrad in physics and mathematics up here in Canada and I'd like to poke a little farther into Mad Dog Everettianism. So basically, it seems like regardless of if you start with fundamental time or not you always have the elements of the hilbert space being dependent on some scalar quantity (functionaly) in such a way as to have derivatives. So correct me if I'm wrong but you are always implicitly assuming somethings about the original hilbert space. Namely that it is some subset of functions from the real numbers to some C1 manifold. Moreover since these are functions it seems natural that you also assume they are at least L1 (L2 is usually assumed for quantum mech). The reason I bring this up is because it makes Mad Dog Everetianism seem like a bit of a misnomer. E.g. your not saying all that exists is a Hilbert Space and a Hamiltonian, instead your saying all that exists is a specific Hilbert Space of C1 and L2 functions. Is this an escapade assumption or are we necessarily confined to functional hilbert spaces? Thanks again for this fantastic series and not shying away from the mathematics. It's always a pleasure to watch them.

[@vector1classified685]

Finally...finally I've found an almost endless amazing listening series after series, awesome stuff Sean, been looking a very long time for a site like yours, very, very apprietted sir'

[@rc5989]

Really enjoyed this glimpse into cutting edge theoretical research. It’s like a tasty treat as reward for following along with all the previous videos in the series.

[@jeremyspayne]

I listen to you a lot. You broke new ground here for me with respect to the relationship between eigen states and symmetry and duality. Mind blown 🤯

[@jcughan]

Sean, when you’re done with this series, please do another one. I don’t care which topic or ideas you cover, I just need more. I don’t want this to end.

[@tanvach]

Thank you for continuing to post these videos. They are so packed with amazing concepts and insights!

[@PavlosPapageorgiou]

1:06:00 You're working on the most interesting question in all of physics, which I think is this: Not what our world is actually like, but of all possible worlds in the most general sense, what properties are the ones that yield a world with evolved beings like ourselves.

[@spnhm34]

I think an intro to the emergence of spacetime is fascinating and welcome

[@James_Stewart]

Surely I'm not the only one finding this walkthrough more intuitive than the emergence video

[@LearnedSome]

Another great lecture and Q&A followup. I'm learning so much! Also, nice strong finish to this one. :)

[@traruhsynred3475]

This discussion of emergence of space and possible time reminds me of the Heisenberg picture of QM in which the time dependence is put in the operators and wave-function is static/fixed. Schrodinger picture seems more intuitive and so that pretty much what is taught, but many Hesenber picture might lead to a different way of thinking about them. How would one talk about Everett interpretation in Heisenberg's way? Would operators 'split'?

[@nathanokun8801]

Dividing things up in the universe starts with a low speed limit to make sure that all "computations" in one area are complete before the next area's computations from the same source begin: the "processor's cycle rate" of determining all physical interactions (angles of balls away from a cue-ball hit, etc.). This would also seem to prevent velocity-based faster-than-light travel within the universe, but perhaps not hyper-jumps through an "exterior" space from one point inside our universe to another, since in that case no computations need be made in-between and the two events (going and coming back somewhere else) can be considered independent events with no cause/effect having to connect them. Causality is the big no-no in time travel or faster-than-light motion, so this seems to bypass that argument.

[@Chirality452]

I think you addressed my question (or Sergey Novikov's) and big surprise it is your current area of research. I think you may well be on to something very significant. I need to watch this again! Bui if gravity is the geometry of space-time and that geometry is an emergent phenomena of quantum mechanics that would avoid the renormalization problem of quantum gravity.

[@apollion888]

I recognize that it's English but we have clearly reached the limit of my understanding. On my list of favorite physicists, you have moved above Lenny Susskind, in case you need an ego boost today 🙂

[@ivocanevo]

I'm very happy about your web site glitch because speculative stuff is way more exciting... Especially from a trustworthy source 🎉

[@PavlosPapageorgiou]

1:08:47 Time is a measure of distance in some abstract space. It doesn't flow, it's just a metric. We flow, or rather we're an extended structure in this abstract space and our structure feels the flow of time because of certain relations like there's more hydrogen periods in a heartbeat or more paths to the future than the past.

