In the early decades of the 20th century the discovery of something called antimatter Raised a significant problem This new substance called into question how our matter filled universe could exist at all. Let me explain in 1928 Paul Dirac came up with a new and elegant equation to describe how particles like electrons Behaved when they travel close to the speed of light Surprisingly Dirac found that his equation always had two solutions sort of how the square root of a positive number always has two answers direct recognize that one solution described the electron but the other well That was a mystery which he first dismissed as a mathematical artifact He later said it took him three tortured years to summon the courage To claim that this other set of solutions was describing something real Antimatter that is the first solution described an electron while the second described an anti-electron the anti electron would have the same mass and spin as the electron, but it would have an Opposite electric charge now since the electron has a negative charge The anti electron would have a positive charge which is why we also call it a positron Dirac’s equation says the same thing is true for all particles Quarks have anti quarks and just as quarks can make up protons anti quarks can make up anti protons and antiprotons And anti-electron x’ they can make anti atoms and so on Dirac’s theory was a remarkable achievement if proven correct, it would double the number of known particles in the world Just four years later in 1932 Carl Anderson Took this picture of a particle racing through a bubble chamber his measurements showed that it had the same masses in electron But a positive electric charge the first detection of antimatter verifying directs mathematical prediction Now we come to the puzzle when matter and antimatter come together They annihilate and this raises a big question.
Why is there any matter left? after all if matter and antimatter are identical except for having opposite electric charge and since as far as we can tell the laws of physics don’t have a preference for a Plus sign over a minus sign we would expect equal amounts of matter and antimatter to be created at the Big Bang And then as they intermingled the matter and antimatter would all annihilate leaving a sea of structureless radiation but if this were the case The universe as we know it wouldn’t exist. So what’s going on? Physicists have been puzzling about this for more than half a century Some have wondered whether the antimatter got separated from matter and might still be out there Existing as anti planets anti stars anti galaxies, maybe even anti universes others have imagined that just after the Big Bang a tiny imbalance between matter and antimatter somehow crept in indeed to avoid total annihilation Scientists have calculated that for every billion anti protons There must have been a billion plus one protons That’s a tiny imbalance, but it would have left over just enough matter to make all we see in the universe today To figure out which if any of these theories might be right scientists are undertaking a range of experiments to understand ant matter with far greater precision and All this is part of a grand quest to answer a question that is as simple as it is profound Given that matter and antimatter annihilate.
How is it that we exist? Thank you very much good evening so that is the question Why do we exist now? Let me just quickly say at the outset That sounds pretty heavy. Right? It sounds like it’s a question of existential angst that we’re going to be dealing with here tonight But as the animation makes clear, we mean it in the most flat-footed direct interpretation of the words How is it that there still is matter around if there was equal matter and antimatter? Early on why didn’t it all annihilate leaving nothing? that’s the issue that we’re going to take up here tonight, and we have some of the world’s greatest experts on these ideas Joining us for this conversation. So let’s get right to it and bring them on to the stage our first participant Is a physicist who is a founding director of the Kavli Institute For physics and mathematics of the universe at the University of Tokyo He received the UK of commemoration prize in 2002 and a home built research award in 2017, please welcome Hitoshi Murray Amma Also joining us is a physics professor at MIT Was the member of the micro Boone and ice cube experiments? She’s a fellow of the American Physical Society and received the Maria coffered my reward for her leadership and experimental neutrino physics Please welcome Janet Conrad Our third participant is the research physicist at CERN where he is a spokesperson of the edgiest experiment He’s also one of the editors of Physics Letters B and also contributed the review of particle properties, please welcome Michael dozer All right next to join us is a distinguished scientist at Fermilab and a professor of physics at the University of Chicago and the Enrico Fermi Institute and an internationally renowned expert on particle physics, please welcome Marcela Karina And our final participant is the director of the Perimeter Institute for Theoretical Physics in Ontario Canada and a founder and chair of the African Institute for mathematical sciences and award-winning physicists who developed and test theories of the early universe, please welcome Neil Turok Alright so welcome to you all and you know Just a quick aside.
You know there aren’t that many Physicists in the world so we all know each other at one level or another, you know And I actually bring that up to this guy in the air. He’s going like this, but let me tell you what that means Do you know when I met you first? Yes 33 years ago Italy in Italy in a reach a you were my teacher at the So it’s a pleasure to have all of you here To take up a question that people have been puzzling about for for a very long time And so let’s get right into the subject which really does begin with Paul Dirac and Maybe Nia can just start us going. What was Direct puzzling about that ultimately led to him writing down this equation that has driven so much of theoretical physics So Dirac was very odd person and actually in the same school that we met in.
