Brian Greene - "The BIg Bang to the End of Time" Student Q & A

we're happy to have professor O'Brien right here today he made it through the snow and the slush of the winter and you know we're excited to actually get things going here so a lot of people are here because you were part of a class that we did sewing the fabric of the cosmos so this is the second book that Professor Monroe and we had a lot of fun doing it I had a lot of fun we talked about a lot of physics things and we tried to relate it a little bit to the liberal arts which I think we were pretty successful with and but I know that we were invited to invest a lot of things so we had you know a short time each week when we could talk about these things and there's a lot of concepts in there so this is your chance to talk to different horses about this so let's start off yeah and ask how did you get maybe tell us a little bit about how you ah en I have to think back a little bit but as you said it's a second book that I wrote and the first dealing universe really was um an emerge from a sense that that there were a lot of wondrous ideas that were happening at the cutting edge of physics that were pretty cut off from the general public even the interested people in the general public didn't have a way in to some of these ideas so in the back of my mind I was thinking about writing a book that was back in nineteen I don't know three guys were born in 1995 or six or something like that and I got a a knock on my office door as a professor at Cornell at the time and it was a publisher from Princeton University Press we said we're convinced the world needs a book about string theory and we're told that you're the guy to do it so yeah we spoke a little bit and sounded interesting and you know it sends me a contract but I didn't have any interest in signing a contract was I've never written a book and I didn't know if I could do it and I didn't want to be bound legally to write something if I didn't think it was going well so I just went off on my own and and started to write it the elegant universe and it was going pretty well so then I went through the usual steps to get the book published and ultimately did with a different publisher but as I was writing the elegant universe I had this persistent sense that it was a parallel story that I kept having to push to the side because otherwise the elegant universe would have gotten bloated and too thick with all sorts of ideas and it wouldn't be a clean description of the search for the unified theory which is what that book was all about so while I was writing a universe I felt like there's a second book that was sort of asking to be written where the more strange features of physics particularly about space and time would have an airing and those are the things that you're familiar with having looked at the books things like entanglement things like is space a real substance all the strange ideas of the quantum effects to do with time like the quantum eraser and all those issues that seemingly really challenge the very basic elements of experience but are at the edge of speculation in terms of what they mean for reality even among physicists and that really drove me to write a book where all of those ideas would have a place to be discussed and that's what that second book was all about that in the advance of you know there was those two things combined they're really there yes into I mean that's the whole the whole challenge of the of the exercise and there's a way in which it is difficult there's a way in which though it's a familiar difficulty because as I do my own work I've never feel satisfied if the only understanding I have of what I'm doing is based on the mathematics and there's some people who are perfectly fine with that the mathematics and their understanding are effectively one and if they're trying to think something through this set of equations that are relevant immediately come to mind and that's the language with which they think through any puzzle in physics I'm not like that the mathematics to me is a tool that ultimately I feel like I want to translate that tool into imagery or words that are not rooted in the technical details that somehow take a step away from it which is what I feel I need to have an intuition about any of these ideas so because I already do that translation of my own work when it comes to a book a lot of it is a matter of relying upon ways of thinking about the subject matter that I've already developed and now just articulating it in oh man that's more accessible to somebody that doesn't have any of the mathematical background so so that's sort of the process but yeah it is definitely a challenge and certainly I may remember for the first book it was even more of a you know a new process in terms of writing about the stuff than then five the time I got to the second book but in the first book the chapter in quantum mechanics was the most intimidating of all I think it's chapter four of the elegant universe and others roughly 15 or so chapters in that book and I didn't write chapter four until the end and chapter by chapter by chapter I kept referring back to chapter four in quantum mechanics that didn't exist so hey kept paying I oh my god that chapters gonna have to do so much work to make everything that follows makes sense and then when it came time to writing chapter four it was like oh my god here it is and um I didn't I didn't know how I was going to go about it but I but I clearly remember at the time I had a had a dog used to walk the dog at night in New York and uh where I lived and just sort of hit me how I wanted to do it and it just struck me I don't know if you've read that chapter in that book or not but you know how do you describe the quantum nature of things to an audience for which that whole conception is going to be pretty foreign it's even foreign to us and by a series of metaphors that in some sense latched on the quantized nature of currency of money there's sort of a very natural way in that it ain't kind of developed into little stories that make it more interesting to read about and in the end it was my favorite chapter of the book but it was definitely the one that from the perspective your question was that the most intimidating I don't think I don't think it really comes from any of the traditional training you know um I do remember one experience that I think was formative for me in the sense of deciding that this was the kind of thing that I might want to do in parallel with more standard scientific research when I was in 11th grade in high school I don't know if you guys have this probably not I hope not but we had a class that for reasons that escaped me was called hygiene I don't know reader T your kids I don't know if it's called hygiene and it was taught by the gym teachers so that was a they they had all of them had a double role in the gymnasium you know doing all the stuff that happens there but they also had to teach a class and this is a class that they all were required to teach and as you can envision a class on hygiene there's not a whole lot of material to cover you know they would do things like tourniquets and CPR and all that sort of stuff but they couldn't fill a whole semester so what they did was they required each kid to teach one of the classes that's what it sort of filled in the rest of the time and so most of the kids were not into doing it and had to do it and would get up there and teach something that the rest of the class wasn't that interested in but I got really excited about it so I taught a class on on sleep and dreams and kind of took an unusual approach these relative to what the other kids were doing and everyone got excited they're interested in asking questions and it just felt to me like wow here's a way you can take some really interesting scientific research on dreams and then sleep in the subject I was focusing on and if you tell the story the right way he'll can get really excited and into it and I didn't do much after that but it was always in the back of my mind that that was something I would want to to do and then when this moment to do the first book arose that kind of naturally kicked in and basically ever since I've been on these two tracks doing this kind of stuff the books but other ways of bringing science to the public - together with the the more standard research side of things so a lot of the discussion that came up in our and I was just wondering similar to this question where did you smoking a lot of dope is a Verya no none of that no it's not well and um you will find if you know if you ever try to do this that if you if you kind of train yourself or push yourself in fact it's not a bad exercise take any of the metaphors in the book to explain something and throw it away and find your own and I bet you dollars you do it you'll be able to come up with some and you may find ones that are better that that work better for you or work better for for everyone because there's a tendency when you learn something from