The Biggest Ideas in the Universe | 8. Entanglement

[@jeremyroy99]

Physics students of the 60s had the Feynman Lectures in print form. We have a Sean Carroll KZbin playlist. What a time to be alive.

[@richardlinter4111]

@Astute Cingulus : Quite right, but GR can be extrapolated to the Planck scale. It's just that doing so we find it disagrees with QM. This I believe is actually Sean's point, or one of them.

[@richardlinter4111]

Amen.

[@ssshurley]

Jeremy Roy Your right. I bet they were loving the print lectures. Hahah

[@tricky778]

In the 60s they had Feynman lectures on cine film, in person, and had tutorials with him directly, plus drinking with him I bet

[@GuRuGeorge03]

we are living in the McDonalidization of knowledge. Type a few words into google on a device the size of your hand and nearly all knowledge of humanity is literally at your fingertips. Now we just need people to enjoy it as much as they do McDonald's

[@robbyjohnson6531]

I am artist with very little understanding of physics. I have been so interested in my whole life, and five or so years ago, gave up on my attempt to understand or appreciate the subjects that you've been teaching in this series. This is exactly what I've been hoping for for so damn long! I have the drive to learn more about this stuff again. Every episode starts with me doubting myself, that I'm too stupid to get it, and ends with my mind being blown, and feeling like I have a new outlook on my ability to understand... well, anything.

[@schmetterling4477]

You are correct. You have very little understanding of physics. :-)

[@dude124353]

Entanglement, yes! Been trying to get my head around it for awhile now, every time I think I have it there's more around the corner, angular momentum was an entire rabbit-hole on its own. Thank you for sharing your knowledge Sean, your videos are my favourite for explanations of complex ideas.

[@scottmiller4295]

this may be off, but i simply think of it as particles sharing information aka energy and the more they share the more entangled that they become. to the point you get stuff like us. any time particles interact in the universe and share information i tend to think entaglement is all over all the time and not wierd at all. i look at information as the key and the type of information secondary. but i could be and probably am way the hell off.

[@billyjoe2128]

Complex ideas?? Just being plugged in and realizing nothing is impossible. Upward and onwards All day everyday

[@Wandering_Chemist]

I would read Nobel Prize winning John Bell’s book, “Speakable and Unspeakable in Quantum Mechanics.” To really understand his Nobel Prize winning theory that was confirmed experimentally, Bell’s Theorem.

[@seancarroll]

Hey, sorry for the mixup with the previous version of this video! Somehow I uploaded the wrong version, I had to delete it. This one should be better in both audio and video quality.

[@Nietzsche_K_Gote]

I love listening to you explain about things I never and always knew I as curious about

[@CuriousCauliflowerX]

Less tearducts, more physics, great!

[@seandimmock5813]

Sean Carroll let us know when that textbook is out!!!! Can’t wait!!!!!!

[@coecovideo]

All good, thanks

[@bombproofmetal]

All of these videos have been amazing thank you so much for your hard work.

[@eminem2]

If you want to see a great man with no pretentious ego, Sean Carroll is one such !!!

[@TheAuriconGroup]

I had some sadness in my life related to the covad-19 thing. The only way I could remove my self from the sadness was to watch this video (I read your latest book). Your talk took me to another place where I had to think really hard to follow along. Not that I understand it all, but it is so very helpful. Thank you.

[@brucegoodwin634]

I hear your pain. Take a hug? Keep plugging…

[@TheAuriconGroup]

@@brucegoodwin634 Thank you so much Bruce. Yea, I will take that hug and back at 'ya. I am so very pleased that Dr. Carroll is doing this series. It expands my mind. What a wonderful thing for him to do. It is like the best collage teacher you ever had.

[@Bronett]

I so enjoy these lectures! With the entanglement episode, you made me think of the story about the blind men and the elephant. Each touching a different part of the animal and from that having an opinion about the nature of the creature. It is hard to state what the entirety of something is (and exciting!) - not knowing the whole creature… Thank you so much! Henry B.

[@stephenbryant7873]

Feynman, Susskind, Carroll ... three great explainers, but with very different styles and emphases. I can’t say which is more influential, but I am so glad that Sean has decided that this is a good use of his time. For me, these talks are very accessible.

[@veronicanoordzee6440]

Susskind, the cookies-munster?

[@nickstu2355]

Your version of Schroedinger's cat doesn't work because the cat is likely to be asleep either way

[@Avenged7Xsick]

A few questions: What relation does many worlds have to the arrow of time? Can wave functions branch "backward" in time? If not, why is the wave function time asymmetric? Does the present moment have multiple possible pasts? Is entropy related to many worlds in any way? Could many worlds be emergent from a more fundamental law of the universe, such as for example, "all things that can exist do" and the branching then happens when different logically consistent possible realities can no longer logically exist together anymore? Could the laws of physics as we observe them be the original branches of the universe? Could other branches have other laws of physics or different values for universal constants? Also, thanks so much for making these videos! I hope you truly understand and internalize the impact they have on the world and especially to your viewers.

