Lisa Randall: Knocking on Heaven's Door – Great Teachers

good evening thank you all for coming and it’s a pleasure to be here as I actually was an undergraduate at Harvard and think of this theater as the place these get to see all the great old movies so it’s really kind of fun to be on this side of the stage as well in fact I felt entitled because I do actually quote class of monka in my book because what I’m talking about creativity because I talk about creativity being in part about asking small questions and big questions at the same time and I refer to these three people don’t amount to more than a hell of a hill of beans and I think well they’re the reason I’m watching the movie so I think these small details are what we focus on when we’re doing science but it illuminates some of the big questions that we have out there them I’m also aware as being here though that I’m going to give a talk it will have some technical aspects to it and some less technical aspects to it in fact when I gave this talk in London the person who introduced me at the end said well the book is really understandable in fact somewhat more than the top so but but there’s a lot of exciting ideas so I just want to give an overview both of the physics and sort of some of the underlying ideas and there’s only so much you can do in an hour and I do more than we should so but there will be questions at the end so feel free to ask okay so I’m going to start with a quote from singer/songwriter Suzanne Vega which i think is really nice because it expresses both what we’re doing in science and also what we do in particle physics which is my field of expertise theoretical particle physics and the quote is and what’s so small to you is so large to me if it’s the last thing I do I’ll make you see and I like it because it both expresses the idea of what I just said in science we’re often focusing on small questions but we have but with with the hopes or with the understanding that a lot of the times it’s these small approachable questions that can illuminate big ideas under Big Ideas we all know what the big questions are at some level but the question is how you make progress and it’s often those small crafts that are ignored by some people that will sometimes shed light and give us really new insights but of course I’m also going to be talking about the world of elementary particle physics what underlies matter that scales much smaller that far far smaller than anything you can see with the naked eye and of course I also think that it’s a big deal what’s there so the quote I’ll also take to refer to that the next slide is also kind of unusual beginning you might say why is it doing that what’s it doing there and you’ll find out in a minute so it’s a slide someone sent me you might recognize the city from the Eiffel Tower in the background and the kiosk was in a fish on it big boulevards so you can tell it’s Paris what do I want you to notice here well once you notice is how much our vision is is a function of the scale at which we’re looking with which we look at things of course if we had very very close resolution very accurate resolution we would see something that looks very different from that picture of the Eiffel Tower we’d see that in the iron grid work and of course if we looked even closer we would see the atomic structure that underlies that so we would see something very different if we looked with very high resolution at a very small scale than the scale with which we dispute that Eiffel Tower from afar but of course what’s really relevant for what we’re doing science as well is that if a resolution was to pour in some sense that the scale is too big we wouldn’t even really know the Eiffel Tower was there in the first place and it’s such an obvious fact about the way we view the world but it’s also critical to what we’re doing when we’re doing science how we how we look at things what resolution we have is critical to telling us what we will be able to see and what it is we’re going to find out and so the theme of scale as we’ll see is important in sort of understanding the role of the kind of physics I to which is extreme distances both the extreme small distances and extremely large distances but the real reason that I wanted to show that picture was because if you blow up the poster you see my name so what I will eventually get you in this talk is how my name ended up on in a fish in near the Eiffel Tower in Paris okay but I’m going to start by talking about scale and if we um just sit back for a min and we think about what we see I mean a lot of the time one of the

reasons I wrote this book I’ve written one other book before or passages which was about extra dimensions of space and particle physics and even people who are extremely interested in the topic I think are often confused about the reality of it and how it how it compares or how it fits into the world we have in our daily lives so I think this scale is a very important concept by which to understand what’s going on and in particular it’s very important to recognize that our intuition is shaped by our vision by what we see in our daily lives and if you think about it our vision is fairly limited we see basically with a naked eye you know scales ranging from maybe millimeter to kilometer we in fact optical wavelengths are a few hundred nanometers that means that if you had something smaller than that scale there’s no way you can resolve it with visible light it would be as if I took a blanket and put it over this room and asked where any one of you was sitting you need the resolution on a scale of a seat to be able to find any particular person and in the same way you need a wavelength that’s small enough that it can identify some small object in order to be