an expert to just take it in you drink it up and now you sort of have it but it's a very different mindset when you take in an idea and try to own it and bring it back out and that step of like taking in the idea and bringing it back out is something that I think is a vital part of the learning process and we typically don't do that right I mean maybe you do in here I don't know but in the traditional class you're sitting there and you're soaking it in from somebody knowledgeable and to me that's half of the learning process and we don't focus enough on the other half which is check it in and then bring it back out because that's the moment you talk to any professor where have you learned the most learning or teaching yeah you know and then teaching side of it I mean every time I teach a class I just taught and we were just briefly talking I did a class in special relativity so I've I learned special relativity a long time ago you know whatever it was nineteen 1980 a long time ago 35 years or something I teach this class and specialty I learned so much because it's one thing to look at the equations and solve the problem is another to like okay how do I explain that and how do I get that idea across and and that process if that were part of the educational system more than it is I think we would all be coming up with these metaphors and ideas all the time because that's the only way they can really get the ideas out there and it forces you to think about things differently so I think it's a matter of work it's not some mysterious thing it's just a matter of really working on your own learning process and that will naturally happen I guess dr. Greene I know that you're very famous physicist and you're well recognized for your work of popularizing all these very beat and they well that's good enough for me thank you can stop right there afraid there's a but on the other side is it come back holding the but so the thing is that I bet there are people working against what you're doing yeah simple because I think you know a lot of people would say physics is such a safer thing and other than is sacred idea is also very hard for Lane I understand I mean this is something that we should keep in to meet class I mean this is where than idea but I mean I read through a website I don't know if you make a website or somebody else did it I noticed depends what you're gonna say that will answer there there are people who are making videos on there obviously one is from Letterman the other one is from the Big Bang Theory and that one I watch from the Big Bang Theory Kevin was poking fun at you when you were talking about some kind of quantum stuff and obviously it was making fun at saying that why are you just doing this kind of popular popularizing all these very vague ideas I mean how do you in real life how do you deal with this kind of stuff and what is your motivation of keep doing what you're doing well I guess I guess the answer is pretty simple which is you know I feel that everybody out there has a choice and if they want to engage with me on these ideas they're free to do so and if they don't want to engage with me or they want engage in something or not at all they're free to do that too so from that perspective the real question is are there enough people that seem that they want in other words if I wrote a book and nobody read it you know I might still have found it a valuable experience but I would be less motivated to continue to do it and the fact that there is enough of a demand a hunger excitement about the ideas that to me is enough that I don't feel like I have to justify or answer to anybody and yeah Holly I think everybody needs to know about these things you know my a real good example is my mother who has no idea why anybody would spend their time working not just describing about working out this kind of stuff you know she's much more watching you know that very basic kind of thing and that's fine because people come at the deep questions of reality from a variety perspectives they don't care about it doesn't matter to their life their whole well-being and state of mind relies upon it you got everything in between but the other question that was sort of in there was should this material be viewed as too sacred in some sense to be kind of blasphemes in the way that it might come across and in a book that doesn't focus on the mathematical underpinnings of everything and my perspective there is there are popularization of physics that I do not like I can't stand them and the reason I can't stand them is because they're all about hyping the ideas trying to make them into more than they are or trying to link them up to the mysteries of life in a more direct way that makes any sense base our current understanding of how things actually work that I that I that repulses me I hate that stuff but my own feeling is that if you're true to the core ideas and bring them out with a degree of nuance and subtlety as opposed to the other very flat-footed non approach that to me last integrity but if you're going to do it in a way that has integrity it feels to me that it's that it's justifiable worthwhile but the thing is everybody draws their line in different places you know there there will be people to look at what I write and it's too far over the line from their perspective and a me hate it as much as I hate the other so but that is a matter of personal choice and personal taste and for the most part I've gotten almost no colleagues who said Wow how could you say that in fact I don't know that that's ever happened that anyone has said that whereas there are a collection of writers from whom I'm I say to all the time at least internally so it's alright it's basically about finding the place where you true enough to the ideas and yet accessible enough to get a large number of people engaged with those ideas let's TSO to the big questions that you know canada the beginning any any of our discussions that we've been having on what the implications are for certain theories kind of correctness or wrongness and whether or not is worth all the research money to be put into things we have our wider and we just like to know kind of what your thoughts are yeah so as far as string theory goes the jury is very much out so the ideas hold together strongly the progress and theoretical research has been robust but there's no piece of experimental data that we can point to that either suggests the ideas are a correct description of nature or that suggests the ideas are not a correct description of nature so we don't know at the moment I would say there's a lot of circumstantial evidence that things are headed in the right direction the way that the idea is hold together the way they are able to embrace almost all of the major earlier discoveries we don't have to sort of throw out the past to bring in the new ideas of string theory rather we can take all the ideas that were carefully developed over the last century and we could have in some sense extracted all of those results from string theory if they hadn't previously been found so I think all that's very impressive but that doesn't mean that it's right and it's possible that a machine like the Large Hadron Collider might give us insight into that you know and that machine powers up again there's a chance that they will see some of the additional particle species that this collection of ideas says should be out there the problem is they don't see those species it doesn't establish that the theory is not correct it could simply be that the machine isn't strong enough to to create those particle but more generally ask the question is it worth spending all that we did ten billion dollars it would ever on the Large Hadron Collider that's a hard question to answer in isolation I think you have to look at the way the world spends money and then look at the money being spent here and say based on what we do does that money make sense and you kind of look over here and you see about how much weight you two rocky where how much was it Oh a couple billion dollars a week and you're going to worry about the world spending ten billion dollars to try to understand the deep nature of reality I don't know feels okay to me my question kind of plays off that what do you feel is the state of science policy in the United States a lot of these projects require federal funding so scientists Congress Lobby you know effectively Sinclair supper and lanterns so what do you think about that you think science policy is going to take a turn for the worse or do you think it's starting to go back up again like what we had in the 60s well see the the funny thing is when you look back at earlier era and often people do look at sort of post 1957 or so and in the period then the funding that was coming forward was not out of some noble desire in the Big Bang or black holes or the structured matter it was to beat the Russians right and so so in some sense of question is will there be a big enough threat that that kind of mentality would kick in again