What We Cannot Know - with Marcus du Sautoy

[Music] and she always makes me laugh when I hear that introduction and I'm introduced as the professor for the public understanding of science because I think everyone expects that I I must know the whole of science and Here I am to explain it to the Royal Institution and it's only when I took over this job a lot of journalists really did expect that I knew it all and I would get phone calls from journalists just asking me to explain every bit of science out there and I remember one particular occasion we just had the Nobel Prizes announce over the last week and I remember the Nobel Prize for medicine adjust screen announced and this journalist phoned me up and said yes just been announced for the discovery of telomeres could you tell me what a telomere is and I thought well I'm afraid biology is not my strong point um so I'm very biased to admit that I was in fact in front of my laptop at the time and I quickly pulled up the Wikipedia page for telomeres and then read very quickly and confidently told the journalist yes there the piece at the end of DNA which controls how long the DNA will last and they generally seem quite happy but um but I realized at that point so well this is crazy you know I can't be expected to to know it all um actually you know who was the last scientist that probably did know all the science that was around at the time I mean maybe Newton or Galileo but certainly Newton the explosion of science I happened post Newton means that probably after that there wasn't a scientists that really could say that they knew all the science that was known at the time but it sort of got me thinking actually about the question of whether what could science know it all not one scientist but could there come a point where where science might know it all or might there be questions that by their very nature will always be beyond the power of science to know so that's what I've been honoured cut journey for the last three years trying to articulate whether there are any questions that by their nature might be beyond the ability of science to be able to to answer them so that this is what want to tell you a little bit about this three year journey I've been on culminating this in this book what we cannot know I think that kind of expectation that science might know it all is it's partly fueled by the fact that every time you open the newspaper there seems to be another extraordinary discovery that we've made and and certainly since I took over this job the sort of things that we have discovered absolutely extraordinary we landed a spaceship the size of a washing machine on the side of a comet we managed to create robots which have made their own language their communicating with each other and we actually don't know what this language is machine learning is given the power to create their own language we've got to interact with these robots to understand what it is they're talking about we've sequenced the DNA of a fifty thousand year old cave girl and we started to use stem cells to to repair the pancreas of diabetic patients so so it is kind of extraordinary just how much we know and I think it's given us that expectation that well yeah maybe science might come to a point where we can answer all the big questions about the universe and I think that desire to know is incredibly basic in us I think it's almost as basic as the desire to reproduce it it's sort of what has helped us in our evolutionary survival and actually I start the book with a quote from Aristotle from metaphysics he declares that the opening of the book everyone by nature desires to know but I think it's probably very dangerous at any point in history to declare well we're never going to be able to answer this because it's quite difficult to know what it is that's just going to be round the corner I mean when is there going to be a new Einstein which completely revolutionizes our kind of perspective on the universe so I kept a few stories in mind just to as a warning to me about declaring that this is a question we will never be able to answer one of my favorites was Auguste Comte who in the in 1835 very confidently declared we shall never be able to study by any methods the chemical composition of stars and you know seems a very fair comment we still haven't visited a star dug a bit out of it and being able to chemically analyze it of course what Auguste can't hadn't reckoned on was actually although we haven't visited a star every night the star visits us so the light from the star several decades later scientists are able to analyze and we have a very complete description of what stars are made out of so I kept this as a kind of little warning story to me that to declare that something cannot be known is like a red rag to most scientists so of course you know I'm not the first to kind of consider questions of unknowns I'm one of our famous 21st century philosophers Donald Rumsfeld very famously summed up states of knowledge in this very cryptic answer that he gave to questions about weapons of mass destruction in Iraq he declared there are known knowns there are the things that we know that we know we also know that there are known unknowns that is to say we know there are some things we do not know what but there are also unknown unknowns those are the ones we don't know we don't know and he got given the foot in the mouth award by the plain English speaking Society for this this response which i think is actually really unfair because I think this is a fantastic description of different states of knowledge the know knows the things that sir we have discovered and in fact the book is very much about the things we know and how we known them and how they've changed how our view of the universe has changed so so this is very much a book trying to understand how we know the things that we do know the unknown unknowns well they're very exciting are the things I can't tell you about because they are unknown they're a bit like those Black Swan events the things which just come out of nowhere and completely change your perspective on on the universe those are exciting things for size but by their nature I cannot tell you about those so I'm after in this book actually trying to pin down the the known unknowns and not the things that will we don't know now we might know are there things that will always remain unknowable actually I think Donald Rumsfeld mr. category here which are the unknown knowns which actually as slab boys yushik pointed out are fairly significant for