Sean Carroll - The Particle at the End of the Universe

good evening everyone I'm Alec John the journalist at the Guardian I'm going to speak just for a couple of minutes just to introduce Sean it hit see him not me and I won telling you a bit about Sean Carroll you you obviously know enough about him to be here and hopefully read his book or you're going to read his book after you've bought it outside outside afterwards but Sean is a theoretical physicist at Caltech this is the institution of Fineman and many other nobel prize-winning scientists it's also he is a specialist in dark energy in general relativity amongst many other things until recently he's also a very prominent blogger at cosmic variance this is a group blog very famous he's all his own blog now and he's a he's a big voice in the worlds of science communication he's also paid on lots of TV shows in the u.s. TV shows I hope one day we'll be shown here including through the wormhole with Morgan Freeman I want to know if he knows more than Freeman later on if he does get the stories about that later on and he's also been most importantly on The Colbert Report which as we all know is a very important topical news program in the States he's also science advisor to many many Hollywood blockbusters if you've got questions at the end of this about the science and the Avengers he is the man that made all that happens so you can ask him all his questions including what's in Avengers 2 Sean is also of course an accomplished author in January 2010 he wrote a book about the arrow of time it was called from eternity to here and his latest book is about the Large Hadron Collider the search for the Higgs boson and the people that made it happen he might even be able to tell us what it is they actually found at the Large Hadron Collider last year in July this Higgs like thing what is it so please welcome Sean to talk about his book the particle at the end of the universe how the Higgs boson leads us to the edge of a new world thanks Alec thanks everybody for coming here tonight thanks the Royal Institution for inviting me to speak it's such a historic venue and much like Michael Faraday sitting in the audience when Humphrey Davy was giving talks way back in the day you too can tweet what is going on as in real time with the hashtag our i particle and i really sincerely want to say how wonderful it is to be not only right here where all these events happen but also in london the spirit of the city and the country is a little bit different than in in my home country of the united states which is sort of like the little baby cousin of england and one of the one of the ways in which this manifests itself is when I am on the Twitter machine myself and I see things like London for lovers suggesting that the particle the end of the universe that's the fascinating date for the science lover so I hope that some you made it you presumably know why I'm here and why you're here on July 4th this year I was lucky enough to be in Geneva Switzerland at CERN the giant particle physics laboratory and home of the Large Hadron Collider the largest machine ever built by human beings and what was happening on July 4th were two PowerPoint presentations very exciting sufficiently exciting that there were plenty of physicists in their twenties camping out overnight to get good seats in the lecture hall just like this I mean none of you guys were out there I was here at 5:00 a.m. and you were not there camping out for the good seats but they were there they wanted to not miss these PowerPoint presentations it was like a rock concert with a lot more Macintoshes open on their laps and then in the actual audience for the PowerPoint presentation they were physicists in their 80s breaking down with emotional a reaction to what was being told to them and what was being told of them of course is that we discovered a new particle of nature something that we think is what we've been looking for for many decades now the Higgs boson but you know there there's particles even discovering particles for a long time why is it that this particular event was so important to so many people so the question of the talk that I'm going to try to answer is what's the big deal why do we care so much why did people line up ahead of time camp overnight in not very comfortable conditions just to get third row seats for a couple of PowerPoint presentations in the early morning in Geneva Switzerland well physicists knew this was coming it was not a surprise we've been looking for this particle for a long time we had hints that we were getting close to it part of the result of these hints was that I wrote a book about the whole thing that you can buy right out there in the lobby and so we weren't surprised and yet we've done a very very bad job of explaining why this discovery is so important it's not that we haven't tried physicists have tried to come up with sort of clever labels and things to sort of impress upon a more general audience that this is a big deal some of those labels are frankly not a good idea and we're regretful that we have invented those labels we've moved on from those but we still haven't really quite nailed it and I had a theory as to why we are not able to explain the Higgs boson very well the theory is that we use the wrong starting point the kind of starting point we use to discuss particle physics is this guy does anyone know who this is a portrait of okay you don't know believe me this is a this is purportedly a portrait of democritus Democritus an ancient Greek philosopher 2,500 years ago essentially Democritus was the first theoretical particle physicist he was the guy who really pushed an idea that also his predecessor also pushed but his predecessor didn't write anything and publish or perish in the academic world so Democritus was the first to commit to print the idea that the world is made of atoms as he called them what we would now call elementary particles because our 19th century forebears skipped ahead and called things atoms even though they weren't truly elementary but that the democraty idea is really so astonishing that we should step back and really appreciate what he was saying you know if you look around you there's air there's wood there are desks uh there's metal there's there's other human beings these substances appear very different right they've different properties they look different they react differently and yet Democritus says they're not fundamentally different they're just different arrangements of the same underlying stuff called atoms and that idea it took a long time to get it right it turns out to be right and what we now the descendant intellectually of democritus's ideas are what we call particle physics now of course because he lived 2,500 years ago there's no surviving image of what Democritus actually looked like all there is is a surviving nickname that he had the Laughing philosopher so because that was his nickname he was a very very popular subject for portraiture in the Renaissance because the portrait painter could just paint a self-portrait of himself laughing and then label it Democritus so this is Rembrandt self-portrait label Democritus we have no idea what Democritus