Harry Cliff: Particle Physics and the Large Hadron Collider | Lex Fridman Podcast #92

the following is a conversation with Harry Cliff a particle physicist at the University of Cambridge working on the Large Hadron Collider beauty experiment that specializes in investigating the slight differences between matter and antimatter by studying a type of particle called the beauty quark or B quark in this way he's part of the group of physicists who are searching for the evidence of new particles that can answer some of the biggest questions in modern physics he's also an exceptional communicator of science with some of the clearest and most captivating explanations of basic concepts in particle physicists that have ever heard so when I visit in London I knew I had to talk to him and we did this conversation at the Royal Institute lecture theatre which has hosted lectures for over two centuries from some of the greatest scientists and science communicators in history for Michael Faraday to Carl Sagan this conversation was recorded before the outbreak of the pandemic for everyone feeling the medical and psychological and financial burden of this crisis I'm sending love your way stay strong or in this together we'll beat this thing this is the artificial intelligence podcast if you enjoy it subscribe I need to review it with five stars in a podcast supported on patreon or simply connect with me on Twitter at lex friedman spelled fri DM aen as usual i'll do a few minutes of ads now and never any ads in the middle that can break the flow of the conversation I hope that works for you and doesn't hurt the listening experience quick summary of the ads to sponsors expressvpn and cash app please consider supporting the podcast by getting expressvpn and expressvpn calm / Lex pod and downloading cash app and using collects podcasts this show is presented by cash app the number one finance app in the App Store when you get it used code Lex podcast cash app lets you send money your friends buy Bitcoin and invest in the stock market with as little as one dollar since cash app does fractional share trading let me mention that the order execution algorithm that works behind the scenes to create the abstraction of the fractional orders algorithmic marvel so big props the cash app engineers solving a heart problem then in the end provides an easy interface that takes a step up to the next layer of abstraction over the stock market making trading more accessible for new investors and diversification much easier so again you get cash out from the App Store Google Play and use the collects podcast you get $10 and cash up will also donate $10 to the first an organization that is helping advanced robotics and STEM education for young people around the world this show sponsored by expressvpn get it at expressvpn comm / Lex pod to get a discount and to support this podcast I've been usually expressvpn for many years I love it it's easy to use press the big power on button and your privacy is protected and if you like you can make it look like your location is anywhere else in the world I might be in Boston now but I can make it look like I'm in New York London Paris or anywhere else this has a large number of obvious benefits certainly it allows you to access international versions of streaming websites like the Japanese Netflix or the UK who expressvpn works on any device you can imagine I use it on Linux shout out to a bunch of Windows Android but is available everywhere else to once again get it and expressvpn comm / flex pod to get a discount and to support this podcast and now here's my conversation with harry cliff let's start with probably one of the coolest things that human beings have ever created the Large Hadron Collider ohc what is it how does it work okay so is essentially this gigantic 27 kilometer circumference particle accelerators this big ring it's buried 100 100 meters underneath the surface in the countryside just outside Geneva in Switzerland and really what it's for ultimately is to try to understand what are the basic building blocks of the universe so you can think of it in a way as like a gigantic microscope and and the analogy is actually fairly precise so gigantic microscope effectively except it's a microscope that looks at the structure of the vacuum in order for this kind of thing to study particles which are microscopic entities it has to be huge yes gigantic Waxhaw so what do you mean by studying vacuum okay so I mean so particle physics as a field is kind of badly named in a way because particles are not the fundamental ingredients of the universe they're not fundamental at all so the things that we believe are the real building blocks of the universe are objects invisible fluid like objects called quantum fields so these are fields like like the magnetic field around a magnet that exists everywhere in space they're always there in fact actually it's funny they were in the wrong institution because this is where the idea of the field was effectively invented by Michael Faraday doing experiments with magnets and coils of wire so he noticed that you know if he was very famous experiment that he did where he got a magnet and put it on top of it a piece of paper and then sprinkled iron filings and he found the iron filings arrange themselves into these kind of loops of which was actually mapping out the invisible influence of this magnetic field which is a thing you know we've all experienced we're all felt held a magnet and or two poles the magnet and pushing together and felt this thing this force pushing back so these are real physical objects and the the way we think of particles in modern physics is that they are essentially little vibrations little ripples in these otherwise invisible fields that are everywhere they fill the whole universe you know I don't apologist perhaps for the ridiculous question are you comfortable with the idea of the fundamental nature of our reality being fields because to me particles you know a bunch of different building blocks makes more sense sort of intellectually so visually like it's it it seems to I seem to be able to visualize that kind of idea easier yeah are you comfortable psychologically with the idea that the basic building block is not a block but a field I think it's um I think it's quite a magical idea I find it quite appealing and it's well it comes from a misunderstanding of what particles are so like when you when we do science at school and we draw a picture of an atom you draw a like you know nucleus with some protons or neutrons these little spheres in the middle and then you have some electrons are like little flies flying around the atom and that is a completely misleading picture of what an atom is like it's nothing like that the electron is not like a little planet orbiting the atom it's this spread out wibbly-wobbly wave-like thing and we know we've known that since you know the early 20th century thanks to quantum mechanics so when we carry on using this word particle because sometimes when we do experiments particles do behave like they're little marbles or little bullets you know so in the LHC when we collide particles together you'll get you know you'll get like hundreds of particles will fly out through the detector and they all take a trajectory and you can see from the detector where they've gone and they look like they're little bullets so they behave that way um you know a lot of the time but when you really study them carefully you'll see that they are not little spheres they are these virial disturbances in in these underlying fields so this is this is really how we think nature is which is surprising but also I think kind of magic so here we are our bodies are basically made up of like little knots of energy in these invisible objects that are all around us and what what is the story of the vacuum when it comes to LHC so what why did you mention the word vacuum okay so if we just if we go back to let us the physics we do know so atoms are made of electrons which were discovered 100 or so years ago and then nucleus of the atom you have two other types of particles there's an up something called an up quark and a down quark and those three particles make up every atom in the universe so we think of these as ripples in fields so there is something called the electron field and every electron in the universe is a ripple moving about in this electron field the electron field is all around we can't see it but every electron in our body is a little ripple in this thing that's there all the time and the quark feels the same so there's an up quark field and an up quark isn't a ripple in the up quark field and the down quark is a little ripple in something else called the down quark field so these fields are always there now there are potentially we know about a certain number of fields in what we call the standard model of particle physics and the most recent one we discovered was the Higgs field and the way we discovered the Higgs field was to make a little ripple in it so what the LHC did it fired two protons into each other very very hard with enough energy that you could create a disturbance in this Higgs field and that's what shows up as what we call the Higgs boson so this particle that everyone was going on about eight or so years ago is proof really the particle in itself is I mean it's interesting but the things really interesting is the field because it's the the Higgs field that we believe is the reason that electrons and quarks have mass and it's that invisible field that's always there that gives mass to the particles the Higgs boson is just our way of checking it's there basically and so the Large Hadron Collider in order to get that ripple in the Higgs field you it requires a huge amount of energy yes opposes so that's why you need this huge that's why size matters here so maybe there's a million questions here but let's backtrack why does size matter in the context of a particle collider so why does bigger allow you for higher energy collisions right so the reason well it is kind of simple really which is that there are two types of particle accelerator that you can build one is circular which is like the LHC the other is a great long line so the advantage of a circular machine is that you can send particles around a ring and you can give them a kick every and they go round so imagine you have a is actually a bit of the LHC that's about only 30 meters long where you have a bunch of metal boxes which have oscillating to million volt electric fields inside them which are timed so that when a proton goes through one of these boxes the field it sees as it approaches is attractive then as it leaves the box it flips and becomes repulsive and the proton gets attracted then kicked out the other side so it gets a bit faster so you send it but then you send it back round again and it's incredible like the timing of that the synchronization that wait really yeah yeah yeah yeah that's I think there's going to be a multiplicative effect on the questions I have is that okay let me just take that attention for a second how the orchestration of that is that a fundamentally a hardware problem or software a problem like what how do you get that I mean I might so I should first of all say I'm not an engineer so the guys I did not build the LHC so they're people much much better at this stuff than I for sure but maybe but from from your sort of intuition from the the the echoes of what you understand you heard of house design what's your sense how what's the engineering aspects that the acceleration bit is not challenging okay okay there is always challenges everything but basically you have these the beams that go around you like see the beams of particles are divided into little bunches so they're called their bit like swarms of bees if you like and there are around I think it's something of the order 2000 bunches spaced around the ring and they if you were if you're a given point on the ring counting bunches you get 40 million bunches passing you every second so they come in like you know just like cars going past from a very fast motorway so you need to have if you're a electric field that you're using to accelerate the particles that needs to be timed so that as a bunch of protons arrives it's got the right sign to attract them and then flips at the right moment but I think the the voltage in those boxes oscillates at hundreds of megahertz so the beams at like 40 megahertz but is oscillating much more quickly than the beam so and I think you know it's difficult engineering but in principle it's not you know a really serious challenge the bigger problem this probably engineers like screaming at ureña probably yeah what okay so in terms of coming back to this thing why is it so big well the reason is you wanna get the