[@tomhepz]

As for the entropy and the arrow of time, QM has the exact same princple, the worlds decohere, and there are many more decohered states, and so statistically you move to a state of 'lower entropy' but there is a tiny tiny change just as there is with entropy that they will 'recohere' but it's so insignificant that you don't need to worry about it

[@dajandroid]

I think that the entropy question with regard to the Everettian interpretation was briefly mentioned in Professor Carroll’s Google lecture but I wonder if he could expand on it here in this “The Biggest Ideas” series?

[@davegrundgeiger9063]

I just discovered this series of videos, and I'm like a vegan in a tofu store. Any update on the undergrad quantum physics textbook mention at 1:38? I searched on Amazon and at preposterousuniverse and didn't find anything. Thanks so much for this great series!

[@arpansircar8858]

Questions: - 1. In the spin example, can the wave function be of the form: 1/sqrt(3) [ (up,up) (down,down) (up,down) ] - in that case if A measures up, the measurement of B is not immediately determined - is this also an entangled system then ? 2. It seems that the concept of many worlds comes out as a result of Everett's 2 postulates. However, is it possible to design an experiment to test the concept of many worlds ? 3. A request: would you please re-do the double-slit experiment explanation from the point of view of many worlds rather than Copenhagen

[@arpansircar8858]

2) Yeah I think he may have said something like that 3) As far as I can recall, in PBS Space Time they used the Copenhagen explanation, I can re-check. Do let me know if you have any link to a video which explains the Double Slit using Many-Worlds

[@JohnDlugosz]

@@chriswarburton4296 *affects

[@alexrsnh]

This was my favorite of this series so far, and they're all great. Brian Greene also provides a really good explanation of Bell's Theorem in "The Fabric of the Cosmos."

[@johnlawrence2757]

Entanglement: one of those words whose meaning changes as the year passes. Like iconic. I am old enough to remember when it involved splitting a quantum particle in two, consigning each of the halves to opposite sides of the universe, then tapping one to make the other jump simultaneously. The logistics of such an experiment were always rather fascinating, I thought. But then I can remember when an icon was a small painting on wood of a Christian subject created in the Byzantine era of the Roman Empire in Constantinople Ah me, those were the days

[@davidcrabtree4718]

Let a thousand flowers 🌺 bloom across the multiverse of speculative ideas.

[@walkercatenaccio]

This is probably the best talk so far of a great series. I finally understand (a little) "Many Worlds," which had always seemed ridiculous to me. It was the orthogonal axes that did it.

[@petrt88]

I have heard about entanglement many times. But this was super duper explanation Professor! Finally it does not seem as a pure magic for me anymore. Thank you for this.

[@3dlabs99]

Amazing how fast you can make these videos -- I love the quarantine :)

[@jerryrobbins5013]

best podcast ever. i had to rewind a few times to get things again. you're a great science communicator, thank you so much.

[@clawpuss2]

Sean is making lockdown bearable.

[@argyriosvlastos321]

Thank you! for making more accessible, these highly abstract and technical concepts to those of us who love physics and...and assuming we're not stupid! SC a fantastic human being, thank you sir for sharing!

[@ToriKo_]

13:00 Sean gives a solid definition of entanglement after motivating it the previous 13 mins. I have a feeling this episode is going to be crucial for a lot of moving parts. I think now in part I am able to articulate some thoughts around the (DSE) double split experiment, which is supposed to highlight the wave-ness of stuff, which collapses into particle-ness when we detect/observe it. We also have this idea and assumption of “a (physical) system”, which might come into play as confusing. So we have some electrons that are being fired out of a gun, through two slits as wave-like, and collapse as they (singular) hit the detector. My sense, which may be wrong, is that the wave collapses as we observe it, which means we are detecting it, which really means it is being entangled with the physical system of the detector. But how does this wave like form leave the gun, which is also a physical system, go through the slits, the walls of which are physical systems, and then hit the detector, a physical system, but only get entangled (collapsed) at the last step? If we are all in the same universe, kind of by definition a universe entangled with itself, how could we ever see directly or indirectly, wave like properties?

[@bruinflight]

OH MY LORD. I never thought I would understand entanglement. Sean you are AMAZING.

[@wenlielicn4248]

"It's not a bug, it's a feature" made me laugh, as I'm a programmer.

[@zoranivanic3543]

I am a simple man. I see Sean Carroll channel. I subscribe.