able to isolate anything on a small scale so that tells us right away that if we’re going to understand the universe on very small scales we’re going to have to do something that seems fairly unintuitive to us at first we’re going to have to use technology to get two scales beyond the scales that we see in our daily lives so before continue the rest of the talk I thought it’d be a good idea to just take a very brief tour of these scales both the large scales and the small scales to get an idea of where everything fits together in terms of the sizes that are involved so we’ll first start with large scales talking about large scales and keep in mind that this get a human scale the scale we’re familiar with is about a meter um each of us is roughly two meters tall there might be variation by as much as 15% which seems huge but basically we’re all about the same size for all a meter to a couple two or three meters tall but the universe of course spends a much much broader range of scales and in fact the known universe is 10 to the 27th meters across that’s one with 27 zeros that’s huge huge number and why do I say the known universe well because that’s because the speed of light is finite and the universe that we know has existed a finite amount of time which means that the known visible universe has a finite size of course that doesn’t mean that the universe as a whole can’t be infinite or much bigger it just means that we will not make observations beyond that scale that is the scale of what we can make observations about and it’s an enormous scale much much bigger than human scale of course now within that universe of course there are many different size scales there’s a huge span galaxies of 10 to the 20th meters solar system 10 to the 13th meters the earth itself ten to the seventh meters but one thing to notice about this is that this even though we’re spanning on 27 orders of magnitude the laws of physics that apply are the same we’ll use the same laws of gravity the same laws of electromagnetism to put together what’s out there and how it functions that should be contrasted with small scales so now let’s go for away from the larger scales bigger than human size to smaller scales smaller than human size so we now have the human at the top a couple of meters tall and now we’re going to go inside and see what underlies this human scale and one thing that’s interesting is although we you know think of physics is very far in some time but even with biology until we actually had the tools to open living beings up and look inside people didn’t know what was there once they could of course they could then once you could look under a microscope you could see red blood blood cells once you could cut people open you can see the circulatory system no one knew about the circulatory system until you can cut animals or people open and see veins and arteries and try to figure out how it all worked and of course sales cells you needed a microscope to see DNA you need the x-ray diffraction so you needed tools to be able to get inside to be able to see what’s there and that is generally the story in the advancement of science we have scales that we can see in art that we’re familiar with that we’ve seen before but to go beyond that we often need to develop new tools that allow us to see what lies beyond and of course in the world of physics that happened with with a revolutionary way when people

were able to look at the scale of an atom once they could look at the scale of an atom they could see that the look laws of physics themselves the way we formulated physics changed dramatically we went from classical to a quantum mechanical description which is really quite different in its very formulation even the kinds of questions that you ask are different and then once you go inside that atom you see even though atom some people weigh I mean I personally find it amazing that atoms were really not known until the turn out of the last century but the previous century so they’re pretty recently known of course people say we’ll the Greeks postulated atoms and they did but they postulated unchanging indivisible objects whereas atoms were actually discovered experimentally because they change and because they’re divisible because they admit there’s a spectrum associated with them and because they could identify the structure inside them the nucleus with electrons going around and the point is that the atom itself is not fundamental it too has in turn structure and that internal structure is a nucleus with electrons going around it and that nucleus itself is also not fundamental there are more elementary objects called quarks bound together through the strong nuclear force so right now really as we speak the experiments running or exploring a very tiny scale the scale 10 to the minus 19 meters it’s the scale where the machine called the Large Hadron Collider is running the Lourdes Hadron Collider the LHC is a machine near Geneva at the French Swiss border it’s 27 kilometers in circumference and protons get accelerated around this ring they go around 11,000 times a second every time they go around they get accelerated a little more and then the protons collide together an enormous lehigh energy and when they do that they will be able to study both higher energies than have ever been studied before and smaller distances this distance scale of 10 to the minus 19 meters so it is the modern-day microscope it is the scale at which we’re exploring today and I’ll give you a somewhat of a flavor of what it is that we hope to discover there but since we have this scale let me just say that if we continue down there are theoretical questions about even smaller distances distances smaller than any scale that we can hope to explore with