particles through that accelerating element over over again so you want to bring them back round that's why it's round the question is why couldn't you make it smaller well the basic answer is that these particles are going unbelievably quickly so they travel at 99.999999 1% of the speed of light in the LHC and if you think about say driving your car round a corner high speed if you go fast you need a very you need a lot of friction in the tires to make sure you don't slide off the road so the the limiting factor is the how powerful a magnet can you make because it's what we do is magnets are used to bend the particles around the ring and essentially the LHC when it was designed was designed with the most powerful magnets that could conceivably be built at the time and so that's your kind of limiting factors if you wanted to make the machines smaller that means a tighter bend you need to have a more powerful magnet so it's this toss-up between how strong your magnets versus how big a tunnel can you afford the bigger the tunnel the weaker the magnets can be the smaller a tunnel the stronger they've got to be okay so maybe can we backtrack to the data model and say what kind of particles there are period and maybe the history of kind of assembling that the standard model of physics and then how that leads up to the hopes and dreams and the accomplishments of the Large Hadron Collider yeah sure okay so for all the 20th century physics in like five minutes yeah please okay so okay the story really begins properly end of the 19th century the basic view of matter is that matter is made of atoms and the atoms are indestructible immutable little spheres like the things we were talking about they don't really exist and there's you know one atom for every chemical element as an atom for hydrogen for helium for carbon photon etc and they're all different then in 1897 experiments done at the Cavendish laboratory in Cambridge where I am still where I'm based showed that there are actually smaller particles inside the atom which eventually became known as electrons these are these negatively charged things that go around the outside a few years later and it's Rutherford very famous nuclear physics nuclear physics shows that the atom has a tiny nugget in the center which we call the nucleus which is a positively charged object so then by in light 1910-11 we have this model of the atom that we learn in school which is you've got a nucleus electrons go round there fast forward you know a few years the nucleus people start doing experiments with radioactivity where they use alpha particles that are spat out of radioactive elements as as bullets and they fire them other atoms and by banging things into each other they see that they can knock bits out of the nucleus so these things come out called protons first of all which are positively charged particles about 2,000 times heavier than the electron and then 10 years later more or less neutral particle is discovered called the neutron so those are the three basic building blocks of atoms you have protons and neutrons in the nucleus that are stuck together by something called a strong force the strong nuclear force and you have electrons in orbit around that held in by the electromagnetic force which is one of the you know the forces of nature that's sort of where we get to by late 1932 more or less then what happens is physics is nice and neat in 1932 everything looks great got three particles and all the atoms are made of that's fine but then cloud chamber experiments these are devices that can be used to the first devices capable of imaging subatomic particles so you can see their tracks and they use to study cosmic rays particles that come from outer space and bang into the atmosphere and in these experiments people start to see a whole load of new particles so they discover for one thing antimatter which is a sort of a mirror image of the particles so we discovered that there's also as well as a negatively charged electron there's something called a positron which is a positively charged version of the electron and there's an antiproton which is negatively charged and and then a whole load of other weird particle start to get discovered and no one really knows what they are this is known as the zoo of particles are these discoveries fundamentally first theoretical discoveries or the discoveries in an experiment so like well yeah what was the process of discovery for these early it's a mixture I mean that the early stuff around the atom is really experimentally driven it's not based on some theory it's exploration in the lab using equipment so it's really people just figuring out hands-on with the fenomena figuring out what these things are the theory comes a bit later that there is that's not always the case so in the discovery of the anti-electron the positron that was predicted from quantum mechanics and relativity by a very clever theoretical physicist called Paul Dirac who was probably the second brightest you know physicist of the 20th century apart from Einstein but isn't as well anywhere near as well known so he predicted the existence of the anti electron from basically a combination of the theories of quantum mechanics and relativity and it was discovered about a year after he made their prediction what happens when an electron meets a positron they annihilate each other so if you when you bring a particle in its antiparticle together they they react well they react they just wipe each other out and they turn their mass is turned into energy usually in the form of photons so you'll get light produced so when you have that kind of situation why why does the universe exists at all if there's matter in any matter oh god now we're getting into the really big questions so you want to go there now yeah that's me maybe let's go there later that's because I mean that is a very big question yeah let's let's take it slow with the standard model so okay so there's matter and antimatter in the 30s mmm so what else so matter antimatter and then a load of new particles start turning up in these cosmic ray experiments first of all and they don't seem to be particles that make up atoms there's something else they all mostly interact with a strong nuclear force so they're a bit like protons and neutrons and by in the 1960s in America particularly but also in Europe and Russia scientist article particle accelerators so these are the forerunners of the LHC so big ring shaped machines that were you know hundreds of meters long which in those days was enormous you never you know most physics up until that point had been done in labs in universities you know with small bits of kit so this is a big change and when these accelerators are built they start to find they can produce even more of these particles so I don't know the exact numbers but by around 1960 there are of order a hundred of these things that have been discovered and physicists are kind of tearing the hair out because physics is all about simplification and suddenly what was simple as come messy and complicated and everyone sort of wants to understand what's going on it's a quick kind of a side and the probably really dumb question but how is it possible to take something like a like a photon or electron and be able to control it enough like to be able to do a controlled experiment where you collide it against something else yeah is that is that that seems like an exceptionally difficult engineering challenge because you mention vacuum to so you basically want to remove every other distraction and really focus on this collision how difficult of an engineering challenge is that just to get a sense and it's very hard I mean in the early days particularly when the first accelerators are being built in like 1932 Ernest Lawrence builds the first what we call the cyclotron which is like a little celery - this big or so there's another widely they're big there's a tiny little thing yeah I mean so most of the first accelerators were what we call fixed argot experiments so you had a ring you accelerate particles around the ring and then you fire them out the side into some target so is eat that makes the kind of the colliding bit is relatively straightforward to use fire it whatever it is you want to fire it out the hard bit is the steering the beams with the magnetic fields getting you know strong enough electric fields to accelerate them all that kind of stuff the first colliders where you have two beams colliding head-on that comes later and I don't think it's done until maybe the 1980s I'm not entirely sure but it takes is much harder problem that's crazy because yet it's like perfectly you had them to hit each other I mean we're talking about I mean what scale it takes what's this this I mean the temporal thing is a giant mess but the spatially like the size mmm it's tiny well to give you a sense so the LHC beams the cross-sectional diameter is I think around a dozen or so microns so you know ten ten millionths of a meters then a beam sorry just to clarify a beam how many is it the bunches that you mentioned yes multiple poles is just one part oh no no the bunches contained say a hundred billion protons each so a bunch is not really one shape they're actually quite long they're like 30 centimeters long but thinner than a human hair so like very very narrow long sort of object so those are the things so what happens in the LHC is you steer the beams so that they cross in the middle of the detector so the basically have these swarms of protons are flying through each other and most of that you have so you have 100 billion coming one way 100 billion another way maybe 10 of them will hit each other okay so this okay that makes a lot more sense that's nice so there you're trying to use sort of it's like probabilistically you're not you can't make a single particle collide with a single oh yeah so that's not an efficient way to do it you'd be waiting a very long time to get anything yeah so you you're basically right see you're relying on probability to be that some fraction of them are gonna collide yeah and then you know which is it's it's a it's a swarm of the same kind of particle so it doesn't matter which ones each other exactly I mean that that's not to say it's not hard you've got a one of the challenges to make the collisions work is you have to squash these beams to very very the basic their narrower they are the better because the higher the chances of them colliding if you think about two flocks of birds flying through each other the birds are all far apart in the flocks there's not much chance that they'll collide if they're all flying densely together and they very much more likely to collide with each other so that's the sort of problem it's tuning those magnetic fields getting them angry feels powerful not that you squash the beams and focus them so that you get enough collisions that's super cool do you know how much software is involved here I mean it's sort of I come in the software world and it's fascinating this seems like it's a software is buggy and messy and so like you almost don't want to rely on software too much like if you do it has to be like low-level like Fortran style programming do you know how much software isn't a Large Hadron Collider I mean it depends at which level a lot I mean the whole thing is obviously computer-controlled so I mean I I don't know a huge amount about how the software for the actual accelerator works but you know I've been in the control center so has CERN there's this big control room which is like bit like a NASA mission control with big banks of you know desk where the engine is sit and they monitor the LHC because you obviously can't be in the tunnel when it's running so everything's remote I mean one sort of anecdote about the sort of software side in 2008 when the LHC first switched on they had this big launch event and then you know big press conference party to inaugurate the machine and about ten days after that they were doing some tests and the this dramatic event happened where a huge explosion basically took place in a tunnel that destroyed were damaged badly damaged about about half a kilometer of the machine but the story is viewed the engineers here in the control room that day they'd one guy told me the story about you know basically there's all these screens they have in the control room started going red so these alarms like you know kind of in software going off and then they assume that lists all wrong with the software cuz there's no way something this catastrophic could have could have happened yeah but I mean when I worked on one when I was a PhD student one of my Jobs was to help to maintain the software that's used to control the detector that we work on and that was it's relatively robust not so you don't want it to be too fancy