[@ringscircles142]

the universe will sing your praises for ever and ever

[@charlesmurphy8978]

I have a question, Mr Carroll. Why do complex numbers are necessary to describe a wave function? I've never had a satisfactory answer to this question during my undergraduate studies in physics.

[@Toocrash]

Amazingly bright

[@Wandering_Chemist]

32:50 This far in and I’m not hearing anything about Bell’s Theorem! He better not disappoint me 😅 36:10 And of Dr. Carroll comes through again!

[@TanioDiazSantos]

Thanks a lot for the videos. I have some Qs for the Q&A: 1) Is there any kind of "profound" connection between each of the conservation laws and each pair of conjugate variables in Heisenberg's unc. principle(s)? Is there a one-to-one relation, or one can arise from the other? 2) Isn't the dismissal of "super-determinism" at odds with the acceptance of the Anthropic principle (which I'm also fond of but...)? If I understand well, it's not about the experiments being able to be imagined, but whether some outcomes will ever happen or not. Accepting the Anthropic principle implies that many of them won't, because those are not the outcomes that would allow us to be here to measure them. And that's very similar to the idea of "super-determinism". 3) Could you comment a bit more on how non-locality fits in the MW interpretation? The idea of decoherence being triggered by the environment seems somewhat local to me (or at least it appears; maybe it's just the word). Does decoherence/branching happen instantaneously everywhere or does it propagate at c? Also, can be particles entangled in any property that is not part of any of the Heisenberg unc. principle(s)? (or conservation laws?). Thanks again!

[@michaeljames5936]

All well and good Herr Schrodinger, but let's see you get the cat into the box in the first place. Might i suggest you propose a simpler and less painful experiment such as 'Schrodinger's tortoise.'

[@Nixontheman]

Thanks for posting, surprisingly easy to follow. 👍

[@DaKoopaKing]

Definitely the best video yet. My only question: Are there any leads on when quantum information decoheres? I remember hearing that we've sent entire molecules through double slit experiments and preserved a wave interference pattern. Do you think there is a hard line (if any) that separates quantum information from the environment?

[@Cygnus__X1]

2nd this question - and to add on, would it make sense to say that the probability of decoherence (due to any interaction, which would include decay/particle emission), is exponentially so much higher for multiple particle systems that it makes it essentially impossible to avoid the decoherence in any realistic experiment. That could explain why we have only been able to show entire molecules (and not a baseball) obey the wave-particle duality.

[@JohnDlugosz]

It's studied in detail and put to practical use in the effort to build quantum computers. I recall reading about how a cloud of Bose-Einstein Condensate can be put in a so-called "cat state" (a macroscopic superposition) where it is in two different places some half a meter apart! The limit is only due to the depth of the hole they have built the experiment in, as it takes place in free-fall. There is no "hard line" per se. It is a matter of including _everything_ that is part of the entangled state as part of the observation, and not letting anything escape. There are also quantum error-correction techniques that increase the robustness of maintaining entanglement by many orders of magnitude; that is, some small loss does not make the states go completely orthogonal, so the branches can still interact. Look for video about QM in biological systems -- I can't remember the guy's name, but he's an interesting character. But examples include photosynthesis and a magnetic sense used by some birds.

[@grahamCracker]

I just wish someone could explain how "entanglement" is any different than simple synchronicity. Two waves are waving at the same frequency. Measure one and you "know" both. They aren't physically "entangled." They are just dancing to the same beat. Can someone help me understand how QE is anything more?

[@grahamCracker]

@eric thefathead Sure, but other properties like spin can have synchronous and asynchronous relationships.

[@samrusbridge8375]

In your example, you might know that the waves have the same frequency, but because of QM they behave as though each wave has two different frequencies at the same time until you measure one of the waves, then you know the frequency of the other. The important thing is that until you measure, they behave as though they have properties of both different "frequencies".

[@tomlakosh1833]