any machine existing today or any technological tool when you get to a small enough scale 10 to the minus 35 meters the world of quantum mechanics is taken over by a world of what’s called quantum gravity a theory that will combine together quantum mechanics and gravity string theory of being the best candidate and I’ll come back to talking about that for a few minutes later but one thing I want you to notice about this tour as opposed to the tour of the large scales is that really we have different physical laws that become relevant at different scales and one of the things that I find people get confused about is what that means are we really just replacing the old laws of physics or are the old laws of approximation of the new ones which is actually the case so I want to spend a little bit of time talking about how we organize this information because it’s a lot of information over a lot of scales so like I said what’s most striking at least to me about this is that that’s an enormous range of scales that we have there sixty two orders of magnitude so we want to have a theoretical tool for organizing all this information and there’s a notion that we have called effective theories where we keep track only of the effective quantities relevant for observations and don’t get caught in unmeasurable details so rather than start by talking about physics let’s just look at a more intuitive example of what I mean so I recently gave a talk at the 92nd Street Y and I’m if you want to find your way there from here you probably won’t want to use a map that has it the same detail as that map on the right you would you would I mean Google Maps makes this really explicit you zoom in or you zoom out and so you want to use the scale that’s relevant for the question you have if you try to keep track of all of those small details you’d never get here you start off with a bigger map by the time you got into New York City you can use the map on the left but you’d start off here with maybe a map with us you’d find your way nearer to New York then you’d get closer and then you would use them then you would use the details to find your way there but you don’t need that detail of the map on the right in order

to get to find your way to New York it’s only when you have the resolution to actually experience the individual city blocks that you would care when you’re on a freeway you don’t care about all those individual city blocks and I like using the New York example because I think New York was sort of epitomized effective series because if you’re in New York you know you’re three block neighborhood is very different from any other three block neighborhood whereas anyone outside of New York just says we’re going to Nero city so I think we all use these sort of effective theory of New York well the New Yorkers are much more aware of the details and it’s a very general way of thinking no matter what field you’re in you probably do divide up your thoughts into sort of big scale questions and small scale questions if you’re doing literature you sort of have close reading versus following a story you’re doing psychology you might look at nerve patterns or you might actually ask about emotions and what I want you to think about is the fact that even if we don’t understand yet the relationship between those two we know that underlying our emotions are our underlying physiological structure so one of the challenges of science is to get from understanding the details as small scales – what’s going on at larger scales but sometimes science isn’t as ambitious we start off by just looking at the bigger scales asking questions about them and then ultimately we hope to derive it from the underlying structure and it’s the reason I emphasize this is because people will talk about nonsensical concepts like the theory of everything and even even if we could find all the underlying elements that’s not the same as answering all questions you’d have to still understand how those ingredients feed into physics on larger scales so although our science of elementary particle physics is looking down and trying to find out what’s there there is still these other questions of how it all fits together that’s just an aside but in physics of course we use this idea all the time when we throw when we learn how to throw a ball I remember in high school but we were taught noonas laws and then afterwards we’re told well Newton’s laws aren’t right there they’re wrong but they’re not wrong they’re they work really well in fact if you’re predicting the trajectory of ball you will still use Newton’s laws you don’t need to use quantum mechanics and in fact if you did use quantum mechanics you wouldn’t predict it where that ball landed any more accurately from the point of view of any measurement you could possibly make it’s only if you had much greater precision or if you were looking at that ball at an atomic scale that it would actually matter you’d have to either have the resolution or the precision to be able to see that difference otherwise Newton’s laws are perfectly OK it’s an effective description it’s an approximation ultimately we know that this podium is made up of underlying matter that looks nothing like it but that world of the atom isn’t essential to when I’m describing how to move this table or around or its podium around so if you think about it that’s kind of essential to how we’re doing physics because of course we can’t possibly know the answer to all the questions we only know the answers about questions that where we’ve had the resolution to study it we can make theoretical conjectures about what’s there but that doesn’t necessarily tell us what’s there until we can make measurements and if we couldn’t ignore all those invisible ingredients we