[@MrPythonnn]

wow wow wow This Clip is truely master piece Sir. you put back Wheeler-DeWitt in their righteous place consistently and coherently. You explain emergence of time , emergence of space. You put network theory in quantum gravity fittingly like jiggzaw puzzle. you called back not popular Entropic gravity in light. If you can coherently put back Lorentz symmetry in the future , this will be most meaningful quantum gravity and theory of everythings as most call it. I hope u can acheive it Sir although it will be the most difficult job to make it in detail.

[@JohnDlugosz]

"We'll see in the future if time is not real" Good place to stop.

[@Fasgorn]

In my branch of multiverse, you are the best physicist philosophist 👍🏻

[@Petrov3434]

Thank you for great lectures !! A comment on the courageous genius-mathematician Roger Penrose, if I may: Roger wrote / published his book on conscience and quantum mechanics (QM) in 1994. He developed his hypothesis and detailed mathematical arguments for QM's role -- the intriguing idea about microtubules came late in the process via anesthesiologist Stuart Hameroff and he used it as "placeholder" there. In all later interviews and books he maintained his analysis and proposition for QM role but expressed increased skepticism about microtubules (which, on the other hand, are indeed astonishingly impressive in their own right). So -- a correct description for Roger Penrose's position is that he maintains that QM must play a major role in "conscience" via a mechanism not understood yet (microtubules or not). I believe Penrose will ultimately be proven right -- as usual. I am still struggling with his 2004 seminal book "The Road to Reality" in which he more explicitly clarifies his position on the above and other physics and cosmology subjects. (Characteristically for Penrose -- in it, once again, he opposes in detail the current universally adopted orthodoxy about Alan Guth's cosmic inflation in first trillionth of a second after Big Bang -- which he considers mathematically as nonsensical to achieve such inflation objectives)..... Best regards -- with immense gratitude for your efforts

[@JohnDlugosz]

I saw Penrose "live", when I attended his lecture on how consciousness must be non-classical because humans can solve "incomputable" problems. This was just after his earlier book than the one you mentioned, "The Emperor's New Mind: Concerning Computers, Minds, and The Laws of Physics" 1989. 30 years of continued research has upheld the view that there is no need for anything beyond normal computation in the workings of the brain. The best (only, really) explanation I've heard is an analogy. There is no algorithm that can determine a car's VIN from its license plate number, or vice-versa. They simply were not mapped via a mathematical process -- the people at the DMV make such assignments that are "not computable" but don't need QM to do so.

[@nadrieril]

Thanks for another amazing video! There are two things you said about time that felt weird to me: The first is that the way you describe how time could emerge looks super naive compared to how you spoke about space. It is as if you had said "for space to emerge, we assume that there is a subsystem that tells you where you are in space". Clearly the story is way more subtle for space, why would it not be so for time? If time and space are expected to be on an equal footing, I'd expect that they emerge together from the geometry of entanglement entropy like you described. I'm super curious to know why you favored the more 'naive' approach there. The second thing that surprised me is that you said the timeless Schrodinger equation should be H psi = 0. This is equivalent to saying that psi is an eigenvector for the eigenvalue 0. That's a strong assumption on the Hamiltonian, right? Why not have psi just be the ground state (or any other eigenvector)? It would still not be evolving with time (modulo global phase), but now all the mereology should still work and no extra assumptions on the Hamiltonian would be needed. Is there a deeper reason for choosing 0 there?