Time/distance and entanglement are mutually exclusive as superposition precludes acceleration needed to calculate the time and distance function. That's why, in my barely educated amateur opinion, we need a dual membrane electromagnetic field with an antimatter half that doesn't have a time function and this brane produces entanglement through strings that are paired with matter strings to form 1 to 3 aspect ratio tori that we call gravitons. The circuit or conduction tensor formed in the torus keeps these strings from annihilating as does the conduction tensor holding graviton clusters together, (looks like a barbell). Time just renders these antimatter strings to a recessive manifestation in the graviton and in the subsequently more complex structures incorporating gravitons. These structures can synchronize wave functions that when they reach zero, allow transport through the antimatter 3-brane. Gravity is just the electromagnetic and fluid dynamics processes applied to the flow of graviton and graviton clusters around and through Standard Model particles when time applies on our 4-brane. The clusters are actually gluons that were formed en mass during the GUT Epoch and are continually formed in SM particle cores. These gluons/clusters act like a dipole gas subject to condensation via Feshbach resonance and BCS field effect, and this condensate is formed in the electromagnetic field of galaxies as dark matter that is scattered by cosmic rays. The dipole gas is spin and charge coupled on the surface of leptons and baryons to form the Higgs field operating as an electromagnetic rectenna generating space-time viscosity as it captures the momentum of gravitons and clusters flying through the field, (kzbin.info/www/bejne/e4fFlZWMnd-Wg5Y&t=288 , the secondary torus represents the Higgs boson terminating/reversing Higgs field flow). The gas is also the working fluid for a gravitational propulsion system operating as an “ion thruster” through the core of the leptons and baryons. Dark energy is just the increase in quantum friction of the propulsion system in barren space where the Higgs field drags the particle backwards toward even less dense space because the propulsion system no longer counteracts the Higgs field generated momentum from the low density gravity flux emanating from the center of the universe. The gluons also form the structure of the SM particles when fused together in rings under activation energy with four graviton clusters forming leptons, six graviton gluons forming nucleus shells and eight graviton clusters forming nucleon shells with each modular element absorbing the strings from the distal gravitons into the linear conduction tensor forming the core of the structural ring. Neutrinos are one of the rings from a lepton that can oscillate because of the triple density string structure in the ring core.

[@jimmcintyre1966]

Does entanglement play a part in light slowing down when travelling through a medium? Some physicists say that the light is slower because scattering lengthens the photons' path while others say that it is because of the interaction of the light wave with the waves of the electrons in the medium. The latter hypothesis seems to reference entanglement.

[@davidhand9721]

The latter reason is true, but it doesn't involve entanglement.

[@Cooldrums777]

At the beginning of the lecture you say that "there is only ONE wave function, and it is the wave function of the universe". Then after describing that the environments in all QM systems are orthogonal and therefore independent of each other you say that Hilbert space contains an INFINITE number of wave functions. So obviously I'm not understanding a key concept. Perhaps you can clarify the discrepancy in the Q&A video.

[@cazymike87]

As a constructive the number 2 can be view as number 1 + number 1 ( or 1 unit +1 unit ) , the same for Number 3 ( but here you can get 1+1+1=3 , 1+2=3, 2+1=3 ....now you move on to number 4 (1+1+1+1, 1+1+2, 1+2+1, 2+2 , 2+1+1, 3+1, 1+3 ) ...etc. Now instead of number , place the waves ! The wave function of the Universe its the Wave equal to Infinity in this exemple.----or more specifically....The Wave function of the universe is the same for all waves , but it has different values according to what is real at that spacetime point , given the QM mechanichs .

[@cazymike87]

Its like a chameleon----it has different shapes , and here you have QM that tells you what it is in that spacetime point --but its the same

[@sinebar]

If you entangled 2 uranium atoms and one decayed how would that effect the entangled partner? Also is it possible that virtual particles are entangled and if so then how would that effect Hawking radiation? I mean would entanglement still be preserved with one particle in the black hole and the other escaped?

[@gamerN77]

When writing the wave fn of the universe at the beginning, you gave in brackets (x1, x2, ... xN, t). How does QM deal with the relativistic notion that every electron technically should have its own time frame and that there is no absolute time?

[@trucid2]

There is a relativistic version of the wavefunction, the Dirac equation.

[@BoazRosenan]

I think that non-Everettian phisysists describe decoherence a bit differently. They state that decoherence is when a simple wave function stops being able to describe the state of the system. Of-course this by definition means that the system is entangled with the outside world (and hence you need more parameters in the wave function for it to explain the observations) but in their view, this is an effect, not a cause.

[@krikeles]

the problem with this new formulation of the Schrodinger Cat is that sleeping gas or not, cats spend a lot of the time asleep.

[@qclod]

m k Haha!! The hidden variable of cat sleepiness.

[@steeneugenpoulsen8174]

Local is only an issue for us living inside time, for something outside time it is always next to each other and always separate, so there is no distance issue for it to entangle and transmit.

[@mby_dk]

At 9:12 Sean refers to particle 1, but he should have said particle 2. At least as I see it. Afterwards he explains what happens in more detail, and here he gets it right.

[@GodlessPhilosopher]

Seems like the word "interpretation" better describes the difference between realist and anti-realist (or ontological ans epistemic) theories: you've got realist interpretations of QM (many-worlds, objective collapse, and hidden variables) and anti-realist interpretations (QBism, quantum pragmatism, etc.).

[@2ndAmendmentX]

If a principal of QM is that waves can interfere with one another as observed in the double slit experiment, wouldn't many worlds also imply that there would be some interference observable in the macro states?

