The weirdness of physics | Robert Wright & Brian Greene [The Wright Show]

thank you all for coming I'm Robert Wright visiting professor of science and religion at Union Theological Seminary here and this is a conversation that's one in a series of public conversations that are part of the insight project that we just launched in fact the launch was a couple weeks ago some of you may have come - there was a conversation about climate change with amitabh gosh I've been asked by people who asked these things that if you feel like tweeting about this you should use the hashtag insight project is that right one word I don't personally encourage tweeting but there are people here who do so our guest tonight is Brian Greene I'm sure most of you are familiar with him he's a professor of physics right here at Columbia right next door also best-selling author of a number of books the elegant universe the fabric of the cosmos Icarus at the edge of time the hidden reality very good thank you that's I practiced the first of those in addition to being a big bestseller was a PBS series starring Bryan or co-starring Brian and the universe and was also a finalist for the Pulitzer Prize in general nonfiction brian is also an actual accomplished physics physicist he's made contributions to physics I can't describe him because I don't understand them but that's what it says in Wikipedia and he also founded co-founded with Tracy Day the world science festival which is here in New York and the 10th was last year when does it when does the 11th I think it's May 29th May 29th so right here in New York World Science Festival I want to say a little bit about how I first made contact with Bryan by way of explaining kind of the context of this conversation so I was brought to Union several years ago to do something different than what I'm doing here now but but that was on a Templeton Foundation grant and the idea was that I would develop and articulate a worldview that qualified for the term spiritual but was completely compatible with science I kind of felt I had such a worldview it was like pieces of it were floating around in books I had written but I'd never put it together so one of the things I did is I gave five lectures at the end of this period that were meant to embody this worldview and after one of the lectures I looked at my Twitter feed and somebody who had been there tweeted something to the effect of I went to a talk by Robert rye and found myself in the presence of greatness now sadly the the greatness part was not a reference to me Brian Greene was in the audience and so and that was the first I heard of it I had actually taken a picture of the audience and he looked at it oh there's Brian Greene I was very flattered and then the final lecture I gave the lecturer we turn to Q&A and a hand went up in the back and oh it's Brian Greene challenging something I had said about electrons now if you're gonna be publicly challenged about something you've said about electrons you'd rather it not be a world-famous physicist who's doing a challenging but that was that was my fate it was actually it wasn't my description of electrons but the way I'd characterize kind of the nature of scientific belief in them but but and we may we may get into that but in any event I just if you're wondering what we're doing talking about physics at a Theological Seminary it kind of gets back to these five lectures in the first lecture in trying to kind of define my worldview Receptus set the stage for it I I cast myself kind of in in contrast to the the worldview of the so-called New Atheists and one of the things I accused them of was a certain amount of intellectual hubris I mean there have been these arguments made by prominent New Atheists you know arguments such as consciousness has been completely explained by science I won't name names but another one another argument was that science tells us all we need to know about values another all these are each of these was a book another was that science has answered the question of why there is something rather than nothing and I thought the problem with these was not just that they they overestimate that the scope of science is domain and overestimate the mysteries that science has in fact solved but I thought there was kind of a failure to appreciate the sense in which modern science is illuminating whole new mysteries and and I don't mean that in a trivial sense I don't just mean that you know when you answer one question it leads to others like once you know that DNA is the hereditary material it leads to questions about how the information is encoded and transmitted I think modern sciences is in some cases pointing to mysteries of kind of a different sort mysteries that that intersect with with philosophy with questions of meaning and suggest in some cases that we may never solve them they are mysteries that seem to point to the limits of the human mind as an instrument for grasping all of reality and in that sense I think that science in some ways is emphasizing how many possibilities are left open by science possibilities of philosophical nature even you might say a spiritual nature you might even say in some cases of theological nature so and I think that there's you know a no single science that does more of this than physics I think there are just a number cases where you just go you know this is impound horribly weird and and so that's the one reason I want to talk to Brian he does not share all everything I all the beliefs I just expressed we'll see how he comes out on some of these but I think he's the perfect person for doing a kind of highlight reel of of kind of modern physics like like mind blowing things in about modern physics and pondering them with me because he's one of the more adventurous thinkers in physics I think so with that as context I want to start with actually with it with a tweet when when you tweeted this event you we both I guess got a reply from someone who said could the notion of particles be the greatest misnomer in the history of physics it is a useful concept for the physicists but gives the layperson an image of something like grains of sand it obscures the reality that they are more like patterns in an infinite sea of energy is that fair I would say it's fair except for the infinite sea of energy part at the end and the most leaning thing ever and in the beginning I'm not sure what's left but particles particles of this leading turn so particle it's misleading if you misinterpret it so so when we use it we really do know what we mean what we mean however does differ from the conventional English word that you'll find in the dictionary so yes particle when you think of a grain of sand that seems like a pretty resonant that's a pretty good illustration of that idea when we talk about particles we have to invoke quantum physics so that's really where the shift in thinking occurred and the shift does cause us to think of a particle as an entity that is described not being at a definite location with the definite speed which is sort of how you always think about a particulate ingredient in the real world instead we think about it as an entity that has a certain likelihood to be at one location or another and that likelihood is described by a probability field and that probability field is completely unfamiliar you won't find that in the dictionary under particle and so we could fill out what that image looks like but that's where the disparity is between English and our use of that term so we never change the word when quantum mechanics came along we still has use the historical term particle but we have a very precise mathematical definition of what we mean by that okay so the idea is as I understand as you said if you ask in some cases if you ask where is this electron right now all we can say is it has like a 30% probability of being here 30% here 20 here 20 here and it isn't just that we don't know it's that in a certain sense there is no answer at that moment now it depends on your interpretation of quantum mechanics and here you come to the beauty of science it's an ongoing exploration and there are unresolved questions you alluded to some of the outset but even within science proper within the field of quantum mechanics there are very basic questions that we've yet to fully resolve and the interpretation that you just gave thinking about probability as not that we don't know it just isn't at any location not everybody will agree with that right that's I would say the the dominant perspective in the field well but there's another perspective where the particle absolutely does have a definite position well Einstein believed that Einstein believed that but he didn't actually have a mathematical theory behind it right since Einsteins time there now is a mathematical theory it's the dark horse of quantum mechanics it's not the one that we teach our students unless I'm teaching the course right I I I like to show them this other approach that doesn't get much airtime it's called bohmian mechanics and it's a guy named David Bohm some people here may know him also Lois Dubrow was instrumental in thinking about the if it is in the 1920s and I think for sociological reasons not necessarily scientific reasons that way of thinking about quantum mechanics never got the airing that it deserved so that's called the hidden variable model the idea is no the particle we can only say that it's 30% chance of here in here but but it's actually one of those places and there's just some some variable we don't know about something in the universe that if we had the information about this thing we'd be able to say for sure I would say it a little bit differently but but that's a that's a that's a fine description of it but in the Bamiyan approach you don't even have to commit to the existence of a variable that would nail down its position if only you knew it you simply come to the recognition that there are things that are definite in the world that yet are beyond your ability to ever access and that's a curious dead but fair that's one that's or unused to but so it's so it's a hidden variable we will never uncover that's right in the traditional bohmian approach the fact that particles have definite positions but they're inaccessible to you is a natural part of the mathematical framework so that's slightly weird but it's not as weird as most of the alternatives I mean well that's the point if your barometer of truth is the level of weirdness yeah and if you say if Theory X requires less weirdness in theory why and they're both compatible with the data right then let's go with Theory X and if that is the approach that you would take I would say that the bomi approach is less weird than the traditional quantum mechanics we find the textbook and the reason is in the traditional approach you have to give up the idea that there are definite predictions you have to go probabilistic but you also have to give