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.
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!
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.
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
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.
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.
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.
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?
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.
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.
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 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!)
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.
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.
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).
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 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.
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. ru-vid.com/video/%D0%B2%D0%B8%D0%B4%D0%B5%D0%BE-YZaHG1eh4-A.html
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
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.
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.
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.
Hi Professor Carroll and the rest of the physics community here on RU-vid. 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!
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.
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
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?
That's a pretty small idea on the scale of the universe. RU-vid exists only a fraction of the length of the universe and has very limited spacial influence existing only locally on Earth.
I cant see the difference between the word emergence and scale, except that scale is principled whereas emergence implies things popping in and out of existence
if the weak emergence is true then we can have a physics theory of life which will be capable in fundamental terms of physics precisely describe the Darwinian evolution and different living structures (whereas consciousness is just a natural feature of complex high level living organisms).. i'm sure we can and very close to find such a physics theory.) and this in its turn will radically change our understanding of the universe and of ourselves as inseparable part of the physical universe.
Nothing in an individual's empirical experience - and especially through the lens of physics - proves even the existence of other minds, and so this limits the potential for science to get anywhere even close to explaining consciousness per se.
@@johnwhorfin3815 In neuroscience there are working theories of consciousness based on spontaneous brain activity and the ability of the brain to accurately create a mental model of the environment (see work by Georg Northoff for his ontic structural realism approach to consciousness). In patients that have locked-in syndrome, or patients in a vegetative state, the ability of the brain to modulate external stimuli in the context of the spontaneous brain activity (measurable) becomes impaired. In terms of qualia, experiences could eventually be mapped to specific pathways of the brain being triggered in succession with release of neurotransmitters in defined, characteristic ways. However, just because we have a framework or mapping does not mean that consciousness or qualia can be explained from a subjective standpoint, only that they can be quantified and predicted. There is perhaps some sort of a hidden function/aspect of the universe that translates the underlying neuronal activity into the subjective experience, or perhaps the subjective experience is simply an emergent property. Regardless, I have no clue how qualia could ever be explained in mathematical terms.
@@NobleCaveman I note that your response makes numerous references to abilities and capacities. The "working theories" about consciousness that you refer to all assume that the subjective consciousness actually exists. The empirical scientist will prefer to discipline the use of this folk concept of consciousness and instead refer to behaviors. Also, there will be no "abilities" since whatever actually occurs was presumably caused by previous physical states.
@@johnwhorfin3815 I have no idea what you're trying to say in terms of abilities or capacities. All I said is that the brain has the ability to model the environment that it observes. If you are asleep, or in a temporarily non-conscious state, the brain is not using this ability, but it nonetheless exists. This may boil down to an argument about the definition of consciousness. In the context of neuroscience, even different neuroscientists have not settled on a consensus. I tend to lean towards the definition of consciousness as the ability of an organism to regulate and modulate its own focus. A subjective experience of consciousness is being able to observe your own thoughts. Are you saying that this does not exist? All leading researchers in neuroscience that I know of have a working definition of consciousness. I would believe that they have such a definition because it is necessary in the empirical study of human psychology, so I'm not sure where your assertion that consciousness is a folk concept that is mutually exclusive from empirical study comes from. The behavior based approach to psychiatry has become outdated and is narrow in scope. How does behavior explain the cause behind it? In order to understand how to treat the source of psychiatric pathologies such as schizophrenia, we need to understand the basis of normal brain function through the use of measurements such as spontaneous brain activity and see how this is modulated by disease.
@@NobleCaveman you say "the brain has the ability to X" - what else has abilities? Is an ability something which may or may not happen under the right circumstances? Or is it some power or agency to create a chain of cause and effect, rather than merely being part of one?
How do we know planets are not moving at the speed of light, relative something? Planets are for instance moving at the speed of light, compared to a light ray. We just say the light ray is really fast while we are stuck in the beat frequency of matter. I might be sophistify to much, but it just looks awkward in my mind, and my emergent mind is all I got
I suspect our theories are not emergent enough. If scientists didn't already know about electricity and magnetism, and were just trying to understand the reactions between atoms and molecules, they might have come up with the short-range van der waals force imagined as mediated by a massive gauge particle like we have now in the weak interaction.
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.
I've just finished Sean Carroll's book "The Big Picture", it is great. I'm viscerally opposed to Many Worlds, but Carroll speaks and writes better than anyone.(Perhaps bar Richard Dawkins)
This is somewhat scary. So the Pauli principle is rather a dichotomy than a statement about fermions. What would the macro world look like from a micro/QM perspective? As opposed to the traditional other way around. No words on the law of great numbers? Why isn't this taught in undergrad school? Regards, Marcus of Sweden
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?