you don't want to sort of fall over too easily the more clever stuff comes when you're talking about analyzing the data and that's where they're sort of you know are we jumping around too much do we finish for the standard model we didn't know we didn't hurry and start talking mark works we haven't talked about me yet got to the messy zoo of particles go back there if it's okay okay that's take us the rest of the history of physics in the 20th century okay sure okay so circa 1960 you have this you have these hundred or so particles it's a bit like the periodic table all over again so you've got like like having a hundred elements sort of a bit like that and people try to start to try to impose some order so Murray Gelman he's a theoretical physicist American from New York he realizes that there are these symmetries in these particles that if you arrange them in certain ways that they relate to each other and he uses these symmetry principles to predict the existence of particles that haven't been discovered which are then discovered in accelerators so this starts to suggest there's not just random collections of crap there's like you know actually some order to this under a little bit later in 1960 again it's round the 1960s he proposes along with another physicist called George Zweig the these symmetries arise because just like the patterns in the periodic table arise because atoms are made of electrons and protons that these patterns are due to the fact that these particles are made of smaller things and they are called quarks so these are the particles they're predicted from theory for a long time no one really believes they're real a lot of people think that there are kind of theoretical convenience that happen to fit the data but there's no evidence no one's ever seen a quark in any experiment and lots of experiments are done to try to find quarks just try to knock a quark out of her so the idea if protons and neutrons say made of quarks you should work to knock a quark out and see the quark that never happens and we still have never actually managed to do that really no so the way but the way that it's done in the end is this machine that's built in California at Stanford lab Stanford Linear Accelerator which is essentially a gigantic three kilometer long electron gun fires electrons almost speed of light at protons and when you do these experiments what you find is a very high energy the electrons bounce off small hard objects inside the proton so it's a bit like taking an x-ray of the proton you're firing these very light high-energy particles and they're pinging off little things inside the proton that are like ball bearings if you like so you actually that way they resolve that there are three things inside the proton which are quarks the quarks that governance why I could predicted so that's really the evidence that convinces people that these things are real the fact that we've never seen one in an experiment directly they're always stuck inside other particles and the reason for that is essentially to do with the strong force the strong forces the force holds quarks together and it's so strongly it's impossible to actually liberate a quark so if you try and pull a quark out of a proton what actually ends up happening is that the you kind of create this that this spring-like bond in the strong force we've imagined two quarks that are held together by very powerful spring you pull it pull and pull more and more energy gets stored in there bond like stretching a spring and eventually the tension gets so great the spring snaps and the energy in that bond gets turned into two new quarks that go on the broken ends so you started with two quarks to end up with four quarks so you never actually get to take a quark out you just end up making loads of more quarks in the process so how do we again forgive the dumb question how do we know quarks are real then well eh from these experiments where we can scatter you fire electrons into the protons they can burrow into the proton and knock off and they can bounce off these quarks so you can see from the angles the electrons come Alice you can infer you can infer that these things are there the quark model can also be used it has a lot of successes you can use it to predict the existence of new particles that hadn't been seen so and basically there's lots of data basically showing from you know when we fire protons at each other at the LHC a lot of quarks get knocked all over the place and every time they try and escape from say one of their protons they make a whole jet of quarks that go flying off it has bound up in other sorts of particles made of quarks so they're all the sort of the theoretical predictions from the basic theory of the strong force and the quarks all agrees with what we are seeing experiments we've just never seen a an actual quark on its own because unfortunate it's impossible to get them out on their own so quarks these crazy smaller things that are hard to imagine a real so what else what else is part of the story here so the other thing that's going on at the time around the sixties it's an attempt to understand the forces that make these particles interact with each other so you have the electromagnetic force which is the force that was sort of discovered to some extent in this room or at least in this building so the first what we call quantum field theory of the electromagnetic force is developed in the 1940s and 50s by Fineman Richard Feynman amongst other people julian schwinger tominaga who come up with the first what we call a quantum field theory of the electromagnetic force and this is where this description of which I gave you at the beginning that particles are ripples and fields well in this theory the photon the particle of light is described as people in this quantum field called the electromagnetic field and the attempt then is made to try what can we come up with a quantum field theory of the other forces of the strong force and the weak the other third the third force which we haven't discussed which is the weak force which is a nuclear force we don't really experience it in our everyday lives but it's responsible for radioactive decay is the force that allows you know in a radioactive atom to turn into a different element for example and there are a few we've explicitly mentioned but so there's technically four forces yes I guess three of them were being in in the standard model like the weak there's the strong and the electromagnetic and then there's gravity in this gravity which we don't worry about that because maybe maybe we bring that up at the end yeah gravity so far we don't have a quantum theory of and if you can solve that problem you win a Nobel Prize well we're gonna have to bring up the graviton at some point I'm gonna ask you but let's let's leave that to the side for now so those three okay fine man a electromagnetic force the the quantum field yeah where does the weak force come in so so yeah well first of I mean the strong force a bit easiest the strong force is a little bit like the electromagnetic force it's a force that binds things together so that's the force that holds quarks together inside the proton for example so a quantum field theory of that force is discovered in I think it's in the sixties and it predicts the existence of new force particles called gluons so gluons are a bit like the photon the photon is the particle of electromagnetism gluons are the the particles of the strong force and so there's there's just like there's an electromagnetic field there's something called a gluon field which is also all around us but these part there's some of these particles I guess the force carriers or whatever they carry that well it depends how you want to think about it I mean really the field the strong force field the gluon field is the thing that binds the quarks together the gluons are the little ripples in that field so that like in the same way that the photon is a ripple in there in the electromagnetic field but the thing that really does the binding is the field I mean you may have heard people talk about things like verge as you've heard the phrase virtual particle so sometimes in some if you hear people describing how forces are exchanged between particles they quite often talk about the idea that you know if you have an electron and another electron say and they're repelling each other through the electro bratok electromagnetic force you can think of that as if they're exchanging photons so they're kind of firing photons backwards and forwards between each other and that causes them to repel therefore time is then a virtual particle yes that's what we call a virtual particle in other words it's not a real thing doesn't actually exist so it's an artifact of the way theorists do calculations so when they do calculations in quantum field theory rather than there's no one's discovered a way of just treating the whole field you have to break the field down into simpler things so you can basically treat the field as if it's made up of lots of these virtual photons but there's no experiment that you can do that couldn't detect these particles being exchanged what's really happening in reality is the electromagnetic field is warped by the charge of the electron and that causes the force but the way we do calculations involves parties let's say it's a bit confusing but it is really a mathematical technique it's not something that corresponds to reality I mean that's part I guess of the fireman diagrams yes is this virtual product okay that's right yeah some of these have mass some of them don't mm-hmm is that is that what what does that even mean not to have mass and maybe you can say well which one of them's have mass or which don't okay so and why is mass important or relevant in this cupboard in this in this field view of the universe well there are only two particles in the standard model that don't have mass which are the photon and the gluons so they are massless particles but the electron the quarks and they're a bunch of other particles I haven't discussed there's something called a muon and a Tau which are basically heavy versions of the electron that are unstable you can make them in accelerators but they don't form atoms or anything they don't exist for long enough but all the matter particles there are twelve of them six quarks and six what we call leptons which includes the electron and it's too heavy versions and three neutrinos all of them have mass and so do this is the critical bit so the weak force which is the third of these quantum forces which is one of the hardest to understand the force particles of that force have very large masses and there are three of them they're called the W plus the W minus and the Z boson and they have masses of between 80 and 90 times that of the the protons they're very heavy learn wow they're very heavy things they're what the heaviest I guess they're not the heaviest the heaviest particle is the top quark which has a mass of about 175 ish protons so that's really massive we don't know why is so massive but they're coming back to the weak force so that the the problem in the 60s and 70s was that the reason that the electromagnetic force is a force that we can experience our everyday live so if we have a magnet and a piece of metal you can hold it you know a meter apart if it's powerful laughs and you'll feel a force whereas the weak force only is becomes apparent when you basically have two particles touching at the scale of a nucleus so if you get two very short distances before this force becomes manifest it's not doesn't we don't get weak forces going on in this room they don't notice them and the reason for that is that the particle well the the field that transmits the weak force the particle that's associated with that field has a very large mass which means that the field dies off very quickly says you whereas an electric charge if you were to look at the shape of the electric field it would fall off with this you know this one called the inverse square law which is the idea that the force halves every time you double the distance no sorry it doesn't have it quarters every time you see every time you double the distance between say the two particles whereas the weak force kind of you move a little bit away from the nucleus and just disappears the reason for that is because these these fields the particles that go with them have a very large mass but the problem that was that theorists faced in the sixties was that if you tried to introduce massive force fields the theory who gave you nonsensical answers so you'd end up with infinite results for a lot of the calculations you tried to do so the basically it turned it seemed that quantum field theory was incompatible with having massive articles not just the force