wouldn’t be able to proceed so if you think about it this is what I said earlier when we did our tour of small scales if you take the atoms that underlies this podium you can then see what it’s made of it has a tiny nucleus surrounded by electrons in some sense atoms are mostly empty space which means in some sense all material matter is mostly empty space but of course that’s not what we see when we experience this hard tabletop that’s not how it appears to us and that’s why these physics seems so unintuitive the law is operating at different scales are very different than the laws that operate in our daily lives and that’s also what makes it so interesting to study we’re not just looking for in the ingredients we’re really looking for what are the laws of physics that underlie what we have here so of course if we go inside the nucleus we find that chew is not fundamental it has more elementary components protons and neutrons which in turn have further elementary components known as quarks the up and down quarks are inside protons and neutrons and there are heavier quarks also and what we are trying to do is understand why are there all these ingredients how they fit together and water the fourth how do the forces tie them together of what are all these forces what if why do they have to the properties they do the masses they do the charges they do we’re trying to put this all together but I can’t help

but share a quote that I think really brings home how effective effective theories are when I wrote my first book more passages I realized that although I was writing a book for a popular audience I hadn’t actually read a whole lot of them so I thought maybe I should just at least look around and see what they look like it so people told me which ones they liked and so I went and glanced around and one of the ones was George gammas one two three infinity so I looked at that one and there was this like fantastic quote a note which which I think is both great news is showing the excitement and also as a cautionary tale so the quote is instead of a rather large number of indivisible atoms of classical physics we are left with only three essentially different entities protons electrons and neutrinos and then he goes on thus it seems we have actually hit the bottom in our search for the basic elements of which matter is formed so it’s very easy today to laugh at him and say but I think it’s makes you appreciate just how your intuition gets sort of adjusted by the environment which you live he was living in a time when they had just discovered these nuclear elements so they had discovered protons they hadn’t even discovered neutrons yet but he knew about the nucleus and about protons and so he realized what a great breakthrough this was they developed these tools they’ve been able to discover these nuclear elements that late were underneath what we see yet he didn’t have the vision to be able to realize that his that it were the time he lived also had his limitations they hadn’t yet been able to explore inside a proton or a neutron which he didn’t even know about they couldn’t look at these smaller scales yeah so it’s really interesting to me that he could be so excited about having discovered fundamental structure yet not think that this underlying structure exists and it sounds really funny except when you think about it in the time we live it’s very easy for us to also think well we know everything that’s there there’s certainly no indication of any underlying structure yet yet it would be really odd if we lived in the in the last time where we’re going to make such a dramatic discovery it’s almost certain that there’s physics that underlies what we see and that’s why research continues and of course in his case he’d completely missed the existence of quarks which were discovered many years later in fact they were in fact motivated by theory to explain why there could be so many different elementary particles the idea was there were these basic components that could be put together in many different ways but they were eventually discovered by experiments where they could discover this hard structure inside and as I said today the frontier energy scale is 10 to the minus 19th meters an even smaller distance scale it turns out it’s a really interesting different scale because it’s very likely to answer some very fundamental questions which I’ll tell you about in a minute but here we see the ring the ring is actually underground so you can’t actually see it when you’re when you’re flying by as some physicists mistakenly have said it’s underground and what you see here is that there’s the LHC which is Large Hadron Collider but then at various points along this ring the protons collide so there are the protons going around as I said eleven thousand times a second it takes 20 minutes to accelerate them to their full energy then when they have that energy they collide together and when they collide together they can form new matter how do we know what’s there well at those collision points there are experiments built around those collision points and those experiments the most important to me are called Atlas and CMS there there are general-purpose experiments that try to just measure everything that comes out most of the time what comes out is junk in the sense of ordinary what we call standard model stuff that we know is there what we’re looking for is the one in a trillion event that goes beyond the standard model that tells us there’s something that goes beyond that that’s new physics that underlies what we see so one of the roles that I and my colleagues who are theorists have is to try to identify what are those distinguishing features that tell you there was something new what is it so they want to be able to both look for the standard stuff but in order to identify what’s new so here’s a small video that someone on the Atlas experiment made what you see are the protons get accelerated they start a linear accelerator then they go around a smaller ring than a bigger ring this is actually the tunnel and the beat this is the protons come down this beam here you can actually go and visit which I did

