If I had to guess I’d say Sean would be happier than anyone to hear you say that. I feel like I’ve been reading his books and following him long enough to remember when he was hesitant, to say the least, to ever refer to himself as a philosopher.
Nye and Tyson are still excellent communicators but my personal perspective is that they lost their continuously ongoing research gusto. Carroll feels right in the heart of it all still while also communicating. And uniquely and excellently
I always rejected the wave function collapse (as a student), and it took me more than twenty years before I came up, on my own, with the many worlds theory; that is, the insight that measurement = entanglement and nothing more. But I never was able to figure out why the resulting observers+environments would be orthogonal, just that they had to be. Now I can finally place the role of decoherence and feel relaxed because humanity, in the form of Sean and others, is on the right track.
Now I see what the problem is with saying that the wave function "collapses". When we use Schrodinger's equation together with the Born rule to compute the probabilities of certain outcomes of a quantum system (position of an electron in an atom, fringes on a screen for the double slit experiment, electron emitting a photon by rotating its angular momentum vector, etc...), the equation has completed its job, it has done what it was meant to do. So once we measure the system, or interact with it in a certain way, to determine its state or describe its behavior, we need to use something else entirely different. Saying that the same equations we used to compute probabilities just collapses makes no sense at all (my two cents contribution!) Fantastic episode!!! watching it just once is not enough!
Nobody has ever actually stated in proper physics that "the wave function collapses". That's not how we teach quantum mechanics at the university level. What we fail to teach is the science history of how Copenhagen became what it is. Maybe professors assume that students will go into the library and pull Heisenberg's matrix mechanics papers out of the shelf and spend a week trying to actually understand what they mean. I certainly didn't do that until waaaay later when I wanted to understand how quantum mechanics became such a misunderstood topic. Your hunch is correct. The Schroedinger equations describes one system. The Born rule describes the interaction between two systems. It can not be derived from the SE without adding at least one more ingredient... in which case it basically becomes a more complicated re-formulation of what we already know. The density matrix formalism allows us to do that, but at the cost of having to introduce another seemingly random assumption instead. It's an intellectual zero-sum game.
Thank you for the very constructive comment! Next January I'm actually going to start my journey towards a master's in applied physics (online from Johns Hopkins!), so I'm very much looking forward to the quantum mechanics course(s) they offer. I hope you don't mind if I ask a few questions from your comment, it seems pretty involved! When you say the Born rule describes the interaction between two systems, am I correct in saying that one of the systems is the one that does the interaction, and the other system is the one that is interacted on? Is the density matrix actually the Hermitian operator that contains the eigen values of a system (maybe I'll watch this video one more time!)? When we measure a system (like putting an electron inside a magnetic field) causing the system to take on a certain state (the electron either emits a photon of a specific wavelength or it doesn't) that corresponds to one of the eigen values, is that the ingredient you mentioned? Is the random assumption you mentioned referring to the inherent random nature of a quantum system whose measured outcomes are governed by the Born rule? Sorry! your comment really got me thinking!
@@rickcygnusx1 Nature can't tell the difference between the quantum system and the measurement system. That is an entirely man made classification of one end of the lab vs. the other. It exists in Copenhagen for historical reasons and it is practical in a lot of low energy scenarios. It is entirely useless and also completely unnecessary in relativistic field theory (aka high energy physics). The sooner you get used to the idea that quanta (including massive charged quanta like electrons) are merely combinations of energy, momentum, angular moment and charge that can be transferred either reversibly or irreversibly from one volume element of an otherwise empty physical vacuum to another volume element of the same empty physical vacuum, the fewer unnecessary ontological roadblocks you will find in your way. More precisely, what's inside a given volume element is not "the electron" or "the photon". What's inside is a the amount of energy, momentum, angular momentum and charge that got irreversibly transferred in there. But that's system energy, system momentum, system angular momentum and system charge. It's not some localized and localizable constituent called "the particle". In certain classical scenarios involving fermions like electrons and compound bosons what you put in is what comes out, but that's already not the case for bosons like photons. If you put a UV photon in a piece of metal what comes out is an electron and then some IR photons in addition. Use something other than metal and less energy might come out than you put it because you might trigger a photochemical reaction etc.. Try to learn to think about quantum mechanics in that context. Sooner rather than later you will lose your distaste for the Born rule because it will become clear that all of non-relativistic QM is just a special case of a special case. It's not how nature actually works. Good luck.
Wow, there's a lot to think about in your comment. I'll be referring back to it over and over again until I fully understand it. Thank you again, I'll let you know when I reach the end of the journey!
I love this guy's (Sean Carrol) intellect, mannerisms, tone of his voice, and everything else I know about him. People like Sean are my Moses, Jesus, Mohamad, and Gurus. With these people leading us or being the right hand of leaders, humanity will live better, and have a much better chance of survival.