or is there a way to actually shift thinking so that these kinds of pursuits are elevated and receive funding further own right as opposed to their capacity to make us stronger in the sense of defense or to win out over some major opponent and that is where of course we would love things to go but there doesn't seem to be any indication that that's the direction that we're headed so think the best that we can hope for is a recognition that a vast majority of the challenges that we currently face the vast majority opportunities that we have when looked at correctly are scientific at their core so the things I have in mind are the obvious ones from alternate energy sources to the possibilities of nano-scale technology to all the issues about human genome personalized medicine genetically modified food the one thing that does capture the public's attention real easily space exploration so among these and a thousand other pursuits when hopefully it's understood that decisions about what's worth doing and what's not worth doing how much should we spend how much should we spend you need to have a scientific understanding of what those pursuits are all about and the hope is that that will drive a greater degree of attention to the underlying science in making the policy decisions whether we'll get there I don't know so it's it's not obvious that the world oh just speaking about kind of getting the public interest it seems that there is a bit of a trend on kind of popularizing with these topics like yours Malcolm Gladwell's works another one in a different area do you think that possibly this continuation of hired like ideas within the different scientific fields might become a trend and that authors might come out and try and express these in ways well you know you go to a bookstore well then over the existing longer but you go to Amazon right and and you see that there are an enormous number of popularization I mean I'm more familiar with the ones in physics many of them written by friends of mine but the number of books written is is large so I think there is a general recognition that getting these ideas out there in a way that people can get excited about is generally good for the underlying science it's good because as you're saying ultimately many of the projects are funded from tax dollars and if the people paying the taxes are excited about where the tax money is going that can't help but be a thing a good mix to to take place so I've certainly been impressed by the degree to which the science community has sort of shifted away from the notion that you were indicating before which may have held sway in the early days when someone like Carl Sagan was a lone voice going out there and many colleagues kind of looked like what are you doing what do you could do and taking our science and bringing it out that way sort of a zero for that is no longer a dominant way of thinking another data point along those lines which really makes it clear is some years ago in New York start an event called the World Science Festival I'm going to heard about it but it's basically for a while though it's expanded now it was five days of intense science programming for general audiences so this event like seventy events that would happen throughout New York on neuroscience and sustainability and quantum physics and cosmology and when we started this back in 2006 we start to think about it we wanted to get a board of scientific advisors behind it to show support for this naturally we turn to Nobel laureates because in the public's mind him rightly so these are the the pinnacle scientists and there's a general sense from people we spoke to that look Nobel laureates of just so many asks on their plate that you're going to get very few who will want to be part of this but we asked 25 Nobel laureates and 25 said yes because the mind set it shifted toward the recognition that bringing these ideas out to the public is important and now when we have these events each year you know we don't have to call up scientists I mean I don't actually do the programming but the team that does they don't have to call up scientists convince them to come for the most part scientists are are knocking on the door of the world science festival with ideas for programming that they want to be part of during the event they want to be out there doing this as opposed to having to be convinced to be part of an event of this sort so I think all of that suggests in answer your question that there really is a recognition of how important is to get the ideas out there the public this is crisis item America my sincere Adak that electrifies earlier I was wondering if you can just give a brief rundown of where we are in terms of experimental confirmation string theory which effect - what's happened since the discovery things goes on have there been any terries of super cited articles or anything it looks like a might be especially not great that's going on right now so in terms of experience victory ya know it's a good question in terms of the experiments behind supporting these ideas other things you all want to talk about that's it's a kind of quick answer which is there's nothing okay no so and and what is this or what does that mean so I hurt means that the ideas are wrong and that would be and that in and of itself would be very interesting supersymmetry one of the ideas that you mentioned I know if you guys are familiar it's a very natural extension of our theoretical ideas which to be true requires a whole collection of particles that we've never seen so the hope is that they would be seen at the Large Hadron Collider and the hope is efforts have seen them by now we haven't that has narrowed the window of opportunity where the particles might be is not rolled it out and it could be that when the machine turns back on they will be found in fact there's a way in which you can view it quite optimistically we've narrowed the window so if these ideas are correct there's not much more that we're going to have to probe to find them because the window is is closing in but if we don't find them it either means that supersymmetry is wrong or that again it manifests itself at an energy scale too high for that machine to reveal the particles so it could be a curious state of affairs it could be that the machine finds nothing and then what do we do at that point because it doesn't say that the ideas are necessarily wrong but yet it's an interesting challenge to go back to the funding sources back to your question and say we need 10 billion or 20 billion more dollars why ah we need it because something really interesting happened at the Large Hadron clutter and what was that we didn't find anything that's a strange argument to make but scientifically justifiable one in fact I wrote an article in The New York Times some years ago anticipating that this might happen because finding nothing is scientifically interesting it suggests that ideas that we've been developed either need radical reshaping or need to be interpreted in a different way so finding nothing is a result but it's not a result that somehow gets people as excited as finding the actual positive and negative is still a result so we'll see what will happen the word on the street is that that the Chinese in China Chinese government is interested in building the next Collider and there's already work underway at least at the planning stages for that and for that to happen that could be the next machine and it would be it'd be great it would put China on the map and in a way that it hasn't been so far it would be the central place on earth for particle physics to take place and people say that if it was to go forward it could be in the order of you know 10 to 20 years that seems optimistic to me but it could be that we'd have a new machine at 10 to 20 years short on you know the timescales of the universe but it's long in the times of a career so there will be people who have retired but and that just may be what happens so we may not know the answers to any even with the next machine you may not know the answers but that's the nature of research you don't know you're willing to take a chance and there's some people who don't want to take that big a chance they want to work in something that on the timescales of months or maybe a year will yield a result or not they can move on and there are many areas of science and physics where you can do that there's some room see the big prize and these are big prizes you find supersymmetric particles that is a radical radical discovery it tells us that there is quantum dimensions to space it tells us that there's deep symmetry principles at work even beyond the ones that were so far confirmed but with big prizes comes big risks and the big risk is you don't find anything so you don't know so what we have here it'd be nice to kind of did really deep I guess explanation for what key brains are yeah and what yeah but some of the extra mention allottee yep needs to the universe yeah so the big discovery which happen again now