before the machine was running of course then the protons come they collide and when they collide they’re now inside a detector and then whatever comes out goes through these various layers of detector to see what’s there and in fact the machine is going to shut down in a year and when the machine shuts down will be a very interesting time to be able to go visit you you don’t go visit when the machine is running reasons but it’s you can visit the control room in some interesting places but to actually walk through the tunnel you can do before the machine was completed and of course once it shuts down you’ll be able to do that again it’s really fun to see what’s going on there so the Large Hadron Collider is I tried to say it’s an exciting machine it’s the biggest machine ever and it really is a machine that you need superlatives to describe which I usually shy away from so the first two quantities are things that make it distinct from a physics perspective why is it so interesting well it’s the highest energy machine it’s seven times the energy of America’s Tevatron which was at Fermilab near Chicago that just shut down about a month ago it also has what’s called the highest luminosity that’s basically a measure of intensity it’s saying that you have a lot of collisions so you can see rare events so it has 50 to 100 times luminosity and when I say these parameters it doesn’t yet have them and that’s important to keep in mind when we hear news reports the plan is for the Large Hadron Collider to run the end of next year shut down and then come back up with increased energy and increased luminosity so that’s what we’re waiting for but to achieve these goals is really an amazing feat of Technology it has the coldest extended region that we know of it’s 1.9 degrees above absolute zero to put that in perspective it’s colder than outer space and the reason it’s so cold is because they use superconducting technology to create the strongest magnets that are in industrial production so there’s a 192 what are called dipole magnets they’re placed around this ring and the goal is to keep these charged protons at high energy inside the ring and the higher energy they are the higher magnetic field you need so the challenge to building this machine is not so much accelerating the protons because you can keep doing that every time they go around but to keep them going around and so with the bigger the tunnel the best the easier it is to do that because you don’t have to bend them as much when the Large Hadron Collider was built there was an existing tunnel so their constraint was how strong the magnetic fields they can have and that’s the constraint on the energy so these magnets really are stretching technology to the limit it also has the biggest most effective vacuum that we know of over extended region as tenth of a trillionth of an atmosphere less than on the moon the pressure on the pressure is less than on the moon the reason you need that is because for one thing you don’t want the protons scattering randomly because you want them to be in collimated beams very so that they’re very focused and can hit each other you don’t want them to get all ruined as they go around but the other reason is because if you had scattering it would raise the temperature and you don’t want that to happen that would quench the magnets so they need a very effective vacuum as I said they’re the strongest magnets in production and the magnetic field energy is enormous so it’s just when you see it it’s beautiful it’s a huge machine but it has an amazing amount of detail in it which is what makes it so impressive as I said the reasons for these extremes are for the physics reasons you want to have energetic protons we know e equals mc-squared so more energy means higher mass it means we can see particles we’ve never been able to see before it also means smaller distances these distances of 10 to the minus 19 meters we also want as many collisions as you can have they’re looking for rare processes and your odds are better if you buy more lottery tickets so basically having more collisions means you’re more likely to see something interesting and as I said you want to have machines that detectors that are as precise as possible to measure everything that comes out what will we learn there well the big question that we might answer within the next year if we’re lucky is how particles acquire their mass how elementary particles acquire their maths that probably sounds like a very odd notion I mean why can’t everything just have mass from the get-go it turns out if that was the case you would end up making nonsensical predictions probabilities of interactions greater than one things that just don’t make sense so we know there has to be a