up the things have a definite position and a definite speed there's two things that you have to give up that Isaac Newton would sit here and say are you kidding me yeah that's that's the way reality is constructed but in the boming approach you only have to really give up the idea that their definite predictions you can still have in your mind the particles occupy definite locations so in that sense it seems less weird than the standard approach okay so let's talk about I mean it's an interest I mean you're kind of paraphrasing Occam's razor in a sense right yeah that's what you mean is the simplest theory should win and weird isn't simple well see the problem with that is there are many different axes along which you can measure simplicity and from a mathematical standpoint some would say well hey when you look at the equations of this bohmian approach it has this like other equation that lacks the simplicity of the equations that we're used to in quantum mechanics it has a sort of nonlinear quality if we allow ourselves to use the technical term and people say oh because of that it's more complicated let's put it aside but the strange thing is in the traditional approach no one has answered the question how do you go from the probabilistic haze that quantum theory describes the world mathematically to the definite reality of common experience right and without bridging that gap you've left out some kind of mathematics so if you recognize that you've left out an equation and you don't know how weird or complex that equation is going to be it's difficult to use Occam's razor because you don't really have a way of judging the mathematical complexity of the full quantum mechanical formalism since part of it even today is missing okay it's getting weird or earlier than I thought it was going to so so let's let's move to what are called the trick some of the traditional interpretations which are even weirder I mean there's one so-called interpretation that's not weird or because it just refuses to interpret the Copenhagen interpretation kind of says well that's the one ahead of mine by the way when I'm saying okay kind of refuses yeah that's kind of a they kind of say let's just don't think about the implications for reality let's just do the math it's successfully predictive within certain constraints and so on but but then there's one that is taken seriously by a surprising number of people surprising to me which is the many-worlds interpretation I mean we should say you know that one thing that is observed is that when you measure the electron suddenly it is in a particular place and and this is kind of the mystery that the puzzle we're alluding to is that is that it seems to be the case that in some sense you know there's this probability function at one point but if you measure it and if you accept the idea that the particle is in no particular place to begin with then it is kind of snapping into definite existence at the point of measurement yes and this Li this has led to a couple of weird interpretations many-worlds I think gets the trophy for weirdest right do you want to you want to talk about that sure so if the mathematics of a theory which quantum theory impact those dus says that as you were articulating say there's a 50% chance of the electrons here and a 50% chance that it's over there and when you make the measurement you say find it over here the puzzle is what happened to the other possibility and you might say well look it just goes away perhaps you know in everyday life and there's a chance of this or that and one outcome happens you don't usually worry about what happened to the other possibility just think it wasn't realized the problem is the math of quantum mechanics does not allow that to happen so what do you do well the most straightforward next step is to say well when you measured it over here yes you found it at that location but the particle was actually also at the other location - it's just in a separate reality a separate universe so you now imagine that when you make a measurement in one universe you find it over here and then another universe is another copy of you that finds it over there each of you thinks that there's only one definite outcome each you is only aware of one outcome of the experiment but each of you would be wrong if you think that's the full spectrum of reality because there are two of you each having those thoughts each measuring the particle at a different spot so in this view I will myself branch off at some future point into multiple versions of me inhabiting multiple universes or multiple world and doing different things yeah the branching idea is okay in a context like this it can get you into trouble if you take it too seriously I wasn't taking it seriously don't worry good good you can almost imagine that they're sort of always are infinitely many of you and they're just all going along in this way and they're all having these distinct realities and you know I mean most people say this is crazy but I want to emphasize that there's not that many clear alternatives to crazy or mean I mean and this is taken really seriously by some really smart people in fact some people say this is not an interpretation many-worlds isn't an interpretation it's what the theory literally says without us putting any interpretive spin on it we have to accept it well that's the amazing thing at however complex it may sound however uh neck anomic alit may feel to invoke this spectrum of realities if you're just following the mathematical equations this is the leanest possible interpretation of what the math is telling you right there in the most basic quantum mechanical equation you see these distinct realities right there in the math and a guy named Hugh Everett the 3rd 1957 said look I want to find the leanest way of interpreting this theory and he said let me just put away all my prejudice about how reality is actually constructed let me not worry about things that sound weird let me follow the math and this is where that trajectory does take you now you can say so is that it are we done and you're right there are some people in the world today who say absolutely we're done we've dotted the ice we've crossed the t's this is the way of thinking about the world there are others and I count myself in that group who look at the arguments and feel unconvinced and I can tell you why if you're interested why I'm on I can think of some reasons becoming it yes I'll give you just give you one so you know you know the basic way of thinking about probability is you you you should not be surprised if an outcome has a high probability and it happens but your intuition tells you that the very meaning of probability is that if something has a very minuscule likelihood of happening very small probability if it takes place there should be a degree of surprise associated with encountering that highly unlikely outcome right that's what probability means but in the many-worlds interpretation when we say that every outcome happens it just happens in a different reality and there's a version of you measuring that outcome well that means there's 100% certainty that there's going to be a version of you that encounters every outcome and any outcome however unlikely it may be so how could you possibly be surprised if there's one of you encountering this unlikely outcome when you know from the outset that every outcome happens and there's a version of you that's going to encounter it so that means you could never ever be surprised if something has a small probability with 100% certainty you're going to encounter it and that seems to go right against the grain of what probability even means now there are answers to this there with this group and Oxford and they've developed a whole spectrum of mathematical ideas to answer this the question is do you find that convincing and at the moment I'm not convinced ok so there's another interpretation that I think is a now a real minority interpretation but it's been taken seriously by really smart scissors physicists I think Leo Szilard may have been one I'm not sure but but the idea is that I mean they looked at this fact that measurement seems to bring the thing into definite existence and they speculated that maybe it's the the person observing the measurement in a sense it's consciousness encountering reality that brings it into definite existence I think that's a real minority view now but again it's an illustration of how hard it is to yeah I mean is it it is a more in review because I think most physicists are uncomfortable talking about consciousness in that we don't have a mathematical articulation of what it means and therefore we feel at sea using words that we can't back up with equations but it's very hard to refute that possibility because anything that we are aware of we are consciously aware of therefore our consciousness is part and parcel of any single observation or measurement and therefore how can you ever say that your consciousness wasn't part of what brought that reality that you are now aware of consciously into existence you know the traditional responses hey so I mean Einstein's response would be so wait so if my consciousness can cause the spectrum of possibilities to ante up and become a definite reality is it because I have a PhD could a mouse have done it could a computer do it could a photon from the microwave background radiation baking into a particle would that be enough of an observation to cause it to have a definite reality upon that interaction and it seems like the answer to all these questions is yes it doesn't seem that consciousness needs to be injected into those processes but for us to check whether that photon bouncing into the particle gave it a definite reality we'd have to be involved and therefore consciousness would be mixed into the soup so it's very hard to ever refute that I'd say it's pretty unfalsifiable it seems like okay okay so one one implication of the most common interpretation of a set of interpretations of quantum physics that is to say the non Einstein e'en and non hidden variable is that things happen in this universe for which there is no cause in this universe in other words truly random things I mean when we flip a coin we think well you can't predict it it's whether it's heads or tails but the reason is there if you knew everything about the wind and so on but according to quantum physics when a particle is going to turn out to be heads or tails so to speak whether it is one or the other has no cause in the physical universe oh come on and the quantum version yeah yeah we're in the mainstream view of quantum physics too which is itself very strange right which sounds like not a scientific worldview in an innocent oh I wouldn't go that far I would say that it's at odds with the historical scientific worldview that we're all used to and one that Isaac Newton laid down and it's shocking that that view is being challenged but