Props to Carroll for frankly acknowledging Bell as a proponent of Bohmian Mechanics, and for debunking the Nobel Prize Committee's mischaracterization of Bell's work as disproving non-local hidden variable theories such as BM. (If anything the recent Nobel Prize-winning experiments make a case that helps vindicate Bohmian Mechanics.) In his account of Deutsch's views, Carroll highlights the point where Bohmian Mechanics diverges from MWI: "In Everrettian quantum mechanics, reality is just described by the wave function. In Bohmian Mechanics, there's two sets of variables: the wave function and the particle-like variables." Carroll then summarizes his own objections to BM: "One of the reasons Bohmian Mechanics just looks wrong is because the wave function pushes around the particles, but the particles do not push around the wave function. This just seems weird." Here's the Bohmian response to this objection: The quantum wave function is not a represention of physical reality, it is instead defined in Configuration Space, a complex-valued domain of potentially unlimited dimensions. The pilot wave that guides the trajectories of particles in physical space likewise manifests in Configuration Space, as the wave function evolves via the Schrodinger equation. This guidance occurs according to the Born Rule, which describes the probabilistic projection of superposed solutions of the wave function in Configuration Space into physical space. While all possible superpositions of a particle's location are manifest in Configuration Space, the only solution that affects events in physical space is the one that corresponds to the particle's actual observed location. The reason particles do not "push around the wave function" is because there is no corresponding quantum mechanism that projects particle trajectories in physical space into Configuration Space.
Interpretation of quantum physics has been going on for 100 years and is still not settled to any degree. That is a testament to how radical reality is at this level compared to our everyday experience. In not having the intellect to comprehend most of the mathematics at this level, I have had to approach the subject from other directions. It is a lifelong attempt to understand something I want to understand but which is beyond my understanding. What is it like to climb K2? I will never have the capability to climb K2. The best I can do is to push myself to climb the harder 14rs or spend 2 weeks with Ram canyoneering to the point of total exhaustion. This hints at what it would be like to do a peak like K2. But I know the experience is of another level and degree that I am probably kidding myself. My attempts to understand the deeper aspects of various scientific fields are similar to my attempt to understand what it would be like to climb the 8,000m peaks. Every once in a while, I experience an insight from reading or listening to a lecture/interview that excites and encourages me. I have listened to this exchange maybe 6 times in total and certain sections of it many more. I get more understanding each time as I reflect and do a bit of research to fill in my knowledge gaps. I could probably follow/understand better than 60% on my first listen. Now, I'm guessing >75%. Yet, this morning, after falling asleep to listening last night, I feel giddy with a sense of a higher level of understanding of existence. Only two cups of coffee, so it's not that 😉
Great episode! I’ve heard these ideas before but it’s great to be able to see the mathematical motivation. I would love to see a similar podcast on objective collapse theories or Penrose’s gravitational collapse theory.
This has been such a valuable slightly more technical addition to all the more 'hand-wavy', 'wordy' discussions about Everett's interpretation. Thank you!
At 1:36:10 @seancarroll talked about Doble Slit Experiment, which says that collection of dots resulting from dots of individual electrons hitting the screen form the interference pattern. Please note that the trace of a single electron itself does not look like a interference patterns, it is only a dot. Then why should we think of an individual electron to have wave nature? It is a property of collection dots of electrons (or is it? read on...). Think of the example of Galton board, where an individual ball bearing falling thru it's pegs ends up in one of the buckets at the bottom, but when many of the ball bearings go thru the pegs of Galton board, the distribution of the counts of ball bearings in each bucket results in a Gaussian distribution. In that case, we do not say that each ball bearing had Gaussian nature (knowledge) themselves to make sure to fall into any bucket so that eventually Gaussian distribution should result. Heck, we do not even say that the collection of ball bearings has the Gaussian nature. The resulting Gaussian nature is really the function of the arrangement of the pegs of the Galton board and partly the size of the ball bearings and their bouncing around the pegs. I have never understood why the DSE is given as example which shows wave nature of (a single) electron and for that matter even a collection of electrons.
This is great, Tim. I look forward to hearing Carroll out on this. He has some great ideas, but one thing that grates on me a little is when he speaks with so much confidence about things that are contentious matters of interpretation. In any case, this is a great service you are providing. I enjoyed hearing his thoughts about the IDW and was releived to see him coming down on your side regarding your anonymous co-author in the Weinstein affair. Great work!
Funny, I find Carroll to be quite humble. Sure he is confident in what he believes, but is very quick to acknowledge which beliefs are common and which are controversial. He credits others when thoughts are not his own and he seems to fairly treat those who he disagrees with. I have heard this complaint before, but I like his tone. Also, must have missed it…when did he comment on the idw?