mechanism that explains how elementary particles get their mass and that mechanism is called the Higgs mechanism it’s named after the physicist Peter Higgs and the experimental consequence of this would be something like a Higgs boson that you might have heard about the search for the Higgs boson it’s a particle associated with this mechanism it’s not the only possible way this can happen essentially what the Higgs mechanism does is it essentially spreads a kind of charge throughout space and particles acquire mass by bouncing off that charge it’s not an electric charge it’s some sort of mysterious charge that’s quite a part of what’s called a Higgs field the question is what is it that distributed that charge throughout the vacuum throughout empty space and that is what we’re looking for when we look for the Higgs particle we’re looking for that sector of the theory at that portion of the theory that is responsible for this and the Higgs boson is one possible experimental consequence that we might learn about very soon will almost certainly learn about within the next year or something we’ll either learn that this elementary theory is wrong or older in the it’s right it’s very exciting another question which seems far removed but is actually somewhat related is why is gravity such a weak force no gravity might not seem weak when you’re climbing up a mountain but if you think about it you can jump up and down even though you have the entire Earth trying to pull you down and the fact that you can pick up a paperclip with a tiny magnet shows us that the force of electromagnetism is far greater than the force of gravity and that’s from the point of view of elementary particles gravity is totally negligible it’s completely weak compared to the force of electromagnetism 40 orders of magnitude smaller so the question is why is that can we understand this weakness or gravity in the process of trying to answer that question we can learn something very deep and fundamental about not just particles but the nature of space itself is there more symmetry out there in the universe than we thought we know about symmetry is that for example say it doesn’t matter in which direction I orient my experiment that’s called rotational symmetry but that symmetry might even be extended into the quantum regime in what’s called supersymmetry which is one of the targets of searches another idea familiar to anyone who read my previous book too would be an extra dimension of space there could be an extra dimension of space that could help explain this weakness or gravity and the final thing that we expect perhaps to learn that we have reason to think we might learn something about is the nature of dark matter the matter that it’s matter it clumps it’s out there is six times the energy in dark matter then the matter that we’re made up of but it’s different because it doesn’t interact with light it interacts gravitationally so we know it’s there but we don’t know at a fundamental level what it is so that’s one of the questions we’re trying to answer now because I talked about effective theory and because I’m asked this a lot I’m going to mention string theory string theory is not going to be studied at the Large Hadron Collider string theory applies at scales far removed we talked about 10 to the minus 19 meters string theory has visible effects most likely at 10 to the minus 35 meters that 16 orders of magnitude smaller scale than what we’re studying at the collider so we really have to put on our effective theory hats because I’m telling you that even though underlying all of matter could be elementary particles or it could be elementary strings things that seem in principle very different if those strings are only 10 to the minus 35 meters long you can’t tell the difference they look like particles from the point of view of something with resolution of 10 – 19th meters furthermore the difference between a string and a particle is that a string can oscillate in different ways that means there could be a whole bunch of new particles but those particles are 16 orders of magnitude too heavy to produce so the reason we talk about string theory is not because of experiments but because there’s a theoretical puzzle a puzzle of how to combine together quantum mechanics and gravity not at the scales we see but at the scales 10 to minus 35 meters its scale that’s very far removed ordinarily I can say when I do particle physics I could ignore gravity when I do cosmology I can use gravity and nor quantum mechanics to some extent but it’s at these scales that are these really tiny distance scales that we would need to have both so there are theoretical reasons to study string theory but not yet experimental reasons so we really have to have our effective theory idea this idea of scale that

tells us this is much too small a scale to be visible yet could underlie what we see and because I’m talking about the scale I’m going to tell you one thing which is completely unrelated and you’re really going to have to put on your effective theory hats because it actually you might ask I told you why that we had this biggest scale of 10 to the 27th meters for the visible universe but I also had a smallest distance scale 10 to minus 35 meters why did I say there is a smaller scale with this again it’s theoretical speculation I don’t know that this is true but excuse me I do have allergies that I know is true but there are reasons to think that the notion of distance itself of length itself might break down at the scale of 10 to minus 35 meters why do we think that well we don’t even know in principle how we could study a distance of that scale now why do I say that remember at the beginning of the talk I said that we need a small wavelength to study short distances well to study a distance as small as 10 to the minus 35 meters you would need a very tiny wavelength of that size but to get a tiny wavelength you need a high-energy wave that’s what we have high energy colliders to study short distances if you think about it a high-energy wave has a higher frequency in a shorter wavelength so if you had enough energy to study 10 to Mai’s 35 meters you would have so much energy inside a small distance that you would make a black hole now we don’t care about the black holes what we do care about for this argument what we do care about is the fact that if I then added more