Erratum: As a couple of people have pointed out, there should be an additional factor of the complex conjugate of the wave function in the expectation value formulas 48:00. See e.g. en.wikipedia.org/wiki/Expectation_value_(quantum_mechanics)
Even if I had never encountered the concept, I had a hunch there was a typo in that point in the video: we're computing an expectation value and the (real nonnegative) probability distribution is |ψ|^2, not ψ (which by the way is complex).
The ovals above representing theories are also part of reality existing in minds, papers, books, etc. It doesn’t make sense to draw those ovals outside reality, even if they are completely false.
A little after 4 pm here in Wales, and I just got back from a visit to the Dentist. What better way to take one's mind off sore teeth & gums, than a new episode of Biggest Ideas with Doctor Sean. Thanks once again Prof. Carroll, for making the World a better place - or one of the Worlds, anyway !!
Sean "never makes a talking mistake" Carroll. Perfect diction, tone & intelligence consistent over time in many, many informative cutting edge physics videos. Many thanks
I really wish advanced undergrad physics class include information like this. I think it's almost always worth it to have a basic understanding about how the subject of interest fit in to a bigger framework of physics
I wish this series was the basis of my college "physics for poets" course - the last physics course I ever took. In my high school physics course students threw pennies at the teacher.
Thank you Prof. Carroll. Your Mysteries of modern physics - Time, is one of the most mind bending audiobooks I've listened to. This feels like a good supplement to that. Learning physics is very motivating when trying to connect the big ideas to everyday reality and clearing up misconceptions.
Your self-criticized writing while talking has improved over the course of this series. It shows here especially. Been hooked since the beginning, and I'm always looking forward to new releases. Keep em comin!
I believe it was on an episode of Veritasium that a theory proposed in a peer reviewed paper says that, and I'm paraphrasing here, that life if an emergent property of entropy. The idea being that in the aggregate, entropy is more efficiently increased in the presence of life as opposed to the absence of life. If we look at the floor of a forest, the immediate impression is one of disorder, or to rephrase that, in a state of high entropy. Where as if you review the photographs sent back from mars via the various rover missions. The surface of the planet seems to be in a relatively low entropic state. For me this was a very important revelation as I've been wondering for several years now as to what property of the universe it is, that provides the needed systemic or environmental pressure so that life might emerge naturally upon a planet where the building blocks are readily available. We know also that our universe is expanding. And that this expansion is accelerating. Is it possible, that entropy is a naturally emergent property of that expansion? Measurement of that expansion has been rated at so many meters per megaparsec per unit of time. However, it seems to me that the only measurement we could actually produce a quantifiable acceleration is the acceleration experienced by normal matter we can observe. It seems only natural that spacetime, the fabric in which all matter resides, must be expanding and flowing past all the stars, planets, galaxies, etc. At a velocity that enormously dwarves the velocity we observe galaxies travelling outward from the center of the universe. An analogy to this would be a large object being moved slowly down stream by the rapid waters of a river. With only the compression or deformation of spacetime via the presence of celestial bodies of matter. Creating a kind of drag upon spacetime, that naturally transfers some of its kinetic energy to the normal matter of the mass in the universe. If this is true, then we have an answer to what dark energy is comprised. Additionally, we know that when massive objects travel through spacetime that the greater the difference in velocity the more massive the objects become. This is general relativity at work. So if spacetime is flowing past us, then does this not also suggest an answer to dark matter? As spacetime flows past galaxies, so to do the mass of neutrons and protons increase in a corresponding measure. This increase in mass being explained via the manifestation of quark/antiquark pairs within the structure of matter. Thus while locally the differential would be too miniscule to effectively measure, in the aggregate it all adds up. Thus making dark energy, dark matter, and entropy emergent properties of our spherically expanding universe. And yes I am aware that certain assumptions are in place in this description upon which we as of yet lack clear consensus. And there are additional ideas I've been kicking around lately concerning the interior of black holes, the big bang, our eventual heat death, and the ways in which multiple verses (as opposed to a universe. Differentiated from the multiverse idea by way of other verses not overlapping our own) eventually interact via massive gravitational waves which might be described as spherical shockwaves traveling outwards for all time. Eventually, if any other verses do, or have existed and have also experienced heat death, might not the interaction of these shockwaves produce ring verses of much smaller scale than our own universe? In other words these shockwaves intersect each other, and if in the aggregate there is sufficient energy, then perhaps torus shaped verses are the predominant form of verse formation. If this were true, and there were a sufficient number at a high enough density, then the overall universe might be something far more akin to the patterns we see produced on the floor and walls of a swimming pool when light shines through the waters surface and there are enough waves to produce seemingly random peaks and valleys. If this view of the universe at large is correct, then it also suggests an answer to the nature of the big bang. Within our uniformly expanding universe, newtonian laws of physics provide a means for the limitation to the amount of material any given black hole has access. This model however would be invalid in the swimming pool analogy. Suppose if you will that we have the presence of a black hole, in the relatively chaotic system of peaks and valleys, such a black hole might rarely have access to incredible amounts of matter upon which to feed. Presuming that such a black hole could feed until approximately an equivalent amount of energy to that present in our current universe. Then perhaps, via some mechanism this could produce an event such as the big bang. Just my thoughts and ideas on the larger picture of the cosmos. I hope you enjoyed reading this narrative. #endhatrednow
Your opening remarks, about how having a certain complexity causes things to happen that you never would have guessed, is a perfect explanation of why software is so difficult. And it also provides analogy to your vocabulary shift to a chunked-state representation: we discovered "metafunctions" in C++ templates, which were designed to provide parameterized types for making strongly-typed collections and the like. Turned out to be a Turing-complete language that developed its own idioms. That's an extreme example of how we strive to *tame* software: make it in layers, to produce a hierarchy of complexity. It's so hard to explain how to write "good" functions that express a _single_ level of complexity, and what we're trying for is just why "gas" is not wave packets: once you abstract over it, you need to stick to the items within the emergent description.
Dude is the finest science communicator out there, period. This Biggest Ideas series is absolutely phenomenal. He's in the absolute sweet spot of communicating these concept at just the right level of detail and sophistication for people who are huge fans of the natural sciences, but don't have the math/science backround to read and comprehend actual papers on this stuff. My top three: Sean Carroll, Sabine Hossenfelder, Jim Al-Khalili. I see anything by them I'm dialed in.
Thanks for the latest video --- I guess you must consider penning a book entitled "The Biggest Ideas in the Universe", with each video being a chapter, or series of smaller books with each book covering a single video!
Okay prof. You're too dang fast... and i love every second of it ... im okay thinking "this week im going to get this one in" boom another one and im like "shit! Im dumb, im dumb, im dumb... hurry up this is basic shit get on board its one hour" ... lol this series has taught me more with out being to over my head than anything else ive ever come across... honestly thank you for taking the time out of your day to make these... it means alot to ppl like me who were never brought up with science and never pushed to see how amazing it is ... so many times in the middle of it i realize i need to learn advanced things but i have my own life and so many times i feel i get the gists so thats good enough?!?... then here you come bridging the gap... it may be nothing to those who know but to me its a perfect balance ... idk if you will read this but you have taught me so much, just wanted to say thank you 🤷♂️... youre a good dude
Hi Sean, I've said it before but you are a legend for doing these, they have really helped me through this difficult time and I'm sure I'm not the only one.. I haven't been able to afford to pay yet but am buying your books 🙂
The centre of mass example being precious and the idea of being able to distil a massive amount of information to one small bit not being understood deeply is very interesting. These limits to understanding are never talked about in undergraduate physics.