[@pettiprue]

Biggest entanglement in your lockdown hair X I so enjoy your stuff. Thank you.

[@eddie5484]

I don't think I'll ever get to visit Alpha Centauri, but I do know that GR tells us there's no inertial frame of reference that you could set up to compare the state of two systems over that distance.

[@schmetterling4477]

You don't have to go that far. That statement is true over any distance and not because of GR. It is already true in special relativity. The tensor product structure of the quantum mechanical Hilbert space is a direct consequence of relativity. That's why it's so boring, as well. There is no new physics in it.

[@HomoAustriacus]

In the awake/sleeping cat example, why for example (cat awake, seen sleeping) is not taken into account- isn‘t that just possible or do we as observer prejudge what makes sense or not - is there a hidden bias of the observer distracting the system (leading to decoherence)

[@tomaskratochvil8740]

Hi Sean, what an amazing series! When I think about the reality through quantum physics eyes, and wonder how nature works, I was compelled by Many Worlds from the begining, though not sure about it, because I felt it is somehow wastefull, by splitting the universe with each interaction. Thanks to you, and your series, I have gained knowledge, in understanding QM as well as Many Worlds in the way I see it through different perspective now, and I like it even better. Always appreciate your lectures and appearances (WSF). Question about topic at hand. Decoherence seems to me like pretty strait concept and I wonder why it had appeared so long after concieving Quantum theory, why Shrodinger and others haven't thought about it? Regards to you, Sir and your very familiar cat in our branch of the wave function of our Universe bouble.

[@matkosmat8890]

Hello, Sean! Watching your videos has actually given me a pretty good picture of the current state of affairs, and I appreciate this immensely, being a total layman in physics. I have this question: if the Wave function is not only a tool to make predictions, but is instead something real, how do you even start studying it? Who sets its values? I'm a bit lost, I can't really formulate my question right, but the reality or unreality of the wave function stops me from even thinking about it. Help!

[@GGoAwayy]

What bothered Einstein was the idea that reality could change faster than the speed of light. But once you discover which universe you're in, that's the universe you're in and you can make whatever inferences possible based on what you know now. The question is really what does a superposition state mean in reality? If Bob is on Alpha Centauri with his particle, it's not like Bob's particle was still in a superposition state the entire time until the instant Alice observed her particle back on Earth. What does it mean where multiverses overlap and you have real superpositions?

[@resurrectedstarships]

26:45 what if you could change the spin of the eelctron, forcing the opposite spin on the other side, which would then be communications....is that possible? Aren't the spins of electrons altered all the time as a matter of course??

[@KaliFissure]

Neutron decay cosmology evolves that electron entanglement is a result of the fact that every proton and each electron are linked as a total paired process to the neutron from which they came. And where they will return as soon as gravity has had enough time. Neutron decay cosmology. The neutrons which contact event horizons become the vacuum energy for one single Planck second then re-emerge in lowest density points of space, deep voids. There the neutrons decay into amorphous atomic hydrogen. This decay process includes a volume increase, energy density decrease, of 10^54 times. Expansion. Dark energy. Lambda. With automatic fine tuning since a gas expands to fill volume. Ingenious. The decay product, amorphous atomic hydrogen, doesn’t have stable orbital electron so can’t emit or absorb photons. Dark matter or some of it. I think the galactic spin issue is undervaluing z pinch in plasma. The condensation of mass and the turnin* of smooth large scale rotation into micro turbulence. Space has a variable Reynolds value. It’s less viscous at higher density.

[@Destrolll]

If branching is direct cause of Schroeder's equation, and the equation is time-symmetric, why do we have process of branching that is directed only to the future, or so it seems. Could you please explain that?

[@LiamHaleMcCarty]

A Mindscape guest awhile back (James Ladyman maybe?) said that he took issue with Many Worlds because he didn’t see a justification for the probabilities. Unlike a perfect coin having a 50% chance of landing heads up because experimentally that’s what the probability approaches as the number of trials increases, the probabilities in Many Worlds refer to separate branches of the wavefunction that by definition can’t interact, so it’s not clear why the probabilities are what they are. Sean, you seemed somewhat caught off guard by this objection and said it was a interesting point. What are your thoughts on it now? Do you have an explanation consistent with Many Worlds, or do you see this as a potential issue with that interpretation?

[@madderhat5852]

Is it weird that I'm more into the 1% of the ideas? Must be my science/philosopher/artist brain. 1:18:30 Totally agree with your wrap up for the show.

[@nowhereman8374]

Okay, Isn't there a mass problem with the Everett's Theory? Seems to me that is an interesting question. One can argue that the vacuum energy of the universe provides the source for the mass creation required as the universe branches and that the continual expansion provides the 'infinite or very large' source required for the increasing numbers of branches. Also how does Everett's Theory fit into the big bang explanation of the universe? It seems to me the data supports that the universe was in a highly entangled if not completely entangled state, so is entropy part of the process by which the universe becames less entangled?