particles actually but even the electron was a problem so this is where the Higgs that we sort of alluded to comes in and the solution was to say okay well actually all the particles in the standard model of mass they have no mass so the quarks the electron they don't have a mass neither do these weak particles they don't have mass either what happens is they actually acquire mass through another process they get it from somewhere else they don't actually have it intrinsically so this idea that was introduced by what Peter Higgs is the most famous but actually they're about six people that come up with the idea more or less at the same time is that you introduce a new quantum field which is another one of these invisible things as everywhere and it's through the interaction with this field that particles get mass so you can think of say an electron in the Higgs field it kind of Higgs field kind of bunches around the electron it sort of a drawn towards the electron and that energy that's stored in that field around the electron is what we see as the mass of the electron but if you could somehow turn off the Higgs field then all the particles in nature would become massless and fly around at the speed of light so this this idea of the Higgs field allowed other people other theorists to come up with a well it was another a unit basically a unified theory of the electromagnetic force on the weak force so once you bring in the Higgs field you can combine two of the forces into one so it turns out the electromagnetic force and the weak force are just two aspects of the same fundamental force and at the LHC we go to high enough energies that you see these two forces unifying effectively so that so first of all it started as a theoretical notion like this is just something and then I mean wasn't the Higgs called the god particle at some point it was by a guy trying to sell popular science books yeah yeah but by me I am because when I was hearing it I thought it would I mean that would solve a lot of the you know file a lot of our ideas of physics was Molloy's my notion but maybe you can speak to that was is as big of a leap is it as a god particle is it a Jesus particle which which you know what's the big contribution of Higgs in terms of this unification power yeah I mean to understand that I maybe helps know the history a little bit so when the what we call electroweak theory was put together which is where you unify electromagnetism with the weak force and the Higgs is involved in all of that so that theory which was written in the mid-70s predicted the existence of four new particles the w+ boson the w- boson the z boson and the Higgs boson so there were these four particles that came with the theory that were predicted by the theory in 1983-84 the W's and the z particles were discovered an accelerator at CERN called the super proton synchrotron which was a seven kilometer particle collider so three of the bits of this theory had already been found so people are pretty confident from the 80s that the Higgs must exist because it was a part of this family of particles that this theoretical structure only works if the Higgs is there so what then happens this question right why is the LHC the size it is yes well actually the tunnel that the LHC is in was not built for the LHC it was built from for a previous accelerator called the large electron positron Collider so that that was bit began operation in the late 80s early 90s they basically did that's when they dug the 27 kilometer tunnel they put as accelerator into it the collider defiers electrons and anti electrons at each other electrons and positrons so the purpose of that machine was well it was actually to look for the Higgs that was one of the things it was trying to do it didn't man I didn't have enough energy to do it in the end but the main thing it was it studied the W and the Z particles at very high precision so it made loads of these things previously can you make a few of them at the previous accelerator you could study these really really precisely and by studying their properties you could really test this electroweak theory that had been invented in the seventies and really make sure that it worked so actually by 1999 when this machine turned off people knew well okay you never know until you until you find the thing but people were really confident electroweak theory was right and that the Higgs almost the Higgs or something very like the Higgs had to exist because otherwise the whole thing doesn't work it'd be really weird if you could discover and these particles they all behave exactly just theory tells you they should but somehow this key piece of the picture isn't it's not there so in a way it depends how you look at it the discovery of the Higgs on its own is it's also a huge achievement in many both experimenting and theoretically on the other hand it's this it's like having a jigsaw puzzle where every piece has been filled in you've this beautiful image there's one gap and you kind of know that that piece must be there something right so yeah so the discovery in itself although it's important is not so interesting it's a good confirmation of the obvious yes at that point but what makes it interesting is not that it just completes the standard model which is a theory that we've known had the basic layout offs for 40 years or more now it's that the Higgs actually is a is a unique particle is very different to any of the other particles in the standard model and it's a theoretically very troublesome particle there are a lot of nasty things to do with the Higgs but also opportunities so that we basically don't really understand how such an object can exist in the form that it does so there are lots of reasons for thinking that the Higgs must come with a bunch of other particles or that it's perhaps made of other things so it's not a fundamental particle that it's made of smaller things I can talk about that if you like a bit that's that's still an ocean so yeah so the Higgs might not be a fundamental particle there may be some in my oh man so that that is an idea it's not you know it's not been demonstrated to be true but I mean there's all of these ideas basically come from the fact that it's a this is this is a problem motivated a lot of development in physics in the last 30 years or so and there's this basic fact that the higgs field which is this field that's everywhere in the universe this is the thing that gives mass to the particles and the Higgs field is different from ever all the other fields in that let's say you take the electromagnetic field which is you know if we actually were to measure the electromagnetic field we would measure all kinds of stuff going on because there's light there's gonna be microwaves and radio waves and stuff but let's say we could go to a really really remote part of empty space and shield it and put a big box around it and then measure the electromagnetic field in that box the field would be almost zero apart from some little quantum fluctuations but basically it goes to naught the Higgs field has a value everywhere so it's a bit like the hole it's like the entire of space has got this energy stored in the Higgs field which is not zero it's it's finite it's got some it's a bit like having the the temperature of space raised to you know some background temperature and it's that energy that gives mass to the particles so the reason that electrons and quarks have mass is through the interaction with this energy that's stored in the Higgs field now it turns out that the precise value this energy has has to be very carefully tuned if you want a universe where interesting stuff can happen so if you push the higgs field down it has a tendency to collapse to what there's a tenon if you do you're sort of naive calculations they're basically two possible likely configurations for the Higgs field which is either it's zero everywhere in which case you have a universe which is just particles with no mass that can't form atoms and just fly by at the speed of light or it explodes to an enormous value what we call the Planck scale which is the scale of quantum gravity and at that point if the Hicksville was that strong even an electron would become so massive that it would collapse into a black hole and then you have a universe made of black holes and nothing like us so it seems that the the strength of the Higgs field is - it could achieve the value that we see requires what we call fine-tuning of the laws of physics you have to fiddle around with the other fields in the standard model and their properties to just get it to this right sort of Goldilocks value that allows atoms to exist this is deeply fishy people really dislike this well yeah I guess well so what would be a so - two explanations one there's a god the design this perfectly and two is there's an infinite number of alternate universes and we'll just happen to being the one in which life is possible yeah complexity so when you say I mean life any kind of complexity that's not either complete chaos or black holes yeah yeah I mean how does that make you feel what do you make that has such a fascinating notion that this perfectly tuned field that's the same everywhere yeah is there what do you make of that yeah well you make of that I mean yeah you like that two of the possible explanations yeah I mean well someone you know some cosmic creator way yeah let's fix that to be at the right level that's more possibility I guess it's not a scientifically test for one but you know theoretically I guess it's possible sorry to interrupt but there could also be not a designer but could never be just I guess I'm not sure what that would be but as some kind of force that that some kind of mechanism by which this this this kind of field is enforced in order to create complexity basic basically forces that pull the universe towards an interesting complexity I mean yeah I mean I has those ideas I don't really subscribe to them as I'm saying it sounds really stupid no I mean yeah and there are definitely people that make those kind of arguments you know there's ideas that I think it's Lise Mullins idea one I think that you know universes are born inside black holes and so universe is that behaved like Darwinian evolution of the universe where universes give birth to other universes and they've universes where black holes can form are more likely to give birth to more universes so you end up with universes which have similar laws I mean I don't whatever but why I talked to dr. Lee recently understand this podcast and he's he's a reminder to me that the physics community has like so many interesting characters yeah it's fascinating yeah anyway so so I mean as an experimentalist I tend to sort of think these are interesting ideas but they're not really testable so I tend not to think about very much so I mean going back to the science of this there wasn't that there is an explanation there is a possible solution to this problem of the Higgs which doesn't involve multiverses or creators fiddling about were the laws of physics if the most popular solution was something called supersymmetry which is a theory which is involves a new type of symmetry of the universe in fact it's one of the last types of symmetries that is possible to have that we haven't already seen in nature which is a symmetry between force particles and matter particles so what we call fermions which held before the matter particles and bosons which were force particles and if you have supersymmetry then there is a superpartner for every particle in the standard model and the without going to the details the effect of this basically is that you have a whole bunch of other fields and these fields cancel out the effect of the standard model fields and they stabilize the Higgs field at a nice sensible value so in supersymmetry you naturally without any concurring about with the constants of nature or anything you get a Higgs field with a nice value which is the one we see so this is one of the written supersymmetry has also got lots of other things going for it it predicts the existence of a dark matter particle which would be great it you know it potentially in suggests that the the strong force and the electroweak force unify high energy so lots of reasons people thought this was a productive idea and when the LHC was just before it was turned on there was a lot of hype I guess a lot of an expectation that we would discover these super partners because and particularly the main reason was that if if supersymmetry stabilizes the higgs field at this nice Goldilocks value these super particles should have a mass around the energy that we're probing at the LHC around the energy of the Higgs so it was kind of thought you discovered the Higgs you probably discover superpartners so once you start