[@TheJasonJoslyn]

Hello Sean, I love this series! I have a question about "Strong Emergence". What if instead of there being a subset of a circle where the Macro has its own rules that are not a part of the Micro, we were to say that those Macro rules that aren't "just the micro" are irrelevant to the micro. Not violating them but also not impacting them in any significant way? For example, in radio everything that happens is completely specified by the micro rules. Except the informational content of the audio signal produced. It doesn't violate or go beyond any rules of electromagnetism or electricity for the signal to speaker action to playback talk radio vs classical music. But as a Shannon information system, the forms that come across the signal may be more or less surprising. So the formal or Informational content could be a "macro" property with its own meaningful rules that are not completely specified in the micro systems. But they also don't violate them. They are essentially irrelevant to the microstate and don't change the microstates complete description of that part of the total system. This might relate to David Bohm's idea of "Active Information". Do you think that this scenario is a valid example of "Strong Emergence"?

[@null_carrier]

Time is real, got it!

[@micronda]

Time is real but does't exist until I measure it. The time I measure is relative time, which I can convert to spacetime. I can then use quantum entanglement, to ask 'The wave function of the universe', to synchronize my spacetime, with absolute 'multiverse' time. #Job done.

[@davidsteinke6581]

Love the photomicrograph of the brain’s information inbox: hippocampus/dentate gyrus. Thanks. Dentatedave

[@RKarmaKill]

Sean Carroll got a haircut! Notify the universes!!

[@SteelBlueVision]

What?? Heretic of Everettian theory! He didn't get a haircut in all universes!

[@christinley5213]

I'm back lol..got sum catchup ta do lol. Sean Carroll...you are always working so dam hard..just want ta tell ya good job and keep up the amazing wrk!!! Your inspirational!!

[@SeanGonzalez]

Is there a discord server or virtual space where people continue to discuss these topics in whatever detail they like?

[@anirudhadhote]

❤ Very good 👍🏼

[@michaelwrenn4993]

Thanks to your generosity and courage to parse physics in a public forum, I have the privilege to witness someone with ample know-how, scrub Hilbert space with a Hamiltonian to explore for emergent properties of time. Using my own, far less competent knowledge and command of quantum properties, I see no hint that time and gravity do or can have quantum substrates. I am compelled by notions of time and gravity that renders them both inherently and purely continuous. I think they cannot be truly represented on a number-line unless the numbers are smeared together and useless. Long before quantum mechanics was discovered, great mathematicians performed wonders with numbers. I was intrigued and aided in my understanding of calculus by the delta/epsilon view of approximations. Numbers are inherently quanta. Isn't it possible that a line in its purest form is not an expression of quanta, but is indivisible, as time and gravity appear to be? Our clocks divide time into useful quanta. At this time, I am hard on the trail, too, hunting for something deeply hidden. My trail is only quantized by the steps I impose upon it.

[@JohnDlugosz]

Discrete does not mean pixelated. Consider that familiar QM with quantization is basically a way to make something with a smallest scale _appear_ continuous: e.g. a single photon still behaves in a manner you attribute to waves. So, as a simplest possible example, suppose that your "space" is composed of positions 1, 2, 3, ... and is not further divided. *But* , the wave function has complex, infinitely continuous, coefficients. So the probability of finding the object at a particular spot can smoothly and continuously evolve from a peak at 1 into a peak at 2 etc.

[@pilliozoltan6918]

If a wormhole exists, what is the volume of that space which includes one end of the wormhole? And what is the maximum entropy in that volume? Is it a maximum based on it's surface, when there is a potentially infinite universe at the other side? :D

[@pilliozoltan6918]

If area is proportional to entropy, and entropy increases in irresponsible processes, that means space must expand when irreversible process happens. Or vice versa.

[@flowtoolz5554]

The subjects are super intriguing. But I can't truly follow, even with a master degree in computer science 🙈

[@drzecelectric4302]

Hahaha I love it. “That’s exactly wrong”

[@TheSanmanju]

This program of deriving space and time in kind of a discrete decomposition of H as a network and the clock and all of that, reminded me of the Wolfram program for the ´theory of everything´. I know it´s been really criticized, but do you think that the algorithmic approach to time and evolution equation for the universe has some connection with what you talked about in this video? I´m a math PhD student. The only physics I know is from this youtube series, so sorry for the naivety.