a politician because they're you're kind of Freudian believes you delusions the things that you deny that you know but actually drive your all your decisions so um maybe he missed one category here so but I'm after these um known unknowns that might remain always unknowable now one of the other motivations for this journey I've been on for the last three years um it is also partly to do with the person that I took over this job from a certain Richard Dawkins who as well as talking a lot about evolutionary biology spent a lot of the latter end of his professorship talking not about science but talking about religion The God Delusion got him into a lot of arguments with various theologians so so I kind of brace myself when I took over this job um for questions not just about telomeres and science but for questions about my religious beliefs so I actually prepared a little of response them because I sort of wanted to put a little bit of distance from that debate and to move back to sort of the public understanding of science so so I actually went journalist would ask me this question I would say actually just declare that I'm a deeply religious man and they were quite shocked by this quite excited and before they got too excited um I went on to explain that my religion is the Arsenal Football Club and every Saturday I go and worship my idols at the Emirates formerly Highbury Stadium every season I reaffirm my faith that this will be the season that we win the premiership when each season my faith seems to be tested at the moment ed Sam do we have any Spurs fans in the audience oh look they're on the front row here well at least we have a very good st. st. tottering um who always ensures that Arsenal are above Tottenham in the Premiership by the end of the season I was a very late arrival by our Saint this year because it was the last day that he actually came and made sure that we we ended up on top so um so that was my religion then as many journalists were happy with that but some were a little bit more persistent and said no come on okay well what what do you are your beliefs um I know especially one Sunday morning on Northern Ireland BBC Radio on a philosophy and religion program so Northern Ireland's a Sunday morning religion isn't too far from people's thoughts and I went I decided to go on this program and I said well I'm very happy to talk about the philosophy of science but I really want to stay clear of the religion questions and journalist seem quite happy and the little light went red and we went live and then he went so Marcus you believe in God oh no that was a dreadful northern act and Island Iced Out I won't do those anymore so you know the agreement went out the window immediately and we were straight into a debate about the existence of God and so we had kind of quite heated to and fro and and at some point I uh you see actually has a mathematician I spend a lot of time proving the existence of things or proving that certain things cannot exist for example Andrew Wiles with Fermat's Last Theorem proved that solutions cannot be found for these equations so actually we've got powerful tools to prove that things exist or they don't but if you're a mathematician you need a very clear definition of what it is you're trying to prove exists or not so I push the journalist so I said okay look I'm prepared to engage my kind of logical mathematical mind on this but I need a very clear definition of what it is you mean by God so the journalist says it how but it's something which transcends definition it's beyond the ability of the human mind to know and either way you've just wiped me out of the game how can we actually engage in wit with that and I sort of went away from the interview feeling a bit frustrated um but I actually sort of worked on me that idea of God as defined as the things we cannot know the things which transcend our understanding and so I began to sort of play without as a as an interesting idea well yeah what what are those things that we will never know what sort of role might they play um actually as a God and actually a few years ago I took part in a debate with the chief rabbi during Jewish Book Week he wrote this wonderful book called science religion the great partnership about how actually science and religion are involved in similar kind of big trying to answer the big questions and in preparation for that debate I actually talked to a philosophy friend of mine at New College in Oxford that's trying to prepare for talking to the chief rabbi and this will also actually referred me to a very interesting theologian Herbert McCabe in flashy a Marxist theologian in Oxford get that quite cool and Marxist theologian he has a lot of kind of strange texts on Christian Christian liturgy and things like that but there was one essay that I read which was very interesting because in it he makes the following statement to assert the existence of God is to claim that there is an unanswered question about the universe now she goes on to say that many religions committed iconic lism as she by giving this quite abstract idea far too many properties that it never should have had and of course that's what we get served up as kids this kind of rather silly version and we reject it quite quickly I certainly did when I came up to my comprehensive school started learning a bit of science and and it just the other thing didn't make sense at all but but maybe we throw too much out with that and maybe there is still something interesting to tease out as kind of firm the the unknowns and of course they were always that God was those unknowns volcanoes or earthquakes or things and but a science has got to know more and more that sort of unknown has got smaller and smaller in fact there's a term the god of the gaps which you may have heard of which actually was a derogatory term created by theologians saying that you know science isn't kind of eliminating God that when to know God's so with a huge rocketry term but partly my mission in this book was just to explore whether - we could reclaim the God of the gaps as actually a positive thing and whether it actually has some value by identifying things that are beyond the science might they have something interesting to say about that idea so I sort of kept that in mind as well on my journey into the unknown to the edges and beyond so the book I divided up into edges I've got seven edges of knowledge that I believe have perhaps potential for questions that might be beyond the world of science so I want to give you a little bit of a