Expanding Our Horizons: Matter, Space, and the Universe

good morning I always find it amusing I you know I do both physics and writing and I find that I like doing writing in the morning and science at night so I'm always impressed that people show up in the morning for science talks so I hope I hope you all had more coffee than I did um so I couldn't remember what title I proposed so I put the title of my book and it will be kind of a running theme the the title of the latest book I wrote is knocking Heaven's Door and it really is about two things and it's about and I think it has to do with also two ways of presenting science which whenever you're giving public lectures especially in a venue like this it's interesting to think about because and and you know I've debated with other scientists about this I mean one thing that you get when you see science talks is sort of just the awe and wonder aspect you know the fact that there are all these exciting things we're discovering about the universe and it's true there are exciting things we're discovering about the universe and I'm going to tell you about a few of them in particular I will tell you about Dark Matter hios on and a little bit about an extra Dimension so so it's a lot I'm going to cover but I'll try to give you a flavor of it and a lot of people are frustrated they're like I don't completely understand it well you can't completely understand very deep physics topics that I'm going to cover in a short amount of time but you can get a sense of what the ideas are and what what it is that's driving us but I think the other thing that I always get asked about and that is interesting is soort of just how we're thinking about science like how are we deciding the questions we're doing and how are we deciding what's right how are we design so basically just what do we do what are the questions we have what drives the guesses I do theoretical phys physics I don't do experimental physics although I will tell a little bit about experiments and it's an interaction between hearing what the data tells us and what we predict and how do we decide what that is and how do we decide what the interesting questions and how do we decide what has a chance of being right and of but the other thing I tried to talk about because when I wrote my when I wrote my first book War passages it was really a science book um about the physics going on about extra Dimensions about how 20th century physics about a lot of how we got to where we are the second book I also was a little bit frustrated by reading the newspaper and seeing just how unscientific people are when they approach a lot of problems of everyday life that actually affect us quite enormously so I try to also talk and I I'll only give a very small flavor of that in this talk just about what I think are important ideas of a scientific way of thinking that affects not just our attitude about scientific problems like climate change for example but also just how we can deal with problems in general so I'm going to start with kind of what looks like a random picture um it's a it's a it's a photograph someone sent me and you can all tell where it is and you can tell it by of course the iconic Eiffel Tower in the background and you'll also notice there's a kiosk in the front with a poster on it so of course this is a picture of Paris so you're saying why am i showing you this picture well because one of the important themes in I think physics but also more generally is that just how we look at something matters what scale we use to look at it and in this case scale means actual size what is the resolution with which we look at something so if you look with very fine resolution you you would see the very nice iron grid work of the Eiffel Tower which you can see when you're standing underneath it and of course if you had um more sophisticated tools you can actually see the atoms of iron and by see of course I'm talking Loosely I mean observe it doesn't mean literally see it with your eyes but as we develop better tools so that we can look at smaller scales we see this fine structure it doesn't tell you when you look at that atom that it's going to be an Eiffel Tower it matters how you look it so if you look at the right scale you see that it's this beautiful structure which is the Eiffel Tower and of course the other thing that's important to think of when we do science and physics and just about anything else is that if you don't have the resolution to look closely you won't see it at all so if you're up in an airplane if you're too far away you don't know the Eiffel Tower is there and I hope this is a little bit clear to you that it's a metaphor for how we do science that when we look more closely we find substructure that we didn't know about and if we don't yet have have the tools we don't yet see it and the important thing to also keep in mind is that if you don't yet see it you can still go ahead and do science you don't have to know everything you just do the science that's appropriate to whatever scale you know about so you learn about the things that we can actually observe and try to put them together into physical laws and I just want to say that um scale matters especially to me because if you went back to that first slide I had and actually blew up that poster you'd see my name on it which is why sent that picture and the and the reason is because um a composer who works at ircom in Paris actually asked me to uh work on an opera which so we had an opera that premiered in the pomp Center that was actually about physics and also about science what drives uh creative thinking and it premiered to the pumpo center and I'll give you a little excerpt at the end but I just want you all to keep in mind that you're using this idea of different scales all the time um physically you're using it when you use Google Maps or Map Quest or whatever you use um you look at the scale that's relevant for you if you're driving across the country you don't need a detailed map of Aspen but when you get here and you want to find out where door hoser is you want a detailed map of the Aspen Institute um and so it's and so it's important to realize that it's okay to neglect those details but you learn more when you can study those details and that's basically what I do as a particle physicist we have one scale that we understand well and then we're looking beyond that so as um I don't know your name but as someone was asking like what goes beyond what you've learned well there's always something Beyond and it's foolish to think that there's not but we still learn a lot at every given scale and that's true in everyday life as well we don't know the details of everything that's going on yet we manage to function and so it we learn more we can build on that information we can derive what happens at other scales but we can always do physics on the scale that's appropriate and I just the last slide just about scale itself is just to remind you and and this is again in response to a lot of questions that was asked after I read the first book A lot of people almost question the reality of the kinds of things that I and my colleagues study because it's not something you see in your daily life that doesn't make it less real I mean that is just a