to say that a perspective is non-scientific to my mind would be to say that it's incompatible with being tested observational II or experimentally and here's a theory which is not only capable of being tested experimentally it's the most precisely confirmed theory in the history of the species you make predictions about the magnetic moment of the electron and you can calculate it with quantum mechanics to ten decimal places and then you can go measure it in the laboratory and digit by digit by digit by digit right down the line there's complete agreement so if one's going to call that a non scientific theory I don't I don't know what science is yeah I just mean it runs against what the average person thinks of is ever since the scientific world views saying there's nothing we can't explain in principle and and here we see things happening that have no cause in the physical university that's right now I wouldn't in a previous conversation I got you to take seriously a kind of a scenario involving this that is you know I don't want you to take it too seriously it's just for purposes of thought experiment and in to suggest you know how far you could go with some of these things in principle and and the the idea was that if you were running the universe I mean if you were God so to speak and you wanted to influence events you could do so within the constraints of this worldview in the following sense I mean the constraint is that the number of heads and tails so to speak have to be 50/50 in the end or let's look at it as a roulette wheel the constraint you're working under is that that once every 36 times it lands on number seven and or a number 36 so the odds have to even out in the long run but if you can put a magnet or something under that roulette wheel secretly you can determine who wins and who loses within the constraints of the overall probability so does that make sense to people so it still looks to the casual observer that well one every thirty six times it lands here it's half the time it's read half the time it's black there's nobody fooling around but there is somebody fooling around there deciding when it's red and when it's black and that's very consequential so in theory you could have you know I mean I don't want to use the term divine intervention in this setting but and it is just just like a thought experiment but it's the kind of thing that's not ruled out true but I suspect and I won't weigh in on it necessarily but that feels like a incredibly impoverished version oh yeah divine intervention that God is doing the calculations that niels bohr told him to do right and he's looking up this probability table and then he's making sure that the magnet mccann put it here now what does Neil say oh yeah I can put it here it just feels like a pretty pretty weak version of a deity yeah although in this scenario he set up the things that niels bohr discovered but i mean haven't it would explain you know once once he does that then I don't see the value of introducing him him or her or it back in the back door because that all-powerful presence would have been able to not be too disturbed by events in our world that lacked the kind of prequel that you're looking for based on you Newtonian intuition but it would explain why all these football players after the Super Bowl say I'm God was on my side and that's why we won right that's important data that we need to point it I have other theories about that no I mean I want to emphasize that this wouldn't even be taken seriously in most modern you might say liberal schools of fiala I mean liberal in the political sense but liberal in the sense of modern theology and by the way Union was kind of the epicenter of that and in the 20th century and and you know people like Paul Tillich we're here and so on so so that's not not that it's not like that's the conception of God prevailing in modern theological circles but it's that agree it's not it's not anything Pat about well and it's testament to just how kind of weird the whole thing is so another weird thing is quantum entanglement we're just you know so again there's two particles they can be heads they can be tails they can be very far apart you measure one it's heads and that instantaneously determines what the other one is going to be I think you might say it's tails usually because their complementarity but whatever the point is instead of anyway the point is influence is moving instantaneously and and and this was something that Einstein thought was not possible he recognized this as an implication of quantum physics he says this is why I think they're wrong about something this couldn't be the case but now we're pretty sure it's the case right yes so so 1935 Einstein with two colleagues Podolsky and Rosen recognizes this weird quality of quantum mechanics and it's quite excited about it because while he wrote the second paper on quantum mechanics and the subject really owes historically Einstein an incredible credit debt of gratitude he didn't like where the theory went so he was happy when he came upon a feature of the theory that he thought if he presented it to the quantum mechanician z-- they would agree that there's something wrong or something else that's necessary and it was exactly the issue that you're talking about you have a particle over here in New York another particle over here in California you set it up in such a way it's that measurement on one seems to have this instantaneous effect I put that in air quotes because it's a very specific quantum mechanical effect but it seems to have some sort of effect on a particle that's very far away and as you say instantaneously and much faster than the speed of light so Einstein in that paper with Podolsk amrosen offered what he believed was the road toward a solution and the road toward a solution was to recognize that the probabilities that quantum mechanics was giving us when it says that there's a 50% chance of particles here and 50% chance that it's here Einstein said that's simply because quantum mechanics is a very weak theory it's not very good theory there's a deeper underlying theory that we have yet to find and if you had that theory it would tell you that the particle is definitely there or definitely there so there's no notion of probabilities there's no notion of things being in an undefined state and when you inject that into this entanglement picture you find that the puzzles in principle would go away the problem is that theory gives rise to not the problem actually the beauty that theory gives rise to predictions that even Einstein didn't realize it took the genius of somebody else named John Bell in 1964 to re-examine Einsteins work and say way to find science right we can actually test that in the laboratory and it took until the 1980s but when this idea that particles always have definite characteristics even if you don't know them when you tested that in the laboratory it turned out that it seemed to violate Einsteins way of thinking about things so what does that mean well the the arguments are quite subtle but many of us believe that what it means is that doesn't necessarily rule out the particles have these definite qualities but it seems to require that the world is non-local seems to require exactly the thing that goes against our intuition that what happens over here really can affect what happens over there and that's not what we're used to right you know I pushed this over here I think you'd all think it was some sort of magic trick if I pushes over here and that cup started to move into right but according to his quantum mechanical idea is in a very subtle and and mathematically precise way what you do here has an effect over there mm-hmm I mean I guess you can see why I'm saying wouldn't like this I mean one of the economy I gather one of the achievements of relativity was that you no longer had to think of gravity as being this thing that you know kind of spooky action it's two things pulling on each other it could be described we probably don't have time to get into details but in terms of just local effect as something rolling along the fabric of space-time as it has been warped by a heavy object or something so he had gotten rid of that weird kind of action at a distance only to run into this and this is now taken seriously and does it do physicists have do they wake up at night no this is too weird I mean you ever is it just well it's taken so seriously I mean you know that the progression of changes of paradigms right at first you know some new ideas put forward ever it says it's impossible right then assuming it's right a little while later people warm to the idea and integrate it into their thinking and start to think yes that's how the world works and then you know five ten years later it's like second nature of course that's how it is so right now entanglement from the standpoint of physics is that it's just yes that's just how the world is and people actually make use of it it's no longer to some abstract idea some strange feature that might be an esoteric mathematical quality we have entanglement being used between you know Chinese satellites and laboratories on the ground allowing them to have this weird spooky connection in the most flat-footed straightforward applied manner but I assume there's a reason this doesn't lead to like Wu type things right yes it does and Andy and the reason for that is the nature of the connection is such that there's no data there's no information that's literally being transmitted from one particle to another rather the connection is so subtle it's so ephemeral that it's better thought of as a long-distance correlation that's locked in by the laws of coordinate but it's not locked in in the sense that like these two things were spinning at the same rate when they were together and then they get separated so the correlation remains the correlation in certain sense does not exist until they're well apart and one is measured as a real thing oh it's a business exactly to me about that I mean you could measure at any point you can right right sure sure same thing would have sir but but yes I mean that the canonical version of this is you have a particle that can spin like a top right and it can spin clockwise or counter clockwise which we typically call spinning up or spinning down and a particle because of the weirdness of quantum physics can be in a mixture of up and down at the same time right and only when you measure it as a snap out either up or down that's the usual weirdness of quantum mechanics the entanglement weirdness is now you've got these two particles that are both in this fuzzy mixture of up and down at the same time right and you measure the one in New York and it snaps up and the other one snaps out of the probabilistic haze in California and spins down and that's the strangeness but notice that it does require that these particles are in the sort of fuzzy they're in the hey and that's