looks like but we give him credit for launching the bandwagon we currently knows particle physics the problem is that particle physics as an idea is not the right way to think about the Higgs boson and that's the stumbling block that we're all faced with so rather than go back to Democritus I like to talk about the Higgs boson by referring to these guys a younger generation of important thinkers these are Americans you might not be familiar with the phenomenon as we might say this is the Insane Clown Posse these two young gentlemen this is Violent J and that's Shaggy 2 dope these are not the names that their mothers gave them but they they're artists and this is a thing in the United States these guys paint their faces and they're they have followers called Juggalos who have big events and they're rappers they're musicians so a couple of years ago they shocked the world by you know most of their most of their songs involve rather autre activities violence you know their partying that's what they do so a couple years ago they shot the world by having a reflective tune about the miracles of the world all around them the tune was called miracles and if you read it they say I see miracles all around me stop and look around it's all astounding water fire air and dirt freakin magnets how do they work fricken was not the word but you can google it you can look it up now the boys received a certain amount of disapprobation from the scientific community by saying magnets how do they work we know how magnets work much of it was demonstrated right here what I'm standing many many years ago so we do have a working scientific understanding of the esoteric phenomenon known as the magnet but I nevertheless want to give them a little bit of credit because even though we understand it even though we have equations we can attach to this idea it is still astounding think about a magnet a magnet is something you can attach to a piece of metal right it'll stick to it a refrigerator or so forth you can stick lots of things to lots of other things you can stick pieces of tape or gum or whatever but when you take a piece of tape to the refrigerator the tape has to touch the refrigerator in order to stick the gum has to touch the refrigerator in order to stick a little insect or gecko walking up the wall needs to touch the thing in order to stick to it a magnet if you hold it close to a piece of metal you can feel it pulling before it touches the magnet reaches across empty space and exerts a force and that the refrigerator exerts a force back according to Sir Isaac Newton that pulls the two things together they don't need to touch each other how is that possible how does the magnet know that there is a refrigerator nearby that it should be attracted to so the answer well I'll tell you the answer but first I'll tell you that there's not just these modern-day philosophers who are puzzled by this there's an older natural philosopher who was puzzled by this we've already given him a name Sir Isaac Newton was very puzzled by this phenomenon which is known as action at a distance Newton was interested in gravity not magnetism but it's the same thing the earth exerts a force on the moon or satellites orbiting the Earth they're not touching each other the earth seems to push out across empty space to exert this for on things in its vicinity Newton said that you can understand gravity throughout the universe in terms of an inverse square law the force of gravity becomes weaker and weaker as you move away as the distance between the two objects squared okay so but he was very worried in fact he said that this phenomenon of action at a distance made no sense even though it was part of his theory to to Newton the action at a distance aspect of his extremely successful theory of gravitation was much like contemporary physicists think about quantum mechanics an incredibly successful phenomenology a set of rules that fits the data - wonderful precision and yet deep down in our bones we think it makes no sense we can't quite make sense of it and Newton's problem with action at a distance was actually solved by another philosopher / scientist Pierre Simone Laplace Laplace came up with a new theory of gravity it turns out it wasn't really a new theory of gravity was the same theory as Newton's no one talks about Laplace's theory of gravity it's a way of rewriting Newtonian gravity but it's a way that gets rid of the action at a distance well the plaza says is that instead of just thinking about you know random forces between objects very very far away imagine there is a field filling the universe and what that means mathematically just that at every point in space there's a number the number the value of the field just like the temperature of the air in this room and every point there's a value the temperature at that point of the air but this is not some phenomenology of the matter this is this a fundamental feature of reality the gravitational potential field and the way it works is that near the earth here's the earth and it's this curve is the value of the gravitational potential the gravitational potential field it's pushed down by the earth then it just climbs up smoothly and the gravitational force that an object feels is just the slope of that line the amount by rich the rate at which the gravitational potential field is changing so there isn't anything acting instantaneously and spookily at a distance there's a smooth change from the position of the earth to the position of the moon the gravitational potential is very low here the earth and it climbs upward as you go toward the moon and that change keeps going forever so the earth is affecting something that stretches throughout the entire universe the gravitational potential field there's nothing acting instantaneously across a very large distance and this idea of a field turns out to be quite useful wasn't just Laplace in fact in the minds of physicists the person whose name is most closely attached to the field concept is Michael Faraday who gave the lectures right here in this very spot he said that the way to think about electricity is in terms of the electric field and that's what we do these days we talk both about particles and about fields in one sense a particle in a field are the opposite of each other right a particle is something that is one location here's the particle it's nowhere else a field is the opposite of that a field is everywhere at every point in space there is a value of the field so if you look at the picture up here on the Left these are tracks of particles through a cloud chamber there are individual lines a particle moves through the chamber and leaves a little trail behind there curving because they're moving in a magnetic field on the picture on the right there is a magnet you can't see the field lines directly but they're traced out by the little iron filings that are in the vicinity of the magnet so you can visualize the fact that around this magnet there's an invisible field filling space so particles and fields are the two things the physicists talk about when we talk about the ingredients that make up reality if you have a tiny bit of physics education you may have come up against