some years ago in 1995 which was already 10 years after the earlier discovery that set string theory in motion and in a big way the big discovery 1995 that string theory is not a theory that only contains strings strings are the ingredient in string theory that we found first mathematically of course but more careful mathematical analyses revealed that there were not just these one-dimensional filaments but they're also two-dimensional membranes or even three-dimensional blob-like configurations even four-dimensional ones in five Domenic it harder to picture but mathematically they're there so this notion of membranes emerged because of this analysis and because these membranes come in a variety of dimensions the idea of a membrane which is two dimensions with renamed as a two brain two-dimensional membrane to brain for short or a three brain three-dimensional membrane three brain for short or in the general case we typically don't use the P but a deep D brain is the collection of these guys but you can certainly have a p-dimensional D brain or a pea brain for short if you like noted language but that is the basic idea that remarkably to many of us in the field who have worked on the subject for a decade before 1995 that hidden within the equations there were more ingredients than we recognized for a long time and most striking of all these ingredients don't have to be tiny so there can be a large three-dimensional membrane a large three brain and what would that look like well turns out it would kind of look like our universe so our universe could be a three dimensional blob in a higher dimensional realm and therefore reality as we know it is just one sliver of this larger spatial expanse within which we would be floating and this is an idea that people have been pursuing brain universe models are called so kind of going off of that discussion my professor from philosophy of science had a question when it has to be here in you with college and Confirmation if a professor philosophy asks the question but it's not actually there what he was wondering is hooking you sequences from the cutting edge yep was if there's any potential that in the future we might have what we think of as knowledge that can't be empirically confirmed since danly week's technology required justified true belief which is something like empirical evidence etcetera I don't think so in any time scale that matters to us or even to the species I can't imagine that we'll ever get to a point when we're really willing to accept ideas without empirical verification if you ask me in a more theoretical sense though I can certainly envision a time wave way off when merely by virtue of demanding logical consistency we might be able to follow a chain of reasoning that yields the laws of physics and then you wouldn't need to verify because if that structure was unique we determined by the one requirement of logical consistency and I think most of us would be willing to buy that to be able to perform any kind of rational explanation to give any kind of rational explanation the universe you've got to assume logic you've got to assume that it's not inconsistent internally so if the requirement of logical consistency uniquely yielded a body of physical law then I think that would be it we'd be kind of done at that stage because no matter what why question you ask they'll be an answer and if you ask why that will be an intern then finally if you ask enough why questions to get right down to the root and the answer will be because logical consistency alone demands it and then there's no further white question to ask because I think that's such a basic axiom that we'd be willing at that stage to say we're done but the likelihood of that happening in any timescale that we can envision I think is pretty small but at least I can imagine along with - are we discussing about - a guest lecturer house mediator convention is so far beyond this work development was it again there's just a way um this is a relatively recent book right yeah yeah I I'm not I've not read it but I do know of it it came highly recommended but I've not I've not read it well this is what I was gonna do if you want to ask this you talk about how funny she got five articles they're not exactly sure how massive there yes I mean the book the work you do a book is because of that is also approximately we've got a scripted and I'm just curious is that one like obviously it's a bit nailing down which is the data you need in some ways some sort of empirical data to map down to where we get conver tidings of this part was definitely this very isolated what's keeping us from getting a certainly combination of both if you look back at the history of say a subject like quantum mechanics there is this almost day-to-day probably little in exaggeration but a kind of day-to-day interaction between the experimental ideas and the theoretical ideas in fact a day to day might not even be that much of an exaggeration because I believe it was the case that when Max Planck wrote down in 1900 his ideas about radiation and cavities that would come from the rudimentary notions of quantization that he was employing at the time the exchange between radiation in the walls of the cavity and the interior I believe it was within a day one of the experimenters had done a detailed analysis of the implications of those ideas and compared it to the actual data give him feedback so so so it was a very hand-in-glove kind of relationship between theory and experiment and obviously that is a powerful exchange to take place and if we had daily input from experiment on what was happening at very high energy scales very short distance scales it would have a profound impact on what we do but the fact of the matter is we've built the machines that we can build and those machines can give us insight up to you know a few thousand times the mass of a proton but the idea is that we work on are taking place at scales that dwarf that so we don't really have any direct input cosmology sometimes gives us some input but we don't have the kind of input that we were having in the early days of quantum mechanics so yes that is a big stumbling block and it means that theorists are and sometimes more free to come up with ideas and they aren't as constrained by having to talk and explain data immediately but that's only part of it the other part of it is we've entered a domain with the mathematical ideas are extraordinarily challenging so string theory is a kind of simple theory to write down at some level but you know strength you're in even quantum field due to some extent these are complicated structures and for the most part we analyze them by doing approximations perturbation theory as it's called and that can only take you so far now we have through the insights of a number of people been able to go much further than any of us would have thought back in 1990 back in 1990 I thought will only ever be able to do this sort of first order second order third order calculations and then along came a variety of great insights which gave a whole new set of techniques that are far more accurate than any of those approaches but still what's left to conquer is is huge so who knows what it will take but certainly tremendous mathematical insight and whatever ideas and illumination we can get from experiment is important but you do what you can you don't just stop because I mean some people say oh these ideas are too hard based on what we know in business we're just so far beyond data that there's no point you no longer doing that's just silly that's just plain silly news it means that you're doing more speculative science because the data is not there to confront it day by day so in the book you talk about the Higgs that's been like this the arrival thing and yet you haven't yet evidence when CERN actually came on set we have pi sigma certainty to the comte explodes you're over your first reaction for that well it was so expected that it was going to happen you know I I don't think I brought him around some article that when I first learned about the Higgs idea back in graduate school it was spoken up by the instructor with such certainty that I didn't know it was hypothetical I thought it was a fact how the world works and it was later on that was like oh oh so that's just not eat we don't know if that's right so that was the attitude among everybody that of course this idea is right it's just a matter of establishing it so on the one hand there were a sense of great we sort of established the stuff that we knew it almost felt like we already knew it and and that that is of course tremendously exciting for mathematical ideas to be confirmed I mean that's what we're doing right now so we want that kind of pattern to persist at the same time there certainly was a sense of wouldn't it have been more exciting if they hadn't found it because they hadn't found it we do back in situation that we sort of discussed before of having to develop new ideas now there's an in this case if you didn't find the