function of physics it's a function of the fact that we see with visible light we see basically although the spec there's this actually tells you exactly which wavelengths are appropriate but we basically can see things between a millimeter and kilometer but of course the universe spans a much broader range of scales the fact that we have this accident that we just see these scales doesn't mean there aren't interesting things to study and that's what we do so I'm going to give you a very brief tour of the universe to give you an idea of what exists on all these scales so we'll just start with large scales notice that the human being which is about a meter tall everyone except for Americans basically use metric system which I would use so we're all basically one or 2 met tall um and but and so we're looking at scales that are larger than us and they're enormously larger um we start off with the scale of the known universe at the top um 10 to 27th M that's a one followed by 27 zeros that is enormous scale that is the scale of the universe and you might say why is it a finite size that I'm looking at why isn't it an infinite size and that's because I'm talking about the visible unit Universe because I want to emphasize what are the things that we can actually observe because the universe has only existed a finite amount of time and because the speed of light is finite we can only see out to a certain scale which is our universe that doesn't mean that there aren't very interesting things that exist Beyond but this is the stuff that we can make predictions about and actually observe um with astronomical or other tools now of course within the universe there are many other objects of many different sizes um so there are galaxies 10 to the 20th M there's this Earth's orbit 10 to the 11th M and there's the Earth itself 10^ the 7th meters 10 million meters but what I want you to think about when you think about this vast range of scales 27 orders of magnitude 27 factors of 10 is that the same laws of physics apply over this enormous range right we use gravity we use electromagnetism the same laws of physics apply over this range and when we get to small scales we're going to learn that we actually learn about new laws of physics as we study smaller scales and we'll come back to that I just want to take a minute since I promised to talk about Dark Matter to talk about one interesting thing we learn about when we study these large scales and of course I think most of you probably know this but one of the many surprising facts about the universe is that ordinary matter is only a small part that is to say if you do an energy count and you ask how much of it is stuffed that we're made of the kind of atoms we know about the kind of stuff we can actually study in our Laboratories so far it's only about 4% of of the universe there's another about six times as Mount amount that's dark matter um there's about these these numbers are actually old about 70% is dark energy which is energy not even carried by matter it's Just Energy spread throughout the Universe not associate with individual particles now I said it's one of the many surprising facts and I think most people when they see this think it's surprising that we're such a small part I actually think that it's quite remarkable that we're as large a part as we are I mean we are we're just this is just an accident of what we can observe and who we are and there's no reason that all of these components had to be so close that you could actually see the slices of pie on this chart it could have been that we were 10 to the minus5 of it or it could have been that we were a very small component it's amazing that we are as big a part as we are and I'd like to think that that actually might be a clue as to what dark matter and dark energy are because why should all of these be so similar why should this other stuff that we think is hardly interacting with us except through gravity be so similar it kind of points to the fact that maybe there are other interactions so what is dark matter I guess I should have said that already but what is it it's matter it's stuff it clumps it comes in it you get it in galaxies you get it in stars but it has gravitational interactions that's what we know so far but we don't know what it actually is Right ordinary matter we know it has other interactions it's charged under electromagnetism for example we don't know what it is we think it's particles we think it's just particles that don't interact with light in fact the name is kind of a Mis misnomer it's not dark it's transparent you can see dark things um well there's some bright stuff but you can see the rug um because it's absorbing light but but dark matter is just not interacting with light at all and we we know it from his gravitational effects I'm not going to go through all the details now but there are many different ways that it affects the structure of the universe that we can actually go out and measure and when I say me I mean my observational colleagues so what is it well we don't yet know and that's one of the thing that things that I as a theorist work on it's a question we're trying to solve um there's a lot of tension devoted to it right now in fact and that's for two reasons I think it's because having not yet figured out what is people are trying to explore broadly what are the possibilities for what it can be and the really interesting thing about that is that there are several different ways that people are looking for Dark Matter today both through very sensitive detection experiments where it can recoil a little bit and leave a tiny bit of energy um or by seeing Dark Matter particles annihilate in the universe or even at the large hron collider the giant particle accelerator that I'm going to tell you about so there's lots of ways people are looking for it and so it's it's important to have a broad spectrum of ideas about what can be what are these experiments telling us um and I I say at the end Prejudice can distract us from the truth because I think a lot of the time people just think I know what dark matter is I have an idea of what it is already and and they're not right and and you can tell that because you go out and try to measure things so you have to have an open mind and that's very important quality when we're doing our research there's a lot of words on this so I'm just going to tell you very briefly one of the in ideas I'm working on um for those of you who are interested I'll be talking more about it at the BBC Radio thing at the derome hotel at noon tomorrow um but it's an idea that maybe not all just like in our universe we have all sorts of different particles um it's not like there's only one element of matter there's many different ones and they have different interactions maybe this Dark Sector is like that too maybe some of the dark matter has strong interactions some of it has less interactions maybe there's even something that I like to call called Dark Light um kind of electricity that we don't experience that this other matter can experience and it turns out that that gives rise to all sorts of interesting consequences both in structure in terms of observations you can have that one of the really exciting ideas is those of you you know when you look