[@thijsh.1565]

Is this a rehearsal for your talk on Tuesday 😋?

[@JohnDlugosz]

0:36 but of the Hamiltonion's that have a local partitioning, why would they have to be the same everywhere? A random collection of nodes and edges will describe 3 dimensional space _here_, a patch of 4-d space _there_, disconnected islands of all types, etc. It doesn't make sense to explain isotrophic smooth space existing _because_ every point in space happens to be properly connected to its neighbors to form a 3D mesh. What if just one were out of place? Rather, it needs to be some principle that applies to the nodes as a collection.

[@SonGoku-oe8mf]

Can you talk about higher dimensions?

[@viewer3091]

Why does the Universe show us the Wave function in the Double Slit Experiment in either ( well one ) situation i.e. When we don’t look ! ! Is the Universe showing off by showing us evidence of the wave function when we don’t look at the two slits ? ?

[@gilbertengler9064]

Just excellent. Many thanks. A general question: if the multiverse exists ( pocket universes à la Alan Guth), is the one wavefunction of the universe present in all these universes or only in our universe? I guess probably only in our universe!

[@barefootalien]

As I recall, Guth's version of the multiverse is one of eternal inflation. In that model, combined with Many Worlds, I believe what would happen is that there is one enormous wave function of the entire multiverse; then as new bubble universes nucleate, portions of that wave function would 'pinch off' in a way that's somewhat but not precisely analogous to branching of the wave function. As they pinch off, likely the vast majority of possible Hamiltonians would become closed off in favor of one Hamiltonian per universe that gives rise to that bubble universe's particular laws of physics. Ultimately it's likely to end up with the same fundamental problem that eternal inflation always comes under criticism for: it doesn't really answer much of anything, just sort of "passes the buck" so to say. All the same questions about what began this universe, why it behaves the way it does, etc are simply passed on to "What began the multiverse, and why does it behave as it does?" It does partially solve the fine-tuning puzzle... but then I suspect as we learn more about the inflationary multiverse, we'll come to find that it, too, is incredibly finely tuned to be able to produce universes that are tuned to create and support complex life. I'm of the opinion, however, that the fine-tuning puzzle is totally a non-issue. Our universe actually isn't very well tuned to create and support life at all, from the look of things; at least, not intelligent life. Almost all of it is incredibly hostile to life, in fact; only one place in the entire thing is known for sure to support life, and in the grand scheme of things, Earth is rather tiny. Even if as many as half of all planets can support life, that still leaves an infinitesimal fraction of the universe's total volume able to support life, with more zeroes before the first non-zero decimal place than I can probably fit in this comment, as a percentage. Also, no offense meant to Alan Guth, but every time I hear his name, I first think of Richard Gott, and then feel a wave of mild disappointment, since Gott is one of my favorite scientists to listen to and I wish he did so much more speaking than he does... Am I alone there? XD

[@gilbertengler9064]

Thanks

[@gilbertengler9064]

I have a problem with the concept of information. There is a tremendeous information stored in our molecules to be able to build up a living system. When you die, this information is in a relatively short time gone! Where goes this information? I have the feeling that the information content is not really changed. Even when all the molecules in our body would become randomly distributed, a particular random configuration is at the microscopic level as unique as a configuration that allows life! Its just ( for us) a less interesting configuration! It just depends on what you mean by specific. Please help me out of my misconception!

[@fredeagle3912]

Call it ‘wild dog’ . I don’t like mad dog. Any idea of how to test these ideas? An experiment?

[@davidcampos1463]

You mean that the quality of being logical and consistent is not much more than at arms reach. If you try to back track anything, you will need mechanics and emergence...and a whole lot of flexibility.

[@FalkenVDP]

Haven't caught up yet, just wanted to say nice haircut!

[@MrPythonnn]

by the way Sir , H= h- i d/d lambda looks like some sort of Guage transformation or simply transformation. I dont think it is coincidence.