Higgs it would really require that you rip out the heart of what we thought to be the case and develop a new approach which would be very exciting for theorists now we're freed of that idea that we thought was true and let's come up with something new so it was kind of both sides excitement but also a sense of huh I guess that's over that part of it that way you move on a lot so I guess as you progressed in string theory like your knowledge of it how do you reconcile the fact that a lot of my bills are not in two days and what kind of like if Michael is too radical like well I think the best way to think about that is historically you know in the time of Newton his ideas were kind of radical because people weren't trying to use equations to describe the world but at least the underlying ideas were completely intuitive you know you throw a ball with a greater force it'll land further away that all makes sense we all experience that but then by the time you get to Maxwell and even further by the time you get to quantum mechanics the idea is that people are developing our pretty counter intuitive pretty not aligned with everyday experience so quantum mechanics has a whole host of crazy ideas particles and waves and tunneling and probabilistic description of how the world behaves and the possibility that reality is one way when it's not being observed and another way when it is being observed so a whole host of completely non intuitive ideas that by any rational account should be wrong this should be wrong but they're right the data shows that they're right so I think that convinces us that we can't trust that our intuition will point us in the right direction when it comes to the laws of physics because if we follow that directive we would have missed quantum mechanics if we missed quantum mechanics we would have missed more or less everything so I think that is good evidence that when an idea is weird or crazy or strange that's not cause to dismiss it so long as the idea is well motivated mathematically articulated and has the to at least in principle hook up with actual observation now the only other thing I'd say about that is there's a danger in that where I've seen this happen so many times people say well they say I've got this crazy idea and the crazy ideas of quantum mechanics are true and therefore since my idea is also crazy my idea must be true because of a curious kind of reasoning and you see this sort of all the time out there I could give you stories of places where I've been where people have made important life decisions based on that kind of reasoning and obviously that's not true not all crazy ideas are right but some crazy ideas should not be dismissed by virtue of their craziness because they may be right so I think was I guess all my dream is over in this life - I disagree with a caking general relativity we made a copy multiple constant this is I'd be also very fond mechanics so I you think like his approach to fixing more theories or like making intuitive well but that's a very good example where the fix was wrong so he didn't agree with the notion of an expanding universe from quantum mechanic from general tivity so to deal with that he changes the equations in a way that's completely sensible it's not like he did something crazy oftentimes people say I enjoy mangled a beautiful math of general relativity to bring it in line with his thinking about their well nothing could be further from the truth the term that he added is the most sensible logical reasonable thing in the world in fact we believe that that term is there just has different value than what Einstein thought so Einstein was trying to force the math to agree with his intuition and nature slapped them you know so I think we should take that to heart you see any way in which this model build with probably signature quantum mechanics and how a kind of skirts causality in a sense would bring it into that logical determination as we talked about no biases of our way way in the future you know where if you ask seems to me you know doing it asking you know why does the child come up over here they're wanting to say there is no you know I'm sure there could be thoughts I'm not really just housing to basically learn Haskell seems a skirt like necessary causation anything else in physics you know dictates issue in that flight suit so yeah I think a lot of people think of quantum mechanics that way but I was encouraging not to it's not so much the quantum mechanics changes anything about causality or causation it simply emphasizes to us that those elements of reality that we thought previously thought defined reality those were the wrong elements to focus upon so in the old days we used to focus upon the position and the speed of particles basically so if you know where every particle is and how every particle is moving then you've described reality and quantum mechanics tells us that that was an incorrect Newtonian notion the way you describe reality according to quantum mechanics is you give the probability distribution of all the particles and then you're done and in that language the probability distribution of all the particles that distribution is governed by ironclad deterministic laws the Schrodinger equation if you like these ideas it's as beautiful differential equation and it plays the role for the probability distribution as F equals MA did for particle positions and velocities so these structures are exactly parallel in the sense of you start with things like this and the equation determined with 100% certainty the distribution later 100% certainty now the weird thing is it's determining with one percent certainty a probability distribution which we feel oh there's uncertainty in there because it could be here or there but again that's Newtonian view that reality is when the particles here their coordinate quantum mechanics this is reality and it is governed by as rigid a mathematical structure as the positions and velocities of particles are governed by F equals MA in Newtonian mechanics no change from that perspective piggybacking off that a little bit so one of the and it's not a metaphor one of the things you talk about in your book in this book that we read is space-time as this concrete entity particularly the time axis that doesn't talk about a difference between the full of time that we perceive and the reality of space-time yeah and you know how the arrow of time simply is due to this low entropy configuration early in the universe with quantum mechanics we have this issue where the observer comes in and affects collapse of the wavefunction you talk a little bit about this idea is called decoherence sort of with a shreditor equation right can't totally be it so how do we connect the micro and the macro I sort of understood that I mean I have some the idea of decoherence but talk about a little talk about that a little bit and I know it's been 10 years well all that has to do with an area that is still unresolved which is the so called quantum measurement problem and the quantum measurement problem exists in the swirl of ideas that you're describing so in quantum mechanics we have this equation that determines the probability distribution but then somehow when we measure a particle we always find it at one location or another which seems to suggest that the probability distribution is affected by the observation forcing it to spike or people call it collapse that the whole wave collapses and only in one location does it spike and it spikes at the location where you found the particle that description often called the Copenhagen approach which was inspired by ideas of Niels Bohr in the whole Copenhagen school I would say very very few physicists believe that that's actually how things work there are there are some and some of them are quite prominent so at least as of a few years ago a guy named Anton Zeilinger who was likely you know worthy of and will likely win the Nobel Prize sometime soon for all his work in quantum mechanics you know as he and I discussed these ideas he would just sort of chuckle in a kind of avuncular way that I was at all disturbed or thought there was a problem he's like no no the Copenhagen that's it there's nothing else that needs to be said but I think most people don't have that view most people have the view that the act of observation is nothing special it's just one collection of particles being brought into contact with another collection of particles at the laboratory equipment or made out and the laboratory equipment is just another collection of particles that's being brought to bear on that single electron that's being measured and since everything is just roots of particles talking to each other it should be the very same Schrodinger equation at work and there is no place in that equation where probability waves can have this collapsing or spiking evolution that kind of evolution doesn't happen in the equation so most of us say well that's that's troubling so does a new process come in at the act of observation again