Very, very exiting, impressive and inspiring! If only i could keep up..... will need to get your books and papers and watch all the videos again and again. Thank you for carrying us to the edge of the known reality which we once would have thought was well over the horizon. Kind of like the 'Beginning of Infinity' heh! We are all in your debt even if not anywhere close to your depth. Down Under
I'm sure this video is great but the gases/gasses thing just blew my mind. makes perfect sense now that I know but I don't think I had ever thought about or encountered that before.
As a physics (master) student in Leiden, I'm so sad I missed your Ehrenfest Colloquium in 2018. At the time, as a bachelor student, I only seldomly attended these because most of those lectures went far over my head. I've just watched the recording online, and I can conclude the same would have probably happened with your lecture. So in the end I'm kind of glad I have listened to it only now as a master student, after a QFT course and a whole lot more physics experience overall. It was definitely a great introduction to emergent gravity from quantum field theory, and I now also have a greater appreciation for Everett's 'Many World' interpretation. (If anyone else is curious, you can watch it here www.universiteitleiden.nl/en/news/2018/09/livestream-sean-carroll-gives-ehrenfest-colloquium by clicking on the livestream link at the bottom) I've really enjoyed your last few lectures of 'The Biggest Ideas'. Especially the one about Entropy gave me new insights and a more formal firmer grasp of the concept. In the past, I've mostly viewed Entropy as the Boltzmann entropy, with other versions as 'things that are the same, but different in interpretation'. Although I knew this to not really be true, I've never really looked into it and therefore never understood the other forms of entropy (nor, as it turned out, the importance as the concept as a whole.) I hope it can help me communicate the topic in a better way to students in the upcoming semester as a student teaching assistant for the 2nd year bachelor Statistical Mechanics course.
So the mumuration behind you would be many to one (course grained) ie lots of birds into one mummur. And I guess in that case heterostructural because the mummur has emerged from the starlings? I love your talks Sean. They help me sleep as well as fascinate me when I am awake. I love the pace and the tap tap tapping of the pen. On so many levels - thank you. Also, as someone who has been run over by a non-dual realisation, I find your talks very meditative. cheers mate. (:
Some people use the term 'reality' for that which is realised, i.e. within a 'mind' - and 'actuality' is what is actually 'out there' (outside of a mind) irrespective of the various perceived 'realities' of conscious beings.
I once played of MIT game 'space-wars' at Stanford coffee house in which there was a bug -- the force law was 1/r (measured it using ruler and watch) instead of 1/r^2 and one could not establish a stable orbit making the game unplayable. Orbits failed to 'emerge'.
You might want to call the "higher level" rules/laws/theories as "Meta-Laws/Rules". This is much like in chess: The rules governing the initial placement and movement of pieces is your "micro" laws and the basic concepts of strategy and tactics to actually play the game are the Meta-Rules. This keeps the two separate, since the Meta-Rules can vary in complex ways while the low-level rules are usually fixed/constant (speed of light, etc.;), as in chess.
That’s surprising but I’m not an academic so maybe I’m only used to the physicists like mr Carroll who speak to the lay person. Those types seem to go out of their way to preach humbleness.
The list of the biggest ideas is already fixed, as he said in a prior episode. I don't actually think string theory is actually a big idea. It's all theoretical that tightly fixes some problems we currently have but in a currently useless way since we can't actually test anything.
You can take approach to it as if classical definition was superior to quantum almost as classical cluster was a sum of all orders of magnitude. Then the clasical potencial describes reality that only matters and you treat wave even without intercepting the classical limit as a sort of partial integral of everything happening under the classical curve. I am sure you know how complex one must be to comprehend so much data at once. The classical limit is where we are rather we like it or not. The point is to eliminate all ignorance related to entropy but still be able to derive consequences of all this knowledge to fit to the classical potential slope and support it. Easy to say probably. With every next part of this series I see more clearly the awesomeness of the whole concept and I deeply appreciate it. Sadly it looks like we are very close to applying infinitesimal to this series. Therefore one must admit that much entropy was consumed over this grat treat marking the genius of its creator. Many thanks for that time.
I am waiting for a video where you lay out the frontiers of large scale experimental and observational physics like LHC, extremely large telescopes, James Webb telescope, ITER, etc and what questions they will try to answer.
I love the fact that, because of a worldwide disaster (Pandemic), we all get the opportunity to hear lectures from Nobel Laureates and people who are really at the cutting edge of their particular disciplines. There was previously no chance that AT THE SAME TIME, people like Sean, Brian Greene, Roger Penrose etc would be able to produce videos about their respective fields while the general public ALL have the time to take it in (whether we understand it or not is a different matter!!) So now, we have the "Perfect Storm". The experts have the time, the public have the time AND the technology is sufficiently advanced and available to allow this to happen. Thanks to the Coronavirus, those of us well enough can gain a whole lot of information. (Imagine if this had been the case in Einstein's time or even Newton's time!)
I notice the murmuration behind the professor. As an undergraduate TP student, emergence or how novel properties emerge from their lower counterparts (the sum greater than the parts) is something that has intrigued me for several years.
Two things. First, as somebody who doesn't believe in reality, I usually phrase it by saying that "reality is hypothetical"; this can be formalized. Second, starting at 26:30 or so, you're drawing *commutative diagrams* in some category! I approve but wish that you'd have said something.
Thx again, you have single handedly filled some major gaps I had in my education as a Chem E in the 80s. I have at least a glimpse of how we have gone from the predicting the familiar world around to the very small which only can see by the tools we have invented. Since my job was to phenomenology predicting the behavior of dry etch plasmas, this knowledge would have been particularly useful.
I have a question: *what would count as empirical proof of strong emergence?* ---- That many microstates give rise to the same macrostate is nothing new and certainly doesn't imply emergence; also, in the absence of an explicit derivation of the macroscopic law from the microscopic one, one could always say that we don't know how to perform that derivation *yet*, and not that such a derivation is impossible in principle. I think an empirical proof of (strong) emergence would be: showing a system for which the microstate doesn't determine the macrostate (which is a weird thing). Otherwise, if the microstate determines the macrostate, I'm persuaded that it follows that the microscopic law determines the macroscopic one (assuming the microstate is always well defined).
@@m.walther6434: I don't see any reason why that shouldn't be perfectly explainable in terms of elementary particles. There is no strong emergence in a flock of birds. Of course, in that case, you have to consider as system the whole flock, together with the air molecules between the birds, or even the whole solar system (since for example birds can be influenced by the direction of sunlight and of Earth's magnetic field).
Hi Professor Carroll and the rest of the physics community here on UA-cam. At around 34:30 - 35:00, you mention that we can describe the motion of a large object in the coarse-grained viewpoint by strictly analyzing the center of mass and that "none of [the] relative positions and velocities matter at all." My question is: if the Center of Mass M and its velocity v_{COM} are "emergent properties" of the system, then what about the angular momentum of the entire body, L? I believe that we need to consider the motion of the constituent masses relative to the COM to calculate the angular momentum of the entire body. Do we consider the angular momentum of the large body an "emergent property" of the system? Or was this example specifically to illustrate that the *linear* dynamics of the system are emergent just from knowing M and v_{COM}? Curious to hear your feedback, thanks!
Hi Professor Carroll - I'm not sure if you'll see this seeing as it's an "old video", but I figured I would ask. Would you be able to add reference textbooks (your favourite, or "the best", books on the subject) to your descriptions at some point? These videos will be invaluable resources for people interested in these topics for a long time, and a comment (from you especially) indicating where people could go for more info, whether more formal or otherwise, would be incredibly useful. Incidentally, it would also be a way to plug some of your books (thinking Spacetime and Geometry for your videos on GR). Thanks again for these amazing videos!