the sense in which the correlation doesn't really exist until the moment of measurement a sense yes so but but you can't as I think you suggest and you can't use this to actually transmit information instantaneously because you can't like yourself decide this is going to be heads and say hey if you see tails it means this you know you you the particle decides itself so to speak what state to assume so we cannot encode information yeah so so I mean the the weirdness only becomes apparent when you take your data over here in New York and let's say you've measured the coin you got heads tails heads heads tails mm-hmm and then I get did my measurement independently of you in California and I got my list we bring them together that we find Wow every time you got a heads I got a tail every time I got a head you got a tail and that's where the weirdness comes into play but it's still a random assortment of heads and tails and therefore there's no information that we can extract from that so speaking of Einstein he in his the Einsteinian universe i guess and i think i think this is a part of his thought that more or less holds up whereas you tell me but I mean hidden variable is now held in some doubt but I think the idea of the kind of block universe or block time where time is just a dimension just kind of like spatial dimensions more than we realize so one implication of that you know it's it's I guess correct me if I'm wrong it's a kind of deterministic notion in the sense that as we move forward in time it's very much like just moving north in space in the sense that whatever you see as you move north was inevitable it was there whatever you had in Direction Chicago you're gonna see Chicago it was there it was inevitable and in Einstein's universe time is kind of the same way you can't see it yet because you're only moving one second per second you know but but it was inevitable and now that's a determined I mean first thing you see is that seems a little at odds with the kind of indeterminacy of quantum physics but I gather that's not a true deep contradiction because the mainstream quantum physicists would would buy into unsigned Universal well the the the vocabulary that you need to use to describe a classical deterministic world which is I think what you have find in Newtonian or nine Stinney inversion the vocabulary is a little bit different from the quantum mechanical one but when the dust settles there for all intents and purposes pretty much the same which is that the equations governing physics are deterministic that is you tell me how things begin and I will then use the laws of physics to predict the state of the universe at any future time and nowhere in there is there a room for you to step in with freewill or further to be something that stands outside the mechanistic deterministic turn the crank mathematics it takes you from here to there now the footnote is what does it mean the state of the universe in an Einsteinian world it's telling you literally how things are in a quantum mechanical universe it's telling you the likelihood that they're one way or but those likelihoods are still rigidly determined by the quantum mechanical laws so there's no room for anything else in this description of reality and if moving forward in time is like just walking along north or south then in principle moving backward in time I mean you hear this that there's no reason and according to physics to think you can't move in principle backward in time yeah I mean the laws are completely agnostic on what's forward in time and what's backward in time they don't care so if you turn the crank one way the laws will take the state of the universe and evolve it toward what we conventionally call the future but if you turn to crank the other way and any reasonable high school student could do this with the equations the laws will take you from the state of the universe and out to the state of the universe and what we conventionally call the past right I I know someone you actually may have heard of this person person some accomplishment who actually thinks I think that he has been contacted by Time Traveller's for obvious reasons I will not mention the person's name but is that I'd love to be able to go say Brian Greene says this is totally possible would you would you that's part of the problem I mean if the person's you know boredom yeah well you can say where are all these people from the future if you could go back in this way and yeah you know we know what we do with them I think that I think they communicate subtly in this scenario but but um you know it's it's one thing to say that the laws of physics are compatible with a sequence of events going forward in time or that sequence of heads going in Reverse in time it's very hard however to execute these journeys and when the journeys for the future time travel if you wanted to say toward the future we know exactly how to do it you give me an arbitrary duration of time that you want to jump ahead on planet Earth and I'll sketch out exactly what you need to do it for the reverse if you say I want to go back a certain number of years there are a number of candy that I will require of you have even a chance of being able to do that and it will be difficult perhaps even impossible for you to meet those those requirements as of today however there are viable time travel to the past scenarios that have yet to be fully ruled out but I think most of us believe that when physics matures at some point we will be able to rule those out and therefore time travel the past won't be won't be possible so did you see the movie interstellar I did yes was it how did that look from them uh well I didn't understand it there were you know there's a book I know there's a book Kip Thorne Nobel laureate brought a book on it I've not read the book but you know if it takes 300 pages to explain them look I like when I go to a movie I just sort of want to take it in and and if I enjoyed it I enjoyed it and there were real scientific moments in there so don't make that the wrong way the visualizations of black holes were the most precise visualizations that we have ever had they were generated by the fundamental equations so that's amazing and also this notion of time slowing down near the edge of a black hole which was a plot device there that also is something that we fully understand from Einstein's general theory of relativity when I say I didn't understand denver's on the end I'm trying to remember and there was one true paradox in the plot but it but that tends to happen with time-travel scenarios famously was a time travel to the past and it was only to the future yes I I think it uh I think it was only to the future I'm just going back over anybody yeah it was right yeah but then they went back right did they go back they communicated medicated back oh yeah they were so amazing that's what I miss there's a bookcase or something so quickly this is actually not in your domain so much because it's more cosmology but there is this since you mentioned black holes and we're talking about weird things there's this Lee Smolin idea that black holes may be the way universes replicate and if you accept that it could be the case that universes the selves are subject to a kind of natural selection in in that those universes most conducive who that had the properties that are most conducive to replication are the kinds of universes that come to dominate just as the most fit animals come to dominate and maybe that's why there are so many black holes and then there's a further variant of this according to which intelligent life facilitates the replication of universes which leads to universes in which life forms it involves where intelligence I just that's just a footnote if you unless you want to say anything about natural selection is most one of the most powerful ideas that have been put forward and the beauty of natural selection is it's almost a tautology right it's one of those wonderful ideas where you can't even imagine how it could not be correct right and so apply it's natural then to take that idea and expand the domain in which it has been applied and people have done that too remarkable effect right so there's natural selection even at the level of molecules that may have been a precursor to the formation of life Lee's idea takes it to a pretty extreme application it makes in principle predictions that our universe should be among those in which the kinds of black holes that we have are the most fecund they are the ones that will generate the greatest number of progeny by a process that you eluded to the problem is it's hard to exactly see what that process is it's hard to nail this down and I think if Libra here we'd say it's still a viable approach and and perhaps it is so it's an exciting idea but I think it's one that is pretty far beyond what anybody now takes and I should say something Lee would say if you were here which is that that second variate I mentioned is not one he's the one where life is a prerequisite for the replication universe is intelligent life is a prerequisite for the Replicators that's not so much his he acknowledges yeah it could be the case but there are other people who kind of put that forth I liked us an area just because it illustrates the sense in which in principle life could have a quote purpose but it was not infused by some deity and traditional since it was just infused by a process much the way organisms are infused with goals like to replicate to reproduce to eat food and so on by the process of natural selection so I have kind of a special fascination but I would encourage you to give up this idea that life has to have a it doesn't have to it doesn't have to but I would even say give up the idea that even if that theory is true that that is the purpose of life I'd say that's the mechanistic role of life in this particular ok way the reality is constructed and I think it's more noble to find your own purpose and not look to some quality of the universe to bestow purpose of mine ok so wait so there's two things there's two things one person agreed with no type.you this reminds me of this reminds me of the time I debated see him here is were you are you seeing here as fans to people who clapped no you can stay I'm afraid you'll have to leave do you think so you're saying purpose isn't the right word you can you can argue a I mean in a way you should be well anyway the some philosophers use purpose in this way like Dan Dennett speaking New Atheists says life you can speak of organisms as having purposes they're just imbued with by natural selection no god no nothing and I think it's a it's a long and separate argument whether there's reason to believe that natural selection events as hallmarks of purpose that there could be a purpose unfolding on earth through nature I've actually argued that there is evidence but I want to emphasize I'm just I'm just talking about natural plain old