most people don't think so but some suggested or is there something else mysterious going on so we don't know the answer but at least one hint of an answer comes from this idea of decoherence so coming out to your question which is that you can establish mathematically that when a lot of particles like in a piece of equipment or the environment comes into contact with say a single particle like an electron and if the electron has a probability to be at various locations an interesting thing happens in that interaction which is the capacity for quantum interference which is the hallmark of quantum mechanics I mean the fact that probability weights are spread out the way they talk to each other is wave interference but what happens with decoherence is we have lots of particles involved the possibility of wave interference you can show mathematically it's driven very quickly to nearly zero so it's virtually impossible for a macroscopic piece of equipment to go into a superposition to be in some sort of interference combination that it inherits from the electron that might be have some nonzero probability to be at different locations so there's a sense in which having a lot of stuff suppresses some of the quantum quality that is quite manifest for a single particle that doesn't answer the quantum measurement problem it just suggests why it is that in the everyday world we don't experience all the weirdness of quantum mechanics in a mortar way through say quantum interference but still doesn't answer the question of that the electron is a 50% chance to be here in 50% chance to be there and you measure it and you find it over here it doesn't tell us what happened to that other possibility it doesn't tell us how it is that the election sort of snapped to attention and I was at a definite location where a moment ago it seemed not to have that quality that still is unresolved I guess I guess I connected us to explain my question just because I mean you sort of described it as a problem for a potential problem for this arrow of time because there is this observer that comes in yeah then that's sort of everything after that wavefunction yeah so I don't know if there's a connection between those two issues the arrow of time and the quadrant measurement problem but they do inhabit sort of the same collection of puzzles right so the hour of time we think has something deeply to do with conditions near the Big Bang as you're recounting from from the book low entropy conditions near the Big Bang seemed to be what set the initial order and we've been living through the degradation of that order ever since and that degradation is the direction that we associate to future as opposed to past but that story requires truly having a quantum understanding of cosmology and that means you need to really put quantum mechanics and gravity together and have it work in the extreme environments of the early universe and that's something that we don't really know how to do so that's why we don't have a full answer to and if you look that sure physics that might lead general public to have misconceptions about what it means and how you address them well you wish you could rename sure the big one of courses there's the word theory which is a sort of physics oriented per se but as you know in science theory is a very precise term meaning you know the most efficient leanest powerful set of ideas able to explain a range of physical phenomenon and that means that if not just Sherlock Holmes having a theory about what might happen in some or other circumstance it really is our best answer in order to the question of how do things work and you know I can't tell you the number of times people conflate the English use of that word with the scientific use of that word in order to in some way shape reform denigrate a scientific perspective as to just being a theory where the just what does that feed judgment that's theories the bread and butter of our currency that that's how we work those are our ideas so I say that through the big one but the other side of course quantum mechanics a language has been taken over by the public in so many ways I mean if you go home and you just google quantum mechanics and almost any other word you'll find them linked so I have these pictures I don't have any with me now where quantum mechanics is used from everything from you know quantum mechanical pizza topping devices that I've seen to quantum baseballs to quantum golf clubs to there's this quantum sleeper you can look up where it's supposed to protect you from bioterrorist just roots so quantum mechanics is sort of become the catch-all phrase of weird features of science that somehow are transformative in their power and I guess it's not such a bad thing but if quantum mechanics is very as you know specific and it's so potent in its own right that it just almost feels tragic if that side of the story winds up getting no airtime instead you know you get your quantum golf clubs so you became three people could you learn more on the looting of time because I thought I can push the car that I've only chained up in woods and so like now that we do is variant I'm like there is caught justice like a penance causation person or commissioning the electrical and sometimes when the court official activity that we email you can really advanced like you get the perfect reference frame be like recent hacking can't be changed may be changed no concern yes so so I guess a couple things so first there are some people who think time actually is illusory and I'm not among those people time is a real thing whether it's fundamental in the make of reality I don't know but certainly at the level of experience that we have access to I think times it is a real thing but I do think that many of the experiences of time that our familiar are illusory and among them I think the flow of time is likely illusory you know the sense that we're going moment to moment to moment is I think an artifact of our brains making sense of perception and organizing our thoughts in a sequence that for whatever evolutionary reasons allows us to survive I think ultimately it is Darwinian evolution that has forced us to think about the world in the terms that we do especially when it comes to time but as far as relativity special relativity in particular what is it tell us well it tells us that the fundamental aspects of time that deserve attention are the cause of relationship so getting to what you're asking so if a can cause B that's something everybody will agree on regardless of their state of motion if they can't cause B because it too far apart and the amount of time between the two events is too short for any signal to get from one to the other that's again something that everybody will agree on regardless of their perspective or the frame of reference but the other things that we ordinarily think of as definite and real such as how long did it take for that event to happen or what's the distance between that location in space-time in that other location those are not invariant those are not real in the sense that not everyone will agree upon them change your frame of motion and you will have a different description of how long something takes place or how much distance there is from one location to another so that is the illusory side of things and Einstein took this further and pushed it to basically saying that the whole demarcation the past present and future which I think everybody holds in their mind right who doesn't think of reality as the things that have happened the things that are happening and the things that will happen I think everybody thinks of reality that way and Einstein was saying it's kind of a mistake to think of it that way because different observers undergoing different motion will have different conceptions of that so there is no universal invariant notion of what is past and what is future what is present so in that sense hanging your hat on them and developing an understanding of reality with that idea is being central as a mistake because all it is is a subjective division that has no universal meaning so I guess is the corporation owned as the university being leaders start setting so the look at the universe of gain with more experiences what we think is next full-time um after my position my from so even these are the most moments aren't actually there might be foundation like recess have some structure well obviously the moments are there but I would consider them to be just these independent moments that constitute reality and they're all just out there every every moment is out there and then all that we do as observers in this reality is each and every one of us organizes those events in a way that makes sense to us so we say oh all of those events those happen at the same moment from my perspective so I'm going to call those at one moment in time and all those events they happened at one moment and put those on one moment of time so we all do this work we we walk into this raw data of all the events and we