At 1:00:05 you talk about Hyperion not spreading into a blob of probability due to decoherence. I'm with you there. Then you go on to say specifically that it's being bombarded with photons all the time that are constantly observing it / branching the wave function of the universe. What about its own internal interactions? Thermal motion of its internal atoms, for example, or the constant electromagnetic forces caused by its various chemical bonds? This is something I've never quite gotten hold of with my mind... I've seen you answer this question several times, at the Royal Institution for one, and in a couple of other lectures Q&A sections, and what you said, to paraphrase, is roughly, "Not all interactions cause branching of the wave function, but there isn't time to specify which ones do and don't and why." Well... the upcoming Q&A video would seem to be the perfect opportunity! :D Did you just omit Hyperion's own internal observations of itself? Or do those interactions (or at least some of them) genuinely not cause splitting/collapse because of reasons? (Entanglement, maybe?) In either case, when *exactly* does an interaction branch the wave function of the universe, and when doesn't it? Or is it simply not well-defined due to something like quantum relativity? I seem to recall a passage in Something Deeply Hidden that mentioned that... but I think it was in the roleplayed conversation between father and daughter and less than perfectly clear. Still, something about what branches the wave function depending on frame of reference, maybe?
The material is an emergent property of the platonic, not the other way around. An adolescent cultural bias should not prevent a brilliant mind from seeing this. “It is clear that these physical-only processes somehow on the one hand give us the right answers, but on the other hand that they are controlled by another world of ideas somehow; they’re coming from somewhere else.” (Nima Arkani-Hamed--- theoretical physicist, permanent faculty at the Institute for Advanced Study at Princeton, and director of The Center for Future High Energy Physics (CFHEP).
@Sean Carroll Love your stuff. What program are you using on the iPad to do the chalkboard. I need that for my channel. Also ever heard of Linea Sketch?
I'm always wondering how QFT approximates (in the limit) F = ma, F = kq1q2/r2, etc. Does it actually work out, or are we thwarted by infinities in the calculation? Also, how can you even have r2 when the positions are uncertain? And is it possible to derive V(x,t) from a wavefunction in a coupled field? E.g. I know psi of electron, can I then calculate V(x,t) for the photon field, or vice versa?
With respect to bosonization, the kinks and anti kinks seem to represent particles, but also excitations (at least in sine gordon where particles are changing state). Is it then useful to think about the kinks as quasi particles like phonons for example? And is this a different kind of emergence, when the collective behavior of interacting particles seem to create excitations that also look like particles?
A question: As quantizing both the classical theories of Sine-Gordon and Massive Thirring gives rise to a relationship between fermions and bosons in a single quantum theory, would there be any sensible connection to be made with supersymmetry, given that supersymmetry also reflects a relationship between fermions and bosons?
What a coincidence, two days ago I was talking to some friends about the nature of consciousness; arguing that I truly believe it is an emergent property of living matter. You mentioned consciousness briefly in this video but do you have any further thoughts on this?
Also please check this out. Ancients could appreciate the philosophical conundrum of the problem of other minds, but now as reductive physics comes closer to explaining all of my neighbor's behavior, I have less reason to believe that he even has consciousness... If consciousness doesn't *do* anything, that means there is no evidence for it. ua-cam.com/video/YZaHG1eh4-A/v-deo.html
Quasiparticles and theories which are using them are good examples I think. How the lack of an elektron could act like a partical and simplify the description of the system. Or an excitation could act like a partical. Or the excited electron and the empty lower energy state could act like a partical-antipartical pair.
The last few diagrams put me in mind of something that is maybe not the same as Strong Emergence, but looks a lot like it, and (IMO) does happen: your micro theory is incomplete, its domain is not all of reality, and you have a macro theory that works for some parts of reality where your micro theory doesn't. Then the macro theory might make accurate predictions that the micro theory can't, but only because you are in a situation where you can't, or shouldn't, use the micro theory anyway.
Question: If theoretically there are a semi- infinite number of 'spectacle-like' theories through which 'reality' can be faithfully observed BUT each have individual limitations, will it ever be possible to see the total of reality except by somehow discovering and then combining all such theories? Would this not be a semi- infinite or infinite venture? Or are we nearly there yet? Thank you for your amazing work.
Do any of your videos discuss theories that attempt to explain the behavioral and sensory changes that occur when, for instance, hydrogen and oxygen combine to form water? Some people think that phenomenon such as this will never have a mathematical explanation and the ensuing emergent properties of water, for instance, could never be predicted, but can only be learned from experience.
Is it possible to quantify or rigorously define how “simple” or “efficient” a theory is, maybe in terms of information? You didn’t explicitly mention Occam’s Razor but this seems implicit in the fine-grained, homeostructural category and maybe for the others too
Thank you Professor Carroll for a wonderfully informative series. My question is (I have many but I'll settle with this one): Are there any hypotheses down the lines of the reason for emergent properties/theories being possible because of the necessary fussiness of quantum mechanics (QM) measurement? Or put another way, are there hypotheses that map the apparent necessary ambiguities of QM to existence emergent properties or theories? Or, in the broadest sense, are their any proposed ideas (from scientists, I'm sure philosophers have many proposals) at all on reasons for the existence of emergent properties?
Dear Sean You talk elsewhere about spacetime being emergent and quantum mechanics being fundamental. I wonder the following: 1. The wave function is characterized by its length and amplitude, but don't they both require space as a precondition? What is wavelength and amplitude without space? 2. Boson and fermions are differentiated by their ability (or lack of) to occupy the same… space. Doesn't that mean that space is a precondition for their emergence? 3. Unless quantum mechanics describe a static unchanging state, if there is any interaction in the quantum world, doesn't that require time as a precondition? Doesn't any quantum dynamics require time as a precondition for their emergence? 4. If the quantum field is a harmonic oscillator, and all phenomena are merely disturbances to the harmonic oscillator, then: (a) don't you need a more fundamental cause of those disturbances? (b) where is the energy required for disturbing the harmonic oscillator coming from? Don't you need a more fundamental source of energy for the quantum field to be disturbed? All the best
In the Q&A video, could you talk about the difference of "throwing away" information vs "compressing" the information? As an example, is calculating the center of mass of the earth not compressing the information of all the individual particles? (vs. throwing that information away)
You can’t reconstruct the mass and position of the individual particles from the center of mass so that information is lost. Compressing usually means that all information can be restored, which is therefore not the case.
Chris Stewart But even lossy compression has an error margin that is ideally small compared to the total size. For the center of mass it doesn’t matter how large or complex the system is, you always only get one point as the result. In other words, infinitely many different systems can lead to the same center of mass so it’s impossible to infer any more data from it i.e. decompress it.
@@chrisstewart4288 But lossy compression DOES throw information away, so it makes no sense to ask about the difference of "throwing away" information vs "compressing" the information if you mean lossy compression.
I thought Emergence was essentially a phenomenalogical proposition. 'As above, so below' Co or mutually generative. So, the big question is: what emerges? A better model or concept for reality.
I didn't fully get the interaction between quantum and chaotic behaviour for Hyperion at around 1:01:00. I always just assumed chaos and quantum indeterminacy were separate realms but this is very interesting
Given the correct combination of atoms and molecules plus the right energy conditions in normal space, a pizza could strongly emerge from an oven ? Whether it is allowed pineapple or not remains a deep mystery.