[@rickharold7884]

Awesome

[@epiphyte8646]

Any chance you could explore the connection between economics, astronomy and physics? Isn't there a connection? Economics is all about how things are ordered, which is a function of interactions/influence. Naturally it is instinctual to want to improve the order of things...

[@sagmilling]

I hope there is no connection. Economics is "the madness of crowds" after all, just an emergent property of a large set of moneys with credit cards.

[@epiphyte8646]

@@sagmilling you take a crowd and have them vote to determine the order of something, such as KZbin videos, and the resulting order will be different than if the same exact crowd had spent their money.

[@JaskoonerSingh]

I wish I was as smart as Sean Carroll

[@johntavers6878]

I wish I WAS Sean Carroll

[@readingRoom100]

@@johntavers6878 if u had a wish to begin with, u could've wish for much better lol

[@devekhande9204]

Sooraj Pancholi is emergent in every CCTV footage.

[@protoword10]

I watched almost all your lectures on top of your podcast and I remember when you said somewhere in some of your lectures last or before last year: Higgs boson is not god particle anymore, because it has been found! I liked that joke of yours, because I’m atheist myself also, but here is new chalenging question to be considerd: Is entanglement god’s comuniacation?

[@JohnDlugosz]

A physics joke: A Higgs Boson walks into a Catholic Church. The Bishop happens to be visiting, and greets the newcomer, but not with a welcome! "So pretentious, calling yourself the "God Particle"! You are not allowed in here." The Higgs Boson just looks dismayed, and responds, "If I'm not allowed in, how can you have mass?"

[@protoword10]

John Długosz LOL 👍😂👍 Thank you for joke!

[@nancymatro8029]

lots of interesting comments and questions, it's too bad that you don't answer some of them.

[@Toefuy]

You could say that you are me. I could say you are me. I am me and you are you. Then I would go to end of the being. Then you would go to the other end of the being.You would still be me being you. I would still be me being you. There is no where you or I can go an not be you or me. You can not leave the space you are in and I can not leave the space I am in. You can go afar from me. You can take different ways than me.You can come at me from any way you like. Meet up with me. Can you become me? Is that up to you or me? It seems that it would be up to you and I if we wanted to become one another.

[@barefootalien]

So with regards to the Quantum Eternity Theorem, joke or not... wouldn't it be the case that it is only time _as a metric_ that goes from -∞ to ∞? It seems to me that time as a phenomenon is under no more obligation to occupy the entire possibility space of its metric than x is under an obligation to go from -∞ to ∞. x as a metric is also infinite, yet the universe could be finite, so why does the appearance of t in an unbounded equation in any way imply that time itself as a phenomenon is unbound? Also... I sincerely do not comprehend how you could be a block time believer and also a Mad Dog Everettian. The Hilbert-sub-universe ⊗ Hilbert-sub-clock version of emergent time sure seems a lot like block universe, yet you admitted it makes a Mad Dog Everettian sad, and is problematic.

[@Hakor0]

Locality Of Velocity Energy

[@Im-just-Stardust]

Sean please reassure me, Ariel is fine ? he seem's too quiet lately.

[@johntavers6878]

dont check or you might kill it

[@JaquelineVanek]

that is frustrating, you never write on cloth

[@aplacefaraway]

Careful Sean, there are some birds right above your head.

[@rktiwa]

Now you look good.

[@lordcrayzar]

Wordpress is a pain!

[@TheSilentWhales]

10:13 Kitty?

[@alfiangunawan5946]

YES

[@alfiangunawan5946]

12:22 too

[@Amateur2k]

second

[@MissEviscerator]

Well, we're not in Kansas anymore...

[@johntavers6878]

yes we are Amber. in a cornfield. in Kansas.

[@MrPDTaylor]

First

[@MattiasEliasson74]

Second!

[@Toefuy]

40:40 48:48 53:53 58:58 1:07:17 1:10:20 Hahahaha What are "we" trying to make?

[@cdgt1]

It appears that physics is just people with educational degrees playing with their Spiro-tot and throwing dice.

[@johntavers6878]

wow physics debunked.