nuts and bolts mechanistic natural selection nothing nothing spooky and and the point is just that if it's the case that doesn't mean you should like this part doesn't mean there's a God could be that it's it's more like a process of natural selection that it that imbued the purpose and in that case I would certainly not say we should where do what you don't want done which is drive your meaning from that I mean I wouldn't say that organisms that the purpose is instill by natural selection are noble that that you know at all no no it depends on yet how you I thought you were referring to the more traditional sense but by the way just a small footnote to your footnote I got nothing against God by the way good well so don't point to me and say hey you like it's gonna go no god I hear that I hear that he's entirely in you to yeah the the anything anything else you want to say about that I mean you're actually you're finishing a book that is that gets into some meaning of life II territory right being a little core here sounds like there's nothing else you want to say about this book right now yeah not right now yeah nothing else about God i I'm happy to talk about whatever you'd like to talk about I am so easy okay well I'll talk about God no I have no questions I just want to hear you talk with our guy yeah it's a little hard to do it that way but does anybody have a question on get we are about to turn to questions but I want to [Music] in about five minutes but I want to um let see if there's anything else well let's get back to the question that was implicit in the way I started this with like well what is an electron really which is kind of is materialism and apt description of the modern world view of physics I mean scientific materialism is kind of the famous phrase associated with science some people find it a depressing a phrase in some cases that's because they associated with determinism maybe which isn't entirely apt in light of quantum physics maybe but in any event you know it's the idea is is some people minded dispiriting to think that everything is just this this like physical stuff there's nothing nothing more ethereal or spookier or whatever and I do without signing on to what their aspirations are I do think the progress of science has tended to make a skeptical the idea that there's really stuff at the bottom you can kind of grab right I mean because it's like okay these molecules that's what it is well molecules are made of atoms okay well that turns out atoms are made of protons in neutral it turns out they're made of something else and it turns out when you describe particles actually they're in a fuzzy haze so what would you say is the status of the word materialism right now well I say it's alive and well but you have to allow yourself to update it based upon discovery so I agree that the rock bottom ingredients like the fundamental furniture of physics is somewhat hazy ER then it was in a time of Newton right I mean Newton it was the stuff that you could touch it was just like smaller versions of it right that's that's what the ingredients would be whereas now we do have to as we started the conversation graduate to a picture where the particles have this more ethereal fuzzy quality but at the same time you can set up equipment where a little dot on that equipment was formed by a photon or an electron impinging on the material so in a concrete sense you can measure the electric charge of the electron and get a number you can measure the mass of the electron and get a number you can fire beams of electrons and predict what they're going to do and they slam into various targets so it is the case that you can't clutch it in the same way that you can clutch tables and chairs but you can clutch it with the mathematical equations with even greater precision then you could have using the Newtonian mathematics and in that way if you allow your clutching of the fundamental ingredients to invoke the equations of physics we've got it fully in our grip yeah it's better than no Tony and in a sense maybe a more precise whatever the word uses yeah that's what I mean just just that but it is only probable predictive unlike Newtonian physics but get over it I mean that some people would call that in some sense a shortcoming I mean a degree of finiteness has been lost a degree of precision a degree of certainty has been lost well I would say that the Newtonian picture of what constitutes reality needed to be updated it was it was a flawed picture it was a nice picture it made us feel good we could really wrap our heads around what reality is it's just what you see scale down but when you scale down it turns out it's not just what you see you have to introduce new ideas new concepts new language but the fact that we've been able to find the language and articulate it mathematically and make predictions that as I mentioned agreed to observations in ten decimal places makes you feel pretty good it makes you feel like you're on the right track makes you feel like yes there was some significant amount of truth in what your Newtonian picture just breaks down at a certain at a certain level and is replaced by water that's the spectacular precise so so if your notion of to go back to your question materialism right invokes these new concepts and the new mathematics then yes as far as we know that is the rock bottom structure of reality but I guess if somebody well let's turn to your your an advocate of string theory I wouldn't say I'm an advocate of string theory you're I work on string theory and I'm an advocate of things that are borne out by observation and experiment which is not yet happen for string theory so and I don't mean to parse words here but I find that I'm often described that way because I happen to write a book on the subject and and I go around and and I talk excitedly about the possibilities of this subject but advocacy doesn't really have a strong place when you're talking about cutting edge ideas observation and experiment is the only barometer that you can use and we don't have that at our disposal yet okay I withdraw the term add okay thank you in any event the idea is with John Horgan sit in the front oh look famous signs just waiting to pounce not quite yet so on this string theory thing on the string theory thing so the idea is that there are that what we think of as different particles actually no they're not different particles and maybe there's a little metaphorical and you'll tell me if I get it wrong but actually no there's just one kind of string I guess they're in circles but in any event one kinds of string and they vibrate at different frequencies and that's what we take to be particles one frequency of vibration means one kind of particle one frequency means another kind so I guess certainly if that's the right metaphor then yeah the particle thing kind of breaks down seems to to a layperson but in any event if somebody says to you what are the strings made of not real string what is the answer yeah so and I I I get that question obviously and I get it frequently and and the answer that I give is that they're they're two possible responses it could be that if string theory truly pans out and is the fundamental rock bottom description that the notion of what the strings are made up would be a kind of question that doesn't actually make a lot of sense because there are things in the world that we're very familiar with and most things I should say are made of something else right but if you're right down at the rock bottom fundamental error ingredients the notion of what they're made of is where that question ceases to have meaning and a metaphor is not a bad one to use in this you know if you take a book write a book has got pages the pages on them have printed paragraphs paragraphs made of sentences of sentences are made of words the words are made of letters but from a you know a phonetic saying you know what is a letter made of I don't know what's a letter made out of right it's a place where the question seems to not really have the import and impact that it does at the higher level of structure and that may be the case with strings but the second answer is we don't know if the series right we don't know if it's even relevant and that being the case be that if it is relevant maybe it's a stepping stone maybe it was molecules two atoms two subatomic particles two strings to something else right and there are ideas that whether something else potentially could be within the mathematics of the theory the description you gave is a good one but it's a description that could have been given and I still give that by the way so I'm not criticizing you but it's a description that really could have been given the 1980s and since the 1980s still today there's been a lot of developments harder to describe but they do flesh out the picture with other ingredients and other ideas yeah well I guess I'm just you could ask the question of an on string theorist you could you can certainly say to the quantum physicist what's this fuzzy wave made of right and and you tell me I mean is it made of information that's a a probability distribution is information right well some some physicists would say the wave is a mathematical device it's not real right so don't take it so seriously it's just our equations that allow us to make these predictions so don't ask me what it's made of because it's not part of the real world in the same sense that tables and chairs are part of the real world others however will say this probability distribution is a real thing it truly is a distribution a field out there in the world like the electromagnetic field or like the nuclear force fields and to ask what it's made of conceivably would be a relevant question there's not much that can be said about it but if it's real you can ask that question whether it's applicable in the sense that there's a sensible answer I don't know yeah now there are physicists who say certainly people who say well at the rock bottom it's information that's what it is and I think I have problems with that of course many of my close friends are among those and it's hard for me to see how that really works to me information needs to be instantiated in something and needs to be carried by something it's hard for me to see that at rock bottom it's just the information and somehow that entails the existence of entities that will carry the information I don't see that link so your point is I mean what we call information like print on a page has the material instantiation you can't say that's just information it's actually molecules of ink on physical paper so the kind of information we are familiar with is not foundational it is it is you know it exists on top of a foundation and I don't know what the people you're talking to would say I guess they have something I mean another interesting thing about information is it the kind of information we communicate put on newspaper