out into this beautiful sky that you get here in Aspen you can actually see the the Milky Way um the plane of the Milky Way so a Galaxy actually has a dis which is a flat structure surrounded by big halo of dark matter the reason that disc formed is because matter itself the kind of matter we know about that interacts with light could cool down into this flat dis so it gets less and less velocity as it cools and it gets into a very narrow structure maybe some of the dark matter is like that and if that's true it's denser and really interesting and probably right on top of us and can give a lot of interesting consequences that we're studying so I'm not going to say any more about that so just to get back to the idea theme just We Believe Dark Matter exists it's been observed through experiments or observations having to do with its gravitational effects but we're trying to figure out what it is we try to figure out what it is based on other things we know about the universe other possibilities we know about what forces and interactions can look like and all the time we're trying to push the testable possibilities to trying to find out what is I find ironic that while we're talking about Dark Matter the lights went off okay um so we're open to even weird possibilities if they're testable and we take that into account and it's a really exciting topic because it involves lots of things cosmology astronomy and particle physics the study of really tiny stuff which we're now going to turn to I told you I'd cover a broad range of ideas so we've done with large scales we're now going to move on to small scales so scales smaller than a meter smaller than the human scale so here the human beings at the top okay so now we're going to ask what we get as we look at smaller and smaller scales smaller than a meter as we have a resolution that can detect smaller things and I actually start off by talking about a few biological things um to emphasize that even in understanding our own bodies until we actually did experiments to look inside people didn't even understand the circulatory system until bodies were cut open and arteries and veins were found and the mechanis of the heart was understood um certainly red blood cells weren't known about till we looked under a microscope and could see them and DNA was found because of X-ray defraction that you could see the structure the H structure so even in understanding stuff about ourselves we learn a lot more when we can look inside and with physics of course we're going to go well beyond that we're going to go to tiny tiny scales and that's why we have these enormous accelerators that probably most of you have heard about because you're trying to study structure that you'd never see unless these tools existed to allow you to look at these very small scales and when you do look at these small scales you learn an enormous amount you learn about atoms for example you learn that all the stuff that we think of as solid is actually mostly empty space it's mostly electrons that are surrounding nuclei in enormous distance away most of it doesn't actually have matter in it even though this thing seems pretty solid I hope or else my computer gets destroyed so it's all very solid but when we look inside we see that they're actually atoms and when we look inside those atoms we see that they're nuclei surrounded by electrons we look inside the nuclei we learn about protons and neutrons and we learn about objects called quarks and that's what those of us who do particle physics study it's called the standard model of particle physics and it's the structure that describes everything we know about so far the most basic elements of matter and their interactions and right now the frontier scale is is 10 to theus1 19th M that's 10 factors 19 factors of 10 smaller than the human size it's a really small scale and that's at this machine called the Large Hadron Collider LHC um it could have been called the large proton collider and then you would understand what that means proton is a form of a particle called hadron that experiences what are known as strong interactions and it's 27 km in circumference particles are protons are accelerated around each time they go around they get another kick which is why it's circular and they get accelerated to enormously High energies with which you can study very tiny distances and look inside and find out what's going on at smaller scales than we've ever studied before and for many reasons we think this is about the interesting energy range that we really want to study and I'll tell you a little bit about the major discovery that we had um about a year ago and again I just want to emphasize because um again referring to the question that was asked before I even started like what's next and I just want to emphasize that Rick sorry every time we look inside we see smaller structures and so when we look inside atoms we see nuclei surrounded by electrons when we look inside nuclei we see protons and neutrons that's what plus and zero are and we look inside those we see quirks objects called quarks the up and down Quirk it's inside all all the nuclei around you there are heavier versions of quirks um they Decay they're not stable and that's one of the things that we study just all these Elementary particles and the question is why are these particles what they are why are the forces what they are why do they have the masses they do what is driving the structure that is fundamental to everything we see and again we can study all the stuff we see without knowing the answers but when we know the answer we have a lot more information about how to put it all together and what are the fundamental laws of physics and I really like this quote because um when I wrote my first book Bo passages I realized I hadn't actually read a lot lot of books for popular audience so I just went and glanced through some of them so George GMA was I was told wrote very good books and he did indeed he was actually a nuclear physicist he it was in 1947 he studied the nucleus which was the frontier scale at in 1947 no one yet knew about corks or all this more fundamental structure but they had discovered the elements of the nucleus so he was very excited and so he said instead of a rather large number of indivisible atoms of classical physics we with only three essentially different entities protons electrons and neutrons so that is the scale at which they understood things at that point but then he went on to make the mistake that a lot of people tend to do and said thus it seems we have actually hit the bottom in our search for the basic elements of which matter is formed so even though he was so excited that they had just discovered this substructure and understood that these were the elements of matter he didn't have the foresight to say you know maybe maybe we've only studied up to a certain scale and if we if we can study it even more maybe we'll find some substructure there and of course that did happen in the 60s and corks were discovered these other more fundamental elements and as I said the frontier energy scale today is 10us 19 M we say it in terms of an energy scale Terra electron volt scale that's how we measure our energies but you see it's this enormous um this this is drawn