start to organize them but different individuals who walk into that room of Vence will organize them differently and it's not like one is right and one is wrong it's just a different organizational scheme that is dictated by the laws of special relativity or general relativity so the events and the moments are real but the way in which we group them is totally subjective even though Newton would have called that objective can you give an example yeah sure so you know where we are right so I go like this now from my perspective I hit the table simultaneously with my right hand in my left hand and from your perspective it should be the same thing you should all because they're all in the same frame of reference right now but you know if you get up and start to walk and you carefully do your measurement you would not agree that they happen at the same moment in time you would say what happened was and it's not a question of sort of the light travel toward the sound travel then I'm not talking in sort of that level of silliness right we all know you go to the baseball game look at the guy on plate hits the ball and like you see it me and then you hear it you don't think all those happen to two different moments like you you process it you're like oh the sound took longer to reach me and the light you undo all that no yes of course those moments happen together you know the sound of the light emitted the same oh I'm going something far deeper your understanding of what happened will be different you'll put them on different moments of time because your clocks and our clocks will fall out of sync when you engage in motion to us there's like a little simple example of course the world we organize the world based upon what things happen at a given moment and your organization and my organization will agree if we're not moving relative to each other but some of the movement will have a different notion of what happens at the same time so in your note the special and throughout give books you talk about the smallest idea that we have in them and you break it down to the articles and works there streams and so it just kind of seems like this flow of getting smaller yeah so the strings vibrate in different dimensions yeah I feel like the strings have to be in something another in quarks but like I've heard quantum foam is an idea or like how small well nobody knows and and again we don't even know if the string 'party that story is true the only one that we really have confidence in they are the electrons and the corpse and a variety of other particles that are very similar to those that we don't talk about quite as much like the muon in the Tau and then but they're all basically electrons and quarks fancier names and we don't know what goes further but the theory suggests that there may be these strings inside of those particles and then there are people who have suggest that maybe strings have finer constituents to so people have studied that possibility and it's something that people do look at and where would it stop now one possibility is that it simply stops with Springs and that's the last time that you can ask what is it made out of that there isn't a finer ingredient to talk about but a that assumes that string theories right and be it assumes that string theory you know is the deepest fundamental explanation neither of those are points that we know to be true when you talk about quantum foam that's actually looking at the nature of space itself space-time region and asking is is space-time in some sense made of something as opposed to being a fundamental idea that you just assume is there and everything inhabits it you don't worry about its fundamental makeup but you may need to worry about its fundamental makeup it could be that space-time itself is made of finer constituents may be strings I don't know or maybe some other idea that we haven't yet gotten to or this whole collection if people I'm something well loop quantum gravity and they think of space-time as it kind of the color spin foam so so there you're at the edge of understanding here we don't even know if it's the right question to ask but if it is the right question to ask then the interesting thing is what's the answer what are the ingredients of space-time and uh and we don't know last shot you devote this one is in theory talking about zero grains and how students are possibly labeled those and I'm just wondering how can some finish having zero dimension cysts make up something in particular that energy that it contributes this string well yes yeah so you know even the in the conventional description of particles that comes to us from quantum mechanics subsequent quantum field theory in that description you do envision particles being located at individual points not sort of a collection of points which would get a little sphere really had a little location so already there you sort of run into a little bit of this conundrum and what does it mean for a particle to to be at a point and usually the least way we think about it intuitively is that even if the particle is a point it's kind of surrounded by a fog associated same with its electric charge there's an electric field around it and that electric field has photons associated with it and sort of this crowd of particles surrounding the basic particle itself but it's it's it's hard to grasp and generally we envision that when you fully include quantum theory into these stores there's a certain kind of fuzziness along those lines it's always there and that's where you can have an image that's somewhat closer to something that seems sensible but yes in in the mathematical description we do sometimes envision things as having no size or no thickness or no length so I guess how can something with those properties make up something well you know take this table for example right this table looks like it's a 3-dimensional chunk right but even without the exotic ideas of say string theory if you look into this table you know that you get two molecules you get two atoms and then you've got the atoms which themselves are little tiny electrons going around the nucleus of the tiny part now now we often say the atom has size why does it have size because you got an electron in some cloud like orbit around the nucleus and there's empty space between them although there's fields that are being exchanged particles being exchanged between the nucleus and the electron itself so even though the particles might be little dots in the conventional description there's still a thing called the atom by virtue of the way the particles are talking to each other and combining with each other and hanging around near each other so there you've got it so you've got this thing whatever it is 10 to Mai's 10 heaters typically for the size of an atom even though in the conventional quantum description the ingredients are little tiny dot particles so sometimes I think a good way to think about is in terms of the the electric fields or the other fields nuclear field to think of electric for now the electric field that these objects produce emanate are what give them more of a tangible structure compared to the dot light description in the mathematics does that help the country not really that's normal just like trying to picture that so if you take like taking a bunch of lies on paper right we're talking about right the line that so say two dimensionally to make it easier yeah the papers on the table I brought it has this whatever it might we'll call it and then it has height tubes a pencil draw but it doesn't have depth yeah up and down so you can stack it to me it seems infinity of those one can on top of each other and you never get any of a third dimension yet that's why I have these particles 0 graves contains 0 dimensions how you combine them yes it's usually a question of the mathematical conception of stacking compared to the physical reality of how these ingredients talk to each other so a concrete example is you may be familiar with say the Pauli exclusion principle is out of the earlier idea in quantum mechanics so that's a nice idea in this context because that tells us that at least for certain classes of particles you can't actually push them all together on top of each other because that would be putting them all in exactly the same state and the equations don't allow that to happen and because of that when you try to mush them all on top of each other they actually spread out because of that mathematical restriction so there you sort of see it the laws of physics at work how that process differs from the mathematical one of either drawing a lot of dots in one spot or a lot of lines on top of each other so that's the way in which sort of quantum mechanics helps to spread out the world in a way that's closer to what we experience and one question just about the nature estranged themselves I've taken acoustics and whenever you model like standing wave on the string you break that string out of the little tiny masses is there any way that we can feasibly do