creating ripples in this fix field you should be able to see these kinds of you should be yeah super fields would be there but I said well at the very beginning I said we're probing the vacuum what I mean is really that you know okay let's say these super fields exist the vacuum contains super fields they're they're these super symmetric fields if we hit them hard enough we can make them vibrate we see super particles come flying out that's the sort of that's the idea the hope ok that's the whole alone but we haven't but we haven't so so far at least I mean we've had now a decade of data taking at the LHC no signs of superpartners have supersymmetric particles have been found in fact no signs of any physics any new particles beyond the standard model have been found so supersymmetry is not the only thing that can do this there are other theories that involve additional dimensions of space or potentially involve the Higgs boson being made of smaller things being made of other particles that's an interesting you know I haven't heard that before that's really that's an issue but could you maybe linger on that like what what could be what could Higgs particle be made of well so the the oldest I think the original ideas about this was these theories called Technicolor which were basically like an analogy with the strong force so the idea was the Higgs boson was a bound state of two very strongly interacting particles that were a bit like quarks so like quarks but I guess higher energy things with a super strong force so not the strong force but a new force that was very strong and the Higgs was a bound state of these these objects and the Higgs wouldn't principle if that was right would be the first in a series of Technicolor particles Technicolor I think not being a theorist but it's not biz basically not done very well there's particularly since the LHC found the Higgs that kind of it rules out you know a lot of these Technicolor theories but there are other things that are a bit like Technicolor so there's a theory called partial composite nurse which is an idea that some of my colleagues that Cambridge have worked on which is a similar sort of idea that the Higgs is a bound state of some strongly interacting particles and that the standard model particles themselves the more exotic ones like the top quark are also sort of mixtures of these composite particles so it's a kind of an extension to the standard model which explains this problem with the Higgs bosons Goldilocks value but also helps us understand we have we're in a situation now again a bit like the periodic table where we have six quarks six leptons in this kind of you can range in this nice table and there you can see these columns where the patterns repeat and you go okay maybe there's something deeper going on here is that you know and and so this would potentially be something this partial composite NOS theory could Lane sort of enlarged this picture that allows us to see the whole symmetrical pattern and understand what the ingredients why do we have wind so one of the big questions in particle physics is why are there three copies of the matter particles so in what we call the first generation which is what we're made of there's the electron the electron neutrino the up quark on the down quark they're the most common matter particles in the universe but then there are copies of these four particles in the second and the third generations so things like muons and top quarks and other stuff we don't know why we see these patterns we have no idea where it comes from so that's another big question you know can we find out the deeper order that explains this particular tape period table of particles that we see is it possible that the the deeper order includes like almost a single entity so like something that I guess like string theory dreams about is this is this part is this essentially the dream is to discover something simple beautiful and unifying yeah I mean that is the dream and it I think for some people for a lot of people it still is the dream so there's a great book by Steven Weinberg who is one of the theoretical physicists who was instrumental in building the standard model so he came up with some others with the electroweak theory the theory that unified electromagnetism and the weak force and here at this book I think it was towards the end of the 80s early 90s called dreams of a final theory which is a very lovely quite short book about this idea of a final unifying theory that brings everything together and I think you get a sense reading his book written at the end of 80s and early 90s that there was this feeling that such a theory was coming and that was the time when string theory had been was was very exciting so string theory there's been this thing called the superstring revolution and theoretical physical very excited they discovered these theoretical objects these little vibrating loops of string that in principle not only was a quantum theory of gravity but could explain all the particles in the standard model and bring it all together and you as you say you have one object the string and you can pluck it and the way it vibrates gives you these different notes each of which is a different part so it's a very lovely idea but the problem is that well there's a there's a few people discover their mathematics is very difficult so people have spent three decades and more trying to understand string theory and I think you know if you spoke to most string theorists they would probably freely admit that no one really knows what string theory is yet I mean there's been a lot of work but it's not really understood and the other problem is that string theory mostly makes predictions about physics that occurs energies far beyond what we will ever be able to probe in the laboratory yeah probably ever by the way so sorry they take a million tangents but is there room for complete innovation of how to build a particle collider that could give us an order of magnitude increase in any kind of energies or do we need to keep just increasing the size of thing I mean maybe yeah I mean there are ideas but to give you a sense of the Gulf that has to be bridged so the LHC collides particles at an energy of what we call fourteen terror electron volts so that's basically equivalent of you accelerated a proton through 14 trillion volts that gets us to the energies where the Higgs and these weak particles live they're very massive the the scale where strings become manifest is something called the Planck scale which i think is of the order 10 to the hang on again that's right is 10 to the 18 Giga electron volt so about 10 to the 15 terror electron volts so you're talking you know trillions of times more energy more the 10 to the 15 the 10 to the 14th larger it's a very big number so you know we're not talking just an order of magnitude increase in energy we're talking 14 orders of magnitude energy increase so to give you a sense of what that would look like were you to build a particle accelerator with today's technology bigger or smaller and then our solar system as start the size of the galaxy the galaxy so you need to put a particle accelerator that circled the Milky Way to get to the energies where you would see strings if they exist so there's a fundamental or problem which is that most of the predictions of the unified these unified theories of quantum theories of gravity only make statements that are testable are energies that we will not be able to probe let and barring some unbelievable you know completely unexpected technological or scientific breakthrough which is almost impossible to imagine you never never say never but it seems very unlikely yeah I can just see the news story Elon Musk decides to build a particle collider the size of our it would have to be we'd have to get together with all our galactic neighbors to pay for everything what is the exciting possibilities of the Large Hadron Collider what is there to be discovered in this in this order of magnitude of scale is there other bigger efforts on the horizon big in this space what are the open problems the exciting possibilities you mentioned supersymmetry yeah so well there are lots of new ideas well there's lots of problems that we're facing so there's a problem with the Higgs field which supersymmetry was supposed to solve there's the fact that 95% of the universe we know from cosmology astrophysics is invisible that it's made of dark matter and dark energy which are really just words for things that we don't know what they are it's what Donald Rumsfeld called a known unknown we know we don't know what they are well that's it's better than an unknown unknown yeah well there may be some unknown unknown but I don't know what those yeah but but the the hope is the particle accelerator could help us make sense of dark energy dark matter there's still there's just some hope for that there's hope for that yes so one of the hopes is the LHC could produce a Dark Matter particle in its collisions and you know it may be that the LHC will still discover new particles that it might still supersymmetry could still be there we just it's just maybe more difficult to find than we thought originally and and you know dark matter particles might be being produced but we're just not looking in the right part of the data for them that that's possible it might be that we need more data that these processes are very rare and we need to collect lots and lots of data before we see them but I think a lot of people would say now that the chances of the LHC directly discovering new particles in the near future is quite slim it may be that we need a decade more data before we can see something or we may not see anything that's the that's what we are so I mean the the physics the experiments that I work on so I work on a detector called LHC B which is one of these four big detectors that are spaced around the ring and we do slightly different stuff to the big guys there's two big experiments called outlets and CMS three thousand physicists and scientists and computer scientists on them each they are the ones that discovered the Higgs then they look for supersymmetry and dark matter and so on what we look at our standard model particles called B quarks which depending on your preference is either bottom or beauty we tend to say beauty because it sounds sexier yeah but these particles are interesting because they of you can make lots of them we make billions or Billy a hundreds of billions of these things you can therefore measure their properties very precisely so you can make these really lovely precision measurements and what we are doing really is a sort of complementary thing to the other big experiments which is they if you think the self analogy that I often use is if you imagine you're looking in you're in a jungle and you're looking for an elephant same and you are a hunter and you're kind of like they said there's the relevance very rare you don't know where in the jungle the jungles big so there's two ways you go about this either you can go out wandering around the jungle and try and find the elephant the problem is if the elephant there's only one elephant the jungles big the chances of running into it very small or you could look on the ground and see if you see footprints left by the elephant and if the elephant's moving around you've got a chance that you're better chance maybe of seeing the elephant's footprints if you see the footprints you go okay there's an elephant maybe don't know what kind of elephant it is but I got a sense there's something out there so that's sort of what we do we are the footprint people we are we're looking for the footprint the impressions that quantum fields that we haven't managed to directly create the particle of the effects these quantum fields have on the ordinary standard model fields that we already know about so these these be particles the way they behave can be influenced by the presence of say super fields or dark matter fields or whatever you like and they're the way they decay and hey've can be altered slightly from what our theory tells us they ought to behave sure and it's easier to collect huge amounts of data and B and B quarks we get you know billions and billions of these things you can make very precise measurements and the only place really at the LHC or in really in high-energy physics at the moment where there's fairly compelling evidence that there might be something beyond the standard model is in these be these beauty quarks decays just to clarify which is the difference between the different the four experiments for example the emission is it the kind of particles that are being collided is it the energies that were which there collided what's the fundamental difference different experiments the collisions are