Guys, I am not a mathematician nor a physicist, not even close. I appreciate your intellect and find great value in the insight you provide. I listen with enjoyment. As a lay person, I have observed a few things. People are people, be it political, business and educational, if you are to be taken serious and respected, you must conform to an established set of norms, those norms being established by people, people that elevated themselves to positions of power and decision making over others. Having been on the planet a while, I have discovered that science theories, once time passes, is very often proven wrong, MC squared and theory of relativity being the exceptions, theories developed via pencil, paper and intellect, void of computers.
Great episode! Also if I remember correctly Feynman actually interpreted the path integral version of quantum mechanics by thinking about particle worldlines and such. There's some talk about this in David Skinner's qft notes.
At 1:01:15, does this mean under the Everett interpretation, EVERY possible outcome is realized? I believe the answer is yes, but would like clarification, thanks.
Absolutely fascinating and helpful discussion. I could not take my eyes off it. Thank you to both to the interviewer for asking good questions and to Sean Carroll for providing his valuable insights.
Conceptually, fundamentally time is simply any change in any value of any property of anything. If there is no change there is no time. The rate of flow of time can be only imagined if there is a repeatable or cyclic subpart of the universe (which is what clocks or rotation of earth or orbits of planets are). The highest possible resolution of time measurement will be the shortest wavelength cyclic process in the universe. Without any cyclic process but if there is change going on then, time simply flows but it's rate of flow cannot be measured.
I think the best bit is I couldn't class it as philosophy or physics. But that's the way it should be, physics should be a an application of philosoical ideas.
The Many World Interpretation of QM (suggested by Bryce DeWitt) is a proper model of Everett’s original Relative State Interpretation of QM, but the MW is neither the only nor the most literal or parsimonious model the RS Interpretation of QM. An alternative model of Everett’s RSIoQM had been suggested by M. Gell-Mann and J.Hartle in 1989 / 1990 which originally went under the ‚title‘ Decoherent histories and later became known as Consistent Histories Interpretation of QM. IMO the Consistent Histories approach comes much closer to Everett’s original intuition than DeWitt‘s - to put it very nicely - clumsy MWIoQM
one source of my procrastination is the idea the some other me from some other world is going to do everything anyway, why bother ? I suspect all other me's in all other worlds are likely to think the same way though.
thanks. I like it that Sean really wants to get the right answer for rhe right reasons. So he tends to be quite precise in his arguments, and also discusses their downsides. That's a very rare attitude, unfortunately.
Even though the measurement is well defined as a projection operator, post measurement the state is technically a pure state but we don't know which one so it becomes a density matrix. But when you describe the reduced density matrix of an entangled pair, it goes from a mixed state to a pure one after measurement.
This is great. Thanks as always. Is the book you're referring to in this video 'something deeply hidden'? Been meaning to pick that up for a while. Might be a good time for me to order it now lol.
57:00 i still dont understand why it has to be the wavefunction squared, and not to the sqrt(wavefunction square). Thats what we use to measure the length of vectors afterall
Do we need to know where these alternate worlds exist. I get the physical world keeps things in line by continually collapsing wave functions even without people. The trees persist in the same place despite a lack of conscious observers. But still all that branching is an astronomically large number of worlds. Where are they?
this is why i think certain versions of holographic conservation of information can allow a universe with no branches and still have local evolution and quantum phenomenology when analyzing coarse grained descriptions or subsystems. meaning what you have in practice in my view are manifestations of every possible branch stitched together into one branch such that you can find any two outcomes in a situation arbitrarily close in context somewhere in the cosmological multiverse on a single branch that correspond to two branches of one resolved superposition, that is to say it can be completely deterministically frequentest without any additional issue to be resolved that doesn't already exist in each individual branch in many worlds.
Great interview, the math was great, helped pull together some concepts from mechanics courses so the “many worlds” label is in reference to the potentially enumerable observer and world spin states relative to the environments….(im not sure how to put this) “Potential”?(what states create what emergence rules as a function of the wave function )From those many observer/world state groupoids- “patterns” at multiple grains of abstraction emerge and in some instances become stable. Wild how we get robust feature vectors with interesting hilbert spaces from eigenvalue diagonals
Phew...good stuff. Thanks. But couple of questions a. Surely Time isn't fundamental? Where is the evidence? What is Time? All we evidence is change. Time is just how we reference change (change of state, change of spatial position, motion etc) and change is reference frame specific; and b. Space is also abstract, its just how we reference spatial position? Spacetime is how we reference changing relative spatial position, i.e. motion? What's emergent? (by the way, the word space and the word time BOTH have two distinct core meanings, both are a collective noun and an abstract framework, it helps to differentiate them)
in an infinite universe there are an infinite number of partial quantum states that are prepared to look the same and then they are measured, so it doesn't matter what the coefficients are. since you cant actually check whether a certain calculus for the probabilities is correct for a single preparation anyway the only possible set of measurement outcomes you could care about the statistics of are similarly prepared states anyway, so the statistics must agree on each branch individually and in any combinations of branches. the statistics are the same on any individual branch no matter how you define it and draw your through line, so i don't see the need for branching at all really, just the need for a frequency of outcomes. maybe i'm missing something but i really don't think so.