above ground but of course it's a tunnel below ground about meters below ground in fact on average it had to be built on a tilt for various reasons because as you can see it's kind of an interesting geological area there's mountains there's a lake so they had to be pretty careful when they built this tunnel so there's actually a small tilt to it which they had to actually take into account when they built the experiments because the experiments shift slightly over the course of time um but these are the two major experiments from the perspective of this talk it's called CMS and Atlas they're what called are called General purpose experiments so the large hydron collider is the machine the things that bang together accelerate and bang together these protons then the experiments that study the consequences of banging together these protons are CMS and Atlas and what they do is they try to measure everything that comes out so what happens is particles annihilate they become energy eal mc^2 so particles which have mass can turn into energy that energy can in turn become other particles and that's what we're looking for now most of the time it's going to turn into stuff we already know about part of the standard model but maybe one out of a billion times we can hope to see something new so one of the challenges of the experiments is to measure all the properties keep only those things that can be potentially interesting and then sort through this enormous amount of data so I'm just going to show you a couple of small videos that show you a little bit what happens when these collisions happened that was made by someone who worked on the atlas experiment so what happens is the protons first go around smaller Rings you don't usually hear about those and then it goes into that big 27 km ring and then there's a big tunnel you can actually walk around it in fact because the machine is off you can go visit now and walk around the tunnel and see these experiments up close if you're interested in in Geneva and then protons come together they Collide and where they Collide they'll build experiments so usually the beams are passing each other then they divert them with magnets and then they Collide and when they Collide we hope something exciting happens something something big always happens but like I said a lot of the time that comes out is just going to be ordinary standard stuff what we're looking for is what is new what's beyond that so we have to characterize everything that's measured so that we can tell what is the needle in the Hast stack that we're looking for so what you have after that Collision so they Collide it goes through different layers that surround this Collision region and so each of these layers is measuring different properties of whatever comes out such as does a carry charge it's measuring momentum it's measuring energy measuring does it experience a strong force so this particular video was made about a particle that actually is in the standard model it's called the zosan um it's like a heavy version of a photon but it decays into the particles that they actually measure and that's another thing to keep in mind about all of these often heavy particles Decay so what you're measuring isn't the actual particle you're measuring the Decay products you're measuring what it turns into and you look at what it turns into and try to figure out what was there and in this casee you figure out it was a standard model particle but sometimes if you're lucky you might find something that's not so standard that's just to say I did visit okay so what are we going to learn why are we doing these measurements and when I say we I mean my experimental colleagues we're going to learn first of all how Elementary particles acquire their masses and I'll tell you a little bit about that in a moment it's very subtle it's it's but it's a very interesting topic and we've actually answered that question to a large extent very recently another question that has to do with some things even more fundamental that we hope to learn is the question of what explains the weakness of gravity now I understand we're an aspen and you definitely feel gravity when you're hiking but that's because the entire Earth is acting on you as far as fundamental particles go if you had just tiny objects the force of gravity is over 40 orders magnitude smaller than the force of electromagnetism for example it's only because you have big massive objects that gravity seems so strong gravity is a fundamental force is actually extraordinarily weak and not only is it really weak but it's it's actually a mystery in the context of quantum mechanics and special relativity why it's so weak because if you just did a calculation you would think that all the forces should be about the same size and the question is how how do you get away with this what we call fine-tuning what is the fundamental physics that underlies that and gives you something more interesting and it turns out it's a really hard problem to solve people have been working on it since the standard mall was put together in the 1960s and 1970s and we really don't know the answer so again it pays to be broad-minded um so the answer could have to do with more symmetry maybe some of you have heard of something called super symmetry which I'm not going to have time to talk about here um it could actually have to do with an extra Dimension which I'm going to tell you very briefly about and the other exciting thing that the large hydron collider could in principle tell us about is about dark matter and that would be if Dark Matter particles happen to be the mass that you could produce at the large hydron collider now that seems like a wild guess except it actually turns out it's motivated by Theory it turns out that if a particle has that mass and you just calculate how much of it is left around today as the Universe goes from very high temperatures and cools down that you have just about the right amount to be dark matter it's so it could just be a coincidence or could be telling us something fundamental so people are looking for Dark Matter also at the large hatron collider so again one question was answered and I say as of this summer meaning last summer um and that is the question of how Elementary particles not all particles how Elementary particles acquire their masses and that's because this particle that probably most of you have heard of by now called the higs ban has been found and it really is a spectacular discovery that gives insights into this data model and they tend to show pictures that look like this which probably are totally meaningless to most people um but it just shows you that the boson has decayed into particles that they can measure that they can put together and say these all have the same mass and this has the right properties to be a hix boson because after all the hix boson is associated with particles getting their masses that means it interacts more with heavier particles less with lighter particles and so you can figure out how often it should decay in different ways it doesn't always Decay the same way but you can figure out how often it should Decay into different types of things and that's what's being studied now to see does it really have the properties of a hix