you know the sound waves of my speeches it's in a certain sense an incarnation of I don't wanna get too weird but an incarnation of human consciousness in a sense I mean it emanates from human minds and so maybe they mean a little you know I I mean maybe I should close with a theological flourish I mean I mentioned it Paul Tillich was here at Union and he famously defined God is the ground of being and was famously criticized because that's sounded like you know just you know meaninglessly abstract or something but I guess I guess maybe you could imagine that the information at the at the foundation of things is an emanation of something like a mind yes and I can give a concrete I don't mean to undercut your theological theory but you know there's a very flat-footed version of that which I think we've discussed at some point which is the possibility that we're all living in a simulation right now I I don't take that idea really seriously but the reason I find it interesting is if we are in a computer simulation and some teenagers garage you know and you know 10,000 years into what we would call the future then yes we would all have emerged from that teenagers computer simulation who presumably programmed it so you could say we are the manifestation of the teenagers mind and that's fine with me because there's there's nothing stands outside physical law that teenager is subject to the laws that apply to the external reality which we may be the the ones that we know about if that has programmed those laws into our world maybe they're completely different so there's a one there's a version of that story where you don't need to use any traditional notion of God or divine being you just allow for this possibility that minds are sufficiently powerful to create worlds in which there are beings that consider themselves sentient that have some conscious awareness and if that's possible you don't know if it is but the future will show it to us one way or another and the vector in my opinion seems to be pointing squarely in that direction then we will have conscious beings who wonder where they came from and they may have come from other conscious beings that we will create everything complex enough to have consciousness or if that teenager programs us with the capacity to program a computer within the simulation yeah then that's what will be going on so if this was all created by a teenager in a garage joke that would explain a lot I gotta say but I mean the other thing well you know that the theory is that you know in the that all things were going well and then that the teenager handed the controls to his dad in in in in November of 2016 and dad little know they got the thumbs going on there yeah but the thing about that is you know you said I'm not sure how much practical difference there is I mean that is a theological scenario right and I agree yeah in fact you know I've had people write to me you know I this is not my idea it comes from various people Nick Bostrom Oxford so I'm gonna take credit for it but I haven't people write to me about articles I've written about this and they say that's the first time in my life when I'm willing to accept something that feels theological feels like a god because there is a creator but the creator is not standing outside of a body of physical law right it's a naturalistic God um so I promised we'd turn to questions and so if people have questions put your hand up and we hope that someone will appear with a microphone this message is for a question is for Brian Greene I was wondering if quantum computers turn out to be real like all the scientists agree that they all work and there's no confidence no like debate as to whether one has more qubits that are working or not working that along with like the double-slit experiment do you think that that would be strong enough evidence to say that the many-worlds interpretation is correct so you have the the quantum computers working and they're trying to factorize large numbers that there's not enough space in this universe to factorize so that means that they must be factorizing them in other universes do you think that if that turns out to be true that that would be strong enough evidence to say possibly the many-worlds interpretation is correct yeah so it's a sort of a famous argument that goes back to people like David Deutsch who was one of the strongest proponents of the many-worlds interpretation who has made statements akin to that III can't say that I am convinced by those statements there you know quantum computers are governed by a quantum mechanical process and the quantum mechanical equations are the same ones that in many worlds person would use and we would go through the same chain of mathematical deduction to understand what they're doing and how they're functioning and it's hard for me to see where somehow in that process I'll be boxed into a many-worlds interpretation the equations are the equations and I'll follow them with the mindset that feels right based on the interpretation that I use so I am NOT one of the people who claim that once we have quantum computers of a sufficient power we are done with all the puzzles of interpreting quantum mechanics but but conceptually is the idea behind some kinds of quantum mechanics that you're actually getting the different versions of the electron to calculate simultaneously yes that's the into the popular description that one would give of a quantum computer is to say hey let's harness right all these different worlds in order to do a calculation much more quickly than we could in a single universe have all these calculations happening through physical processes taking place in these power world and then somehow pick out the answer that we're looking for from one of those worlds and in that way we've done something that we could never do in a single world but everything that I just said it does have a translation in a more prosaic you know depending on your your metric version of the quantum mechanical story so I don't see it Brian what keeps you up at night well I actually have been unable to sleep the last few weeks I'm so I'm wondering if if if if somehow you're aware of that maybe you can tell me time time traveler but but but talking more poetically the questions that that that really drive me strongly and that I hope that maybe will have some insight into before you know I pass on to some other realm you know where where does time come from you know I think that to me is the big one somehow space spaces got its own weirdness to it but time somehow maybe because it's so intrinsic to how we live a life it's in some sense the most precious commodity that any of us ever has and yet even though we know so much about the nature of time from Einstein's special relativity Einstein's general theory of relativity some work that's now being done even in string theory and quantum mechanics is talking about weirdnesses of space and time as well but is time fundamental is it something that we impose on the external world in order to organize perception in a way that allows us to exist or is it is it something else could it be the time like this table is made up of more elementary ingredients could there be atoms or molecules of space and time that can exist and yet only yield familiar time when they choreographed themselves in the right way how amazing would that be tis her to have a an atom of time but does that make any sense those are the kinds of questions but but if I'm if Einstein is right and time is in a pretty fundamental sense very much like spatial dimensions I think I ask you this one couldn't I mean isn't the weirdness of time just an artifact of the way our minds happen to work in other words can you imagine animals find enough manuals be sort of beings with different a priori assumptions built into their brains and to them it's like time yeah I mean I look back you know it's it's I see the future I see the present it's this north-south thing that's weird I just can't tell what North is going to bring tomorrow right I mean sure yeah I mean q right I mean there are there we have imagined I mean science fiction writers have imagined such things it's hard for me to think about what would be required in the conscious experience of such a being to have that as their true perspective on space and time but yes in some way that I don't understand if I could sit here and see the full expanse of time I just sort of do this and see the full expanse of time and somehow I can't do that for space of course they now would be the puzzles would be isomorphic and interchanged but it's hard for me with my understanding of how reality is constructed to imagine how that's possible I share your intuition that time is weirder than space from a layman's point of view I'm trying to understand the nexus between science and spirituality and Brian had mentioned when it got to be kind of like whoa I don't go there and you also had mentioned Brian that in the equation sometimes as a part of an equation that's missing so my question is for both of you what is what is consciousness why is it such a problem is it at the border is it the nexus between where the two of you are sitting is that is that I'm a layman yes trying to understand the you know consciousness yes I give one and you I mean so I think the the the caveat that probably should be said at the outset is nobody has any idea what the real answer to your question is so let's place that as the at the starting point but researchers have made progress in ways that I think shed light on the puzzle at least and to my mind it seems as the recent work suggests that consciousness may be less mysterious than our intuition leads us to believe it is very odd that right now I have this little voice chattering inside my head it's very odd that what I can't sleep at night I can't get that voice to shut off it's even stranger when there multiple voices in there but I'll leave that for my discussion with my therapist you know so so the question is what is that right and that was a joke by the way I see a couple people looking at me like not that there's anything wrong with having now I'm in a very strange but if you shut the camera off right now I'd appreciate that so so the question is what is that what is that and there's there's um there's work that suggests that what we are as as as beings that have survived part of how we survive by a natural selection is we've been able to formed various models of what happens out in the world quick-and-dirty models that allow us to size up the environment so that we can survive right you know I look around and I quickly size up the floor is solid I feel like I can walk over there very very basic intuitions and judgments about how the world is constructed now we also have models of other beings and and Anna who came with a term called the intentional stance other people call theory of mind when I look out and I see a living being I tend to ascribe