the question is light for example a particle or a wave a wave is sort of a vibration in a field so what what is more important is it the particle aspect of reality or is it the field aspect of reality it's fields that's the answer it's not a mystery they always tell you that question they never tell you the answer I what decades of my life so what's the answer to this this is the answer it's fields any questions about that so I'm going to go into a little bit more detail but not too much but this is the crucial slide okay there's no more information nothing more to come on this slide the reason why the Higgs boson is a concept is hard to grasp it's because you need to stop thinking of the world in terms of particles you need to start thinking of it in terms of fields and you say to yourself well but things like this table are made of atoms and atoms have electrons and so forth in them and and electrons are particles right there are particles in the world no there aren't that's the secret that we physicists have never told you but here I am I'm going to tell you right now the reason why you're allowed to think of particles is because of quantum mechanics the world is made of fields but quantum mechanics says when you look at the world you don't see it directly what really exists according to quantum mechanics is immensely richer than the things we can actually observe so the reason you think that there are particles is because there are actually all these fields fill the empty space at every point in space there's dozens of little vibrating fields in front of you but quantum mechanics says that when you look at the fields closely enough they resolve into individual particles so on the picture on the right here is from David Deutsch and Oxford physicists one of the founders of quantum computation theory and he says imagine you are a frog he doesn't care whether you're a frog or not but frogs it turns out have slightly better vision than human beings do and what that means is that frogs can see individual particles of light photons you're all seeing light from the light bulbs here from the screen and so forth light is two things right light is a wave in the electromagnetic field so there's a field filling space at every point here there's a little electric field a little magnetic field there vibrating and that's the light that is coming to you the quantum mechanics says you look at that light very carefully it turns into individual particles called photons photons are the particles that you see when you look at a wave in the electromagnetic field so if you think a light bulb or a lantern and someone is moving it away from you on a dark night it gets dimmer and dimmer as it goes out in the distance and to you it just fades away but if you were if your vision were better if you were as good as a frog at looking at things it would stop getting dimmer and start flickering so there's a point below which the brightness never goes it just becomes more intermittent and what's happening is you're making a transition from seeing lots of photons all at once to seeing individual photons hitting your eye the reason why light resolves into photons is because quantum mechanics says that when you look at it that's what you see the relationship between particles and fields is that fields are what the world is made of particles are what you see so the atoms in this table the electrons the quarks the protons these are all vibrations in fields there's a quark field that is vibrating you look at it you see quarks there's an electron field that is vibrating this neutrino field that is vibrating is a gravitational field that is vibrating and so on and so on that's quantum field theory it is be very Hart the central organizing concept of modern physics and no one tells you until you buy my book all right so let's put this in a little bit of context let's imagine where we were a few decades ago in the 1930s at the birth of particle physics which you now really know should be called field physics but we'll stick with the old way of talking about it in 1935 you could have been accepting if physicists were getting ahead of themselves a little bit because they had these three particles they had this vision of what the universe was there were atoms that made up this table the air you and me and they knew what the structure of the atom looked like there was a nucleus in the middle that had protons and neutrons big heavy particles stuck together there was electrons orbiting on the outside and the electrons are attracted to the nucleus by the electromagnetic force there is also the nuclear force inside the atomic nucleus that was holding the proton and neutron together and there's gravity that is holding the whole shabang gravity says that every particle pulls on every other particle and you look at this picture circa 1935 and you say that's a picture that seems to fit reality pretty well out of these ingredients you can make everyone you ever met you know the people you like the people less so they're all protons neutrons and electrons arranged in different combinations we have nevertheless science did not stop we kept doing things we discovered more particles and we complicated the picture a little bit too much but a little bit for one thing we looked inside the protons and neutrons and we found there were these things called quarks there's the up quark and the down quark combined in different ways to give you protons and neutrons so as far as that goes there was not an increase in the number of particles but instead of proton and neutron we say up quark down quark there was an increase in the number of forces we went from the straw from one nuclear force that held the proton Neutron together to two different nuclear forces the strong nuclear force that holds the quarks together the weak nuclear force then you can go through your everyday life and never notice the weak nuclear force is weak that's why they named it that way but nevertheless it is important if you walk outside in Los Angeles we have this thing where you walk outside you look up into the sky there's a bright spot that is shining down light called the Sun and sometimes it appears in England as well but the force the way that that bright spot called the Sun is giving out energy is essentially from the weak nuclear force when two protons come together one of those protons can convert into a neutron spinning off another particle called a neutrino and then they stick together and make a little atom energy is released and we have nuclear fusion so that's the new picture now for reasons we still don't understand these four matter particles neutrino the down quark the up quark and the electron for particles that make up matter turn out to be a single family of particles and there's another family and another family there are three generations if you like nobody knows why that's true it's the same pattern repeated three times that little bit is a mystery otherwise we have this picture and if you want to make it a little simpler I made a flowchart for you and you can go through the flow chart you want to know what particle you are here's the little questions you should be asking yourself so you have the three