that strings I couldn't go deeper than the string itself in principle yes so so it's sort of related to as you're saying related the other question you know people have envisioned that strings could sort of be a kind of necklace like structure of more fine entities whose analog in the classical mechanics of strings that you're talking about would be the little mass elements of along a length DX along this journey so yes is that possible it is is that right I don't know I don't know string theories it is right but it is something that people study for sure so in this room we have a number of senior physics majors who are heading off into their careers on many different paths and I'm just curious what advice would you give to someone at this beginning phase of their career in science well it sort of depends on what what kind of beginning that you're talking about so it's funny just before I came here I got an email which is not an unfamiliar one where some kids somewhere wrote you know read your book and love these ideas I'm the I'm not doing that well in school in my classes but you know I thought I really just love these ideas is what I want to do and you know and the answer is is you know great deal of it really excited love it is get to work do well in your because you've got to learn all the basic stuff if you're ever going to go forward in and you know that that story's going to recapitulate so many times now have people come to my classes you know in the first day I have like hundreds of students in the class and by like the third day I'm down onto a sense remember why they kind of all thought that it was just going to be the ideas and that's okay if you're in if you're not trying to actually go forward in the actual physics research but if you are going for the physics research you have to really engage at a much deeper level than in say Faculty of the cosmos or the open universe so so my first piece of advice to anybody actually wants to do this stuff is get excited by the ideas but recognize that it's hard work and you really have to do that work if you if you want to be involved in that way but there's also the flip side it's it's tremendous just to spend time in your life regardless of what you're doing struggling with the ideas and then forget about the math just try to get the ideas as deep as you can and that's something I try to communicate not just through books so you know you know the programs that I've done try to get things in out that way right now Frank I've been spending more of my time developing theatrical words it's has it's a bit of a strong word Naspers but works that are somewhere in between lecture and theater that allows an audience again who doesn't technical background to not just hear these ideas put forward in a way that I will do later today which is just me talking about these ideas and hopefully it'll be somewhat interesting maybe even entertaining I don't know but it is still just the ideas whereas there are other formats that can communicate the drama of scientific discovery in a more effective way and and and I think that's another side of the story so I think there are many ways these ideas can play a part in how one lives their lives but getting back to the project if you actually want to be involved in pushing the frontiers you have to engage with the man and there's no something going to jump into string theory before quantum mechanics and quantum field theory and general relativity and complex analysis and differential equations and all that good stuff because you need it all to be able to make progress um did you explain a little bit more about this theatrical stuttering or motion because I'm a physics major from also a theatre oh that rabbit rillette I know there was such a thing yeah well so a a couple of years ago I was involved in a piece that was called spooky action drama quantum mechanics and it was a 90-minute program in which I in some sense played the role of narrator in the piece and the goal was to take an audience and knew nothing about quantum mechanics and take them through basically what you've read in fact with cosmos all that stuff entanglement and even Bell's Theorem which you may recall was in if you if you had the courage to read those sections of the book and but I wouldn't do it alone on stage I did it with three actors who spoke words that were completely taken from the historical record those were the words of Einstein Bohr and Heisenberg Schrodinger and Pauli and Freeman Dyson and all these folks and they didn't try to embody those words in any realistic portrayal which I find ultimately off-putting and cheesy so there is no person with Einstein hair up there so you know as a woman who is playing Einstein and completely crossed catch him an Indian fellow who is playing boar so there's no opportunity for an audience to say no if that person looks right that was not part of it but all the words were taken from the record and what it did was it allowed an audience to get the ideas but feel what it was like to discover these ideas to feel what it was like to be Heisenberg walking in a park in Germany in the middle of the night muttering to himself could reality possibly be as absurd as she appears these quantum mechanical experiments and feeling like the world was collapsing around him because the solid foundation of classical physics was disappearing and when an audience can kind of go along for that journey it does two things one it just makes science so much more of a human experience as opposed to just these hard ideas that make your head hurt but what it also does is it gives the audience a sense of relief because as they're struggling to understand the ideas so is Einstein so it is Bohr so is Heisenberg and therefore you feel okay about how difficult it is to grasp what's going on and that experience I think is a strong one and being part of that has encouraged me in Sparta so we're doing another one this year on the general theory of relativity it's the hundredth anniversary general here so we're doing another kind of lecture if the after I know what the right word is somewhere in that gray space between the two so that'll be in May in New York that will again take some approach to general food this is kind of a guess a little bit of a darker side of it but you talk about Eisenberg and kind of having his world kind of collapse around and I was wondering is there I guess in the kind of work that you've been doing and kind of like in a near-future physics is there anything that you fear I guess about like the consequences of some of the science or just kind of been possible meanings of the universe or what the universe could have underlying principles in well if you're talking about things like applications of these ideas that be unpleasant know I don't really fear anything like that that could sort of welcoming because these ideas are so divorced from any application I don't care what it is if I go forward but if you're talking more at the level of the kind of reality these ideas suggest might be out there is that is that at all frightening and yeah if you actually really take these ideas too hard I think they portray a universe that's quite indifferent to human existence and that's a hard idea for many people to swallow but it's almost certainly true it's almost certainly true that these little creatures walking around on this totally nondescript rocky object that's orbiting this completely ordinary star that's sitting in the suburbs of a completely ordinary galaxy which is itself one of into billions of galaxies out there are you kidding me the universe cares about us that's absurd and if you take that idea to heart it is a frightening place we find ourselves in I mean we are in this vast universe and we are all alone yet there may be other life out there doesn't matter we are all alone in the most profound sense if you take that in yeah is it frightening it is on the other hand if you flip it around and you say how amazing is it that these lonely little creatures have able to figure out so much of the universe right I mean we've got the series that allow us to peer back to a fraction of a second act to the beginning allow us to roll the film forward and look eons into the future we can make predictions about electrons that are accurate to ten decimal places that's cause for the most enormous celebration so it kind of both sides of the corner so that's actually five o'clock that's our time good time Lee I think we'd all like to thank Brian for coming and spending some of his afternoon with us here with the weather that would all just be a bank but I'm looking forward to the talk that's coming up this evening I hope everyone else is going to be there as well and just leave you with some of these balls and stuffing through the rest of okay thank you guitar Amiga

Channel: Rhodes College

Views: 28,397

Rating: 4.8697677 out of 5

Keywords: Brian Greene, Rhodes College, Communities in Conversation

Id: LQ89Br6aoh0

Length: 89min 13sec (5353 seconds)

Published: Wed Apr 08 2015