guided tour and we're going to depth in a couple of them and I'll show you some of the other challenges and I think are out there as you going to start with the first stage because that's very much at the heart of my own subject of mathematics and this is the challenge or can we know the future before it becomes the present can we predict what's going to happen next and a lot of this want to do that we really need to know in order to be able to plan what's going to happen next and make decisions we would like to have that kind of knowledge so is it possible to know what's going to happen next naturally on my journey to the edges of knowledge I took with me an object in each edge so each edge has a an object associated with it which kind of gives me a useful tool to kind of like tease out this particular challenge so the object I took with me on my journey to the edge of trying to predict the future was an object which I think really sort of captures the idea of the unknowable the unpredictable it's a casino dice so I mean the excitement of a dice is that we don't know what's going to happen when we throw it on the table so this time I got a six am this kind of feeling like Alcorn Chile actually science could no I mean mathematics has a lot of tools to be able to work out what's going to happen as that old hits the table rolls and certainly I thought that maybe um you know the mathematical things I've learned over the years perhaps I could use these to actually cash in and make a lot of money so I went off to Vegas and I went to the craps tables and I decide yeah this isn't just a problem in dynamics I I can analyze this and I try to apply my math to be able to make some predictions about how this falls and I'm poor I lost a lot of money um but they let me keep the casino dice we played with so this is actually the casino dice that I brought back from Vegas um but you know I think you know how unknowable is this and I think it's my hero I guess in this story um it's Isaac Newton because he did give us the tools to to give us that kind of belief that actually we should be able to know what this is going to do next the laws of motion tell us how this is going to fall from my hand what's going to happen when it oh gosh it's CAC well that's kind of unpredictable but um uh-huh as it cascades across the there are I lecture theatres and then the tools of the calculus calculus gives us a mathematical language to be able to analyze a world in flux a changing world to be able to understand how the speed of this as it changed changes so you know Newton gave scientists that believe that maybe yeah if we know the equations we know how the universe is set up then everything is just deterministic it just follows from the mathematics um so Newton gave scientists post Newton that belief that maybe we can know the future before it becomes the present Laplace certainly talked about our have this thing the Laplace is demon we just kind of sense yeah well it just if you know the universe you'll know everything into the future well if Newton is my hero then this guy here is my nemesis in this story this is honorary Poincare Abe who discovered the mathematics of chaos theory at the beginning of the 20th century and he explained how even if you do have the equations and you have a very good description how the thing is set up just a very small error can cause your predictions to be completely untenable and something completely different can happen and this can control just very simple systems which you have the equations for can give rise to incredibly complex behavior and one of my favorite examples is pendulum so actually a pendulum is usually so predictable we use it to keep track of time but this is a slightly different pendulum I've got here it's called a double pendulum so it's got two pieces of metal jointed together a little bit like a leg and so the geometry mathematics of this is very simple to describe these two pieces of metal the physics which controls how this will fall is also not that complicated but being able to use that to predict the behavior of this thing is almost impossible whoa oh look at this and I think the fact that you're laughing is a perfect example of the fact that this is unpredictable laughter observe sponsor whoa I wasn't expecting that to happen but the real challenge of chaos theory that one gray raises okay that was very complex behavior but can I repeat the exact same behavior now see I have a little notch here and I try to start the pendulum off in exactly the same place so let's see whether if you can remember what it did before is it going to do whoa that's already doing something completely different I mean still quite funky but um okay and then it seems to - this is my favorite desktop toy I can play with this for absolutely hours so if you'll indulge me I'm just going to do one more because it's just like okay whoa aah whoa I mean where did that come from unbelievable Oh give it a round of applause so this is the challenge of chaos series actually just automate very complex behavior but being able to repeat that behavior so I've got another desktop toy actually which I have on my desk at home it's again a pendulum but it's got six magnets which attract the pendulum and over each magnet is actually an answer to a question so I use this to make all my decisions in life very so so you can ask it a question so for example should I make a bet on Arsenal beating Swansea on Saturday so we get this going to set this thing going and so the answer so I try again no way definitely maybe yes ask a friend so here's a little one we did in the lab so this is an example of this pendulum I've got just three magnets here but you try and predict which magnet the pendulum is going to end up at I mean it sees wobbled it of all between them all is it going to end up at the top one and then right at last it ends up at the bottom one but it seems incredibly so here we get maybe well that's not good enough so actually it's a challenge I mean this is a bit like an asteroid flying round and the magnets are like planets and you're going to try and decide well which planet is going to get wiped out by this asteroid in fact one crane discovered this chaos theory and when he was trying to understand the solar system to see whether the solar system was stable or not and what he is is definitely great yes it's always right something and he understood that even the solar system trying to predict whether that is stable or not it's incredibly sensitive to just very small changes in that where the the