boson and is it really telling us about how particles acquire their masses so what is it well it's a particle associated with particle masses and I say this very precisely because it's Associated a lot of the time in the news or in the you'll hear things like the Hig boson gives particles their masses this is probably a subtlety that you don't actually care about but if you want to be smarter than your neighbors it's not the hix Bon that's giving particles their Mass it's something called a hix field and I'm going to come back to that the hix boson is almost an appendage that tells you that this mechanism is right but of course you know it's not the Hig boson because we haven't seen the Hig boson before so if it required the Hig bosons to be around nothing would have had Mass before it's actually something called the Hig field but the boson is closely associated with it so we know what to look for and this is what I just said um so what do I mean by a Hig field well you probably know a little bit about magnetic fields for example it's stuff that spread throughout space so for example if you hold a magnet near a refrigerator door you feel something even though there's nothing in between and that's because although there's no particles in between there's no mass in between there's actually a field in between the magnetic field the hick field is something that's spread throughout all of space so it's a little bit as if there are like charges throughout space it's not exactly this but you can think of it a little bit as charge not actual matter but charge spread throughout space and particles interact with that charge and in interacting with it they acquire their masses so it's not actual particles but it's this field this higs field that's spread throughout that gives particles their masses so why do we care so much about the higs Bon well first of all the discovery of this particle tells us that that's right we didn't know for sure it was right that's what we all thought and the the reason we thought you needed this mechanism was because otherwise you get nonsensical predictions if you just said particles had masses from the GetGo it would be nonsensical there has to be some mechanism and most people saw it this higs mechanism was right by the way higs is named after the physicist Peter higs and he had a couple of other people worked on this idea so that's the higs field the particle tells you this is right and furthermore we hope it tells us what it is that gave this field in the first place and that's one of the things we're trying to learn about by measuring all these detailed properties that I mentioned earlier so it's abstract and actually when I wrote my first book describing the higs Bon and the higs parle and the higs mechanisms is really one of the most challenging things because you know unlike when you talk about space um it's very hard to imagine these things because again I want to emphasize these are things that are happening at smaller wavelengths than visible light would even let you see a visible light would just cover it all up so it's really happening at these tiny scales so it's hard to imagine what's going on if you try to picture it but theoretically and in in words you can understand how it is that these things are happening and of course mathematically um we didn't know it would be found for me this was a really exciting Discovery I've been doing physics for a while now and there have been discoveries but we always knew something would be there when they found it pretty much this was something we really didn't know for sure it would be there because we thought the higs mechanism was right but we didn't know it had to be something like the higs boson that was found it could have been a more complicated thing it could have been heavier it could have had different properties the fact is we were kind of Lucky in a way that it happened to be the mass that it was and it could be seen and it could have decayed in different ways but it decayed in the ways that were predicted so now we're studying its properties more and it turns out it does seem to correspond to this simplest model and that's why they knew where to look precisely and found it and we're being and it's being studied more to see what it tells us beyond the standard model in some sense people say that it's part of the standard M it sort of told us the standard mall is right it's sort of the Capstone something that had to be there and so we sort of understand the standard mall but there still are these remaining questions like the weedness of gravity that we're still trying to answer and we're hoping the large hatman collider will tell us something about and so this is a little advertisement but I had an ebook where I told you some of the ideas about this out in paper back in the fall um so where do we go from here which is of course another question that as soon as people are happy they understand the higs like so what's next why is the large hydron collider still running well there's a lot of questions that we don't answer and those questions might tell us something even more deep and fundamental not just about elementary particles but really about the nature of space and time um we don't know that that's true but those are the as I said the question of the weakness of gravity turns out to be a really hard problem to address and it seems like whenever we find a solution it really involves something deep and fundamental so if we find the answer to that we might learn something really exciting and as I said it could be symmetries it could be a new dimension so I'm going to very very briefly how we're doing on time here tell you an idea about an extra Dimension um actually we're doing okay but I want to have time for questions um so um I just want to briefly tell you just the schematic of why we think the idea of an extra Dimension could be relevant to answering this question give you a slight flavor of what it is and then give you a clip from the Opera okay so what are the goals today well of course we want to go beyond what we know about this D mod so we're going to try to understand the higs better but we're trying to look for new things we're trying to take advantage of the fact that we are at this distance Frontier this scale Frontier this energy Frontier and one potential big idea is the idea that there could be another dimension of space beyond the three we know about forward backward left right up down those are the ones we see but if I've taught you anything I hope you realize there's a lot of stuff we don't see out there in the universe we don't see in our daily lives so it could even be that there is a dimension of space very hard to picture I can't picture it any more than you are than you can um but we can think about it in many different ways and there could be a dimension outside those we observe and they could perhaps be relevant for our universe now why would we think about such a crazy idea well one is we actually don't know that there are three Dimensions we know we've observed three but maybe there are more and in fact if you look at Einstein's theory of general relativity that tells us about gravity it works for any number of Dimensions so maybe there are more um something called String Theory which I think Aspen