generations here's the up quark down quark electron and neutrino but then there are other generations of matter particles on top there are bosons and then way up all by itself in the corner there's this lonely little thing called the Higgs boson so why in the world with all the success of this picture of particle physics do we need other particle another field pervading the universe called the Higgs boson what goes back to the 1950s and 60s when particle physicists were trying to understand those nuclear forces okay if you think about it it's the nuclear forces that you don't notice in your everyday life electromagnetism every time you open your eyeballs you notice electromagnetism light is an electromagnetic phenomenon heat is an electromagnetic phenomenon remote controls laser pointers electromagnetism all the way down gravity you certainly notice that's easy enough you don't notice the nuclear forces and why is that it's because gravity and electromagnetism extend over very large ranges they can go in principle infinitely far they're not they're important not only in this room but in cosmology in the structure of the universe itself whereas the strong and weak nuclear force is only stretching very very short distance and that made no sense from the point of view of the 1950s we understood gravity electromagnetism but if we followed our noses and said well maybe the strong force and the weak force are just like gravity and electromagnetism we kept bumping up against a prediction that was obviously wrong the prediction was that gret that the strong force the weak force should also be infinitely ranged it was not a coincidence it was a prediction of the model and one way of saying that is that the particles that carry the forces the photon for electromagnetism the graviton for gravity are massless they move at the speed of light they have no weight unto themselves they can just travel throughout the universe carrying the forces with which they are associated and the math kept predicting that the particles that carry the strong nuclear force and the weak nuclear force should also be massless and therefore should give rise to long-range phenomenon but they didn't so this was a puzzle this annoyed people they figured it out and many Nobel Prizes have been handed out along the way it turns out just to make the lives of physics graduate students difficult the nature has chosen to use completely different methods of giving a short range to the strong nuclear force and the weak nuclear force the strong nuclear force think about if I go back to the previous slide think about that lantern that is being taken far away from you just like the force of gravity or the force of electromagnetism is an inverse square law the brightness of a lantern is also an inverse square law the brightness goes down by the distance squared as the lantern gets further and further away from you so somehow what we want is for the bright we want a strong nuclear force Lantern or a weak nuclear force Lantern to be very bright if you're very close to it and then get really really dim very very quickly as it moves away not gradually like electromagnetism or gravity so the way it works in the two cases are really different in the strong nuclear force the particles that carry the force are called gluons and they are massless but it says if someone has put a shudder around that lantern that they're carrying away from you so all the gluons bounce around inside the proton or the neutron and they cannot escape they're confined we say so they are indeed massless particles but there's a barrier passed which they can't go so if you're looking inside the proton the strong nuclear force looks really really bright and then as soon as you get outside you barely notice it at all Nobel Prize a few years ago for this discovery of confinement and thus the strong nuclear force the weak nuclear force uses an utterly different idea it says what if it's a foggy night what if you may have noticed this phenomenon here in England there's sometimes at night the air is full of something that gets in the way of you seeing fog or smog we have in Los Angeles it's an advanced form of fog and what happens is that the light gets absorbed on its way to you so you see a lantern right up close and you have no trouble seeing at all but if you move it further away you suddenly don't see it and the reason why is because the light is just attenuated by it keeps bumping into this field of stuff filling space smog fog or what have you so in the weak interactions that's how the universe works there's a thing a field a substance in empty space that absorbs the lines of force associated with the weak interactions meaning that the weak interactions can only stretch a little way before you don't notice it anymore and with that note what that turns out to predict is that the W bosons and Z bosons they carry the weak nuclear force are massive are very very heavy that is a prediction of the theory of this obscuration theory you might guess that this was not the idea of a single lone genius like Einstein it took many many sociable geniuses to put this idea together so here is my attempt to give some credit where it is due Phil Anderson was a condensed matter physicist who first suggested this idea that there is some sort of obscuring field that makes that makes force carrying particles get mass Francois Claire Robert Brout Peter Higgs Tom Kimble Gerald Guralnik and Richard Hagen all took Anderson's idea and made it respectable they made it compatible with special relativity they ripped down explicit theories and equations that we could go then solve and look for these guys tell the glass how Abdul Salam and Stephen Weinberg realized that the usefulness of this idea is not in the strong nuclear force but the weak nuclear force and they showed how it actually gave masks to all of the particles not just the W and Z bosons and your order toughed was the one who showed that the whole thing was mathematically respectable that the equations made sense and once it tuft came along he was a graduate student at the time by the way he showed all this made sense the bandwagon was launched he and his thesis advisor won the Nobel Prize several years later so what is this idea I've said it already but let me say it again because it is the deep thing that makes the Higgs boson so special so hard to understand and so precious to professional physicists even in empty space the Higgs field is not zero so I already told you that the world is made of fields there's an electron field neutrino field an electromagnetic field gravity field and if you go far away from everything else in the universe if you shield yourself if you're looking at a little region of space which is as empty as it is possible to be empty the fields are there but they're just sitting at zero they're not doing anything they're at their minimum energy state they're gradually vibrating a little bit because of the miracle of quantum mechanics quantum mechanics says you can't quite quiet down fields to a perfectly quiet state there's always a little bubbling and boiling because of the Heisenberg uncertainty principle but they're close to zero on average they're sitting there at zero