the same what's different is the design of the detectors so Atlas and CMS are called they're called what are called general purpose detectors and they are basically barrel shaped machines and the collisions happen in the middle of the barrel and the barrel captures all the particles that go flying out in every direction so in a sphere effectively they can flying out and it can record all of those particles and what's the site of interrupting but what's what's the mechanism of the recording oh these detectors if you've seen pictures of them the huge like Atlas is 25 meters high in 45 meters long and vast machines instruments I guess you to call them really they are they're kind of like onions so they have layers concentric layers of detective detectors different sorts of detectors so close into the beam pipe you have what a record usually made of silicon their tracking detectors so they're little made of strips of silicon or pixels of silicon and when a particle goes through the silicon it gives a little electrical signal and you get these dots you know electrical dots through your detector which allows you to reconstruct the trajectory of the particle so that's the middle and then the outside of these detectors you have things called calorimeters which measure the energies of the particles and in very edge you have things called muon chambers which basically met these muon particles which are the heavy version of the electron they are there like high-velocity bullets and they can get right to the edge of the detectors if you see something at the edge that's a muon so that's broadly how they work and all there's being recorded that's all being fed out to you know computers must be awesome okay so LHCb is different so we because we're looking for these B quarks yes B quarks tend to be produced along the beam lines so in a collision the B quark tend to fly sort of close to the beam pipe so we built the detector that sort of pyramid cone-shaped basically that just looks in one directions we ignore if you have your collision stuff goes everywhere we ignore all the stuff over here and going off sideways we're just looking in this little region close to the beam pipe where most of these B quarks are made so is there a different aspect of the sensors involved in the collection of the B quark yes Jack thérèse there are some differences so one of the differences is that one of the ways you know you've seen a B quark is that B quarks are actually quite long-lived by particle standards so they live for 1.5 trillions of a second which is if you're if you're a fundamental particle is a very long time because you know the Higgs boson I think lives for about a trillionth of a trillionth of a second or maybe even less than that so these are quite long-lived things and they will actually fly a little distance before they decay so they will fly you know a few centimeters maybe if you're lucky then they'll decay into other stuff so what we need to do in the middle of the detector you want to be able to see you have your place where the protons crash into each other and that produces loads of particles that come flying out so you have loads of lines loads of tracks that point back to that proton collision and then you're looking for a couple of other tracks maybe two or three that point back to a different place this may be a few centimeters away from the proton collision and that's the sign that little B particle has flown a few centimeters in decayed somewhere else so we need to be able to very accurately resolve the proton collision from the B particle decay so we are the middle of our detector is very sensitive and it gets very close to the collisions so you have this really beautiful delicate silicon detector that sits I think it's seven mil millimeters from the beam and the LHC beam has as much energy as a jumbo jet takeoff so it's enough to melt a ton of copper and as you have this furiously powerful thing sitting next it's tiny delicate you know sense of the consent sir so that into those aspects of our detector that are specialized to desert to discover these particular B quarks that were interested in and is there I mean I remember seeing somewhere that there's some mention of matter and antimatter connected to the be the these beautiful quarks who's that what what's the connection wha yeah what's the connection there yes there is a connection which is that when you produce these B particles it'll be these particles consider to the B quark you see the thing that B quark is inside so they're bound up inside what we call beauty particles where the B quark is joined together with another quark or two maybe two other clocks depending on what it is there a particular set of these B particles that exhibit this property called oscillation so if you make her for the sake of argument a matter version of one of these B particles as it travels because of the magic of quantum mechanics it oscillates backwards and forwards between its matter and antimatter versions so just this weird flipping about backwards and forwards and what we can use this for is a laboratory for testing the symmetry between matter and antimatter so if the if the symmetry but transparency is precise its exact then we should see these B particles decaying as often as matter as they do as antimatter because this oscillation should be even it should spend much time in each state but what we actually see is that one of the states it spends more time and it's more likely to decay in one state than the other so this gives us a way of testing this fundamental symmetry between matter and antimatter so what can you sort of return the the question or before about this fundamental symmetry it seems like if this perfect symmetry between matter and antimatter if the equal amount of each in our universe it would just destroy itself mm-hm and just like you mentioned we seem to live in a very unlikely universe where it it doesn't destroy itself yeah so do you have some intuition about about why that is I mean well I I'm not a theory I don't have any particular ideas myself I mean I sort of do measurements to try and test these things but I mean it's in terms of the basic problem is that in the Big Bang if you use the standard model to figure out what ought to have happened you should have got equal amounts of matter antimatter made because whenever you make a particle in our collide collisions for exam but when we collide stuff together you make a particle you make an antiparticle they always come together they always annihilate together so there's no way of making more matter than antimatter that we've discovered so far so that means in the Big Bang you get equal amounts of matter antimatter as the universe expands and cools down during the Big Bang not very long after the Big Bang I think a few seconds off the Big Bang you have this event called the great annihilation which is where all the particles antiparticles smack into each other annihilate turn into light mostly and you end up with a universe later right if that was what happened then the universe we live in today would be black and empty apart from some photons that would be it so there's stuff in this there is stuff in the universe it appears to be just made of matter so there's this big mystery as to where the how did this happen and there are various ideas which all involve sort of physics going on in the first trillionth of a second or so of the Big Bang so it could be that one possibility is that the Higgs field is somehow implicated in this that there was this event that took place in the early universe where the higgs field basically switched on it acquired its modern value and when that happened this caused all the particles to acquire mass and the universe basically went through a phase transition where you had a hot plasma of massless particles and then in that plasma it's almost like a gas turning into droplets of water you get kind of these little bubbles forming in the universe where the Higgs field has acquired its modern value the particles have got mass and this phase transition in some models can cause more matter than antimatter to be produced depending on how matter bounces off these bubbles in the early universe so that's one idea there's other ideas to do with neutrinos that there are exotic types of neutrinos that can decay in a biased way to just matter and not to antimatter so and people are trying to test these ideas that's what we're trying to do at LHC B is there's neutrino experiments planned they're trying to do these sorts of things as well so yeah there are ideas but at the moment no clear evidence for which of these ideas might be right so we're talking about some incredible ideas by the way never hurt anyone be so eloquent about describing even just a standard model so I'm in awe just listening if you're interesting just have having fun enjoying it so the yes the theoretical the particle physics is fascinating here to me one of the most fascinating things about the Large Hadron Collider is the human side of it that a bunch of sort of brilliant people that probably have egos got together and we collaborate together and countries I guess collaborate together you know for the funds and that everything's just collaboration everywhere because you maybe I don't know what the right question here to ask but almost what's your intuition about how was possible to make this happen and what are the lessons we should learn for the future of human civilization in terms of our scientific progress because it seems like this is a great great illustration of us working together to do something big yeah I think it's possibly the best example maybe I can think of of international collaboration it isn't for some unpleasant purpose basically you know it's I mean so I I when I started out in the field in 2008 I as a new PhD student the LHC was basically finished so I didn't have to go around asking for money for it or trying to make the case so I have huge admiration admiration for the people who managed that because this was a project that was first imagined in the 1970s and the late 70s was when the first conversations about the LHC were were mooted and it took two and a half decades of campaigning and fundraising and persuasion until they started breaking ground and building the thing in the early noughties in 2000 so I mean I think the reason just from uh sort of from the point of view of this sort of science the scientists there I think the reason it works ultimately is that everywhere everyone there is there for the same reason which is well in principle at least they're there because they're interested in the world they want to find out you know what are the basic ingredients of our universe what are the laws of nature and so everyone is pulling in the same direction of course everyone has their own things they're interested in everyone has their own careers to consider and you know and pretend that there isn't also a lot of competitions this is funny thing in these experiments where your collaborators your eight-hundred collaborators in LHC be but you're also competitors because you're academics in your various universities and you want to be the one that gets the paper out on the most citing you know new measurements so there's this funny thing where you're kind of trying to stake out your territory while also collaborating and having to work together to make the experiments work and it does work amazingly well actually considering all of that and I think there was actually I think McKinsey or one of these big management consultancy firms went into CERN maybe a decade or so ago to try to understand how these organizations functions they figure it out I don't think they could I mean I think one of the things that interests one of the other interesting things about these experiments is that their big operations like say outlets there's 3,000 people now there is a person nominally who is the head of Atlas they're called the spokesperson and the spokesperson is elected by usually by the collaboration but they have no actual power really I mean they can't fire anyone they're not anyone's boss so you know my boss is it prefers the professor a professor at Cambridge not the head of my experiments the head of my experiment can't tell me what to do really and I mean there's all you got is independent academics who are their own bosses who you know so that somehow it nonetheless by kind of consensus and discussion and lots of meetings these you know things do happen and it does get done but it's like the Queen hearing you in the UK is the spokesperson again so no actual don't elect her know whatever everybody seems to love her I don't know from the at my outside perspective yeah but yeah giant egos brilliant people and moving forward do you think there's I would pick up one thing