[@wcm5150]

Thank you, you are doing a service to humanity Professor Sean Carroll.

[@isbestlizard]

Could you make a universal compass with lots of entangled particles? Send someone on a spaceship with a 1000 pairs of electrons that are guaranteed to be spinning in opposite directions, then once they arrive measure the spin of each of the ones that stayed home and measure the spin on alpha centauri and if they match 100% you know the axis you're measuring in is exactly the same as the one back home but if they are completely random 50% you know you're measuring along an axis that totally isn't right?

[@trucid2]

I don't think you do justice to explaining superdeterminism. It doesn't reject initial conditions, but rather that certain states of the universe are invalid *because* they don't have valid initial conditions. It's a rejection of counterfactual definiteness. Have you read Sabine's paper on superdeterminism?

[@migueldiez9834]

Is Sean talking to us from his quantum foam jacuzzi ?!

[@avadhutd1403]

Hi Sean , Many thanks form India for great great lecture But I want to ask one thing 1.whats Ur thought on experiment that monkey is sit on type writer and one of possible worlds it creates Shakespeare play ,or quantum immortality,these are the weird implications What's Ur thought folks please share

[@bartk07]

Professor Carroll, could you explain what is going on after the measurement with, say, a particle and its wave function? When we see "collapsed" wavefunction giving us the position, does it somehow "recombines" from this definite "peaked" value to fuzzy wavefunction again? When and how it is done and how does it look like in all of those theories (or interpretations) you mentioned?

[@barrerasciencelabuniverse6606]

Groundbreaking discovery: Milkyway immense gravitation causes Special Relativity! (see Barrera/Thelin IOSR 2015 about galaxies)

[@PavlosPapageorgiou]

Are you able to start from wave functions and describe a classical process like two particles bumping into each other and scattering in different directions?

[@qwertasd7]

IMO QM describes "our" uncertainty of measurement, which is not the same as saying nature acts random (for example schrödinger), its, therefore, more a theory statistics doing it mostly predictable, as to describing the underneath moment. Hence the problem is more related to how "we want to see it", in our abstractions of geometry and forces. ---.-- Just thinking it might be the many world interpretation might be forever colapsing to a single world. Endless possible histories, but a single current colapsed reality, a collapse as a (minimal entropy ) solver. Where larger systems influence smaller systems histories. (emerging structure, emerging reality). And the freedom of those larger systems is related the smaller system chaos. (I end here starts to sound wacko).

[@nujuat]

I was wondering if you could give the Sean Carroll treatment to the Heisenberg picture vs the Schroedinger picture? The seem pretty relevant in the quest to find the “correct” perspective on quantum mechanics. Do you think one of the pictures looks at things the way things are “really going on” better than the other?

[@pizzacrusher4632]

Does schroedingers cat not begin to decompose until it’s observed dead?

[@musicalcacti]

We need to get him to 100k!!

[@kidmohair8151]

the spooky action...is the disappearing hand: but... if A is spin up by virtue of B getting spin down, has not communication taken place, regardless of distance...deardear

[@teghem6723]

So, not only God does play dice, but the required size of the dice is that big that it encompasses all the events involved. After all , what might be the size of a "background microwave photon" wave function before it collapses? This can let us keeping talking about "action at a distance" without entanglement.

[@mediocredude2264]

If multiple worlds is to be believed, what happens when you make a measurement? Does the wave function change? Are you just figuring out what branch of the wave function you inhabit? Or something else?

[@relaxingnature2617]

Mabie the 2 entangled particles are really 1 entity ..like a ball where each side has an opposite side no matter what side you look at ..and entangled particals at a distance are just like an inflating ball with 2 particles on opposite sides . // ..2 entangled particals could be described as 1 entity that will increase in size when you pull the 2 particles farther apart ..no matter how far, it remains 1 entity

[@pelimies1818]

Same famous experience, but if a cat in the box is replaced with a man and we wait for 5 years before opening the (quite) large box.. Now, with a chance of still living after 5 years (food, water, etc. stored in the box) is a possibility, but he might have died after day 1. If he died after day one, the cadaver would have decomposed. Surely it is not possible that the man's wavefunction alters at the moment of opening the box, between a alive man, or a chunk of bones?

[@PaulSebastianM]

Feels like listening to a Vulkan on Trellium D.

[@americansoil8260]

Separation can’t be fully recognized or complete due to non conformation of bi nominal trajectories. Electrons and protons immersed into two dual states supersede the trans nominal factors that can’t be equivalent in separation much more than the tangled mix match of pure protons electrons absent. Constant separation is completely impossible. Look at roegans proton scheme of separating under existential factors.