so if you were to plot this here are all the fields in the universe out there in empty space there's some value that the field has here's where you are in space so electrons quarks gluons they're all just vibrating because of quantum mechanics in the vicinity of zero close to zero the Higgs field is different the Higgs field has the property that when you're out there in empty space and you ask what is the field doing in this little empty region of the universe it's not at zero it is displaced at some constant value it would take a lot of energy to move the Higgs field back to zero we say the Higgs field has a nonzero expected value even in empty space so the Higgs is also sitting there quietly vibrating a little bit because of quantum mechanics when it vibrates by a lot we call that a Higgs boson particle a particle is a substantial vibration in the wave but even when there's no particles around there's still the Higgs field it's everywhere you go you personally move through Higgs field as you travel through the day and that's crucially important to how your personal physics works because all of the particles that you're made up of interact with this Higgs field the weak nuclear force is attenuated because of the Higgs field but also the other particles that you're made up of get heavier because of the Higgs field so if there were no Higgs field turns out this is a whole long story that most of us just don't want to talk about so we just talk faster and faster which is exactly what I'm going to do turns out if you try to make our sensible theory the weak interactions you predict it not only is the weak interactions mediated by a massless particle but the electron is massless the up quark is massless all the quarks all the leptons are exactly massless if the weak interactions make sense if you don't have the Higgs field we know that's not right we know that the electron has a mass without the Higgs the electron would zoom around at the speed of light why would you personally care about that because if the electron were moving around at the speed of light it would not settle into atoms okay if there was no eggs filled filling empty space there wouldn't be atoms there be electrons and quarks and so forth but the electrons will be zipping around like photons at the speed of light everywhere in the universe they would not settle down make an atom there be no atomic physics therefore there would be no chemistry there'd be no possibility for two atoms to get together therefore there would be no I know you don't like chemistry but it's important to you because without chemistry there's no biology with biology without biology there is no life there are no lectures at the Royal Institution and so forth without the Higgs field life as we know it would be utterly impossible it'd be essentially that no one knows of a way that you can even get any interesting complex structure in the universe if it weren't for the Higgs field but you put a Higgs field there an empty space now that electron is moving through this thick treacly like Higgs field and it picks up a mass thereby instead of zipping along of the speed of light now the electron is keeps talking to the Higgs field all around it and it gets some heft because of that it has a mass it takes effort to get it moving the electron can now settle down we can have atoms we can have chemistry we can have life you're getting an idea of why this I this notion of the Higgs field filling empty space is so important to physicists important enough that we built giant machines to go look for it so just to summarize where we are the reason why the Higgs field is interesting is because it's based on a field that is not zero an empty space a purely theoretical construct from 1964 meant to address the question why are the weak interaction so short-range and ever since 1964 we've been looking for the thing and the Large Hadron Collider at CERN is the most recent version of our attempts to look for the Higgs boson the particle that you get when you set a vibration going in the Higgs field this is a pictorial illustration of what the Large Hadron Collider looks like this is the cern airport lake sorry the Geneva Airport Lake Geneva about one out of every 16 passengers that lands at Geneva Airport is associated with CERN in some way it's a big deal it's also underground you couldn't see it you know you notice it's under are these buildings people live right on top of the Large Hadron Collider zooming underneath them many numbers you can attach to show how impressive it is 27 kilometers around about nine billion dollars to make 10,000 people involved in the construction and operation of the thing what it does is it takes protons heavy particles made of quarks and accelerates them to 99.999999% the speed of light then it smashes them together and we watch what comes out okay this is what particle physical physics is just you know kids grown up given 9 billion dollars what are they going to do they're going to smash things together see what comes out the interior of the pipe through which the protons move is empty it's about as empty as they can make it it's more empty than the atmosphere of the surface of the Moon because you don't want your protons bumping into things along the way and also the protons you don't want to go in a straight line because then you can't bring them around to hit each other so the reason why 27 kilometers is because the set of protons hundreds of trillions of protons at any one time are moving around the total energy of those protons is comparable to that of a freight train moving at top speed so you want to have magnets that curve the protons around the ring you need giant superconducting magnets that are colder also than empty space colder than the universe itself 1.8 Kelvin it's a big deal it took a long time to make it a lot of credit goes to these guys Carlo Rubbia who was director general of CERN the European particle physics laboratory and really insisted that CERN plan on building the Large Hadron Collider even though the United States was planning on building a competing machine the United States ultimately lost its nerve and therefore rubia was right to do that and Lyn Evans a Welsh physicist who was given the task of guiding the LHC from from planning to completion he is the person who is most responsible for the LHC as we currently know it now let me pause for a little parenthetical extra talk that you didn't come here for but I want to give you anyway because when I give this kind of talk I love not only talking about the physics and the machines but also the people because science is a human endeavor right we do things it's human beings that make science happen it's not just falling down from the sky so I like showing you pictures of these people but you will have noticed all these pictures I'm showing you of the people they're all guys and you might get the wrong impression you might get the impression that it's only guys who do physics who are good at physics so I need a little parenthetical it's not that is what I want to make the point and because I'm a scientist I'm going to show you charts so these are data these are studies that were done by sociologists what they did was