energy instead of studying a shorter distance I would get a bigger black hole so we don’t even know in principle in principle how to make a probe to study a distance of that size and there are other arguments to that make us think that the notion of distance itself might break down at this scale and again you might say well that sounds horrible how can we have distance breaking down but again we don’t operate at those distance scales we are safely away from those skills we’re at much larger scales where things appear to be continuous length continuous distances so again we have our effective theory notions but it’s just an interesting fact if we’re thinking about grating things according to scale but I’m not going to say any more about that I this is what I said earlier I’m going to skip that slide but we can come back to it I’m just going to say the goals today the goals today are in general always in science to go beyond the established theories and find the missing pieces in this particular case it’s a really exciting time because we really do have experiments the LHC is something that’s been in development for over a quarter of a century we also have very interesting experiments studying dark matter and dark energy going on today so we really are poised to learn more not just with theory which we’ve been doing for years now but with experiments so you want to make discoveries that can’t be explained within the current framework in our case the standard model of particle physics and we want to use experiments to choose among the potential underlying theories we’re not just looking for experiments to verify ideas some of them will rule out ideas and I’m in my book I talk a lot about what are the guides we have where we’re trying to go beyond this denim model both in theory and with experiment and we’re going to probe new energy and distance frontiers so I’ll just show you one more video here which is just the continuation of what we had before those protons collide the particles come out and they go through different layers of the detector measuring different things charge momentum energy and based on what each of those layers measures they try to identify which was the particle in this case the video was made to show a particle of the standard model known as the Z boson it’s a particle like a photon but in this case it’s heavy and it decays to an electron and a positron so the way you find that particle which is the way you find a lot of new particles is you look for the decay products you look for what came out in this case an electron and it’s antiparticle of positron and you put it together to find out what was there and that’s what they’ll be doing when they’re looking for new particles as well and this is just proof that I was there so before I close I just want to tie these ideas back with what I talked about in the beginning namely my name on a poster so I’m just going to say one more big physics idea and again I’m going to go through this rather quickly but I just want to give you a flavor for the exciting exciting new ideas we’ll be looking for I’m going to say this very quickly but one of the things we could actually search for experimentally is a

new dimension of space a dimension of space beyond the three were familiar with beyond left right forward backward up down a genuinely new dimension of space why would we even consider such a thing well one is we actually don’t know that there are three dimensions the history of physics has taught us anything it’s that unless you look you’re not going to find things but when you do look you have surprises and in fact Einstein’s theory of gravity works for any number of dimensions not just three so there’s a real possibility that there could be dimensions beyond what we see another reason is string theory string theory claims to unify quantum mechanics and gravity but it doesn’t work if there are only three dimensions of space if string theory is right you need two mentions beyond the three that we know about but perhaps the best reason to think about it is we have a chance of understanding connections among physical parameters there now universe and in particular this question about the weakness of gravity is a question that’s been around for decades and we’ve tried to solve it and not just we means the entire body of theoretical physicists have looked for solutions and there’s no completely satisfactory solution so at that point it makes sense to look beyond and see is are there some exotic ideas that given a nice explanation and the one additional ingredient that comes into this is something called a brane world the notion is based on the word membrane so it’s a lower dimensional world inside a higher dimensional one in this case it could be that we live in three dimensions inside a higher dimensional world and the reason my collaborator Raman syndrome and I were excited about this idea is we realized that if you had not just one brane world but two an extra dimension it could naturally explain why gravity is so weak it’s obviously not something that I can go through right now but we just solved the equations of general relativity in this context and I should say that these brain worlds come naturally out of string theory but they’re not necessarily proof of string theory but these brain worlds do come out of that context and we found that gravity varies exponentially in a different dimension so even though gravity could be really strong very nearby and by very nearby I mean a fraction of a centimeter 10 to the minus 30 of meters away really close we wouldn’t know about it yet because it interacts only gravitationally and gravity is so weak yet it could explain why gravity is so we in our universe because it’s exponentially falling as it goes