[@fyohox742]

Thats what i also think, that everything is related, but the problem of this hypothesis in some way converges to the superdeterminism hypothesis and i don't like it.

[@nicolasargon1436]

Great lecture! Love the vids :) I have a few questions: 1. Are all functions vectors? I guess there's a few ways to pose the question. Conceptually I think that a function may have many representations, of which a vector is one. So on some level I feel like 'functions' can be represented by a vector as well as other things. On a more grounded level, maybe the claim is that physical reality manifests functions as a vector. So its less about "all functions = vectors" than, all functions in the real world manifest as vectors? At the beginning you (sean carroll) describe how the wave function "associates amplitudes with the entire configuration of a system not part by part". Two questions from that: 2. Is this a form of 'harmonization'? I know you called this 'entanglement' but when describing the state of the entire universe, how could the complexity of everything come to be defined in a single function? (keeping with the first question, as 1 vector?). I feel like there is this problem with abstraction, where if you abstract to a sufficient degree you are inclusive of all things without defining anything. Like saying "there is". Technically this is true. Its an abstraction which brackets every phenomenon, yet is so sparse as to be non-functional. Maybe I'm comparing things of too different a nature, but I still wonder about. 3. Does it make sense to have a 'closed quantum system'? If the wave function harmonizes or entangles everything, then the notion of a closed system (what schrodinger's cat seems to imply with 'the box') is a non-starter. How can we think about the notions of closed and open systems in the quantum framing, if it is at all possible to do so? Finally on to the many worlds, here're my questions. 4. You followed through with the Schrodinger's cat example, demonstrating how the 'environment' would be described completely differently in Hilbert space when comparing the dead cat vs. the live cat. On a technical level, how do you map states and particles onto Hildbert space? And how do we know that when comparing these two states (live vs dead cat) that the vectors would be orthogonal? Now disregarding the technical questions for a moment, you then suggest that since the vectors are orthogonal that these two systems could coexist without interference. Now I wonder what it looks like down the line. Keeping in mind that the wave function harmonizes or entangles throughout, then would the vectors ALWAYS stay orthogonal? They are independent worlds, and its not inconceivable (at least to me right now) that in each universe pursuing their existence that these vectors get continually shifted and bumped and entangled, an in a way that does not preserve the orthogonality with other universes... Is this possible? Or how is the orthogonal states of the different universe remain so for the next billions and billions of years? Thank you!

[@nicolasargon1436]

@mc2161 Anyone really, just formulating my thoughts and understanding and if someone has a clarification I would definitely appreciate it!

[@lukedigiacomo7184]

Mathematically, is saying the wave function collapses equivalent to saying the observer and observed particle became entangled?

[@AnAdmi]

Question, how is the spin example any different from like, if i had a box with a red ball and a black ball and i gave one to Alice and one to Bob and then sent Bob to Alpha Centauri without either of them looking at what color they had, now when i see that Alice has the red ball for example, that tells me instantly that bob has the black one, but that doesnt mean that theres spooky action, it just tells me that i didnt have the knowledge of the initial state. so for me the issue then becomes similar to laplace's deamon or am i missing something obvious? (other than like there is no actual 'color of the balls' in quantum physics because by assigning the probabilities we ourselves state a correlation which we are surprised by when it comes true)

[@dajandroid]

Thank you! Always instructive. I do wonder if the induced collapse hypothesis and the many worlds hypothesis, with a selected branch outcome, are not the same interpretation? For instance: The photon absorbance in the “wake cat” state could also be an induction, a decoherence event, that leads to the collapse of the wave equation into the “wake cat” state. I suppose the more detailed and rigorous statements of the QM equations and the probabilities of state are persuading you towards the Everett interpretation? If you could help me to understand where these two possibilities of Everett and Induced Collapse are not identical I would be most grateful. (Also, an accounting for the dof for changes in configurational entropy is not really being made here (branch selection or objective collapse) and I believe there is good mathematical reasoning available and might lend itself to a further understanding how the “macroscopic” branches of the QM ensembles, you are describing, are selected in the making of our reality.)

[@DiegoItzep2012]

If the collapse of the wave function is not instantaneous but it takes a finite amount of time, can the many world interpretation of QM explain it? If there is a time limit associated with ANY measurement then how is this explained by the MW formulation of QM?

[@schmetterling4477]

There is no such thing as a collapse of the wave function. There are only people who are listening to bullshit on the internet.

[@jonwizard3989]

Excellent!