asteroid is so here's some three computer models that I did so of where the pendulum is going to end up so I've colored those three magnets yellow red and blue and I started the pendulums in the top left-hand corner the first experiment the thing wiped out the blue planet but then I changed the sixth decimal place of one of the coordinates of the starting position so you can't even see that it's changed but up but when I then ran the model well it's sort of followed the same path for a while and then completely veered off and did something completely different and that time it wiped out the planet NOW then I change the sixth decimal place again again it's similar sort of trajectory to start with and then wipes out the yellow planet so that very small change causes a massive difference in the outcome and so this is incredibly difficult to predict even though I have the equations and I might have very accurate knowledge about the starting position unless I have complete knowledge I really cannot know what the answers going to be and this computer graphic helps you to try and make a prediction about where the pendulum will end up so if I start the pendulum over a yellow region that means the pendulum is going to end up at the yellow magnet so you can see there are some regions which are knowable I mean if your so the yellow magnet is sitting under that big yellow blob there and sure enough if I start the magnet the pendulum next to the yellow magnets and the other two can't pull it and so it's just going to wobble and then settle on the yellow magnet there's another area to call it sort of opposite the yellow magnet which if I start it there it's again quite predictable a little arrow won't cause it to do anything terribly different or just swing backwards and forwards and eventually the other two magnets can't pull it either side it ends up again at the yellow magnet but I started my pendulum in the top left-hand corner and this is an example of something called a fractal so a fractal of these mathematical geometric shapes which have infinite complexity so as I su min on this area it never simplifies it never suddenly becomes oh now it's all yellow so I know that if I got um any I've got the accuracy up to this point I know it's going to hit the yellow magnet it just keeps on being yellow blue red yellow blue red as i zoom in I try and get more and more accurate still the fiftieth decimal place can tip it over from being yellow to blue so this is a region which says if you're here you really cannot know what is going to happen next but so you got that infinite sensitivity to just a very small change something we call the butterfly effect now of course the trouble is this chaotic dynamics affects so many things we would like to know about the future the weather for example the solar system even population dynamics and and so actually I took with me on my journey to the edge each of these edges and expert in this area somebody who's been at this edge trying to push it ever further so the expert I took actually on my journey to try and predict the future was a colleague of mine in Oxford Bob May who's a mathematical biologist and he was one of the people who understood that population dynamics very fit simple sort of feedback equation which controls the population of animals from one season to another can also have this incredible sensitivity to small changes so I went to go and talk to him about his ideas and actually he's now Lord may I shouldn't call him Bob may Lord may he's a cross-party member of the House of Lords and he's actually working with Andrew Hall Dean at the Bank of England and trying to look now not at population dynamics but at the economy to see whether the economy the equations for the economy is just data and numbers and and and kind of rules to which control how those numbers will evolve they're trying to see whether the banking crisis of 2008 might have been a result of very sort of chaotic motion that would have been very hard to predict so it's actually working with governments trying to explain to them the limitations of being able to know what's going to happen next even if you know that how the theory which controls it and you I went and had lunch with him at the House of Lords and he made this statement to me whilst we were having lunch he said not only in research but in the everyday world of politics and economics we would be better off if more people realized that simple systems do not necessarily possess simple dynamic properties I'm sorry I asked him how he was getting on trying to explain some mathematics of chaos theory to the MPs at Westminster and he said no Marcus I'm mostly interested in their egos here not in mathematics um but then I came back to this dice and I was intrigued well it's the reason that I can't no this dice because the dynamics are chaotic and I got a little bit of surprise I discovered a piece of research have been done just recently by some Polish mathematicians who they've used high-speed cameras to record what the dice is doing as it hits the table and rolls and and they've actually understood that under some circumstances this is much more knowable and might think so actually I colored the faces of the dice different colors and we're going to draw some similar pictures to the one for predicting where the pendulum is going to go which will help us to to know what what arrangement of the dice do I need to make it land say on the red side or the blue side and so here are the pictures that the Polish team created and the interesting one is the top left-hand picture because in this picture the colors are not fractal it's a very clear sort of a signal about where this thing is going to land so what this is measuring on the two axes is so on wax one axis is the height above the table and the other one is the angle at which you launch the dice from your hand and because this picture isn't fractal it means that as you small change isn't gonna alter the side that it's going to fall on so what are the the table that's being described in this particular picture is a craps table which actually is quite soft and um if the dice dissipates a lot of energy when it hits the table so it's kind of like a bit of an old squidgy craps table so you know perhaps a casino that's had seen better days so this is the one that you should go after because it turns out that actually if the dice is losing a lot of energy as it hits the table if it's a soft table then actually this thing is quite predictable and so if you take one thing away from this talk