36:35 I'm not sure if emergent macroscopic behaviour is the phenomenon, or a certain reduction of extant configurations is the phenomenon. You can abstract the Earth as a point mass because mass tends to clump not in every possible way but in spherical bodies. Decoherence is another vast reduction or configurations that can be seen. So emergence as well as Dennett's patterns may be clues to that vastly compressed reality where only a tiny subset of the mathematically possible configurations actually exist in some sense. In a sense the job of physics is to map that reduction at every scale.
Prof Carroll, you keep emphasizing structure, mapping in your videos. Are you secretly a physicist that uses category theoretical thinking in the background?
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?
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?
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.
It seems sometimes say "multiple theories" and sometimes "multiple models". I'm not sure the difference. I suppose a theory gives "laws" of predicting future behavior. When I hear emergence, I think of consciousness, and E.F. Schumacher said we need to recognize 4 levels of being to help distinguish what a model can predict. en.wikipedia.org/wiki/A_Guide_for_the_Perplexed#Levels_of_being For Schumacher one of science's major mistakes has been rejecting the traditional philosophical and religious view that the universe is a hierarchy of being. Schumacher makes a restatement of the traditional chain of being. He agrees with the view that there are four kingdoms: Mineral, Plant, Animal, Human. He argues that there are critical differences of kind between each level of being. Between mineral and plant is the phenomenon of life. ... Schumacher realizes that the terms-life, consciousness and self-consciousness-are subject to misinterpretation so he suggests that the differences can best be expressed as an equation which can be written thus: "Mineral" = m "Plant" = m + x "Animal" = m + x + y "Human" = m + x + y + z In his theory, these three factors (x, y and z) represent ontological discontinuities. He argues that the differences can be likened to differences in dimension; and from one perspective it could be argued that only humans have 'real' existence insofar as they possess the three dimensions of life, consciousness and self-consciousness. Schumacher uses this perspective to contrast with the materialistic scientism view, which argues that what is 'real' is inanimate matter, denying the realness of life, consciousness and self-consciousness, despite the fact each individual can verify those phenomena from their own experience. He directs our attention to the fact that science has generally avoided seriously discussing these discontinuities, because they present such difficulties for strictly materialistic science, and they largely remain mysteries. ... Schumacher points out that there are a number of progressions that take place between the levels. The most striking he believes is the movement from passivity to activity, there is a change in the origination of movement between each level: Cause (Mineral kingdom) Stimulus (Plant kingdom) Motive (Animal kingdom) Will (Humanity) One consequence of this progression is that each level of being becomes increasingly unpredictable, and it is in this sense that humans can be said to have free will. He notes increasing integration is a consequence of levels of being. A mineral can be subdivided and it remains of the same composition. Plants are more integrated; but sometimes parts of a plant can survive independently of the original plant. Animals are physically integrated; and so an appendage of an animal does not make another animal. However, while animals are highly integrated physically, they are not integrated in their consciousness. Humans, meanwhile, are not only physically integrated but have an integrated consciousness; however they are poorly integrated in terms of self-consciousness. Another interesting progression, for him, is the change in the richness of the world at each level of being. A mineral has no world as such. A plant has some limited awareness of its immediate conditions. An animal, however, has a far more rich and complex world. Finally, humans have the most rich and complicated world of all. ... Schumacher argues that the ideal science would have a proper hierarchy of knowledge from pure knowledge for understanding at the top of the hierarchy to knowledge for manipulation at the bottom. At the level of knowledge for manipulation, the aims of prediction and control are appropriate. But as we deal with higher levels they become increasingly absurd. As he says "Human beings are highly predictable as physico-chemical systems, less predictable as living bodies, much less so as conscious beings and hardly at all as self aware persons."[6] The result of materialistic scientism is that humanity has become rich in means and poor in ends. Lacking a sense of higher values Western societies are left with pluralism, moral relativism and utilitarianism, and for Schumacher the inevitable result is chaos.
I find the way of talking about limits as "hbar goes to zero" or "G goes to zero" to be misleading. If that was necessary for the limits to exist, they would not be noticeable in the real world, as the constants are in fact constant. I find combining the constants with parameters of the problem and saying "as hbar becomes negible compared to this" much more enlightening.