“Two possibilities exist: either we are alone in the Universe or we are not. Both are equally terrifying.” - Arthur C. Clarke I feel the same sentiment towards Strong Emergence - which happens in reality or does not. Either way, it boggles my mind. To believe, understand, and possibly know that each of us is only a smattering of nougat within a colossal wave function and derivable from a quantized, basement-level particle physics seems irreconcilable with our subjective conscious experience. But what is the alternative? Invoke some goofy analog of the luminiferous aether?!? Science peters out around the edges (presumably because we're not done yet), but its core principle of reductionism is not soft around the edges - it's as crisp and well-defined as the monolith that mesmerized our ancestors in Clarke's 2001: A Space Odyssey. I'm particularly taken by the example of the 3+1 dimension Conformal Field Theory (CFT) being the boundary condition of a 4+1 dimension Anti-de Sitter (AdS) space. Makes me wonder if there's a philosophical analogy to be had - like abstract objects being a lower-dimensional boundary condition of the concrete. For example, many philosophers believe that number is the essence of quantity - that numbers are mind-independent objects and that a description of reality would be incomplete without their inclusion. Perhaps this so-called essence is profitably thought of as a lower-dimensional boundary condition. But so far, going from AdS to CFT seems more straight-forward than the other direction. It feels far easier to agree that gravity in AdS doesn't imply any contradiction within CFT, but I don't quite see how gravity is to be inferred from CFT - and it must be inferred if the emergence is to be weak, right? (It feels even stranger to suggest that an abstract object infers a concrete object. What's next - inferring an ought from an is?!?) Finally, is there any limit to the chain (or web) of inference? Is the 4+1 AdS just a boundary condition for a 5+1 Something Else, with another spectacular reality like gravity popping out from it? It's like turtles all the way up - like we could synthetically generate a never-ending progression of knowledge. Anyhow, I think it was essential for Dr. Carroll to broach the topic of Strong Emergence and I'm so glad he did. As a scientist, he's properly committed to naturalism and reductionism but also properly open to investigate a purported counterexample. He's making both science and philosophy better in the process.
Seems to me that central limits theorem is a origin of lot of emergence. If, e.g., the force between particles (and walls) was 1/d rather than faster fall off (2d case?) then pressure would not emerge as from averaging over a lot of collisions. Does that sound right?
What you bring up is something called curse of dimensionality, it says that length scale in different dimensions are disproportionately scaled. In your example, I think what is known as pressure may exist in arbitrary dimensions, but the magnitude of that decreases as the dimension increases.
What about General Relativity as an emergent theory of gravity where the standard model or an expanded GUT would be the micro-theory. Think of Sakharov's ideas on this. This gets around the pesky problem of quantizing GR by consider it as an emergent theory analogous to thermodynamics compared with statistical mechanics. The gravitational constant G would be derived from this micro theory and they gravitational field would be distortions of the quantum vacuum. In this concept gravity doesn't exist and the level of particle physics but emerges at the macroscopic level.
This clock has no moving hands. It is still a true clock describing real time, it is just that its domain of applicability is only noon. If you can make a correspondence between a particular sand heap and a mathematical theory of physics does that mean that the sandheap is a a theory of physics. How much of emergence is property of clever mappings between otherwise unconnected abstractions. Is reduction in the eye of the beholder?
Is ehrenfest’s theorem why in a bubble chamber, a particle leaves a trail that appears to be a particle on a trajectory? NVM, right after that you answered it
Isn't the measurement effect pretty much strong emergence? More accurately the Born Rule, which is not covered by the Lagrangian, that in principle applies to particles in mass via probability?
" *Gases* is written with one 's' and not two; I've written this word a thousands times " Welp. I felt that, because I've been spelling it *gasses* for my entire life....fml
I know the video is about weak emergence. But I am curious how Professor Carroll arrives at being a compatible-ist for free will, while being totally against strong emergence. I’m going to listen to his Mindscape Podcast with Dan Dennett again...
That's a pretty small idea on the scale of the universe. UA-cam exists only a fraction of the length of the universe and has very limited spacial influence existing only locally on Earth.
43:16 Fun fact: The name *"Ehrenfest"* sounds like a completely plausible German compound noun, meaning "festival in honor (of someone/thing)" - but this word does not exist. (I presume the name comes from the adjective "ehrenfest", meaning "honorable" - "fest" translates to "firm, sturdy" here instead of "festival", cf. "steadfast". But it's archaic and therefore not widely known even among native German speakers.)
I spotted a small mistake in minute 48:16. The formulas given for the expectation values of position and momentum (x-bar and p-bar) are missing the complex conjugate of the wave function inside the integrand (for p-bar, the derivative applies only to the wave function, and not to its complex conjugate). Also, not sure if hbar has been set to 1, but if it hasn't, p-bar should have a factor of hbar.
I am developing an emergent, mostly mathematical theory of cognition that is applicable to seemingly different portions of reality: nervous systems (of course), microbial life, genetics and epigenetics in the tree of life, immune systems... About consciousness and qualia, maybe they are emergent properties of cognition. I still don't know and have to think a lot more unless I get the kind of insight I had about cognition.
I have to make a comment about Strong VS Weak Emergence. Clearly all macro level reality is the result of the micro level reality. We don't need to run a simulation to see this as real life is a simulation that already shows this. However I don't think this is the point of advocating for Strong Emergence. The point of Strong Emergence is that the macro level reality is so far divorced from the micro level reality that for all intent and purposes it is as if the macro level reality cannot be computed from the micro level reality. So while technically Strong Emergence can't be true but in practice it is effectively true. Furthermore there is also another way in which Strong Emergence could be effectively true. You are correct to say that "the only way the micro doesn't build up to the macro is if the micro is wrong" (I'm paraphrasing). However it may just be that many of our micro models are always wrong. They are just wrong in ways that don't mess up predictions of micro phenomena. It is very possible for there to be things that are missed at the micro level that only become apparent at some macro level. For instance there could be numerous missing dimensions that are too small to be noticed at the micro level. Only when these missing dimensions come together in some consistent way through a particular macro phenomena, do they add up to anything observable. It seems to me that we would have to be very lucky for reality not to have any such "vanishing dimensions" at the micro level. If this turns out to be very common between micro and macro systems so that most of our micro models are wrong (just not in any way that impedes making micro level predictions) then this also effectively makes Strong Emergence true.
Question for Q&A: Regarding emergence, is spacetime something that needs to emerge from quantum gravity, or can it be skipped as long as you can describe its results?
Erratum: As a couple of people have pointed out, there should be an additional factor of the complex conjugate of the wave function in the expectation value formulas 48:00. See e.g. en.wikipedia.org/wiki/Expectation_value_(quantum_mechanics)
Respect Mr. @Carroll. Crispy as a nacho(s) but your kindness is emerging from a life dedicated to science.
@@ai._m That Stanford lecture was legendary. Just like what Mr. Carroll is doing as well
Even if I had never encountered the concept, I had a hunch there was a typo in that point in the video: we're computing an expectation value and the (real nonnegative) probability distribution is |ψ|^2, not ψ (which by the way is complex).
Fb: #lock3dinthesh3d
Dr Carroll I have a question regarding the incompatibility between GR and QM. Would you mind answering for me please?
When he does "silly things" is a reminder for us that he's human after all.
Love from Chile. Thanks for being such an amazing educator.
@CL CL I really don't want them to stop... we need bigger ideas!
@@aurelienyonrac Thanks ♡
Drawing a rough oval shape and saying "so, here's reality" is probably the coolest move a person can make.
Probably not
I understand.... ignorance will deny the oval
The ovals above representing theories are also part of reality existing in minds, papers, books, etc. It doesn’t make sense to draw those ovals outside reality, even if they are completely false.
A little after 4 pm here in Wales, and I just got back from a visit to the Dentist. What better way to take one's mind off sore teeth & gums, than a new episode of Biggest Ideas with Doctor Sean. Thanks once again Prof. Carroll, for making the World a better place - or one of the Worlds, anyway !!
Yay! Thanks, Sean. You absolute rockstar.
"Something Deeply Hidden" Dr. Sean Carroll, will be in my book collection, thank you so much for training us. ❤
I’m reading it. It’s brilliant
Sean "never makes a talking mistake" Carroll. Perfect diction, tone & intelligence consistent over time in many, many informative cutting edge physics videos. Many thanks
Sean Carroll is really a philosopher who does physics!
I think Newton and such considered themselves “natural philosophers” so it makes sense
I really wish advanced undergrad physics class include information like this.