audience that's all heard about um uh theory that combines together quantum mechanics and gravity actually tells you that there are additional Dimensions the question is are they relevant for anything we actually observe but I think for me the most interesting reason to study it is that it actually gives predictable consequences if it occur if they have certain properties and it could actually explain or address the kind of questions we were talking about earlier like this question of the weakness of gravity so I'm just going to very schematically tell you why an extra dimension of space could be relevant for this question of the weakness of gravity with some work that I did with Ramen syndrome so you need one more big idea before I tell you this and that is the idea of a brain world so I said we could possibly have an extra Dimension but within that extra Dimension there could be lower dimensional objects even three-dimensional objects which we call brains it stands for it's like membrane so if you think of a shower curtain in a two-dimensional shower curtain in a three-dimensional room there can be lower dimensional objects where stuff gets stuck on it that doesn't get explored so it doesn't explore all the dimensions of space and in the same way our entire universe which certainly seems to be three dimensional maybe really is three-dimensional maybe it's only gravity that experiences these extra dimensions and we really are stuck in three dimensions which of course would explain why it looks to us like they're only three dimensions of space so let's assume for the moment that we do live on a brain world that is to say we and our universe and all the forces except for Gravity really are stuck on a three-dimensional brain within this higher dimensional world what Ramen and I found is that the strength of gravity actually varies as you go into the extra Dimension if you have one extra dimension of space surrounded not by one but by two brains that bound this universe again rather abstract concept I grant you but suppose that we are on a threedimensional brain and there's another one it could turn out that gravity is really strong on that other brain and we found by using Einstein's equations of general relativity that it actually varies exponentially in strength so that it could be very weak weak as long as you're not really just right on top of that gravity brain so actually the strength of gravity varies as you go out in ex Dimension extraordinarily quickly which would very naturally explain why gravity is so weak or why we experience so weak and one of the remarkable things that this is that this is actually a testable idea even though it's this abstract idea about an extra Dimension they're actually experimental consequences and those consequences are in the form of particles particles that travel in that extra dimension they're called cutline particles they're named after the physicist and mathematician who first thought about these kinds of things they're particles that travel in the extra Dimension they look to us like ordinary particles but they're heavier why are they heavier because they have momentum in the extra Dimension so when the large hron collider turns on again you could have protons Collide they could produce one of these particles just like we talked about in Zeb ozon being produced before you could produce one of these cut toim particles and it itself could Decay into particles of the standard model thereby telling us that there's actually this extra Dimension so that was all for the physics and I promised you an excerpt from the Opera which is just kind of fun I don't know if the sounds going to work but it was um somebody a composer who works at aircom um again a premiered at the pomp Center um has been several places since then I wanted to do something he writes electronic music where he could really use the idea of an extra Dimension just to really have physics and and explore his composing in the context of this extra Dimension but also to think about the ideas of what drives creativity for a composer or drives there for physics so you wanted something where there really was physics if you look at most movies or things about science they really rarely actually have the sence in it so it really was kind of fun to have something extra dimension in fact it have more physics than I would have put him uh so he he forced it but I'll just give you a little bit of a sample if I can make this work so there were two people one who's in the three threedimensional world one who's exploring the higher Dimension you can see it [Music] di we had to figure out schematic problems like where do you put the orchestra if you're in the pomp Center in the ground St because they don't have an orchestra pit so we have behind a translucent screen um he really did want physics so he actually picked out an equation that he wanted in there so she actually sang in which I found hilarious um and he's exploring and Matthew Richie did the so he did the videos and the and so they're trying to reconcile their two points of [Music] view okay so again just to refer to what I said in the beginning there were two kind of two themes I wanted um you know what we're exploring today La dark matter what they call the world's Top Model just the model building kind of work we do but also really ideas about what goes into scientific thinking and ideas that I think really could be applied more broadly what it means to be right and wrong what is the role of uncertainty when we say something we don't know it 100% so presenting things with the uncertainty in what we say how to use measurements the role of scale which we did talk about in organizing thoughts and the role of Truth and Beauty in understanding how we move forward and of course the role of creativity so I'll close with one final slide I think is kind of silly but to say it's important to know where to look and this is um this is actually a friend of mine writes for The Big Bang Theory so I was given the task of being um in the in the lunchroom and be inconspicuous which apparently I did extremely successfully unless you know where to look you don't know him there even though I'm like right in front of you so that's basically the side so that's why you have to know what you're looking for and where to look cuz even something right in front of your eyes you're not going to see it so I will now stop for for questions thank you yep how do you know when you have a correct answer to one of your various questions right and that's a great great question so first of all from a theoretical point of view you want to make sure it all fits together you want to make sure that it's consistent with everything we know before that we can work it out but of course that's why we even though we're doing Theory we care about measurements because we want to have testable predictions so if they found something that looks like what we said then of course it's right but if they don't we won't so this theory of dark matter it turns out there are tons of testable predictions that people didn't know about so we're working out what they could be so when they look for Dark Matter could they find could they find this kind of thing so that's why I I failed to say this but it's one of the reasons