it agency I tend to ascribe it consciousness I look at you and I pretty much assume what's going on inside your head structurally it's pretty much what's going on inside of my head and that's a pretty good assumption to make because it helps us to survive right if we make a mistake and I ascribe agency to the piano big deal it's a little silly for me to imagine the piano is thinking but if I fail to ascribe agency to a snake out there on the savanna and it comes and bites me I can die so the brain tends to place agency all over the environment now those models of agency out there and the world we also apply it to ourselves right so I would describe consciousness as my being aware that I'm aware and that awareness of my own awareness is itself a model it's an incomplete model it's a model that leaves out a whole rash of underlying details and because of that it feels like my sense of self is floating in this ethereal space between my ears but that would be an artifact of an incomplete model that has allowed us to survive I don't consider that to the be the be-all and end-all of what consciousness is but I for me personally a cast it in a light where it feels like there's going to be a physical explanation a biochemical explanation that ultimately boils down to consciousness is a particular motion of particles surging through the particular structure inside your head that we call a brain and that's all that it is now saying that's all that it is is not meant to denigrate it's highly complex it's rich it gives rise to all of the experience that makes life worth living but in the end of the day it's only particles moving through a structure and that's it I don't personally see how consciousness could just be the particles moving through anything I see how consciousness could be generated by that in a very straightforward way and and I guess this gets back to the way I'm conceiving of consciousness I like the way Tom Thomas Nagel phrases it you know the fact of consciousness is the fact that it's like something to be alive right it is like something to be you you experience pleasure and pain you have subjective experience and I just don't that could that could boil down to particles moving the particles moving could generate consciousness the way a steam engine generates steam or something right they could be an epiphenomena kind of a product consciousness could be a product of this in a very straightforward way this is called epiphenomenalism but I think that's different from saying that it only it which is kind of the view of Dennett which is I think very much like saying consciousness doesn't exist I mean and I and a number of people have accused antennae to believe in the consciousness doesn't exist it gets him really upset so I encourage you to do that if you see him but but that's you know so to me that this is the most in a way mysterious thing about reality is that it is like something to be alive and you'll note that it is what gives life meaning right I mean the fact that people can experience pleasure and pain that's why we talk about ethics that's why you know that's why life has meaning and I and I think it's just notable that there is no satisfactory explanation because if you if you do view consciousness as an Epiphone Amin as a mere byproduct of the physical stuff then the question is well what is it for right I mean if if I if when my hand goes into a flame the fact that I would draw it has nothing to do with my sensation of pain but just just the physical information flow well then what's the pain for right it has no functional significance so in this scenario which is a pretty common one the epiphenomena then the thing that gives life meaning has no function well that's interesting it's like a freebie thank you whatever is responsible for consciousness it it didn't have to be here we could be these animals that behave exactly as complex ly as we behave we can generate speech with sound waves it would hit the ears about animals that would roll around their brains and elicit more speech waves and so on all this could be the case in principle except this conversation where we're talking about consciousness but in general animal life could go on imprint in this scenario the F phenomenal scenario without with without consciousness so the fact that it's here is the thing that gives like meaning is like a freebie that's an interesting basis for whatever you want to do with it gratitude whatever else the alternatives aside from the kind of Dennett view that in my mind is not tenable unless he same consciousness doesn't exist which is even less tenable because it's definitely like something to be me the alternative step of phenomenalism are almost contrary to science in a sense because then you get back to some kind of Cartesian dualism where this there's this ethereal stuff known as consciousness it's actually influencing the world now I'm not here to rule that out but I would note that according to this analysis you've got two main choices one is that the the Cartesian one things are much weirder than a scientific worldview would have you believe because there's this ethereal stuff influencing the world influencing my behavior the consciousness is in some sense generating behavior then the other scenario is we'll know it it's this is more compatible science in the sense that you can explain all behavior without reference to consciousness but in that case it's like what is consciousness for that's kind of mind-blowing in its own right so I I just think one way or another consciousness is just like the like the strangest thing in the world and I and I think the thing that almost most gives us most reason to believe we just may never figure this stuff out because or that science in particular may never figure everything out because one feature of my private subjective experiences it's private it's not scientific data my you know it's data that I'd say I'm hot or I'm cold but the feeling of cold or hot itself is subjective it's private so it's not just give Facebook a little time my friends yeah yeah well no they pick up on the cues for them for them what I say is enough but anyway that's my take on consciousness my question is for either one of you what's the difference between artificial intelligence and natural human artificial intelligence consciousness and natural human consciousness well I mean there may come a point when the the there isn't a distinction right at this particular moment in time I think it's pretty easy for us to point to what we would call a conscious being that emerged via the natural progression of the physical chemical biological laws that have been placed on earth for the past four and a half billion years versus an approach toward intelligence that we have inside of a computer so at a structural level I think it's pretty clear that we can point toward the differences between them but I for one think that that's just a moment in time far into the future I don't think there's going to be a difference between them at all they're all going to merge together all going to meld together and it's just going to be intelligence okay this has been great guys I mean that was one of the clearest discussions of the paradoxes of quantum mechanics I've ever heard it was it was really terrific so here's my question and oh you can stop there thank you it's really a softball question I'm curious and I guess this is mainly for Brian because I know what Bob thanks do you think that with further research physics and maybe other fields of science will dispel the mystery of reality do you think so you guys have been talking about all these puzzles that have arisen from quantum mechanics itself it seems to be making the world even stranger than it used to be back in the 19th century let's say do you think that string theory or some other unified theory some kind of maybe observational breakthrough will suddenly make every thing clear not only to you guys but to everybody else yeah so I think it's a it's an engine it's interesting interesting question for the following reason the clarity of which you speak depends upon the brains that are perceiving the explanation and so to me it's more a question of will the evolution of intelligence either natural or artificial or some melding of the - will that be such that the the brain power of that intelligent system is is so penetrating that the explanations that we give feel intuitive I think that's what we mean when we say does it make sense it's like does it make sense in your bones does it make sense in some visceral way and that I think is so dependent upon the the beholder right I mean if I if I take this and I throw it I have a really good intuitive sense of the trajectory so much so that I had to do no calculation at all I put out my hand and I catch it and most of us could do the same that's spectacular that is a deep insight into Newtonian physics without math you all know where to put your hand to catch an object that I throw maybe we'll get to that point with the motion of electrons or the vibrations of strings or the nature of black holes or vibrations in the fabric of space-time maybe our intelligence augmented perhaps in some way will give us that kind of deep intuitive insight into the nature of the world so I don't think it's so much will you physicists come up with explanations that will be so transparent that everybody says okay I've got it I think it's really questions you physicists go along what you're doing figure out as closely you can get to the deep laws of reality and then hopefully intelligence augments in some natural or artificial way so that there's a Mel building and meeting of the two okay so we shouldn't keep your a lot longer so maybe what we should do is go around to three people and they should just go ahead and ask the questions I'll write them down and then we'll we'll we'll answer them and that'll be it what do you think about Jordan Peterson's claim I mean what do you think about well piece of Peterson using using religion or like biblical stories against science I have no idea who that is should I so you should you totally should Jordan Jordan Peterson's a fascinating figure I'm all ears well maybe maybe I'll say three words about that and so we have three questions left to go because Brian won't have anything to say about them hi professor I earlier you mentioned that you are not very convinced by many worlds one more time many worlds interpretation and because it doesn't it just follows from math and it doesn't describe the reality we seem to know but you are also I was going to use proponent but you're also working on string theory but string theory also requires some kind of well the mathematical formalism of string theory also requires our reality to be for instance three more than three dimensional in space-time so my question is in what sense do you think string theory is more realistic or real compared to many worlds theory why it's more