you said just that just the brilliant people thing cuz I'm not I'm not saying that people aren't great yeah but I think there is this sort of impression that physicists will have to be brilliant or geniuses which is not true actually and you know you have to be relatively bright for sure but you know a lot of people a lot of the most successful experimental physicists and not necessarily the people with the biggest brains they're the people who you know particularly one of the skills that's most important in particle physics is the ability to work with others and to collaborate and exchange ideas and also to work hard and it's a sort of often it's more a determination or a sort of other set of skills is not just being you know kind of some great brain very true so in I mean there's parallels to that in the machine learning world if you wanted if you want to solve any real-world problems which I see is the the particle accelerators essentially a real-world instantiation of theoretical physics and for that you have to not necessarily be brilliant but be sort of obsessed systematic rigorous sort of unbel stubborn all those kind of qualities that make for a great engineer so this science scientist purely speaking the practitioner of the scientific method so you're right but nonetheless Timmy that's Timmy has been my dad as a physicist I argue with him all the time to me engineering is the highest form of science and he thinks that's all nonsense that the real work is done by the theory edition so he in fact we have arguments about like people like Elon Musk for example because I think his work is quite brilliant but he's fundamentally not coming up with any serious breakthroughs he's just creating in this world implementing I'd like making ideas happen and have a huge impact to me that is that's the Edison that Timmy is is a brilliant work but to him it's you know it's messy details that somebody will figure out anyway that's it I mean I don't know whether you think there is a actual difference in temperament between say a physicist and engineer whether it's just what you got interested in I don't know I mean because you know a lot of what experimental physicists do is to some extent engineering and it's not what I do I mostly do data stuff but you know a lot of people would be called electrical engineers but they trained as physicists but they learn electrical engineering for example because they were building detectors so there's not such a clear divide I think yeah it's interesting I mean there but there does seem to be like you work with data there does seem to be a certain like I love data collection there might be an OCD element or something that you're more naturally predisposed to as opposed to theory like I'm not afraid of data I love data and there's a lot of people machine learning core more like they're they're basically afraid of data collection afraid of datasets afraid of all that they just want to stay more than theoretical and they're really good at it space I don't know if that's a genetic that's your upbringing the way you with it the way you go to school but looking into the future of LHC and other colliders so there's in the in America there's the whatever was called the super there's a lot of super superconducting supercollider is super gonna desert roll desert Ron yeah so that was cancelled the construction of that yeah which is a sad thing but what do you think is the future of these efforts will a bigger Collider be built will LHC be expanded what do you think well in the near future the LHC is gonna get an upgrade so that's pretty much confirmed I think it is confirmed which is the it's not an energy upgrade it's and what we call the luminosity upgrade so basically means increasing their data collection rates so more collisions per second basically because after a few years of data taking you get this law of diminishing returns where each year's worth of data is a smaller and smaller fraction of the lot you've already got so to get a real improvement in sensitivity you need to increase the data rate by an order of magnitude so that's what this upgrade is gonna do an LHC be at the moment the whole detector is basically being rebuilt to allow it to record data at a much larger rate than we could before so that will make her sensitive to whole loads of new processes that we weren't able to study before and you know I mentioned briefly these anomalies anomalies that we've seen so we've seen a bunch of very intriguing anomalies in these B quark decays which may be hinting at the first signs of this kind of the elephant you know that the the size of some new quantum field or fields may be beyond the standard model it's not yet at the statistical threshold where you can say that you've observed something but there's lots of anomalies in many measurements that all seem to be consistent with each other so it's quite interesting so you know the upgrade will allow us to really homed in on these things and see whether these alumni's are real because if they are real and it kind of connects to your point about the next generation of machines what we would have seen then is you know we will have seen the tail end of some quantum field in influencing these big quarks what we then need to do build a bigger Collider to actually make the the particle of that field so if these are if these things really do exist so that would be one argument I mean I mean so at the moment Europe has going through this process of thinking about the strategy for the future so there are a number of different proposals on the table one is for sort of higher energy upgrade at the LHC where you just build more powerful magnets and put them in the same tunnel that's a sort of cheap cheaper less ambitious possibility most people don't really like it because it's sort of a bit of a dead end because once you've done that there's nowhere to go well there's a machine called clique which is a compact linear collider which is a electron positron Collider that's uses a novel type of acceleration technology to accelerate at shorter distances we're still talking kilometers long but not like 100 kilometers long and then the probably the project that is I think getting the most support it'll be interested to see what happens something called the future circular Collider which is a really ambitious long-term multi-decade project to build a 100 kilometer circumference tunnel under the Geneva region the LHC would become a kind of feeding machine it would just feed for the same area so there would be a theater for there yeah so it kind of the edge machine would be where the LHC is but it would sort of go under Lake Geneva and round to the Alps basically since you know up to the edge of the Geneva base and so basically biggest it's the biggest tunnel you can fit in the region based on the geology alarm yes it's big it'd be a long drive if your animal experiments on one side you got to go back to CERN for lunch so that would be a pain but you know so this project is in principle is actually to accelerators the first thing you would do is put an electron-positron machine in the 100 kilometer tunnel to study the Higgs so you'd make lots of Higgs boson study it really precisely in the hope that you see it misbehaving and doing something it's not supposed to and then in the much longer term a hundred with that machine gets taken out you put in a proton proton machine so it's like the LHC but much bigger and that's the way you start going and looking for dark matter or you're trying to recreate this a phase transition that I talked about in the early universe but you can see matter antimatter being made for examples there's lots of things you can do with these machines the problem is that they will take you know the most optimistic you're not going to have any data from any of machines until 2040 or you know because they take such a long time to build and they're so expensive so you have W a process of R&D design and also the political case being made so la seal cost a few billion depends how you count it I think most of the sort of more reasonable estimates that take everything into account properly it's around the sort of 10 11 12 billion euro mark what would be the future sir I forgot the numerator future circular Collider future circular because you mean I would call it that when it's built because it won't be the future anymore but a very big Hadron Collider I don't know but yeah that will I know I should know the numbers but I think the whole project is estimated at about 30 billion euros but that's money spent over between now and 2017 probably which is when the last bit of it would be sort of finishing up I guess so you're talking a half a century of science coming out of this thing shared by many countries so the actual cost the arguments that are made is that you could make this project fit within the existing budget of certain if you didn't do anything else it's earned by the way we didn't mention what is CERN CERN is the European Organization for Nuclear Research as an international organization that was established in the 1950s in the wake of the Second World War as a kind of it was sort of like a scientific martial plan for Europe the idea was that you bring european science back together for peaceful purposes because what happened in the 40s was you know a lot of particular scientists but a lot of scientists from Central Europe had fled to the United States and Europe and sort of seen his brain drain so it's a desire to bring the community back together for a project that wasn't building nasty bombs but was doing something that was curiosity driven so and that has continued since then so it's kind of a unique organization it's you to be a member as a country you sort of sign up as a member and then you have to pay a fraction of your GDP each year is a subscription I mean it's a very small fraction relatively speaking I think it's like I think the UK's contribution is 100 or 200 million quid or something like that yeah which is quite a lot but no not that's fastest man I mean just the whole thing that is possible it's beautiful it's a beautiful idea especially with when there's no wars on the line it's not like we're freaking out as we're actually legitimately collaborating mmm to do good sighs one of the things I don't think we really mentioned is that in the final side that sort of the data analysis side is there a break there was possible there and the machine learning side like is there is there a lot more signal to be mined in more effective ways from the actual raw data yeah a lot of people are looking into that I mean so what we know I use machine learning in my data analysis but pretty knotty you know basic stuff because I'm not a machine learning expert and just a physicist who had to learn to do this stuff for my day job so what a lot of people do is they use kind of off-the-shelf packages that you can train to do signal noise you know just like a cleanup yeah but one of the big challenges you know the big challenge of the data is a it's volume there's huge amounts of data so the LHC generates now okay I bought the actual numbers are but if you we don't record all our data we record a tiny fraction of the data it's like of order one ten thousandth or something I think right around that so it's it votes mostly gets thrown away you couldn't record all the LHC data because it would fill up every computer in the world in the matter of days basically so there's this process that happens on live on the detector something called a trigger which in real time 40 million times every second has to make a decision about whether this collision is likely to contain an interesting object like a Higgs boson or a Dark Matter particle and it has to do that very fast and the software algorithms in the past were quite relatively basic you know they did things like measure mementos and energies of particles and put some requirements so you would say if there's a particle with an energy above some threshold then record this collision but if there isn't don't wear as now the attempt is get more and more machine learning in at the earliest possible stage because cool at the stage of deciding whether we want to keep this data or not but also even even maybe even lower down than that which is the point where there's this you know generally how the data is reconstructed is you start off with a digital a set of digital hits in your detector so Scannell saying did you see something do you not see something that has to be then turned into tracks particles going in different directions and that's done by using fits that fit through the data points and then that's passed to the algorithms that then go is this interesting or not what we better is if you could train machine learning to look at the raw hits the basic real base level information