why I think theory is so important because experiments today are so difficult that unless again unless you know where to look you don't see things so one of the things we're doing is telling them what to look for and and tell them what the implications of what they're measuring are yeah how are they so how are they so sure that they have found the higs BOS on right so that's a great question so when if you have a particle so first of all we don't know for sure that it is the hix boson and you'll hear there very careful wording about it because it's a hix bosan now why do we why do we think it's even a hix boson well it turns out that that particle decays in different way way it decays to photons which I know sounds weird because they're massless but as a quantum mechanical effect it can Decay to photons which are the particles that communicate light it can Decay into other heavier particles again and you can predict how often it should do each of these okay furthermore when you reconstruct what those particles look like you'll see that you get what we call a bump right so if you if you found took everything and then tried to deduce what was there you could figure out what the mass of that object is if you know its energy and its momentum momentum by knowing its Decay products you can figure out the energy and momentum of what was there and you can thereby calculate the mass so if you see a whole bunch of stuff piling up at this particular mass that isn't predicted by the standard model you almost certainly have a new particle now of course to really know that you have to understand what the standard model predicts what the so-called background is it's a very tricky thing so you have to make sure that it's you really are seeing the new thing and not just some accidental fluctuation of the old stuff but if you see that if you see enough events then you also so then you say well there's a new particle then you say what is this particle and then you look and say does it decay in the different ways that I would predict based on the idea that it's associated with giving particles masses so you can calculate both how often it should be produced and how often it should Decay based on its mass which was the only thing you didn't know if it's a standard particle so you really have all these detailed predictions and that's what they're doing and that's that's why they thought it was a hi bone yep Rick still confused and maybe that's normal you have the higs mechanism you have the higs B on and you have the higs field are they three independent entities or effects or are they is the on would Hicks field be there okay so first of all there's and there's also of course Peter Hicks okay so so there's the higs mechanism which is sort of the whole theory of how particles acquire in their masses acquire their masses in the presence of a Hig field okay so Hig field is an essential element of the Hig mechanism and it's that field is essential to them getting their masses now what a particle is and this is a very quantum mechanical kind of idea is if you add energy to that field and it fluctuates so for example if you had an electric field and a fluctuate you could produce particles which are photons you could produce actual particles so if you have this Hig field and you have enough energy you can produce the particles which are hix bons and so when you have this giant collider you have enough energy to make the actual particle which is a fluctuation of the field it's not something that's around at all time it's not there in the background but it's there when you have enough energy and that part but because that particle is a fluctuation of the field that's why you know its properties because it interacts with particles the same way that field interacts with particles that is to say the heavier ones interact more the lighter ones interact less um in the excitement of the confirmed discovery of hick oon particle it was said on CNN so it must be true that um this meant that we could now rewind the videotape back to the big bang and to before the Big Bang could you help a visual artist understand is that true yeah I can help a lot no oh thank oh thanks um we can go so so just let's think about what this means okay so the universe so the standard Big Bang Theory which which is ironic because it sort of tells you everything except what banged in the beginning it doesn't tell you the very beginning but it tells you how to trace back in time or how to go forward in time now we what we do know is that the Universe was very hot and dense in the beginning and then it cools down as it expands so I told you that this energy scale which probably is a meaningless unit to you but it's about a teev so the universe starts off at a much bigger energy scale about 18 ORD of attitude bigger but it very very quickly cools down to the scale so you're looking back to this time when the energy is about a TV you can't look be beyond that I mean that's why we try to make experiments that go to higher and higher energies because you get closer and closer to that beginning and you get closer and closer to the answers to those questions but it's not looking that early on a time and it certainly isn't looking before the Big Bang is time linear it's time linear um I'm not really sure what you mean by linear have to exist on the xais um it depends what you mean by the x-axis right um I mean I'm not being fous okay there's an additional Dimension as you describ couldn't that involve non so so there's so there's often confusion about this and it's actually is one of the more how space and time get mixed up because of Relativity what it does seem that the only sensible theories we have are theories where time has a direction it moves forward and there's only one dimension of time doesn't mean it's it doesn't mean that everyone scales it the same way in fact time gets in addition to space being rescaled in warp Dimension time gets rescaled which means that the clock use in one place could be different than the clock use in the other but that's sort of a question of how we're measuring time but in terms of the actual time itself it does seem to be something that we can only at least make sense of if there's a single dimension of time and a single Arrow of time at least where we are yes you can you please wait for the m if there was a Randall particle what would you want that to be um um well this clut the theory that we did with the expension is actually known as Randall sendin Theory so we call it a clut aine particle but that would probably be the most likely it would probably be called a Rand sundrum particle or if if anything got named after me that would be it if it was F but probably won't happen but it' be nice if it was yes thank you in science um there's lots of um evidence that perception of beauty equals a truth and you mentioned that in um so how does that correspond to particle physics yeah so I actually have a whole chapter about this um because you know that again this is a question of sort of how you make your guesses what you do mon so people often talk about beauty as if that's the goal I mean I think what I would say in science is that economy is the goal you want things to be as simple as possible because then you can make more predictions