JHU is an excellent research University. However, it’s quite small (relatively speaking). Perhaps this was one reason JHU was a good fit for Prof Carroll, less bureaucratic overhead + superior academic creds. I graduated from JHU many years ago. In my experience, JHU profs are the hardest working in academia. My profs would be there every day from early morning to late in the evening.
1:16:00 Unrecoverable measurement. It seems that there have never been any problems with QM already within the framework of GR (for example, in the case of the Schrodinger/Carroll cat). A live cat breathes and, accordingly, emits gravitational waves according to the formula GR with intensity: I(G)=(2G/45c^5)(M^2)(l^4)(w^6), where M is the mass of the cat, l is its characteristic size, w is its frequency breathing.The frequency of gravitational radiation should be on the order of w~ 2π/т where т is the characteristic time of accelerated mass movement (pulsation, rotation, collision, non-spherical explosion).It is clear that the dead cat is not breathing and I(G) =0. In principle, all this lends itself to a certain (improbability) constant measurement without opening the "black box", since gravity is not shielded [w=w(m)]. Moreover, the behavior of the radiation source is also controlled, since it emits only in an excited state. * Of course, Carroll's sleeping cat breathes, but differently (can be measured) than the waking one.** Sweet dreams to you QM, on the interpretation of the Born wave function. P.S. Why didn't Einstein use this argument? He wasn't sure about the reality of gravitational waves and assumed only the presence of hidden parameters… --------------------- *) - If the cat is replaced with a detector, then with each absorption its state will change (which makes measurement possible). It is clear that this will also cause additional radiation of gravitational waves, since the included detector is already a source. **) - The formula can be given in the following form for a photon: I(G)={[w/w(pl)]^2}ħw^2. Of course, this approach is also applicable to the case of entangled particles. "When physicists offer metaphysical explanations for physical phenomena, I start swearing." (Raymond Tallis). {Frame of reference in GR: "In the general case of an arbitrary variable gravitational field, the metric of space is not only non-euclidean but also changed with time. This means that the relationships between different geometric distances change over time. As a result, the relative position of the "test particles" introduced into the field in any coordinate system can not remain unchanged." ( Landau-Lifshitz, II). It turns out that since the Big Bang, all the particles in the universe speak, hear and listen to each other in the language of gravity (= irreducible spontaneous measurement).}
Pilot Wave theory is the most intuitive straight forward interpretation of Quantum Mechanics, but it is clearly incompatible with Special Relativity, but it is compatible with Galilean Relativity, where space and time are absolute and field propagation is not limited by the speed of light. I propose that Relativity is just an optical illusion. Relativity has a simple built in logical fallacy, and no theory based on a logical fallacy can be true, no matter how many experiments seem to prove it, or how many people say it is true. Below is a very simple logical argument highlighting the logical fallacy, using the same terminology Einstein used to derive Relativity. According to Relativity, observers on a moving train and on a stationary train platform will disagree on the size of the ""Train"" and the passage of time on the ""Train"". This is a complete logical contradiction if the size and the passage of time of the train are real. If the size of the train is real, then the ""Train"" can not be both contracted and not contracted. The same goes for the observed passage of time on the ""Train"". If these effects are observed, then the only possible conclusion is that it is an optical illusion. Things that are real must appear to be same from all frames of reference. If not, then by definition it is an illusion. Again the argument is very simple and it is the argument Einstein used to derive Relativity, and no acceleration is used in the argument. A train with length (L) traveling at constant velocity (v) relative a stationary observer on a station platform. According to Relativity, the stationary observer will see the train contracted (L/r, where r is the Relativistic gamma), whereas an observer on the train will see it not contracted (L). So the train is both contracted (L/r) and not contracted (L) depending on the observer. This is a complete contradiction (L not equal L/r) and can not be true if length is real. The same argument applies to passage of time on the Train, where both observers will disagree on the passage of time. If time is real, it can not be both dilated and not dilated (T not equal rT). If space and time are observed to be both large and small simultaneously for one inertial reference frame, such as the ""Train"", then it must be an optical illusion. This argument is only the tip of the iceberg. There is much more evidence including both theoretical and experimental, so please keep reading. Hi my name is Dr William Walker and I am a PhD physicist and have been investigating this topic for 30 years. It has been known since the late 1700s by Simone LaPlace that nearfield Gravity is instantaneous by analyzing the stability of the orbits of the planets about the sun. This is actually predicted by General Relativity by analyzing the propagating fields generated by an oscillating mass. In addition, General