on my book it's the following okay now that more often than not there's a higher probability that when you play on such a table that when you release the dice it will actually land on the face which is down on the palm of your hand when you release it some so it's I wonder whether well let's let's um take yourself let's make a soft craps so oh gosh yes No - I forgot over that well we'll try and I'll try and get dressed in a bit so let's make this kind of soft and let's see whether we can make this work all right so so okay so I'm going to have the six on the bottom so I'm going to try and get a six so I'm going to fall it let this fall out to one husband bit right that's why I chose Matt's you know the proofs make sure these things works but that you know of course it's a probabilistic thing so more than likely so one in six times that works but actually so but as the table gets more and more rigid so the table I got here is a very rigid table and it bounces a lot this is described by the Pratt pictures which are becoming more and more fractal done so it says that on this table again they're very small change that butterfly effect we call it some a very small change can cause it to go from the four to the sixth one and again it says that you cannot know what this dice is going to do next now Vonage is actually very under very classical kind of 19th century ideas of science but some of course in the 20th century we realize that maybe the universe isn't as predictable and deterministic as mutant actually thought and so the next stage I'm going to take you to is the edge which we discovered is beginning of the 20th century there may be actually unknowability is actually at the heart of the way we must do science and this is the science of quantum physics so quantum physics almost has embedded in it the fact that you cannot know and so the object I took with me on my journey to the edge of the quantum was was this pot of uranium which I bought on the internet it's amazing what you can buy on the Internet these days so the interesting thing about this pot of uranium is that on the side it tells me the activity so it tells me that there are a per minute on average there are 984 bits of radiation being kicked off that was probably shouldn't do that they are there 984 bits of radiation being kicked off this uranium per minute but that's on average and what this pot can tell me and in fact what physics at the moment cannot tell us cannot know is when it's going to do that there is no mechanism currently known and it's believed that there is no mechanism it's a fundamental part of the way we do physics that there is no mechanism which will tell me when the radiation is going to kept get kicked off okay on average 984 but when is it going to do it it seems to be totally random we don't seem to be able to and this is at the heart of something you've probably heard of Heisenberg's uncertainty principle Heisenberg's uncertainty principle kind of articulates the what at the fact that we cannot know certain things so Heisenberg's uncertainty principle says that for example if I want to know where an elected ascribe an electron and if I'm trying to do Newtonian physics I need to know where the electron is and how it's moving so I need to know its momentum but Heisenberg's uncertainty principle says well actually you can't know both of those things simultaneously that the more you know about where the electron is the less you can know about how it's moving so this is actually it's not a wishy-washy statement is a very precise mathematical formula actually comes out of the mathematics the formula I've written here is that the the Delta X is the error so that the error is getting smaller and smaller I know more and more about where that electron is to make this equation work the error in the momentum it means the momentum can suddenly have more kind of a whole range of different possible values and if I get to note so you might say oh I know where the electron is now so now I'm going to measure its momentum well as you get to know more about how that thing's moving you suddenly lose knowledge again suddenly the electron could be anywhere as the error gets larger and larger um so if you indulge me up my favorite physics joke is about Heisenberg so Heisenberg is bombing down the motorway in his BMW and the police pull him over a policeman gets Heisenberg out of the car and said to him sir do you know how fast you were going and Heisenberg says no but I know exactly where I was good yeah you're a good audience you see so anyone who's sort of sitting there I don't why were they laughing that wasn't funny you shouldn't have to explain a joke I know but um but the point is you know because he knew exactly where he was it meant it was an uncertainty and about the different values that his speed could have been so it could be in a whole range of different values so here's the follow-up to the joke so the police officer says you were going 200 kilometers per hour noise in burgos dah now we're lost now more people getting that one yet so exactly so because we now know how fast he was going he's lost information about his position there's a third bit to the joke you can ask me any questions well you know the follow-up to that one but um Schrodinger happens to be in the back of the car is that well we'll get but actually a modern physics has a different interpretation about this it actually says well maybe it's kind of our language which is wrong that actually this electron doesn't have a position and a momentum at the same time that's a very sort of old Newtonian classical way of thinking about it actually we should think that this thing doesn't have a position until we observe it so actually we have this thing with a quantum wave function so this kind of tells you the likelihood of finding where the electron is but it actually isn't there doesn't have a position until you make the commitment of observing it and then it collapses into a position and the waves are when if a wave is high it says you're more likely to find it here if it's low it says now you're very unlikely but there is a chance you'll find it there now I find this totally unsatisfactory um it's because you know my feeling is that you do an experiment if you set it up the same way you're going to get the same answer each time this is no you're just not going to know you can set up the same experiment do it over and over again and each time you do it the electron can do something completely different so there's no determinism here there's no mechanism