[@trebledog]

Mr Carroll, with all due respect, if you are going to bubble up out of some kind of purple soup, I think you should also devise some sort of campy costume to wear and a new mane of hair. How can we take “entanglement” seriously if it looks like you’re the pitch man for hi energy purple laundry soap. Actually I’ve been following all your YT talks, lectures because I flamed (flunked) out my differential equations class and trying to make up. So my question is where does the 1/sq root 2 comes from at the beginning of the equation. I vaguely recall 1/2 when doing limits, but that was 50 years ago. I really want to feel this stuff, hear this stuff, know this stuff. Sincerely.

[@briancohen-doherty4392]

From the numerous videos I have watched from different presenters, it seems that the isn't enough emphasis on figuring out the "Observer". That appears to be a major gap in everything I have seen, but as it seems to be a foundational aspect of quantum mechanics, I feel like it needs deeper attention. I would love any references for things happening in that area as well!!

[@stephenkamenar]

"the observer" is anything. "the collapse" is relative. pretty simple

[@life42theuniverse]

@@stephenkamenar If the observer is anything why don't the molecules of air observe the slit with incoming particles/waves collapse the wave function in the double slit experiment?

[@nmarbletoe8210]

​@@life42theuniverse If I am running a two slit experiment, any thing that gives me "which-way" information could be considered an "observer" An observer is something that interacts. Any interaction collapses SOME kind of wave function, but not necessarily the one you are looking at (like the interference pattern).

[@philoso377]

When we can’t differentiate energy isn’t mass, we have stumbled into another world, a virtual world of quantum mechanics. When we mistaken the operating principle of how light speed is measured in 18th century onwards we also stumbled into another world, a virtual world of Relativity, but reality. When we mistaken condense matter (fluid and solid) is compressible, we stumbled to a virtual universe, an universe with black hole. When we don’t understand light speed slow down in a loaded Aether space around solar (and keep dreaming about light speed is universal constant), we’d stumbled on an expanding universe with Big Bang origin.

[@woody7652]

Thanks, Sean!

[@traruhsynred3475]

The following story illustrates your point that cat's are intrinsically entangled with with their environment. It's called Schrodinger's Cat and the Law. The story turns on the fact that life itself is a process of decoherence. bit.ly/2nZNK4RSchrodingerCatAndLaw Your discussion of S's Cat is one of the few I've seen that made sense. I like the way you presented 'many worlds'. At least you make it apparent what a huge number of worlds would have to exist. Most discussions are act like it was set of more or less binary spits, but in reality it's very large number (perhaps an uncountable infinity?) [a] depending how different outcomes need to be be orthogonal in Hilbert space. [a] Imagine a photon hitting a photo-tube. Which layer does it convert in? What energies and angles do the electrons come out at? Those are real numbers so the number of possibilities is uncountable. How many distinguishable ways can the shower develop? To an experimentalist like me all those 'worlds' seem implausible and the Hilbert orthogonality criteria don't seem well defined -Arthur Snyder, SLAC

[@jimjackson4256]

Why can’t you use entanglement to communicate faster than light?

[@sipplix]

Did Sean’s temperature rise when discussing Bell’s Theorem? Soft spot eh?👍😜

[@lewisshrubb6778]

would it be possible to use entanglement to seperate hydrogen atoms from oxygen in water? entangle one group to spin up, the other to spin down run it through a magnetic field? I read that physicist have managed to entangle large groups of atoms no just single particles, if that is the case then surely it would be possible, though probably not yet efficient

[@williambunting803]

Whoops, I think that I may have understood some of that. But here is a thought, If scientists disagree with one another and change the interpretation of quantum concepts, then don’t you set up a situation where reality can be one thing and quantum description of reality is another thing, thereby creating a Schrodinger’s cat situation where reality and quantum evaluation exist in a superposition with one another?

[@luizdegrande711]

Very good! How do you measure the spin of a particle?

[@schmetterling4477]

For photons we measure helicity (they don't have spin) with polarizers and for charged fields we can use a Stern-Gerlach.

[@jimjackson4256]

2*1/2 ? to how many places does the universe calculate this number.

[@glenncaveart]

Dr. Carroll, the hair is lookin' good!

[@gravijta936]

Spooky action at a distance makes me very "SA@aD".

[@GreenLight11111]

wonder what the next breakthrough will be!

[@positivelycurvedpikachu]

why/how Bell thought that no local theory can match qm predictions years before and without any experimental notion ?

[@schmetterling4477]

That's not completely correct. One can easily beat Bell with superdeterminism, which can be implemented completely locally, but that's a very cheap trick.

[@clavo3352]

"the world is not local." Means that Alice and Bob are not 2 but 1? What happens to Alice anti-happens to Bob. Nothing travels faster than the speed of light when the universe is 1. It doesn't have to travel; as, there is no space from an electron's point of view. All light and matter is a hologram of everything. So; I think.

[@spracketskooch]

Keep the long hair man, it looks cool.