but of course if you look at the world around us in many ways it's beautiful and many ways it's very messy so we're not just studying symmetries we're studying symmetry breaking which actually the higs mechanism has to do with two so we're not so you know I I it's like if you look at you know completely symmetric things they're not really beautiful they're orderly and they're nice but if you look at something slightly skewed that's kind of mostly symmetric but has a little bit of unsymmetric stuff in it that actually is quite beautiful often and in fact that is often what happens in physics you're looking for sort of organizing order but then you're looking for why don't we see that order represent in the universe so you're trying to get to a theory that's as predictive as possible and of course you know but there's but you know there's a lot to say about that because of course what I see is beautiful what you see is beautiful what a single individual sees is beautiful over time changes so some theories that were considered ugly in the beginning we now consider incredibly beautiful and theories that were considered beautiful are now considered ugly so it's not like there's one particular Criterion but I do think there is some sort of sense you have of something being too complicated if you have to add a new ingredient to explain every new phenomena that's not science you want something that where you can make predictions is that the new book yeah and knocking at's door do you yourself believe that there's a unified theory of everything um I talk about that too you know so I'm not the biggest believer in a unified theory of everything but even even if there was a physics theory that was most fundamental again this notion of scale is very important because even if I knew all the fundamental ingredients that doesn't explain say how our bodies work you're you're not going to be able to derive it from those most fundamental ingredients you're going to need what we call effective theories theories that work at different scales because it's just too complicated like even though we know quantum mechanics and relativity when we predict what happens when you throw a ball we still use Newton laws because they're good enough at that scale at which we make measurements so it wouldn't be a theory of everything it again and I think this is really important because I think it's a misunderstanding a lot of people have and it's in part because it's presented wrong but when we look for fundamental structure we're saying that that structure is essential to what's there but that's not the same as explaining what's there I mean you can understand the forces that exist at that fundamental level but then you still have a lot of questions about how it turns into all the interesting structures that we see so those are separate questions so it wouldn't be a theory of everything even if it was a theory of fundamental structure so again I talk about and I and I talk about that too because I think it's actually at the root of a lot of PE things people say incorrectly about Ro of religion and all these sorts of things because they don't understand what it is precisely that science is saying sometimes um a less detailed question um where the the hadron colliders in Geneva was there also a the Swiss French border yeah was there also one in Chicago and did that change and why you talk about where the research has taken place over time and yeah so basically the over time there have been bigger and bigger colliders that have been built that can explore higher and higher energies in fact there was a m the biggest machine before the large hron collider had about 17th the energy um was something called the tatron it was located near Chicago at a place called FY lab and that actually very recently shut down so we no longer have a big high energy it's the first time that we are not the country that has the big high energy collider there's one like we said in Europe but we don't have it here there was one that was proposed for here that they even started to build that would have been three times the energy even of the LHC which was the Super conducting super collider that they started to build in Texas in the 1990s but then that got stopped by Congress so so we don't have a high energy collider now China um not yet um but we'll see what happens of course you know people I mean there's actually talk of a machine being built in Japan um actually I don't know if it'll be true it won't be a higher energy machine but it'll be a more precise machine they'll collide together not protons but electrons and positrons so there's some talk about doing that what's the difference between what's the difference between this one and CERN what's it CERN isn't there something so the large hon collider sorry I didn't clarify that it's a machine it's located at CERN so CERN is an accelerator complex it's a big Research Center it usually has like one big Flagship project which is now the LC but they do have other research projects going on as well and so CERN is the organization Lisa thank thanks so much um for your very informative talk I just wanted to let the audience know if you are really interested in these themes of dark matter and dark energy we're going to be exploring them more tomorrow in this same room at the same time in a session that I'm going to be moderating with Dan Hooper from Fairy lab and Richard Massie from the UK called we are the 5% uh identifying the hidden 95% of the cosmos so please join us for that okay and there's also the session at noon at the derome if you want to hear more yes doing it's a lot of stuff about physics this year it's kind of plenty of stuff about interesting physics tomorrow one more question there and I guess we'll be up soon um I'm really looking forward to reading your books I'm a non-scientist where where would you encourage people who are non-scientific background type people to get who are really interested in this subject era where would you say okay start reading this now and go to here here here here and here or just look at your bibliography online or what would you recommend um I always have trouble with that because I mean and and one reason I do is I really do think there are many different readers there are some readers that really want everything laid out for them right away there's some readers who will know that they're not going to understand everything on the first past at one point I was asked to give a list of books to Amazon which um like 10 best and honestly it was totally random because I don't really read these books I did look a little bit um so I mean you're better off asking someone who's a friend but I do like to think that you can learn something from reading my books which is why I write them but there's but I will tell you I do actually try to give the full science story so there are some that'll be that'll um have less that seem easier but they will give you as fullest story thank you Lisa

Channel: The Aspen Institute

Views: 141,284

Keywords: matter, universe, Aspen (City/Town/Village), lisa randall, Aif2013, aspen institute, space, aspen ideas festival, higgs boson particle, Physics (Idea), Hadron Collider

Id: 0eaWHUMjgqk

Length: 54min 36sec (3276 seconds)

Published: Wed Jul 10 2013