which is going to say when this thing is going where it's going to be now actually this controls the arm it's the same sort of mechanism which is at the heart of explaining the radiation of this uranium so actually I know quite a lot about the momentum of the bound particles inside the nucleus of the uranium which means I know very less about the position the position can be on a whole range of possibilities and when we observe it sometimes that position can be most the times it's still inside but sometimes it can be outside this thing called tunneling and then it radiates and so this kind of undetermined I see is actually at the heart of explaining the radiation but I just cannot believe there isn't something that we haven't found you something that will tell us when it's going to do that I mean is it genuinely something that we can No or is it just that physicists have given up and it's you know this theory works very well so why do we need to bother because it tells us I everything we need to know and I'm not alone in thinking that surely this is actually not genuinely something we don't know it's just that we haven't had the revolution which would give us the mechanism and Einstein was certainly a believer in this being not the final answer he wrote very famously quantum mechanics is very impressive but an inner voice tells me that it is not yet the real thing the theory produces a good deal but it hardly brings us closer to the secret of the old one I am at all events convinced that he does not play dice and he's certainly true that theory is probably one of the most well tested theories that we have on the scientific books it you know to use this theory of probability in quantum physics it's good enough for nearly everything you want to do but surely there's something going on you know inside this uranium which is was controlling when it's going to radiate we now know of course that this mechanism if it exists is a very weird one the idea of entanglement has made us understand that it won't be kind of localized inside the uranium it will be something which actually spans the whole universe which is controlling the the decision about when this is going to radio ate or not but but is there a mechanism maybe there isn't and maybe this is genuinely something we cannot know now I I said that I was going to kind of tease out a little bit of implications of the unknown for the idea of religion and God and so I was quite interested to talk to some scientists who are actually religious and see you know what they how did they marry up their ideas doing science and religion and the person I took on my journey to the edge of the quantum world is actually an interesting scientist it's John Polkinghorne John Polkinghorne the quantum physicists trained with the best trained with Fineman Dirac can ask for better teachers than those too but then halfway through his career he decided he wanted to be ordained as a priest in the Church of England he kind of refers to himself as a kind of like like a vegetarian butcher but I was quite visited because you know for me it was quite remarkable how many of the signs I talked to had some sort of religious belief but but I think there are two sort of religious scientists and there are the Deus --tz-- and the theists the Deus --ts are those who say for example you know one of the big unknowns is well where did all of this stuff come from what what created all of this sinners table this dies the the pendulum where did it all come from and many scientists were we just do not know the answer to that we don't know the answer to that and some people will call the answer to that that unknown I don't know the answer and I'm just going to call that the God which created in and we might find out more about what that God is but that's what I'm calling God and now I'm a scientist and I do my science and I don't think this thing acts in the world and changes it though so those are the days and I think probably Einstein when he talks about God is thinking more about that kind of idea of the unknown but Polkinghorne is a slightly more interesting because he's a theist these are people who believe that their God actually acts in the world and transforms in changes in that maybe you can actually help influence this God to change the world and so I was interested to talk to him about well okay you're a scientist how is your science actually working to actually have and some sort of action in the world and I wondered as a quantum physicist whether he might see that sort of unknown of quantum physics as a as a window of opportunity for an external force to actually make some action because if actually within the system we can never know where the electron is going to be um then maybe that's an opportunity for something external to be going okay well now I'm gonna put the electron there and because chaos theory actually means that a very small change can have a big outcome maybe actually where the electron will go can cause quite a big effect on the outcome but poking on didn't go for quantum physics um he said well no that still depends on an observer you see you have to observe the setting in order for the wavefunction to collapse and he didn't believe that sort of God would be waiting for his God would be waiting for observations to happen and he actually chose chaos theory has his little kind of window the unknown for his God act in the world so he believes that as humans we can never know how a system is completely set up so they'll always kind of be decimal places which are unknown where you can actually start to tinker with things and actually have an effect on the system you don't have to affect things like conservation of energy that is still possible to move the system conserve energy and he believes that that might be a place for his God to act in the world interestingly this is not a new idea Newton himself also very religious scientists also believed that there was in the decimals that his God could actually change and affect the world and he had a big fight with Leibniz um you have many fights with live minutes over the calculus and things like that but one of his fights Leibniz said well I don't get it why wouldn't God have set up the system to be so perfect in the first go I mean it why does he need to serve interact or he or she or it need to interact with the things so so it's interesting that it's not a kind of new idea to use the ideas of those small changes can have big effects but for me one of the interesting things is that quantum physics actually might