they made a CV a resume for job applicants and they gave them to professional scientists and this is not you know back in the 1950s this is 2012 they gave them to scientists and said who would you hire they did this for different people sometimes the person's name was John sometimes the applicants name was Jennifer on the left you see how they were ranked if their name was John and on the right you see how they're ranked if their name was Jennifer for competence higher ability mentoring and the salary that they would be paid if we did hire them exactly the same resume just different genders for the applicants and by the way so you see that women were consistently biased against even if their accomplishments were exactly the same as those are the male applicants and by the way the bias was absolutely the same for the male professors and the female professors everyone discriminated against women trying to get trying to get a break coming into science this is a problem that we have to do something about the good news is we are doing something about it the this graph is the percentage in the u.s. of women in PhD in bachelor programs in physics and it is going up like gangbusters and it's not you know if you look at the percentage of women in doctoral programs in physics from 1965 to now it's gone from 2% to 16% this is not because the intelligence of women has increased by a factor of eight this is because women and some men have complained about it and we're event we're gradually doing better so a hundred years from now when you come back to the RI because by that point we'll all be immortal and uploaded into the singularity and you hear about new results in physics there'll be just as many women having contributed them as guys so that's the end of my little mini talk in the middle there now let's build a hadron collider building something like the Large Hadron Collider is not something you are ever trained to do because it only ever happens once in the history of the universe you notice that there is this is a pretty big part of one of the experiments this is part of the CMS experiment many of the size constraints of the components that these experiments used come from the fact that they knew that at some point they would have to be trundled through a road of a small French village on the way from wherever they were built to the experimental site so this is as big as it could possibly be to get through there and no bigger than that then you dig a tunnel you dig it a to where you could lower the pieces down so you have thousands of these magnets that are the strongest magnets well that the largest-scale magnetic fields ever built to supercool the to make superconducting magnets you would lower them down there's very little tolerance it's a few centimeters on both sides you do this for thousands of magnets sometimes as you're building this you know they had to build a new tunnel because one of these there's two experiments Atlas and CMS that do the general purpose physics at the LHC they flip they didn't flip a coin but let's say they flipped a coin and one of them got to be close to the main CERN campus the other is at the other end of the Ring CMS had to be at the other end of the ring so they need to build a new tube to lower CMS to the ground and they only went a couple meters down when suddenly ancient Roman ruins I mean it's in the middle of the France Swiss border there's been civilizations been going on for a long time so the physicists get kicked out the archaeologists get brought in for six months as you carefully look through and they found you know coins in this little establishment from here from London as well as from Rome and from elsewhere and also the streets of the village obsessing where the CMS actually exists now our parallel to the streets of the ancient Roman village that were there so these streets never went away they were just you know improved and and built upon over the years eventually the archaeologists do their job they clean up you keep building you put it all together you turn it on and it explodes ten days after the LHC turned on in 2008 there was an explosion six tons of liquid helium were splashed around the floor had anyone been standing there they would have been hurt pretty badly safety procedures were in place no one was hurt at all but the LHC shut down for over a year this this was an accident of course it was not planned but it was an accident that would have kept happening if they just tried to push the thing so instead they shut everything down they went in they fixed everything tighten the screws check the wires and as a result when they turned back on in 2009 the machine worked really really well that extra year really sort of focused everyone's attention and since 2009 the Large Hadron Collider has been going like gangbusters there are as I said these two experiments Atlas over here that looks like an alien spaceship CMS both of these are very big neither CMS is a little bit smaller than Atlas neither one of them would fit inside this room if you want a little sense of scale I circled the people here so that's a person that's a person this is a particle physics experiment this is a beam where the protons are going to come and smash into each other these are giant magnets that help you detect the particles like I said the world is changing here the bosses of these two experiments Fabiola Gianotti is the boss of Atlas currently the boss is known as the spokesperson in the particle physics lingo Joe and Candela from UC Santa Barbara is the is the spokesperson for the CMS collaboration but each collaboration is over 3,000 physicists when CMS for Atlas writes a scientific paper there are 3,000 authors this is the tradition in particle physics everyone who works on the experiment is an author of every paper written not that they had read the papers that they were authors on but they are in the list of authors it is in every way overwhelming the LHC CERN particle physics as a whole it is you know a truly impressive monument to human beings trying to figure stuff out trying to figure out how the universe works they put together this amazingly complex machine it could have just not worked at all and it worked amazingly well some of the aspects of it are not in any way gargantuan my favorite part of the Large Hadron Collider is the source of protons so a proton is just the nucleus of a hydrogen atom so literally this fire extinguisher size things like this big it's full of hydrogen it is the proton source for the Large Hadron Collider they open the little spigot protons come out they zap the protons with electricity separate the electrons off they start accelerating the protons and you're off to beat the band hundreds of trillions of protons around the LHC but there are many more than 100 trillion protons in a canister of helium this canister of helium is enough to charge up the LHC with protons for about 10 billion years there's protons are not the scarce resource when you're building a particle physics laboratory so you take these protons you accelerate them the 99 point etcetera at the speed of light smash them together and this is what you get you usually get a mess you get a lot of particles coming