like yeah so it should clarify well let's go ahead and let's go ahead and do the other the other two right for the sake of time yeah yeah keywords so it just seems like a unique opportunity to ask each of your individual perspectives on why there seems to be such a long and strange affinity between Buddhism man in theory going back to plank and born-oppenheimer Heisenberg it seemed like especially with the two of you if you could comment on that kind of weird corollary okay so one more on the heels of that question actually I was wondering if if there's a perspective on the history of the Christian mystics in terms of perception of this sense of direct experience of God of the silence of one's mind for 20 or 30 or 40 years the plasticity of the brain can there be a conception within quantum physics that a certain individual who has had some sort of discipline or practice of mindfulness in some tradition for an extended period of time might have an awareness or perception of reality that is different than a mathematical formula can produce and and where that might fit into all of this okay so you've got that question in your mind they start they better start here yeah are we ready I think so should I say something about Jordan Peterson I mean is Jordan Peterson from people who don't know he's this Canadian psychologist is kind of burst on the scene in an interesting way by violating what he calls politically political correctness in a very spectacular fashion and it being on video and going viral and and then but it turns out he's a long written about religion I I would say that so far as I can tell it's it's a little bit like you know like Joseph Campbell with a little taking a step further in other words a real emphasis on drawing on archetypes of myth mythological archetypes and applying them to your life or religious archetypes and applying them to your life I gather one thing he does is say okay there's these three parts of the mind and I don't know what they are but and I don't know I doubt I'd buy that division of the mind but mini-van he says they're like the trinity that's like the father and the Son and the Holy Ghost and this has resonance for certain kinds of people I would guess mostly Christians in that case and I think that's a certain the religious part of his worldview it's it's it's interesting to see what what it is it appeals to modern seekers and then aside from that I mean his take-home messages get your act together clean your room is his famous phrase you know you can't save the world I guess it's like it was a Voltaire who said tend your garden who but anyway you know clean up your own backyard he's an interesting phenomenon I don't claim I know any more about him than that so I'll stop there so do you want to pick up on the Christian mystics yeah so yeah you know let me let me frame it the following way and I don't know if we have time for follow-up so I don't know if this is going to be useful or not but I am a firm believer that at rock bottom as we've been discussing it is some mathematical law or perhaps even some law framed in a different formalism to that that undergirds reality so let's take it to be quantum mechanics because that's our most refined version today and I do believe that that is it there's nothing else needed from the outside there's nothing that we need to inject into that structure to have a complete description of what reality is now having said that I also am a firm believer that when you engage with the reality they're different levels at which you can engage with it right you can gauge with it at the level of particles if you're a particle physicist and maybe an aficionado of those kinds of ideas but most of us don't live down at the level of particles most of us engage with the reality at higher levels and at those higher levels the vocabulary the language the ideas that are relevant to have a full description of what's going on need not make any reference to the underlying particulate language that we particle physicists use so some would say that that means that you're connecting with new things that there are new ideas that are coming in if you train your mind in one way or another maybe you're better attune to channeling those qualities of the I don't use that language because I do think that underneath it all it's just the particles acting themselves out in spectacularly complex ways but I am a fan of being willing to change my perspective changed my language and make use of the more familiar concepts when you're trying to describe familiar life I would never take a baseball and try to you know Aaron judge hits it right I would never try to use quantum mechanics to describe the motion of that baseball I mean they're 10 to the 23 particles in there to try to apply Schrodinger's equation to that I mean it would take the you know that quantum computer to the nth degree that try to actually calculate using it be ridiculous so instead you change perspective to use Newtonian ideas which are a pretty good approximation what happens to the baseball just scale that up and it applies to the happenings of everyday life it can go further than that as well so I don't think there's any channel I don't think there's anything else to be found from that perspective but I would just shift it a little bit and say hey the poet's the novelist the composers the artists they are giving us deep insights into the world that you don't need to be a particle physics to grasp appreciate and grow from so the next one and these are gonna have to be the last ones the ones that have already been asked Buddhism in quantum mechanics why why art again well why are a number of quantum physicists inclined toward Buddhism or maybe Eastern mysticism more broadly I mean you wrote the book man so I should toss it to you but I will say one thing and you know I am did an event I don't know if we discussed this at any time I did an event some years ago in in Houston I think it was and and the Dalai Lama was there part of the event and so we had a public conversation and in that public conversation I asked him like there are all these books that speak of you know Eastern religion and quantum mechanic you know you know the ones I'm referring to and and so what do you what do you think of that Dalai Lama and and he said when it comes to fundamental physics we need to turn to you guys we need to follow what the physicists tell us he said when it comes to consciousness we have something deep and important to offer mm-hmm but when it comes to quantum mechanics and fundamental physics you guys lead the way and we will follow you yeah I I don't think I have a good answer now Erwin Schrodinger was something of a he was inclined toward this right I mean his book what is the little book that is paired with mind and matter he wrote a little thing called mine and then the more famous book is paired with it but what is it is what is life what is life okay so what is life and mind and matter are paired together and mind and matter is very kind of mystical and what his life is a very profound book I mean he and and I don't know I mean the first question I'd ask is is is this not somewhat true of scientists generally could you not find other scientists who are inclined this way in which case maybe part of the answer is that they were disabused a hundred years ago of what you might call primitive conceptions of a deity they were entering the modern world maybe sooner than the average American and and that the version of Buddhism that made it to America which is actually the part that stripped of the religion that's actually part of Buddhism in Asia but anyway meditation and the philosophical part of Buddhism very appealing I'd also say I think you know the philosophy of Buddhism is very sophisticated and in a sense very scientific in spirit there's a tremendous emphasis on the pervasiveness of causality believe it or not and that's the reason that like the notion of the self is cast in doubt that's one reason is because there's an awareness that what I think it was my self this autonomous thing that's that's doing the deeds and thinking the thoughts and making the decision it's actually being influenced all the time but all the stuff from my environment and maybe it's better described as a mediator than as an autonomous things so I can think of reasons one Buddhism would be appealing to scientists I'll think about the the quantum physics thing I mean was they did bone a little mystical if someone certainly say that so I don't know it's a very good question I haven't answered the last question which is for you alone is about many worlds in string theory yeah sure so so when I noted that many of us resist the many worlds interpretation as currently formulated I definitely framed it in the guise of it violates our sense of reality bothers our intuition especially when it comes to the intuition about probability but that really has a mathematical incarnation even though I used that everyday language and again not everybody agrees with this but what's difficult for us to make sense of is how do you even mathematically defined the notion of probability and in many worlds interpretation some believe they have solved that problem others are more skeptical that that solution really is what it what it purports to be so when it comes to many worlds it's it's though I'm a frame it with intuition and our sense of what the world should be it's really a brute-force mathematical issue in the laws of quantum mechanics so when we now turn to string theory and there's some strange counterintuitive qualities some of what you point out that there may be more than three dimensions of space and the many other weird things too I see it as a completely oblique direction relative to the critique of the many-worlds approach I'm perfectly happy to go in strange directions so long as the mathematics is taking me there and the mathematics of many worlds I don't find it taking me to many worlds as yet but the mathematics of string theory is taking us to ideas of extra dimensions so we follow and see where it leads okay so I'm afraid that should be about it let me let me let me say two things Brian and I have to actually be somewhere at 8:00 getting a car so I'm afraid I'm sure a lot of you have other questions for him he's not going to be able to stick around so what I would recommend is you go to the World Science Festival in May and try to corral him there that I don't I have no idea whether it's possible there but it gets me off the hook tonight so and finally I mean I know you've already given us one round of applause but Brian has really exceeded my already high expectations and for for somebody who hasn't been getting much sleep he's been incredibly dynamic articulate clear profound and so on so let's thank him one more time [Applause] you

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Id: g9Y-W4xXoQM

Length: 97min 32sec (5852 seconds)

Published: Tue Jun 05 2018