give us an answer to one of those big unknowns which i think is responsible for many people being religious which is where did all of this Stumpf stuff come from I mean for example my part of uranium where did that come from well well I bought it on Amazon actually is um it's amazing you know you can write reviews underneath so some of the reviews are amazing look there one guy said so glad I don't have to buy this from Libyans in parking lots of the Mau anymore as it is though it's one who's complaining so I've had this for four billion years and it's half full yeah I see I I love your order you get the half-life jokes but no where where did this come come from okay well it came from a mine Ultima somebody dug it up from a mine but okay but where did the uranium come from in the mine well we now know that that uranium had to be created inside a supernova crashing all of these particles together to fuse them into this very heavy atom but then where did all of those electrons the protons and the neutrons come which slammed together well you know if you work it back then you're back to the Big Bang and you're like well yeah so where did it where did one of these particles come from what it's possible that quantum physics might have an answer because Heisenberg's uncertainty principle swill applies to different sorts of measurements I've told you the one about position and momentum but there are other things which are bound together in a kind of uncertainty principle and the other two that are interesting in this case are energy and time so it means actually that it's not possible to have a true vacuum because remember energy equals mc-squared so energy is actually equivalent to mass so if you if you actually narrow the window of time it means there's an uncertainty in the energy because of this uncertainty principle so it means that you can never have a region of space which is truly a vacuum because in each a very small window of time that can't be set to zero the energy because they're there has been an uncertainty there so sometimes the energy can have a positive value which can give rise to particles and so it's a little bit I think here the equation 0 equals 1 plus minus 1 so the zero sort of sunny turns into a particle and an antiparticle was very often just an oily to each other and it goes back to the zero state but sometimes those can separate and so you can get something out of nothing and she this is at the heart of Hawking's discovery of radiation from a black hole that's actually on the event horizon of a black hole you can get these quantum fluctuations happening such that a particle forms on one side and an antiparticle on the other and then they can't actually get to each other particle emits the anti particle starts to degrade the black hole and it's a way that black holes can actually sort of start to sort of seep away the rate is so small that at the moment we haven't observed it which is why he hasn't won the Nobel Prize yet but once is an observation made of it that that will probably follow so so it's the same principle about why black holes are actually berm radiating so but you know actually think about it ok still empty space isn't nothing there's really nothing where do the empty space come from it's a three dimensional space or maybe an 11 dimensional space so where did that come from these still grants are that yeah ok once you've got space it might have fluctuations which give rise to particles but now sort of our ideas of quantum gravity are beginning to give us even the possibility that fluctuations in quantum gravity can give us space out of genuinely nothing so it's interesting that quantum physics might be a way to answer one of the really big unknowns which causes a lot of thing people I think to to have to create a creator and so that was a little exploration into the edges of the unknown of quantum physics um so I give you a little a wizzy guided tour how we doing got 10 minutes left good ok so we've got to do five are great unknowns in ten minutes oh my god Wow that's set myself a challenge and so one of the things I was intrigued in is working what is what is the uranium made out of because uranium ok so I've mentioned electrons protons and neutrons so but actually the the electrons we believe are indivisible but what about the protons and neutrons so at one point we thought atoms were kind of indivisible with then they pulled apart into these electrons protons and neutrons and then the protons and neutrons we discovered are not indivisible they pulled apart and we now know there are quarks at the heart of those and that we think is the kind of on the indivisible bits which build all of matter but that's our generation and as my book so illustrate I go through near the history of science and we just see each new generation has a different story about the next layer down so how can I ever know actually that I've hit the last layer well how do I know that there won't be another the quartz will come apply into something else and those will come apart into something else so can I ever know that I've hit the last layer is that's actually an unknown because maybe it's Turtles all the way down you know so so the unknown of the race small and also the very big what about the universe um is the universe infinite if it is is that something we could ever know um we we've can explore the universe but actually Einstein has given us a kind of a limit on what we can actually see about our universe so I mean take it into here and there's a kind of cosmic horizon surrounding the US beyond which we cannot actually know anything because information travels at the speed of light the universe means going for 13.8 billion years that means actually we can only have received a finite amount of information coming into us um then at that bubble beyond that no information could have reached us we can't know anything about beyond that bubble now that bubble is growing so it's sort of seeing more and more but will only ever see a finite bit so how we ever know it's infinite but not only that it turns out the universe is accelerating in its expansion it's actually pushing things over our cosmic horizons so as time goes on we're actually seeing less we're going to get to a point where actually all the galaxies are pushed over the horizon we'll come back to a very ancient kind of view of our universe that we are just one galaxy in a massive void so so I think that's a kind of challenge could we ever know that the universe is infinite if it is so that was the the very big I