Relativity predicts that in the farfield Gravity propagates at the speed of light. The farfield speed of gravity was recently confirmed by LIGO. Recently it has been shown that light behaves in the same way by using Maxwell's equations to analyze the propagating fields generated my an oscillating charge. For more information search: William Walker Superluminal. This was experimentally confirmed by measuring radio waves propagating between 2 antennas and separating the antennas from the nearfield to the farfield, which occurs about 1 wavelength from the source. This behavior of gravity and light occurs not only for the phase and group speed, but also the information speed. This instantaneous nature of light and gravity near the source has been kept from the public and is not commonly known. The reason is that it shows that both Special Relativity and General Relativity are wrong! It can be easily shown that Instantaneous nearfield light yields Galilean Relativity and farfield light yields Einstein Relativity. This is because in the nearfield, gamma=1since c= infinity, and in the farfield, gamma= the Relativistic gamma since c= farfield speed of light. Since time and space are real, they can not depend on the frequency of light used. This is because c=wavelength x frequency, and 1 wavelength = c/frequency defines the nearfield from the farfield. Consequently Relativity is an optical illusion. Objects moving near the speed of light appear to contract in length and time appears to slow down, but it is just what you see using farfield light. Using nearfield light you will see that the object has not contracted and time has not changed. For more information: Search William Walker Relativity. Since General Relativity is based on Special Relativity, General Relativity must also be an optical illusion. Spacetime is flat and gravity must be a propagating field. Researchers have shown that in the weak field limit, which is what we only observe, General Relativity reduces to Gravitoelectromagnetism, which shows gravity can be modeled as 4 Maxwell equations similar in form to those for electromagnetic fields, yielding Electric and Magnetic components of gravity. This theory explains all gravitational effects as well as the instantaneous nearfield and speed of light farfield propagating fields. So gravity is a propagating field that can finally be quantized enabling the unification of gravity and quantum mechanics. The current interpretation of quantum mechanics makes no sense, involving particles that are not real until measured, and in a fuzzy superposition of states. On the other hand, the Pilot Wave interpretation of Quantum Mechanics makes makes much more sense, which says particles are always real with real positions and velocities. The particles also interact with an energetic quantum field that permeates all of space, forming a pilot wave that guides the particle. This simpler deterministic explanation explains all known quantum phenomena. The only problem is that the Pilot Wave is known to interact instantaneously with all other particles, and this is completely incompatible with Relativity, but is compatible with Galilean Relativity. But because of the evidence presented here, this is no longer a problem, and elevates the Pilot Interpretation to our best explanation of Quantum Mechanics. *RU-vid presentation of above argument: ru-vid.com/video/%D0%B2%D0%B8%D0%B4%D0%B5%D0%BE-sePdJ7vSQvQ.html *Paper it is based on: William D. Walker and Dag Stranneby, A New Interpretation of Relativity, 2023: vixra.org/abs/2309.0145
1:20:54 Well, there is a basic difference here: In a Newtonian deterministic world, Laplace's Demon could give, in principle, a (coarse grained) prediction for some specific future event to an emergent living entity ( to a " human being" living in that world , for example) with certainty. This isn't the case with an hypothetical "Everettian Demon" in a Quantum Multiverse. Although the evolution is deterministic, according to the Schrödinger equation, that "Demon" couldn't give any definite prediction for the outcome of a measurement ( to an experimentalist, e.g.) even in principle! Physics and science, in general, depends on the outcomes of measurements and observations. Even if the elementary description is deterministic, there's still is an irreducible stochasticity at the level of the emergent descriptions/ phenomena that cannot be avoided, even in principle, so in a sense is already "fundamental". Even Everettian demon himself cannot predict the future.
it seems therefore to me that branching with such an infinite universe just makes copies of copies of copies because the correct frequencies must preexist on any branch sequence you could possibly choose in an everettian multiverse.
Wowww that aspect of branching and decoherence keeping us from losing localization is an absolute mindfuck. Amazing perspective when considering the fuzziness of a particle. Probably gonna need the rest of my life to still not wrap my head around it lol
@@voodoochild24262 So you, too, have a PhD in physics because you actually acted on that curiosity and went to university and later worked at CERN and a couple of American high energy physics labs? Sure you do, kid, sure you do. ;-)
Sean, why can't you experimentally determine what counts as an observer. eg. If we record with a video camera and the wave form collapses, then it's an observer.
von Neumann was a mathematician. He merely formalized things that were already known. The formalism is not the problem here. The problem is that we don't teach why the formalism is the way it is (which has perfectly valid logical foundations).