out and the particles do not have little labels on them saying I'm a muon the particles come out with different velocities different susceptibility to colliding with other kinds of particles different electromagnetic fields and so forth so there's a tremendous amount of effort put into analyzing the particles that you see almost all of the collisions give you absolutely boring results because we understand physics so well that the known physics is almost every collision in the if you were to take the data produced at the LHC and write it all to disk you would fill up the largest database in the world in a matter of a couple of seconds you can't do that even CERN cannot write data to disk that well so they throw out about 999,999 out of every 1 million events they keep the data from about one event in a million so you need to be very careful to try to look at the good data you look at the data very very quickly look the event say is this potentially interesting okay I will keep it this one is very interesting you see the little blue lines these tiny blue lines are electrons these long blue lines are muons that's a hard thing to make at a proton proton collision it's not impossible but it's hard so you keep this one put it on your webpage try to analyze it what you're looking for is the Higgs boson and there's two problems when you're looking for the Higgs boson one problem is because of quantum mechanics you don't predict exactly what the Higgs boson decays into you predict the distribution of things it can decay into we could decay into bottom parts W bosons gluons etc so you have many many different channels as we say to look for things that could be produced by first making a Higgs boson in this collision and then the Higgs boson very quickly decays you never see the Higgs boson directly the Higgs boson decays in about one Zepto second you don't need to know what that is it's a very tiny period of time you could see things that happened on timescales as small as a millionth of a second Zepto second is way way tinier than that so you never see the Higgs boson you only see what the Higgs boson turns into and when the Higgs boson turns into something else the other problem is there are other ways to make that stuff so that if the Higgs boson decays into two muons and two electrons there are other ways you could have created two muons and two electrons so it's a matter of statistics so sometimes people say looking for the Higgs boson at the LHC is like looking for a needle in a haystack right is a cliched analogy it's also not accurate looking for the Higgs boson at the LHC is like looking for hay in a haystack it's like looking for slightly more hay of exactly a certain length than all the other hay that you have because if you create you know two W bosons by a Higgs decaying well you could have done that many other ways but maybe there's a few more than you expected because the Higgs boson decayed also so the kinds of things after many many hours of genius-level manpower go into this this is what you are left with if you if you look at the book that I mentioned that I wrote a book there's these two plots are in the book these are the only pictures in the book where my editor at first said no we don't to have that that looks to sciency looks too complicated and scary and I said we paid nine billion dollars for these plots you should put them in the book concei said okay nine billion dollars the price of the LHC these are the exciting results from the LHC as you see this is the number of certain kinds of events the particular events we're looking for is when you smash the protons together and two photons come out it's actually not that easy to get only two photons and no other junk coming out when you do that so this is a rare event you see that even though you have hundreds of millions of collisions per second at the LHC you only get thousands or hundreds of events this type and then you count up the total amount of energy in those photons and this is in weird particle physics units so we don't measure energy in kilowatt hours or something like that because then ordinary people might understand what we're talking about so we measure them in billions of electron volts and so for you know 100 billion electron volts hundred and ten etc here are the number of events like this that we produced at the Atlas experiment here the number we produced at the CMS experiment and you wouldn't notice it except for the fact that the helpful particle position a curve through it but there's a bump right there and right there that bump is what we call the Higgs boson there's a new particle why is there a bump there because all the other stuff is just sort of random nonsense that comes out because you've collided protons together the bump comes because there's a new way to make those photons first you make a Higgs boson 126 billion electron volts worth of mass and then the Higgs boson decays so you look for new particles by bump hunting by looking for slightly more events of a certain kind then you would predict if that particle weren't there you're looking for hay in a haystack slightly more hay of a very specific length now even though these bumps don't look that big there's two experiments that's very very important right so one experiment cannot just be pulling the wool over our eyes and they've analyzed to death these data with very sophisticated mathematical machinery there's no question that this bump is real there is a in the only way that we can think of to make it is a new particle with precisely that mass a particle that has all the properties of the Higgs boson we're not a hundred percent sure yet that it is the Higgs boson that was envisaged by Peter Higgs and his contemporaries back in 1964 but it it walks and quacks just like the Higgs boson does it's certainly a very Higgs like boson so somebody is going to win the Nobel Prize we don't know who actually I don't even know for sure if somebody will win it what I do know for sure is that this kind of discovery is better than Nobel Prize status it's you know some discoveries get elevated in importance by having a Nobel Prize attached to them sometimes the Nobel Prize gets elevated in importance by becoming attached to certain discoveries no question in the world the discovering this new particle is worthy at a science level of recognition such as the Nobel Prize the problem is there's a tradition among science Nobel Prizes that they can't give it to organizations they can only give it to people and they can't give it to more than three people for any one thing so how many think back how many people are on the experiment three thousand people on two different experiments how many people came up with the idea of the Higgs boson well you know six seven eight depend on how you count never three or less than that so nobody knows what will happen how many people built the LHC many thousands also there's at least three Nobel prizes that deserve to be given one for predicting that Higgs boson one for finding it and one for building Large Hadron Collider in the first place I have no idea what actually will be done no one's paying me to answer that question therefore I'm not going to do it but it's also not