think one of the other great unknowns is time the question of what happened before the Big Bang we ever know that it's a singularity we can't know the maths denies us access to time before the Big Bang will time go on forever or does it have an end it turns out it seems like and don't find time is actually finite um now I used to buy grew up with the belief that you can't ask what's before the Big Bang but there are kind of rumbles in the cosmological corridors that actually maybe we can enter to answer that one we can talk about what happened before the Big Bang so time is still one of the big mysteries I asked you the last edge I talked about is my own area of mathematics which is actually partly an inspiration for this whole book because in my area of mathematics we actually have a proof of the limitations of our tools it's something called girdle's incompleteness theorem which says that there are true statements about mathematics which you cannot prove are true within your system of mathematics so actually we've been able to prove there are things which are true which we cannot prove are true which is amazing so you know so that that was partly my inspiration but I think the penultimate edge why I've got five minutes to tell you whether there's some which i think is a really interesting one because it goes to the heart of who we are and this is the question of the hard problem of consciousness um what is it that makes us have a sense of ourselves inside our bodies is that something we can ever know now actually the object I took yeah I mean I think the real challenge vikram Stein kind of summed it up and consciousness is a little bit like we've all got this box and inside it there's something we've all caught a Beatle but nobody can look it out in anybody else's box and so we don't know whether your Beatle is anything like my Beatle um and this is a real challenge you know I you're you're all conscious I hope I mean some of you looking a little bit dazed by that arms um but you know I assume you're all conscious yeah this kind of idea of homogeneity you're all quite like me so I assume your consciousness is quite like mine but how can actually know that now how can I actually be sure that tonight you haven't all sent your avatars along to this lecture and in fact you're all at home sort of catching up on pull dark or something and and and in fact there isn't it you know doing a very good impression of a conscious being but how can I actually know that there's anything going on and I think this is the real challenge um uh uh you know I've actually understanding firstly what it is what is it about putting electrons and protons and neutrons together which gives a sense of self then secondly how can I ever know that somebody else has them as I said I think you're all fairly similar to me but but what about my iPhone I mean where is my phone so the actually the object I took with me on my journey to the edge of consciousness was an app that I downloaded on my iPhone and it's what it does it's a chatbot app so I I talk to it and it talks back to me and and it kind of tries to be human it's trying to pass the Turing test and I'm not maybe it is maybe there's somebody on the other end of the line actually typing these things in and and that's the kind of challenge how can I know whether that's conscious or or not maybe remember their granny who has always put very polite words in Google because she assumed that somebody was actually answering these questions so please could you tell me the so but I think the real challenge of consciousness and the challenge at this the heart of this edge is actually well how could I ever know that this has become conscious how can I know that the the the activity outside there's actually got a sense of self you know it's a need Sonny declares iPhone think there for iPhone am you know should we oh my gosh well you know I met a not switch it off tonight I mean so I think that the challenge of consciousness is potentially one which by its very nature may be is protected because I can't ever feel what it like it's like to be you we all call this a red dice but is your sense of red anything like mine than pain if you stub your toe it's that pain anything like mine how can we actually quantify what it feels like to me you we certainly got to a very exciting stage aware you know it's a bit like being Galileo with a telescope suddenly the universe was opened up to him we do have telescopes into the mind we can actually see the activity of the mind at work and when it's asleep and those tools have given us many things that we can tease out about consciousness and it's interesting you mentioned Francis Crick because some Francis Crick after doing DNA consciousness was something no scientists go anywhere near was regarded as something that you couldn't know it was the domain of the philosophers and the theologians but Francis Crick said no actually maybe we can know much more about this and the person I took on my journey to the edge of consciousness was actually this guy here Christophe Kok who worked with Francis Crick right at the beginning of his work on consciousness when it was a very unfriendly thing to do but the kind of insights we've got a beginning to give us some sort of idea of what it is about the network in the brain which might actually answer the question of consciousness um but actually so I've met Christoph many times in America I've had him over to Oxford to give talks and but I my last interaction with him we had a Skype call together where I kind of really pushed him okay you know might know all of these correlates of consciousness but can you ever really know that something is conscious and and maybe that isn't unanswerable he got very angry with me and he's kind of shouting down the Skype call I assumed it was him maybe as an avatar that he uses to I'm but he said what sort of research program is it Markus where you throw up your hands and say forget about it I can't understand it ever it's hopeless that's defeatism and I think actually it's the mindset of the scientist and it's an important mindset that we go into every challenge actually thinking there is nothing we cannot know thank you you have a distinction between something that doesn't exist and something we don't know

Channel: The Royal Institution

Views: 319,984

Rating: 4.6130776 out of 5

Keywords: Ri, Royal Institution, science, limits of science, marcus du sautoy, mathematics, math, physics, lecture

Id: reeU09R4TIA

Length: 51min 37sec (3097 seconds)

Published: Wed Jan 04 2017