Last post I commented why so short and here it is. You did allide to quantum computing in the beginning and I am hoping to hear if many worlds lends credence qc or vice versa. Much like emergence topic 4? would lend more credence
and btw when i say individual branches i mean not necessarily that the born rule is empirically embodied in every branch, just that most branches have it manifest in large numbers, you could for example have no single branch have the born rule manifest in a natural way but still get born statistics for averages over all branches.
whats the difference between the wave function not branching the branches always existing prior to the resolution of a superposition and the universe branching in the moment of such a situation? meaning simply that there are two ancestors in a 2 outcome superposition instead of one. in the same way you would expect there to be roughly as many situations in the universe where fair dice lands on 1 as lands on 6. that seems just as reasonable.
I would like to disagree slightly with @andrejbecker8955 and his characterization of Timothy's attempts to show that he has a clue about the topic. Think of it as 2 guitar players, one older, one younger, sitting in a guitar store, checking out the instruments. They both end up ripping off their best licks to show off, but then end up jamming together once the "who is the strongest Gorilla" argument gets settled. So Tim was just trying to show that he knows and then Sean (obviously the "Biggest Gorilla") just settled in to jam with him without trying to call him out on it. I was fine with it once I figured out what was happening.
Is the electron an observer of the quantum state of an atom? It has to know the state of the atom to know how to move next… ie isn’t any quantum element an observer of the other states?
If persetive of cat obesrver in open box but according to observe cat is quantam mechanical object. But according to cat observer is not quantum mechanical object.
i just don't see the need for branches its just much simpler to say each branch coexists prior the resolution of the superposition in my view, especially in an infinite universe which contains all possible configurations already. a quantum state after all is just a classification for a subsystem prior to us having completed some procedure to gain information about its evolution.
You are in favor of the Copenhagen (classical) interpretation? What makes the multiverse a no-go for you? Very curious. Penrose's CCC could be interpreted as a serial multiverse, whereas Everettian QM is interpreted as a parallel branching multiverse.
@@paulmichaelfreedman8334 I'm a bit hesitant to start such a conversation ( especially here in YT). Very briefly, there are some heuristic but still very convincing arguments that some kind of irreducible stochasticity has to be incorporated in the basic, fundamental laws of physics. Although I agree that Copenhagen kind of interpretations have their own issues ( like every other interpretation or alternative theory - like Pilot wave/ Bohm or physical collapse) they are still closer to the real world than MW. I don't think that QM as it is today is the final word, the fundamental framework for the basic laws of physics in all details, but it's still very close.. Strictly deterministic ( and fully predictable) laws are suitable only for simplistic toy models. Our teal world ( that's full of complexity) needs, besides determinism, some fundamental probabilistic/ stochastic element, that's why I'm in favor of the Copenhagen -related versions of QM.
@@paulmichaelfreedman8334 Penrose has his own gravity - induced physical collapse model, so I think that he agrees that although QM ( as it is ) is very close to the real world, it is not entirely "there", it needs some modification.
@@dimitrispapadimitriou5622 I can agree on most accounts, it's the reason there are so many different interpretations. Something is missing, maybe a hidden variable, that would select the correct interpretation, or a whole new one. I can totally understand why Sean is also interested in philosophy. He likes to dream up exotic situations and then check them with the current data to see if it has merit. He doesn't just go for the numbers, allthough everything does have to add up.
@@paulmichaelfreedman8334 Sean Carroll is an excellent science communicator and although he's primarily a physicist he's interested also in philosophy and that's good. He's willing to discuss in detail all interesting issues without oversimplifying, so his podcasts/ conversations not only are fun to listen/ watch, but they have an interest even for people that are already familiar with the problems he's referring to.
It's the "worlds become true" part that i have trouble with. Ontologically this is ill defined. It still looks like a conflation of possibility and actuality. Whereby all possibilities are just actuality set side by side with each other.
It's a simple counting mistake. Everett mistook an ensemble theory for a microscopic description of single systems in his thesis. Why Sean Carroll is peddling this nonsense is the only mystery here.
@schmetterling4477 I think that these issues in physics are so mind boggling that scientists become willing to make very strange, intuition crushing metaphysical and ontological assumptions. Those also sell popular books. So there's that too.
@@kvaka009 I don't find quantum mechanics mind boggling, to be honest. It's not being taught well, neither in QM 101 courses in university nor in the public square. The theory itself, however, is close to trivial and its structure can be easily explained with classical examples using dice. There is one thing that people have to learn to accept: the world is not classical. It was never classical. Physicists in the 19th century knew, already, that classical theories could not possibly be the end of it all. They were incapable of explaining even trivial observations like the stability of matter, let alone would they give rise to quantitative explanations of e.g. optical spectra. Physics between 1800 and 1900 was basically just hording data about unexplained phenomena. It couldn't explain anything past the motion of classical objects and thermodynamics. Part of the problem lies with our education system: we are over-training the high school student on classical physics. It should be the other way around. We should show students non-classical phenomena, first (like magnets) and then explain to them that we are only going to teach them a tiny subset of physics concerning the motion of objects. Everything else (maybe except for the photoelectric effect) is university level material. That would clarify that the material that is being taught is NOT the core of physical reality.