not have any of the reconstruction done and it just goes and it can learn to do pattern recognition on this strange three dimensional image that you get and potentially that's where you could get really big gains because our triggers tend to be quite inefficient because they don't have time to do the full whiz-bang processing to get all the information out that we would like because you have to do the decision very quickly so if you can come up with some clever machine learning technique then potentially you can massively increase the amount of useful data you record and you know get rid of more of the background earlier in the process yeah to me that's an exciting possibility because then you don't have to build a sort of you can get again without having to have to put an ephod whereas per hardware yeah but I do you need you need lots of new GPU farms I guess so hardware it still helps but yeah the you know I got a talk to you so if I'm not sure how to ask but you're clearly an incredible science communicator I don't know if that's the right term but you're basically a younger Neil deGrasse Tyson with a British accent huh so and you but I mean can you save where we are today actually yeah so today we're in the Royal Institution in London which is an old very old organization has been around for about two hundred years now I think maybe even I should know when it was founded so the early 19th century it was set up to basically communicate science the public so it was one of the first places in the world where scientists famous scientists would come and give talks so very famously my Humphrey Davy who you may know of who was the person who discovered nitrous oxide is a very famous chemist and scientists also discovered electronic sis so he used to do these fantastic was very charismatic speakers who's to peer here there was a there's a big desk they usually have in the inner theater and he would do demonstrations to the sort of the the folk of London back in the early 19th century and Michael Faraday who I talked about who is the person who did so much work connection Magnussen he used he lectured here he did experiments in the basement so this place has got a long history of both scientific research but also in the communication of scientific research so you gave a few lectures here how many - I've give I given you I given a couple of lectures in this theater before so I mean that's think so people should definitely go watch online it's there's just the explanation of particle physics that all the good thing it's incredible like your your lectures are just incredible I can't sing it enough pray so it was awesome but maybe can you say what did that feel like what was if you like to lecture here to talk about that and maybe from a different perspective more kind of like how the sausage is made is how do you prepare for that kind of thing how do you think about communication the process of communicating these ideas in a way that's inspiring to what I would say your talks are inspiring to like the general audience you don't actually have to be a scientist you can still be inspired without really knowing much of the you you start from the very basics so what's the preparation process and then the romantic question is what does that feel like to perform here I mean profession yeah I mean the process I mean the talk that the my favorite talk that I gave here was one called beyond the Higgs which you can find on the on the all institutions youtube channel which you should go and check out I mean and their channels got loads of great talks loads of great people as well I mean that one I sort of given a version of it many times so part of it is just practice right I and actually I don't have some great theory of how to communicate with people it's more just that I'm really interested and excited by those idiot and I like talking about them and through the process of doing that I guess I figured out stories that work and explanations that well you see a practice you mean legitimately just giving just giving talks given I said I started off you know when I was a PhD student doing talks in schools and and I still do that as well some of the time and doing things I haven't done a bit of stand-up comedy which was sort of went reasonably well even if it was terrifying and that's unusual as well there's also a new I wouldn't I wouldn't necessarily recommend you check that out I'm gonna post the links several places to make sure people click on it yeah it's basically I kind of have a story in my head and I is I you know I kind of I have a think about what I want to say I usually have some images to support what I'm saying and I get up and do it and it's not really I wish there was some kind of I probably should have some proper process this is very sounds like I'm just making up as I go along and I sort of am I think the fundamental thing they said I think it's like I don't know if you know who a guy named Joe Rogan is yes okay so he he's also kind of sounds like you in a sense that he's not very introspective about his process but he's an incredibly engaging conversationalist and I think one of the things that you and him share that I could see is like a genuine curiosity and passion for the topic I think that could be systematically caught you know cultivated I'm sure there's a process to it but you come to it naturally somehow I think maybe there's something else as well which is to understand something there's this quote by firemen whichever you like which is what I cannot create I do not understand so like I'm not I'm not like particularly super bright like so for me to understand something I have to break it down into its simplest element yes and that you know if and if I can then tell people about that that helps me understand it as well so I've actually I've learned I've learned to understand physics a lot more from the process of communication because it forces you to really scrutinize the ideas that you're communicating in a coffin makes you realise you don't really understand the ideas you're talking about and I'm writing a book at the moment I had this experience yesterday where I realized I didn't really understand a pretty fundamental theoretical aspect of my own subject and I had to go and hide to sort of spend a couple of days reading textbooks and thinking about it in order to make sure that the explanation I gave captured the got as close to what is actually happening in the theory and to do that you have to really understand it properly and yeah and there's layers to understanding yeah it seems like the more there must be some kind of Fineman law I mean the the more you the more you understand services simply you're able to really convey the you know the the essence of the idea right so it's just like this reverse the reverse effect there's like the more you understand the simpler the final thing that you actually convey and so the more accessible somehow it becomes that's why faint fineman's lectures are really accessible it was just counterintuitive yeah although there are some ideas that are very difficult to explain no matter how well or badly you understand like I still can't really properly explain the Higgs mechanism yeah with because some of these ideas only exist in mathematics really and the only way to really develop an understanding is to go unfortunately to a graduate degree in physics but you can get kind of a flavor of what's happening I think and is trying to do that in a way that isn't misleading but always also intelligible so let me ask them the romantic question of what to you is the most perhaps an unfair question what is the most beautiful idea in physics one that fills you with are is the most surprising the strangest the weirdest there's some a lot of different definitions of beauty mmm-hmm and I'm sure there's several for you but is there something just jumps to mind that you think is just especially I mean I well beautiful there's a specific thing in a more general thing so maybe the specific thing a first widget is a cone i first came across this as an undergraduate i found this amazing so this idea that the forces of nature electromagnetism strong force the weak force they arise in our theories has there a consequence of symmetries so symmetry is in the laws of nature in the equations essentially that used to describe these ideas the process whereby theories come up with these sorts of models as they say imagine the universe obeys this particular type of symmetry is a symmetry that isn't so far removed from a geometrical symmetry like the rotations of a cube it's not you can't think of it quite that way but it's sort of a similar sort of idea and you say okay if the universe respects the symmetry you find that you have to introduce a force which has the properties of electromagnetism or different symmetry you get the strong force or a different symmetry you get the weak force so these interactions seem to come from some deeper it suggests that they come from some deeper symmetry principle I mean depends a bit how you look at it cuz it could be that we were actually just recognizing symmetries in fact as you see but there's something rather lovely about that but I mean I suppose a bigger thing that makes me wonder is actually if you look at the laws of nature how particles interacts when you get really close down they're basically pretty simple things they bounce off each other by exchanging you know through force fields and they move around in very simple ways and somehow these basic ingredients these few particles that we know about and the forces creates this universe which is unbelievably complicated and has things like you and me in it and you know the earth and stars that make matter in there caused by this from the gravitational energy of their own bulk that then gets sprayed into the universe that forms other things I mean the fact that there's this incredibly long story that goes right back to you know the big it we can we can take the story right back to you know a trillionth of a second after the Big Bang we can trace the origins of the stuff that we're made from and it altum Utley comes from these simple ingredients with these simple rules and the fact you can generate such complexity from that is really mysterious I think and strange and it's not even a question that physicists can really tackle because we are sort of trying to find these really elementary laws but it turns out that going from elementary laws and a few particles to something even as complicated as a molecule becomes very difficult and so going from a molecule to a human being is a problem that just you know can't be can't be tackled at least not at the moment so yeah the emergence of complexity from simple rules is so beautiful and so mysterious and there's not either we don't have good mathematics to even try to approach that emergent phenomena that's why we have chemistry and biology and other subjects as well yeah I don't think I don't think there's a better way to end it Harry I can't I mean I think I speak for a lot of people that can't wait to see what happens in the next 5 10 20 years with you I think you're one of the great communicators of our time so I hope you continue that and I hope that grows and um definitely a huge fan so it was an honor to talk to you today thank someone on it thanks very much thanks for listening to this conversation with Harry cliff and thank you to our sponsors expressvpn and cash app please consider supporting the podcasts by getting expressvpn and expressvpn comm slash flexpod and downloading cash app and using collects podcasts if you enjoy this podcast subscribe on youtube review it with five stars an apple podcast supported on patreon are simply connect with me on Twitter at Lex Friedman and now let me leave you with some words from Harry cliff you and I are leftovers every particle in our bodies is a survivor from an almighty shootout between matter and antimatter that happened a little after the Big Bang in fact only one in a billion particles created at the beginning of time have survived to the present day thank you for listening and hope to see you next time you

Channel: Lex Fridman

Views: 119,805

Rating: 4.9192152 out of 5

Keywords: square, artificial intelligence, agi, ai, ai podcast, artificial intelligence podcast, lex fridman, lex podcast, lex mit, lex ai, lex jre, mit ai, physics, higgs boson, lhc, god particle, cambridge, b quark, beauty quark, dark matter

Id: 8A-5gIW0-eI

Length: 98min 20sec (5900 seconds)

Published: Wed Apr 29 2020

Reddit Comments

[u/anon16r]

Very highly recommended but as a pre-requisite please do watch this series: Subatomic Stories by Prof. Lincoln of Fermi Lab first**.**

​

Also by the guest:

• Beyond the Higgs: What's Next for the LHC? - with Harry Cliff

[u/anon16r]

Excerpts (TODO):