Why we’re a scientist? the scientists are researchers, and asking questions, and thinkers, and finders, so any areas in science if you can understand and helps the others, so you should enter, and share your opinions, if this is not the duties of science, so what it is?
27:14 that diagram is very category theory. I wonder if it would make sense to take a categorical limit and find the "least" theory that ecapsulates special relativity and Newtonian mechanics.
The tiger has entered the cage. Is there anyone who can close the gate, please. We have just one wave function for the entire universe. Separate classical objects have unitary evolution from this wave function (Schrodinger). Although we don't know the algorithm of the evolution (and may never know), we have tools to get a feeling of knowledge of the design. Maldacena's duality is one. Maldacea also conjectured that the whole universe is an error correcting QC function, again we don't know the algorithm (perhaps known to the cosmic consciousness-the mind of god). The initial conditions of the function, involves the quantum field and the wave function.
@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?
For every choice of macro evolution operator and coarse graining function, won't there always exist a (possibly empty) subset of reality where the diagram commutes? In this sense it seems that "strong emergence" is ill-defined. One way to make it well-defined is to use the set-picture that you subsequently drew, where "strong" means that there exists a subset W of reality where the macro theory applies but not the micro theory. Then "weak" is just the special case of "strong" where W = ∅. So the naming "weak" and "strong" seems to be really quite unfortunate. Weak emergence not only has a stronger hypothesis but also aligns more strongly with our conceptual view of the word "emergence". Using this definition, it seems plausible (though perhaps unlikely) that our quantum and classical theories could be "strongly" emergent, where there are certain situations where QFT is wrong yet CFT happens to be right, given that QFT is probably not the theory of everything.
As you increase the momentum of a particle, it gains energy. Eventually it gains enough energy that the single particle could be described equally well as a combination of multiple particles. Recall that particles are just a pattern in the quantum field. So at high energies, the particle splits into two or more particles with lower momentum. This can actually be done with quarks. If you try to pull one quark away from its bonded quark, you introduce enough energy to create a new quark-antiquark pair of particles between them.
Yes, it is an emergent theory on the level of atoms to gas, it only includes other substances like liquids and solid (and those between). So no strong emergence.
I think the idea of "strong" emergence is indistinguishable from the case where the microtheory is not accurate. It's incomplete somehow. Evolving it forward will give you an answer, but the real-world macro behavior is exquisitely sensitive to the exact behavior of the microtheory, so it doesn't match. The theories we _use_, on any scale, are "effective", anyway. A good simulation will not produce the ideal gas laws -- a poorer simulation would! I think you're right in that "strong" emergence is not possible, and any such observation is actually a clue to probing the physics beyond the microtheory being used. For sociology etc. I think the admission that it's not possible for us to _do_ it because of measurements or computational load is what it actually stems from.
I am sorry, but the concept of emergence seems to me to be used in a very hand-wavy manner here and by most people. I don't think it has as much explanatory power as is commonly assumed.
isn't everything we know something of an emergent theory? almost seems cocky to assume the "fundamental" equations of reality are findable/knowable. similar to believing there's a point where science ends.
Because we hope that results we get from studying AdS/CFT point into a direction that might give us the ability to apply similar ideas to de-Sitter space.
7:18 - "Fundamental sounds like it's more important" - No, it sounds like it logically subsumes something else. As in: you can *deduce* the temperature of a gas by knowing the velocities of its molecules, but you can't *deduce* velocities by knowing the temperature.
It depends on what you define as "important." If you think that because some concept is a "deeper" than another concept, meaning that concept can explain more about the world than another concept because that first concept explains the 2nd concept and possibly more concepts, then that original concept is more "important" because it is more "useful" because you can explain and do more things with it. If you know the temperature and composition of a gas, then you know it's shape, it's color, roughly how it will react with surrounding gas, and all that with a set of numerous other things. But if you are LaPlac's demon and know the position, velocity and identity of every single last particle of gas, even the tiny few odd particles of a different gas that got mixed in that the previous person didn't know we're there, the sky is the limit as far as what you can explain. Not only could you deduce the temperature (in theory) but you could also know with exact precision any and everything that did and will happen within that gas. And the concepts of position and velocity (vectors) doesn't just apply to temperature, but macroscopic motion of objects. Because you can explain more with the "deeper" theory it 'seems' more important intuitively because you can do more with it. If you get taught temperature, what you can do is limited, bit if you get taught Newtonian mechanics, you could derive the concept of temperature and a number of other things on your own. Just trying to explain what he probably meant xD