@@schmetterling4477 stop it. There's a Feynman quote floating about basically saying that no one really understands quantum mechanics. And anyone who says otherwise are suspect.
47 minutes, the system, the observer, and the environment. 76 minutes in, Timothy its never good to hear, I'll draw a picture after a verbal presentation. Just razzing you kid. Well done Timothy, thank you both Sean and Tim, great discussion. Peace
The many worlds hypothesis is not very satisfying psychologically. It’s schizophrenic since now I imagine all these near copies of me I’ll never meet doing different things in different worlds when I’m reality I have to focus on the one me in this world.
imagine you measure spin of an electron and you measure consecutively individual different electrons in one direction. you get 50% up or 50% down. on average. each measurement according to many worlds happens so you measure up and down in separate universes. However this means that there must be a universe where you measure n times and you get up or down n times therefore not 50-50 %.because your universe split and there is a branch where this spilt results in all up or all down. Our universe never happens to be one in which these consecutive measures result a deviation from the 50-50. How can the many worlds explain this?
(1) If you wait long enough, you not only can but must see n results in a row even with 50/50 probability. (Search "how many times do I flip a coin to get heads n times in a row?" and you'll see the equation for the expected number of flips.) (2) It happens in some universes but not ours. (3) Even in our universe, very very unlikely things still happen. And (4) in the universes where that does happen, people are in comment sections like this demanding an explanation for that.
There are more universes in which the measurements are 50-50 than there are universes in which it's n-0. So it's like entropy but across the possibility space. There might be a universe where you unscramble an egg.
@@EdwardCurrent yes but you can make billions of measurement separated by time and space and if you make like a 10000 measurement, you still have 50-50 probability, maybe 48-51 but never like 70/30, (do not stick to 0/100 example) . so these answers do not really explain it. You just state , well, we are the most probable result. but in all cases, every time, and not even a bit deviating? come on...
@@tokajileo5928 It's not sarcasm, but it was curt because I didn't think I had space to explain it fully. But let me try again in a more straightforward way. But since I’m writing this off the cuff I think it'll be long. Well, first the simple answer can be short: In some universe the 50/50-chance flips of a coin will still lead to a vastly improbable number of heads in a row. That looks like it's not 50/50. But if you flip an infinite number of coins, even a 50/50 chance will lead to 100 heads in a row, or 1000, or a million, etc. because you're flipping infinite number of coins. That's how you can have 50/50 chance process having a non-50/50-chance-looking result. Now for the longer part. You have to back up and ask what does 50/50 chance really mean? It means in the space of all possibilities, 1/2 of the space is spin-up, 1/2 of the space is spin-down, and at every branching point, any individual’s human consciousness is going to find him or herself taking a truly random walk through that space. The truly random walk (from your perspective) ensures that you're going to have a 50/50 chance at every branching point to enter into spin-up or spin-down territory. But since there's an infinite number of random walks, just like flipping an infinite number of 50/50 chance coins leads to non-50/50-chance-looking-paths, an infinitesimal number of them will have a non-50/50-chance-looking path of a large number of spin-ups, even though that path is still really a 50/50 chance for the same reason I mentioned above with the coin flips. Okay, there may be a point in what I said above that can help explain it in another way. There are two ways to look at probability in MWI, from the perspective of the "Wave fxn of the Universe" (following the Sch. Equation) and from "your perspective". From the perspective of the wave fxn of the universe, there is indeed no 50/50 chance. It will follow the evolution of the S.E. with 100% chance. No probability involved. Where the 50/50 chance comes from has to do with the fact that some special sub-sets of the WFotU (what Sean calls factorializations, which mereology discusses, the study of the relationship between parts & the whole) some special sub-sets manifest classical physics with conscious humans in them. It just turns out that the SE is going to always create these sub-sets symmetrically, because the quantum property of “spin” is symmetrical. Spin is (heuristically) a thing rotating about a center point, and if every path around that point happens, it’s easy to see that every path in one direction must be matched by a path in the opposite direction, and you can’t have a path that doesn’t have an opposite-path that’s still “spinning” about the center. (It’s in a complex space, so it’s not actually easy to imagine, but the gist is still there.) So for every spin-up there's always a spin-down. This symmetry ensures that 1/2 the possibility space is one result and 1/2 is the other. The random walk you see yourself taking through the full possibility space is just because your physical brain, your consciousness and memory, retain the history of the random walk path that brought you to this point in time and space from your perspective. Particles are symmetry representations in the quantum factorialization, so we’re really talking about the random walk “particles” take through the foliations of all the universe branches. As that suggests, they’re “representing” or evolving as what they are “symmetrically”, for every spin-up electron there’s a spin-down one. By the way, quick interlude on the anthropomorphic principle. In the universe where every single electron spin is spin-up, classical physics is collapse and everybody in the sad region where that happens will instantly die and of course not be in a position to measure that result. Anyway, I think that should answer your question now: (1) WFotU isn't 50/50 chance, it's 100% chance, (2) Classical physics is a factorialization of the WFotU creating separate “world”, (3) the space of all possible world histories are evenly split 50/50 spin-up and spin-down because of the symmetry of spin, (4) particles (and the human consciousness and memory that they underlie) take an essentially random walk through the full possibility space, (5) thus the chance to measure spin-up or spin-down MUST be a 50/50 chance from the particles' (i.e., your) perspective, (6) but if there are an infinite number of paths, some of those paths must manifest a greatly non-50/50-chance-looking result even with a 50/50 chance for the same reason flipping an infinite number of coins will require some infinitesimal subset of those coins to see as many heads in a row as you like, which doesn’t look like a 50/50 chance, but it is. The confusing part is just that you’re flipping an infinite number of coins / taking an infinite number of random walks through the full many-worlds space, and that plays tricks with your intuition about what 50/50 chance means. I think this should answer your question better.