across another dimension and to return to the theme of scale what’s really going on is that your measuring stick is changing as you go across an extra dimension so something that you expect it to be very heavy in fact could turn out to be extremely light and therefore gravity is so weak now this is a theoretical idea but what’s amazing is that even though it sounds so exotic it has to do with an extra dimension and formed extra dimensional space it actually has consequences for the Large Hadron Collider as do any potential explanations of the weakness of gravity in this case it’s something called the production of something called a Colusa Klein particle a particle that travels in the extra dimension has momentum and energy associated with the extra dimension appears to us like a heavy particle that just like that Z boson would decay inside the detector into in this case electron positron put into many other particles and by looking at the different ways it decays one can determine is it this particle associated with an extra dimension so we have a real chance of answering this probably not before the Machine turns down shuts down and comes back on but once it comes on at full energy they can do a real search for these particles so I just want to say a quote of course Steve Jobs was in the news a lot and so again I’m sort of misappropriating it he was talking about his life at the Stanford commencement speech and he said again you can’t connect the dots looking forward you can only connect them looking backwards so you have to trust that the dots will somehow connect in your future and again I think it’s a nice statement about science because we sort of have a hope that we’ll see something we have ideas but we don’t know until we’ve actually done the experiment and of course in the case of particle physics it’s literally connecting the dots to see what those tracks were and find out what was there so we’re waiting to see maybe these ideas will be shown to be real it’s going to be an interesting few years where we get and interpret results some of these ideas are really elegant and beautiful but that’s not good enough I want to see so I’m just going to spend the last few minutes just tying together

with what I had in the beginning so I’m going to talk about how these ideas were realized in a couple of projects I did not physics but in our projects it is not teaching the physics that some people seem to get think it is but really just introducing the concepts so there’s an art show actually going on at the carpenter center right now that moved from LA it’s called measure for measure I carried it with Leah hall around an artist and it was really designed to illustrate the theme of scale so boramae did this enormous sequoia tree but what she did is she did it as a sequence of small pictures so if you focus on that just like the Eiffel Tower pictures in the beginning if you focus was on the left it’s nothing like what you’ll see when you go to the picture on the right and each of the pieces this was a very literal way of doing it but each of the pieces Illustrated this theme in their own way whether its economic scales from someone who gave out cupcakes to sort of art someone who had faces in sort of a pop art looking thing so you can actually see this at the carpenter center it’s up for the next month it just opened up but to get back to the efficient that was because Hector Parra who’s a composer asked me to write a libretto for a small opera so I will just amuse you but letting you see some of what was in that opera so I’ll play it some of this and I’ll talk about some of the themes which were basically how people see the universe what it means to do experiments to really explore what creativity meant what discovery means what drives it and so it was both sort of used literally in physics to sort of guide Hector’s composing and Matthew Ritchie’s sets but it was also just an abstract way to sort of metaphorically talk about extra dimension as a way of exploring so I’ll just show you a little bit of that if I can as an actual equation he insisted so basically it was the comparison between the way the two of them see the world and what drives you to discovery and what drives you so she got to explore this more colorful wider extra-dimensional world while he lived in a smaller world and tried to understand it but it’s also interesting from the point of view of understanding what an experiment means because in the sense we’re not going to the extra dimension it’s coming to us and we’re trying to interpret what’s going on and what’s there so in my book I’m not just talking about the physics that I present today but I’m talking about what goes into scientific thinking what are the roles of creativity and discovery what is the role of scale but also what is the role of uncertainty when we’re doing science and it’s really important because I think science often gets abused in the popular press and it’s not understood that uncertainty is part of presenting a scientific result and also I talk about how we actually do our physics what are the chapter called truth and beauty and other scientific misconceptions what is actually the role of beauty when we’re doing science but of course it’s also what works more today and what is the physics we hope to explore so we’ve come a long way but there’s a lot to learn so just close with one final picture that I saw when I was in the tape Museum which I think really nicely illustrates the idea that we can be living in a world where there’s richer’s riches yet to be explored what I didn’t know when I saw this picture was that’s actually the chateau de chillon which is very close to CERN that houses the large how to an collider so clearly it’s not a coincidence so well thank you you