I think it's almost always worth it to have a basic understanding about how the subject of interest fit in to a bigger framework of physics
I wish this series was the basis of my college "physics for poets" course - the last physics course I ever took. In my high school physics course students threw pennies at the teacher.
Thank you Prof. Carroll. Your Mysteries of modern physics - Time, is one of the most mind bending audiobooks I've listened to. This feels like a good supplement to that.
Learning physics is very motivating when trying to connect the big ideas to everyday reality and clearing up misconceptions.
Your self-criticized writing while talking has improved over the course of this series. It shows here especially. Been hooked since the beginning, and I'm always looking forward to new releases. Keep em comin!
I believe it was on an episode of Veritasium that a theory proposed in a peer reviewed paper says that, and I'm paraphrasing here, that life if an emergent property of entropy. The idea being that in the aggregate, entropy is more efficiently increased in the presence of life as opposed to the absence of life. If we look at the floor of a forest, the immediate impression is one of disorder, or to rephrase that, in a state of high entropy. Where as if you review the photographs sent back from mars via the various rover missions. The surface of the planet seems to be in a relatively low entropic state. For me this was a very important revelation as I've been wondering for several years now as to what property of the universe it is, that provides the needed systemic or environmental pressure so that life might emerge naturally upon a planet where the building blocks are readily available.
We know also that our universe is expanding. And that this expansion is accelerating. Is it possible, that entropy is a naturally emergent property of that expansion?
Measurement of that expansion has been rated at so many meters per megaparsec per unit of time. However, it seems to me that the only measurement we could actually produce a quantifiable acceleration is the acceleration experienced by normal matter we can observe. It seems only natural that spacetime, the fabric in which all matter resides, must be expanding and flowing past all the stars, planets, galaxies, etc. At a velocity that enormously dwarves the velocity we observe galaxies travelling outward from the center of the universe. An analogy to this would be a large object being moved slowly down stream by the rapid waters of a river. With only the compression or deformation of spacetime via the presence of celestial bodies of matter. Creating a kind of drag upon spacetime, that naturally transfers some of its kinetic energy to the normal matter of the mass in the universe. If this is true, then we have an answer to what dark energy is comprised. Additionally, we know that when massive objects travel through spacetime that the greater the difference in velocity the more massive the objects become. This is general relativity at work. So if spacetime is flowing past us, then does this not also suggest an answer to dark matter? As spacetime flows past galaxies, so to do the mass of neutrons and protons increase in a corresponding measure. This increase in mass being explained via the manifestation of quark/antiquark pairs within the structure of matter. Thus while locally the differential would be too miniscule to effectively measure, in the aggregate it all adds up. Thus making dark energy, dark matter, and entropy emergent properties of our spherically expanding universe. And yes I am aware that certain assumptions are in place in this description upon which we as of yet lack clear consensus.
And there are additional ideas I've been kicking around lately concerning the interior of black holes, the big bang, our eventual heat death, and the ways in which multiple verses (as opposed to a universe. Differentiated from the multiverse idea by way of other verses not overlapping our own) eventually interact via massive gravitational waves which might be described as spherical shockwaves traveling outwards for all time. Eventually, if any other verses do, or have existed and have also experienced heat death, might not the interaction of these shockwaves produce ring verses of much smaller scale than our own universe? In other words these shockwaves intersect each other, and if in the aggregate there is sufficient energy, then perhaps torus shaped verses are the predominant form of verse formation. If this were true, and there were a sufficient number at a high enough density, then the overall universe might be something far more akin to the patterns we see produced on the floor and walls of a swimming pool when light shines through the waters surface and there are enough waves to produce seemingly random peaks and valleys.
If this view of the universe at large is correct, then it also suggests an answer to the nature of the big bang. Within our uniformly expanding universe, newtonian laws of physics provide a means for the limitation to the amount of material any given black hole has access. This model however would be invalid in the swimming pool analogy. Suppose if you will that we have the presence of a black hole, in the relatively chaotic system of peaks and valleys, such a black hole might rarely have access to incredible amounts of matter upon which to feed. Presuming that such a black hole could feed until approximately an equivalent amount of energy to that present in our current universe. Then perhaps, via some mechanism this could produce an event such as the big bang.
Just my thoughts and ideas on the larger picture of the cosmos. I hope you enjoyed reading this narrative. #endhatrednow
Your opening remarks, about how having a certain complexity causes things to happen that you never would have guessed, is a perfect explanation of why software is so difficult.
And it also provides analogy to your vocabulary shift to a chunked-state representation: we discovered "metafunctions" in C++ templates, which were designed to provide parameterized types for making strongly-typed collections and the like. Turned out to be a Turing-complete language that developed its own idioms. That's an extreme example of how we strive to *tame* software: make it in layers, to produce a hierarchy of complexity. It's so hard to explain how to write "good" functions that express a _single_ level of complexity, and what we're trying for is just why "gas" is not wave packets: once you abstract over it, you need to stick to the items within the emergent description.
Dude is the finest science communicator out there, period. This Biggest Ideas series is absolutely phenomenal. He's in the absolute sweet spot of communicating these concept at just the right level of detail and sophistication for people who are huge fans of the natural sciences, but don't have the math/science backround to read and comprehend actual papers on this stuff. My top three: Sean Carroll, Sabine Hossenfelder, Jim Al-Khalili. I see anything by them I'm dialed in.
Thanks for the latest video --- I guess you must consider penning a book entitled "The Biggest Ideas in the Universe", with each video being a chapter, or series of smaller books with each book covering a single video!
Okay prof. You're too dang fast... and i love every second of it ... im okay thinking "this week im going to get this one in" boom another one and im like "shit! Im dumb, im dumb, im dumb... hurry up this is basic shit get on board its one hour" ... lol this series has taught me more with out being to over my head than anything else ive ever come across... honestly thank you for taking the time out of your day to make these... it means alot to ppl like me who were never brought up with science and never pushed to see how amazing it is ... so many times in the middle of it i realize i need to learn advanced things but i have my own life and so many times i feel i get the gists so thats good enough?!?... then here you come bridging the gap... it may be nothing to those who know but to me its a perfect balance ... idk if you will read this but you have taught me so much, just wanted to say thank you 🤷♂️... youre a good dude
Hi Sean, I've said it before but you are a legend for doing these, they have really helped me through this difficult time and I'm sure I'm not the only one.. I haven't been able to afford to pay yet but am buying your books 🙂
Same here!
This Buds for you SEAN!
The centre of mass example being precious and the idea of being able to distil a massive amount of information to one small bit not being understood deeply is very interesting. These limits to understanding are never talked about in undergraduate physics.
Very, very exiting, impressive and inspiring! If only i could keep up..... will need to get your books and papers and watch all the videos again and again. Thank you for carrying us to the edge of the known reality which we once would have thought was well over the horizon. Kind of like the 'Beginning of Infinity' heh! We are all in your debt even if not anywhere close to your depth. Down Under
I love watching and learning this stuff. Really appreciate your videos my man!
love your "who cares?" approach to the semantic arguments ppl love to get lost in
I'm sure this video is great but the gases/gasses thing just blew my mind. makes perfect sense now that I know but I don't think I had ever thought about or encountered that before.
As a physics (master) student in Leiden, I'm so sad I missed your Ehrenfest Colloquium in 2018. At the time, as a bachelor student, I only seldomly attended these because most of those lectures went far over my head.
I've just watched the recording online, and I can conclude the same would have probably happened with your lecture.
So in the end I'm kind of glad I have listened to it only now as a master student, after a QFT course and a whole lot more physics experience overall. It was definitely a great introduction to emergent gravity from quantum field theory, and I now also have a greater appreciation for Everett's 'Many World' interpretation.