*Solution to the "Time Light Problem"* The reason why people often stumble over the *assumption* that light years in outer space equals the same measure of distance and passage of time on earth is because general relativity is not being taken into account. In general relativity, the local rate of time and the measure of distance depend on the amount of matter or mass in the vicinity. Locally, the rate of time and measure of distance doesn't change much inside of our galaxy. However, the distance in our line of sight between us and distant galaxies is extreme and running at a much faster rate of time as well as an expanded measure of distance outside our galaxy compared to where we are near Sagittarius A's Milky Way black hole (where our rate of time is much slower and our measure of distance is much more contracted). The same way the earth appears flat locally, our universe also appears to be flat locally. However, over great distances throughout the universe there are differing measures of distance and differing rates of time from black holes to the lagrange points between black holes where there is very little acceleration compared to our relatively flat contracted local frames of reference near Sagittarius A. When we observe other galaxies, we are effectively looking at vastly differing measures of time and distance relative to our local observations within the gravitational force of the mass of the Milky Way galaxy. This can lead to various observed phenomena as we look into outer space such as redshift, superluminal motion and the apparent faster motion of the outer spiral arms of galaxies. It's not the same as our flat observations of cats and dogs locally here on earth where we don't observe differing measures of distance and time. So the supposed expansion of the universe, imaginary inflatons, invisible dark matter and dark energy or vacuum energy are *not* required to explain the observed redshift of light from distant galaxies or the faster than expected motion of the outer spiral arms of galaxies. As predicted by general relativity, the expanded space between galaxies due to the absence of matter in our line of sight where much less acceleration can explain the observed redshift without the need for a nonsensical universe expanding into oblivion for no apparent reason and it explains the faster than expected motion of structures and objects the farther it is from supermassive black holes. It turns out that the vacuum energy of space is due to the frame dragging of black holes that are growing from gobbling up spacetime regardless of the amount of matter being consumed. Recent findings of a team of scientists have found that dark energy or vacuum energy is associated with supermassive black holes that are all growing in size, as opposed to an ever expanding universe. It turns out that light is blue shifted going into a gravitational well so the converse is true of being redshifted traveling great distances outside of gravitational wells. Supermassive black holes are the most powerful forces in the universe with far reaching effects of gravity and vacuum energy. The problem and solution is that between galaxies, all of the galaxies all around are all together pulling and drawing in spacetime as well as exerting equal gravitational forces on empty space. This is the reason there is very little acceleration between galaxies and where there is expanded distance and a faster rate of time. The clocks are running faster outside of galaxies and the measuring sticks are larger meaning things are actually less distant than they appear. The more gravity drops off outside of the galaxy and in between galaxies, the more distance will be expanded and the faster the rate of time will be. As predicted by general relativity, the expanded space between galaxies due to the absence of matter in our line of sight where there is less acceleration explains the observed redshift without the need for a nonsensical universe expanding into oblivion for no apparent reason at all. The differing rates of time and differing measures of distance also explain *how* a day is the same as a thousand years and a thousand years is the same as a day, at the same time in the same universe. 13.8 billion years is the same as 6,000 years and 6,000 years is the same as 13.8 billion years *within the same created universe!*
To speak on the wave function with no mention of phi, perfect damping, the interference function, harmonics or musical theory (4ths and 5ths) is blasphemy.
Sean Caroll is what happens when you take philosophy out of science. His 'philosophy' can't really be called that. His science is weak and tunnel visioned. He is massively over rated and he has the most annoying voice I have ever heard.
We don't even understand 95% of observable universe, i.e., dark energy/matter, yet you want to speculate on untestable seperate universes. Back to basics me thinks..