the end of the road we've been very very excited by discovering the Higgs boson I mean this is literally the idea of the Higgs boson came here on earth before I did I have never been alive at a time when we didn't know about the idea of the Higgs bow that's how long we've been looking for it that's why Peter Higgs got a little misty at the seminars at CERN when it was discovered that they actually found it I mean here's a young guy right you know graduate student postdoc kind of level and everyone everyone doing this at the time was very young and they were puzzling with this problem wire this nuclear forces short range they came up with this idea and they wrote it down and everyone ignored them and then over 40 years later someone says oh yeah here it is we paid nine billion dollars and we found it that's just science at its absolute working best but we're not done Large Hadron Collider was not built just to find the Higgs boson it was built to find new particles it just shut down for the moment it's good it's in the shutdown mode for two years now well they tighten the screws once again and they're gonna lift it up to a much higher energy so the LHC will turn back on in 2015 we're going to be peering at a regime of physical reality at which we have never appeared before so we're hoping to discover new things this is one example of what we're hoping to discover twice as many particles if you're if you wonder that maybe we just don't have enough elementary particles there's an idea called supersymmetry that says for every kind of particle we know of there is a friend called a super partner there are we didn't go through this because I'm just giving a one-hour lecture not a series of 12 1 hour lectures but there are matter particles in the universe called fermions and there are forced carrying particles called bosons and the real world the fermions we know bare no obvious relationship to the bosons we know but supersymmetry says that for every boson there's a Fermi on partner and vice-versa so because in the standard model of particle physics there is no relationship the idea is that there are new super partners and just you know keep our spirits up while we're looking for them we invent clever names if you have a Fermi on its boson ik partner gets an S at the beginning so there are squarks for the quarks so there are spot 'm squarks and so forth the bosons they're fermionic particles get an Ino at the end so there's a glue on a gluey no W and Z we nose and z nose and so forth and we're looking for these super partners if they exist and if they are within our reach the LHC will be able to find them they might not exist it turns out that the idea of supersymmetry is not just a cool idea it has all sorts of beneficial consequences it helps explain the dark matter in the universe it helps explain the mass of the Higgs boson it is it is part and parcel of superstring theory which is our most promising theory of quantum gravity so many people want supersymmetry to exist the universe does not care what we want you may have noticed so we may or may not find it but it is one of the things we're looking for as a bonus one of the things that supersymmetry predicts is that one Higgs boson is not enough if supersymmetry is right the world has five different Higgs bosons so even if the particle we have found is a Higgs boson it may turn out to be only 20% of the Higgs bosons that we will find in the years to come so we're very optimistic that cool new things will happen of course this is only an idea this is not data here is data here are data whatever you want to say we know that the standard model of particle physics is not the end of the story for the universe we know that because the standard model of particle physics makes up what we call ordinary matter it explains you and me and the table in the air and the Sun and the moon and the stars it does not explain the universe because we can map out the gravitational field of stuff in the universe and we see pictures like this this is a map constructed by looking at the deflection of light through galaxies scattered throughout the universe we can basically weigh the universe well we find is there's a lot more stuff than we can possibly account for then in the standard model of particle physics we call the extra stuff dark matter it's not quarks it's not electrons it's not neutrinos or Higgs bosons it's something absolutely new so we can't be done with particle physics there's some new particle called the dark matter particle or maybe twenty new particles called the dark matter of many different particles we don't know yet we're looking we're looking underground for dark matter particles to bump into things we are also trying to create dark matter or other particles associated with the dark matter at the LHC so it's absolutely clear not just a wishful thinking kind of thing that there must be new physics out there the LHC is on the mark to try to search for it we'll have to see if nature is kind or a little malicious to us in the meantime if you don't tune your telescope on the rest of the universe if you stay in this room and you think about your life as long as you're not a professional physicist or astronomer if you think about the physics the laws of physics underlying the phenomena that you experience every day so the table the chair the sun shining you and me rabbits and bunnies and trees and and grasses and bugs and so forth these are all made of particles described by the standard model of particle physics there are no new particles you need to describe bunny rabbits I can guarantee that because if there were quantum field theory says we could make them at the LHC we would have made them a long time ago as long as quantum field theory is right within the regime of a bunny rabbit we know the particles that make up the bunny rabbit protons neutrons electrons the quarks inside them and the four forces that hold them together and the Higgs field filling empty space was the last piece of that puzzle so on the last slide I try to emphasize that physics particle physics search for the ultimate laws of nature is nowhere near done we know we have a long way to go but as far as the fundamental physics underlying us particle physics is done we have done it July 4th 2012 was going to put the final piece of the puzzle of the matter that you and I are made of together we've been looking for this for 2,500 years since Democritus and we finally been able to do it we're not done yet there are worlds beyond our everyday experience but this moment in history is not going to be forgotten a thousand years from now we will remember the day that we found the Higgs boson that is why it is such a big deal thang you you

Channel: The Royal Institution

Views: 1,209,462

Rating: 4.7596741 out of 5

Keywords: LHC, Higgs Boson, CERN, Higgs, Particles, Physics, Quantum Physics, Dark Matter, Quarks, Sean Carroll, CMS, Particle Physics, Fields, Nobel Prize

Id: RwdY7Eqyguo

Length: 58min 6sec (3486 seconds)

Published: Fri Jan 18 2013

Reddit Comments

[u/DogBotherer]

Thanks for this, fascinating. Sean Caroll is great. I watched his series of lectures on Dark Matter/Energy for the TTC which is also to be highly recommended.