(If anyone else is curious, you can watch it here www.universiteitleiden.nl/en/news/2018/09/livestream-sean-carroll-gives-ehrenfest-colloquium by clicking on the livestream link at the bottom)
I've really enjoyed your last few lectures of 'The Biggest Ideas'. Especially the one about Entropy gave me new insights and a more formal firmer grasp of the concept. In the past, I've mostly viewed Entropy as the Boltzmann entropy, with other versions as 'things that are the same, but different in interpretation'. Although I knew this to not really be true, I've never really looked into it and therefore never understood the other forms of entropy (nor, as it turned out, the importance as the concept as a whole.)
I hope it can help me communicate the topic in a better way to students in the upcoming semester as a student teaching assistant for the 2nd year bachelor Statistical Mechanics course.
So the mumuration behind you would be many to one (course grained) ie lots of birds into one mummur. And I guess in that case heterostructural because the mummur has emerged from the starlings? I love your talks Sean. They help me sleep as well as fascinate me when I am awake. I love the pace and the tap tap tapping of the pen. On so many levels - thank you. Also, as someone who has been run over by a non-dual realisation, I find your talks very meditative. cheers mate. (:
24:11 - Category Theory sneaking in, at least heuristically
Hi Sean, thank you so much for your lectures, I don't understand some but when I read books some of your ideas click and make more sense.
Simply beautiful...Can't be any better!!
Thanks for doing these!! Wonderful!
This is such a great series and this episode is very very helpfull. Thanks a lot.
*Love these series of Videos. Absolute masterpiece*
Some people use the term 'reality' for that which is realised, i.e. within a 'mind' - and 'actuality' is what is actually 'out there' (outside of a mind) irrespective of the various perceived 'realities' of conscious beings.
Your didactic is superb, thank you Sean!
I once played of MIT game 'space-wars' at Stanford coffee house in which there was a bug -- the force law was 1/r (measured it using ruler and watch) instead of 1/r^2 and one could not establish a stable orbit making the game unplayable. Orbits failed to 'emerge'.
You might want to call the "higher level" rules/laws/theories as "Meta-Laws/Rules". This is much like in chess: The rules governing the initial placement and movement of pieces is your "micro" laws and the basic concepts of strategy and tactics to actually play the game are the Meta-Rules. This keeps the two separate, since the Meta-Rules can vary in complex ways while the low-level rules are usually fixed/constant (speed of light, etc.;), as in chess.
This is one of the only physicist I have ever heard admit that theories they hold could be wrong. Honestly refreshing.
Really? Who else do you have in mind?
That’s surprising but I’m not an academic so maybe I’m only used to the physicists like mr Carroll who speak to the lay person. Those types seem to go out of their way to preach humbleness.
Sean, thanks again for do this series!
Prof. Sean Carroll please make the next episode of 'Biggest Ideas in the Universe' on String Theory and M - Theory
The list of the biggest ideas is already fixed, as he said in a prior episode. I don't actually think string theory is actually a big idea. It's all theoretical that tightly fixes some problems we currently have but in a currently useless way since we can't actually test anything.
Another super-duper video ;-) Love all that you do Sean!
You can take approach to it as if classical definition was superior to quantum almost as classical cluster was a sum of all orders of magnitude. Then the clasical potencial describes reality that only matters and you treat wave even without intercepting the classical limit as a sort of partial integral of everything happening under the classical curve. I am sure you know how complex one must be to comprehend so much data at once. The classical limit is where we are rather we like it or not. The point is to eliminate all ignorance related to entropy but still be able to derive consequences of all this knowledge to fit to the classical potential slope and support it. Easy to say probably. With every next part of this series I see more clearly the awesomeness of the whole concept and I deeply appreciate it. Sadly it looks like we are very close to applying infinitesimal to this series. Therefore one must admit that much entropy was consumed over this grat treat marking the genius of its creator. Many thanks for that time.
I am waiting for a video where you lay out the frontiers of large scale experimental and observational physics like LHC, extremely large telescopes, James Webb telescope, ITER, etc and what questions they will try to answer.
I love the fact that, because of a worldwide disaster (Pandemic), we all get the opportunity to hear lectures from Nobel Laureates and people who are really at the cutting edge of their particular disciplines. There was previously no chance that AT THE SAME TIME, people like Sean, Brian Greene, Roger Penrose etc would be able to produce videos about their respective fields while the general public ALL have the time to take it in (whether we understand it or not is a different matter!!)
So now, we have the "Perfect Storm". The experts have the time, the public have the time AND the technology is sufficiently advanced and available to allow this to happen. Thanks to the Coronavirus, those of us well enough can gain a whole lot of information. (Imagine if this had been the case in Einstein's time or even Newton's time!)
Hi Sean! Love the idea of emergence.
Great video!! Thanks Sean 😁
I notice the murmuration behind the professor. As an undergraduate TP student, emergence or how novel properties emerge from their lower counterparts (the sum greater than the parts) is something that has intrigued me for several years.
If you could talk about emergent gravity ( in reference to E.Verlinde's paper) in the Q & A session, that will be really great. Thanks in advance!
Are you going to talk about fractals and the feigenbaum constant in one of these videos?
He's a physicist, not a mathematician. So I wouldnt count on that.
Two things. First, as somebody who doesn't believe in reality, I usually phrase it by saying that "reality is hypothetical"; this can be formalized. Second, starting at 26:30 or so, you're drawing *commutative diagrams* in some category! I approve but wish that you'd have said something.
This is the second time I've awaken from a bizarre, science heavy dream, to find Sean Carrol on my TV.
Thx again, you have single handedly filled some major gaps I had in my education as a Chem E in the 80s. I have at least a glimpse of how we have gone from the predicting the familiar world around to the very small which only can see by the tools we have invented. Since my job was to phenomenology predicting the behavior of dry etch plasmas, this knowledge would have been particularly useful.
I have a question: *what would count as empirical proof of strong emergence?* ----
That many microstates give rise to the same macrostate is nothing new and certainly doesn't imply emergence; also, in the absence of an explicit derivation of the macroscopic law from the microscopic one, one could always say that we don't know how to perform that derivation *yet*, and not that such a derivation is impossible in principle. I think an empirical proof of (strong) emergence would be: showing a system for which the microstate doesn't determine the macrostate (which is a weird thing). Otherwise, if the microstate determines the macrostate, I'm persuaded that it follows that the microscopic law determines the macroscopic one (assuming the microstate is always well defined).
Take a flock of birds as an example. The flock emerges through the interaction of the birds.
@@m.walther6434: I don't see any reason why that shouldn't be perfectly explainable in terms of elementary particles. There is no strong emergence in a flock of birds. Of course, in that case, you have to consider as system the whole flock, together with the air molecules between the birds, or even the whole solar system (since for example birds can be influenced by the direction of sunlight and of Earth's magnetic field).
I like his audio-only podcasts because there's none of that blackboard writing things down business.
awesome video，compare to other too mathy ones, this one relatively easier to understand and very interesting
Hi Professor Carroll and the rest of the physics community here on UA-cam. At around 34:30 - 35:00, you mention that we can describe the motion of a large object in the coarse-grained viewpoint by strictly analyzing the center of mass and that "none of [the] relative positions and velocities matter at all." My question is: if the Center of Mass M and its velocity v_{COM} are "emergent properties" of the system, then what about the angular momentum of the entire body, L? I believe that we need to consider the motion of the constituent masses relative to the COM to calculate the angular momentum of the entire body. Do we consider the angular momentum of the large body an "emergent property" of the system? Or was this example specifically to illustrate that the *linear* dynamics of the system are emergent just from knowing M and v_{COM}? Curious to hear your feedback, thanks!
Hi Professor Carroll - I'm not sure if you'll see this seeing as it's an "old video", but I figured I would ask. Would you be able to add reference textbooks (your favourite, or "the best", books on the subject) to your descriptions at some point? These videos will be invaluable resources for people interested in these topics for a long time, and a comment (from you especially) indicating where people could go for more info, whether more formal or otherwise, would be incredibly useful. Incidentally, it would also be a way to plug some of your books (thinking Spacetime and Geometry for your videos on GR). Thanks again for these amazing videos!
At 1:00:05 you talk about Hyperion not spreading into a blob of probability due to decoherence. I'm with you there. Then you go on to say specifically that it's being bombarded with photons all the time that are constantly observing it / branching the wave function of the universe.
What about its own internal interactions? Thermal motion of its internal atoms, for example, or the constant electromagnetic forces caused by its various chemical bonds? This is something I've never quite gotten hold of with my mind...
I've seen you answer this question several times, at the Royal Institution for one, and in a couple of other lectures Q&A sections, and what you said, to paraphrase, is roughly, "Not all interactions cause branching of the wave function, but there isn't time to specify which ones do and don't and why."
Well... the upcoming Q&A video would seem to be the perfect opportunity! :D
Did you just omit Hyperion's own internal observations of itself? Or do those interactions (or at least some of them) genuinely not cause splitting/collapse because of reasons? (Entanglement, maybe?)
In either case, when *exactly* does an interaction branch the wave function of the universe, and when doesn't it? Or is it simply not well-defined due to something like quantum relativity? I seem to recall a passage in Something Deeply Hidden that mentioned that... but I think it was in the roleplayed conversation between father and daughter and less than perfectly clear. Still, something about what branches the wave function depending on frame of reference, maybe?
Are you going to talk about Fractals???
The material is an emergent property of the platonic, not the other way
around. An adolescent cultural bias should not prevent a brilliant mind
from seeing this.
“It is clear that these physical-only processes
somehow on the one hand give us the right answers, but on the other hand
that they are controlled by another world of ideas somehow; they’re
coming from somewhere else.” (Nima Arkani-Hamed--- theoretical
physicist, permanent faculty at the Institute for Advanced Study at
Princeton, and director of The Center for Future High Energy Physics
(CFHEP).
Thanks for explanation ❤
@Sean Carroll Love your stuff. What program are you using on the iPad to do the chalkboard. I need that for my channel. Also ever heard of Linea Sketch?
SpeedOfSoundOfGravity He's using Notability. He mentioned it in an earlier video, though I forget which one.
I'm always wondering how QFT approximates (in the limit) F = ma, F = kq1q2/r2, etc. Does it actually work out, or are we thwarted by infinities in the calculation?
Also, how can you even have r2 when the positions are uncertain? And is it possible to derive V(x,t) from a wavefunction in a coupled field? E.g. I know psi of electron, can I then calculate V(x,t) for the photon field, or vice versa?
With respect to bosonization, the kinks and anti kinks seem to represent particles, but also excitations (at least in sine gordon where particles are changing state). Is it then useful to think about the kinks as quasi particles like phonons for example? And is this a different kind of emergence, when the collective behavior of interacting particles seem to create excitations that also look like particles?
The Blind Men and the Elephant by John Godfrey Saxe (a poem). Also, the four stages of scientific acceptance by J.B.S. Haldane (not a poem).
A question: As quantizing both the classical theories of Sine-Gordon and Massive Thirring gives rise to a relationship between fermions and bosons in a single quantum theory, would there be any sensible connection to be made with supersymmetry, given that supersymmetry also reflects a relationship between fermions and bosons?
WHERE DID THE ENERGY FOR THE UNIVERSE COME FROM ???
What a coincidence, two days ago I was talking to some friends about the nature of consciousness; arguing that I truly believe it is an emergent property of living matter. You mentioned consciousness briefly in this video but do you have any further thoughts on this?
Check out the mindscape podcasts
@@benwincelberg9684 Ah yeah nice thanks
Also please check this out. Ancients could appreciate the philosophical conundrum of the problem of other minds, but now as reductive physics comes closer to explaining all of my neighbor's behavior, I have less reason to believe that he even has consciousness... If consciousness doesn't *do* anything, that means there is no evidence for it. ua-cam.com/video/YZaHG1eh4-A/v-deo.html
I like this episode Carol.
Interesting ideas. Good video
Quasiparticles and theories which are using them are good examples I think. How the lack of an elektron could act like a partical and simplify the description of the system. Or an excitation could act like a partical. Or the excited electron and the empty lower energy state could act like a partical-antipartical pair.
The last few diagrams put me in mind of something that is maybe not the same as Strong Emergence, but looks a lot like it, and (IMO) does happen: your micro theory is incomplete, its domain is not all of reality, and you have a macro theory that works for some parts of reality where your micro theory doesn't. Then the macro theory might make accurate predictions that the micro theory can't, but only because you are in a situation where you can't, or shouldn't, use the micro theory anyway.
Question: If theoretically there are a semi- infinite number of 'spectacle-like' theories through which 'reality' can be faithfully observed BUT each have individual limitations, will it ever be possible to see the total of reality except by somehow discovering and then combining all such theories? Would this not be a semi- infinite or infinite venture? Or are we nearly there yet? Thank you for your amazing work.
Do any of your videos discuss theories that attempt to explain the behavioral and sensory changes that occur when, for instance, hydrogen and oxygen combine to form water? Some people think that phenomenon such as this will never have a mathematical explanation and the ensuing emergent properties of water, for instance, could never be predicted, but can only be learned from experience.
Is it possible to quantify or rigorously define how “simple” or “efficient” a theory is, maybe in terms of information? You didn’t explicitly mention Occam’s Razor but this seems implicit in the fine-grained, homeostructural category and maybe for the others too
Amazing, fantastic
Thank you Professor Carroll for a wonderfully informative series. My question is (I have many but I'll settle with this one):
Are there any hypotheses down the lines of the reason for emergent properties/theories being possible because of the necessary fussiness of quantum mechanics (QM) measurement?
Or put another way, are there hypotheses that map the apparent necessary ambiguities of QM to existence emergent properties or theories?
Or, in the broadest sense, are their any proposed ideas (from scientists, I'm sure philosophers have many proposals) at all on reasons for the existence of emergent properties?
Dear Sean
You talk elsewhere about spacetime being emergent and quantum mechanics being fundamental. I wonder the following:
1. The wave function is characterized by its length and amplitude, but don't they both require space as a precondition? What is wavelength and amplitude without space?
2. Boson and fermions are differentiated by their ability (or lack of) to occupy the same… space. Doesn't that mean that space is a precondition for their emergence?
3. Unless quantum mechanics describe a static unchanging state, if there is any interaction in the quantum world, doesn't that require time as a precondition? Doesn't any quantum dynamics require time as a precondition for their emergence?
4. If the quantum field is a harmonic oscillator, and all phenomena are merely disturbances to the harmonic oscillator, then: (a) don't you need a more fundamental cause of those disturbances? (b) where is the energy required for disturbing the harmonic oscillator coming from? Don't you need a more fundamental source of energy for the quantum field to be disturbed?
All the best
In the Q&A video, could you talk about the difference of "throwing away" information vs "compressing" the information? As an example, is calculating the center of mass of the earth not compressing the information of all the individual particles? (vs. throwing that information away)
You can’t reconstruct the mass and position of the individual particles from the center of mass so that information is lost. Compressing usually means that all information can be restored, which is therefore not the case.
Compression can be lossy. It doesn't change the fact that it's compression.
Chris Stewart But even lossy compression has an error margin that is ideally small compared to the total size. For the center of mass it doesn’t matter how large or complex the system is, you always only get one point as the result. In other words, infinitely many different systems can lead to the same center of mass so it’s impossible to infer any more data from it i.e. decompress it.
@@MegaManki Decompression isn't needed. I'm only pointing out that the information is encoded, in part, in the center of mass.
@@chrisstewart4288 But lossy compression DOES throw information away, so it makes no sense to ask about the difference of "throwing away" information vs "compressing" the information if you mean lossy compression.
I thought Emergence was essentially a phenomenalogical proposition.
'As above, so below'
Co or mutually generative.
So, the big question is: what emerges?
A better model or concept for reality.
I didn't fully get the interaction between quantum and chaotic behaviour for Hyperion at around 1:01:00. I always just assumed chaos and quantum indeterminacy were separate realms but this is very interesting
Given the correct combination of atoms and molecules plus the right energy conditions in normal space, a pizza could strongly emerge from an oven ? Whether it is allowed pineapple or not remains a deep mystery.
Awesome. Love the video! Thx
“Two possibilities exist: either we are alone in the Universe or we are not. Both are equally terrifying.” - Arthur C. Clarke
I feel the same sentiment towards Strong Emergence - which happens in reality or does not. Either way, it boggles my mind. To believe, understand, and possibly know that each of us is only a smattering of nougat within a colossal wave function and derivable from a quantized, basement-level particle physics seems irreconcilable with our subjective conscious experience. But what is the alternative? Invoke some goofy analog of the luminiferous aether?!? Science peters out around the edges (presumably because we're not done yet), but its core principle of reductionism is not soft around the edges - it's as crisp and well-defined as the monolith that mesmerized our ancestors in Clarke's 2001: A Space Odyssey.
I'm particularly taken by the example of the 3+1 dimension Conformal Field Theory (CFT) being the boundary condition of a 4+1 dimension Anti-de Sitter (AdS) space. Makes me wonder if there's a philosophical analogy to be had - like abstract objects being a lower-dimensional boundary condition of the concrete. For example, many philosophers believe that number is the essence of quantity - that numbers are mind-independent objects and that a description of reality would be incomplete without their inclusion. Perhaps this so-called essence is profitably thought of as a lower-dimensional boundary condition. But so far, going from AdS to CFT seems more straight-forward than the other direction. It feels far easier to agree that gravity in AdS doesn't imply any contradiction within CFT, but I don't quite see how gravity is to be inferred from CFT - and it must be inferred if the emergence is to be weak, right? (It feels even stranger to suggest that an abstract object infers a concrete object. What's next - inferring an ought from an is?!?) Finally, is there any limit to the chain (or web) of inference? Is the 4+1 AdS just a boundary condition for a 5+1 Something Else, with another spectacular reality like gravity popping out from it? It's like turtles all the way up - like we could synthetically generate a never-ending progression of knowledge.
Anyhow, I think it was essential for Dr. Carroll to broach the topic of Strong Emergence and I'm so glad he did. As a scientist, he's properly committed to naturalism and reductionism but also properly open to investigate a purported counterexample. He's making both science and philosophy better in the process.
Seems to me that central limits theorem is a origin of lot of emergence.
If, e.g., the force between particles (and walls) was 1/d rather than faster fall off (2d case?) then pressure would not emerge as from averaging over a lot of collisions. Does that sound right?
What you bring up is something called curse of dimensionality, it says that length scale in different dimensions are disproportionately scaled. In your example, I think what is known as pressure may exist in arbitrary dimensions, but the magnitude of that decreases as the dimension increases.
What about General Relativity as an emergent theory of gravity where the standard model or an expanded GUT would be the micro-theory. Think of Sakharov's ideas on this. This gets around the pesky problem of quantizing GR by consider it as an emergent theory analogous to thermodynamics compared with statistical mechanics. The gravitational constant G would be derived from this micro theory and they gravitational field would be distortions of the quantum vacuum. In this concept gravity doesn't exist and the level of particle physics but emerges at the macroscopic level.
i'd also like to hear a few Prof Carroll's thoughts on Erik Verlinde's heuristic theory of emergent gravity. his ideas look very promissing to me.
awesome, just awesome!
This clock has no moving hands. It is still a true clock describing real time, it is just that its domain of applicability is only noon.
If you can make a correspondence between a particular sand heap and a mathematical theory of physics does that mean that the sandheap is a a theory of physics. How much of emergence is property of clever mappings between otherwise unconnected abstractions. Is reduction in the eye of the beholder?
Is ehrenfest’s theorem why in a bubble chamber, a particle leaves a trail that appears to be a particle on a trajectory?
NVM, right after that you answered it
Isn't the measurement effect pretty much strong emergence? More accurately the Born Rule, which is not covered by the Lagrangian, that in principle applies to particles in mass via probability?
Heres hoping Sean sees this lol
Thanks!!!
" *Gases* is written with one 's' and not two; I've written this word a thousands times "
Welp.
I felt that, because I've been spelling it *gasses* for my entire life....fml
I know the video is about weak emergence. But I am curious how Professor Carroll arrives at being a compatible-ist for free will, while being totally against strong emergence.
I’m going to listen to his Mindscape Podcast with Dan Dennett again...
I'm thinking that one of the biggest ideas in the universe is putting the biggest ideas in the universe into a series of UA-cam videos.
Certainly one of the best ideas
That's a pretty small idea on the scale of the universe. UA-cam exists only a fraction of the length of the universe and has very limited spacial influence existing only locally on Earth.
12:35 Lenguaje
22:34 Maps entre teorías.
38:30 Universality!
46:55 Ehrenfest
Decoherencia
1:03:00 !
1:14:15 Ads/CFT correspondence
43:16 Fun fact: The name *"Ehrenfest"* sounds like a completely plausible German compound noun, meaning "festival in honor (of someone/thing)" - but this word does not exist.
(I presume the name comes from the adjective "ehrenfest", meaning "honorable" - "fest" translates to "firm, sturdy" here instead of "festival", cf. "steadfast". But it's archaic and therefore not widely known even among native German speakers.)
I spotted a small mistake in minute 48:16. The formulas given for the expectation values of position and momentum (x-bar and p-bar) are missing the complex conjugate of the wave function inside the integrand (for p-bar, the derivative applies only to the wave function, and not to its complex conjugate). Also, not sure if hbar has been set to 1, but if it hasn't, p-bar should have a factor of hbar.
great, can there be a theory which suggests why 'real patterns' may exist? under which conditions ?
I am developing an emergent, mostly mathematical theory of cognition that is applicable to seemingly different portions of reality: nervous systems (of course), microbial life, genetics and epigenetics in the tree of life, immune systems...
About consciousness and qualia, maybe they are emergent properties of cognition. I still don't know and have to think a lot more unless I get the kind of insight I had about cognition.
I hope I'll understand all these amazing things by the time I'm 500.
I have to make a comment about Strong VS Weak Emergence.
Clearly all macro level reality is the result of the micro level reality. We don't need to run a simulation to see this as real life is a simulation that already shows this. However I don't think this is the point of advocating for Strong Emergence. The point of Strong Emergence is that the macro level reality is so far divorced from the micro level reality that for all intent and purposes it is as if the macro level reality cannot be computed from the micro level reality. So while technically Strong Emergence can't be true but in practice it is effectively true.
Furthermore there is also another way in which Strong Emergence could be effectively true. You are correct to say that "the only way the micro doesn't build up to the macro is if the micro is wrong" (I'm paraphrasing). However it may just be that many of our micro models are always wrong. They are just wrong in ways that don't mess up predictions of micro phenomena. It is very possible for there to be things that are missed at the micro level that only become apparent at some macro level. For instance there could be numerous missing dimensions that are too small to be noticed at the micro level. Only when these missing dimensions come together in some consistent way through a particular macro phenomena, do they add up to anything observable. It seems to me that we would have to be very lucky for reality not to have any such "vanishing dimensions" at the micro level. If this turns out to be very common between micro and macro systems so that most of our micro models are wrong (just not in any way that impedes making micro level predictions) then this also effectively makes Strong Emergence true.
Question for Q&A: Regarding emergence, is spacetime something that needs to emerge from quantum gravity, or can it be skipped as long as you can describe its results?