I met Dirac when I was a student Oh, is that right? Yes and There’s a biography of him called a strangest man, and he pretty much was He came to the school with his wife, but they would never be seen together. I Had breakfast separately, you know she was this she I do that with my wife Thank you saw she went off to the left, right That’s right, but no Dirac was very obsessive individual He came to the school where there were a lot of other Very distinguished figures in physics and they were all talking about the glorious days of physics and how wonderful physics was and all that trying to inspire all the students and Dirac basically said You know the Golden Age of physics was the 1920s and it’s come and gone and you’re all too late The the school the school was I think 83 yeah 83 So yeah, what did Dirac do so Dirac was? Obviously genius and he took on the task of unifying relativity which Einstein had invented with quantum mechanics which bore and other people had invented and Somehow nobody else could manage in the way directed He had a precision and the clarity and a simplicity about his work.
That was just stunning and so Whenever people had paradoxes or problems with quantum mechanics, you know, they would always turn to Dirac. What do you say about this? He wrote down this equation that achieved that goal. Yes, but as the story goes and I believe the story is true We sort of see the acquit You don’t have to know what this means of course, but this is the Dirac equation in a simple form. Yes I think we may even have it You know notation in physics can hide a great degree of complexity do have a more spelled out version of it.
Yeah. There we go Simplified version too, right? I wanted to draw the full one, but I ran out of time on doing everything but um so he writes in this equation and It makes a strange prediction I would like to say that when Any of you is looking at that equation Might be you know a bit push backwards because doesn’t look so easy But I would like to make the analogy If you are not a trained musician, and if you are looking at the notes on stave They will not really talk to you very strongly. But then if you have a virtuoso who comes and interprets this Music then you will have an amazing melody coming out of it So the same way I would say that this I read equation that you are looking at there from your perspective was Powerful enlightening for someone of the genius of Dirac and Out of that equation. He basically predicted the whole anti world and so I would say that One has to think about that when when one looks at equations mathematicians and physicists might have a take on it but the beauty of this equation is something that We as scientists should Try to convey to you in many different ways as the music as the musicians and the dancers Do with their interpretations.
Does that analogy? Give us a way of thinking about Dirac’s resistance To the prediction of his own equations because you’re right. He writes down this equation It does put special relativity and quantum mechanics together out of the math There is this strange prediction there as we sort of said in the animation There are two solutions when they really only should be one and he doesn’t believe it would that be like Bach writing a fugue and then like Yes Now you also have to cast your minds back because in those days people were more parsimonious with adding new particles in the world and I say that as someone who’s part of a field that’s added a Lot of particles that have never been seen in the world But in those days to do this was a radical move, very, right So I’m just wondering if you put yourself interact shoes and imagine that you write down this equation.
I Know what I would have done. I think I would have thrown it away. I would have said it’s predicting these other particles They don’t exist and therefore something’s wrong. Exactly. Do you do you think you’d have the well, I will be scared actually No, one had ever predicted a particle in that way before. Yeah and actually what happened is they try many of the physicists that we’re trying to understand and discuss with Iraq it took three years for him to really Finally accept that what he has predicted was a new type of particle that was not there before and there has not yet been discovered Yeah, that’s very important. So The beginning he thought maybe you know, that was a proton So then they thought maybe something different. Okay, and so it took him quite some time and we think three years is a lot but maybe Maybe we think about that.
We will come back maybe later about the Higgs mechanism that took fifty years Pretty fast he was kind of lucky in in first of all recognizing that that was a new anti world in front of him and then actually a year later so only four years after the first Antiparticle. The first positron was actually discovered. Yes. Why don’t we talk about that? Without that I don’t think we would be having this conversation here However, beautiful the equations were and Dirac was very fond of saying math is beautiful and that’s why it really describes the world But it has to be data. So so Janet wanted to give us a sense of When was this? Confirmed and how is it done? Well, the confirmation of it was happening. Actually, you can see on the screen in this in this cloud chamber picture which shows the The event that do you want to speak to this one? which other well, this is actually a cloud chamber and this was the first time that a Positron to tell us what the cloud chanting everybody knows So basically it’s like air and vapor can condense when a particle goes through There are some vacuum and some electric fields and magnetic fields and so basically when a particle goes you give a tract of paper of liquid and On something that is basically air.
Okay, and that’s what you see there So this is the trace is the trace of a positron and one can decide many things there But the point is that because of the magnetic field D and because of what they understood after a while also that you know Carl Anderson was the one who discovered the positron and Caltech and the point was that they were also confused about well, maybe you know, this was a particle that actually comes from a decay of Cosmic rays so it comes from the outer atmosphere makes it up to here And so they were thinking well, maybe you know the we don’t know where the is an electron That is bending in the wrong direction.
That was the but maybe the electron is coming Upwards instead of downwards and then that would be okay or maybe the positron that we already know at that time we only knew positrons and electrons maybe suppose it’s wrong with the right charged positrons are charged like protons Protons and positrons have the same positive charge so maybe it’s a proton that is coming there and it took some time and car and Rizzo had to basically Improve a lot his device. Yeah in order to be able to Recruit ibly show that this was for the first time The trace of antimatter in this case a positron so an anti-electron It took quite a little while to improve them the the instrument and I Always get very impressed about you know, Janet is an experimentalist and here Michael as well So I think it’s humbling to see what our colleagues experimentalist can do To learn about nature. Yep. So Janet, well, I I thought that maybe you all would like to find your own positrons So everybody should have a little envelope. I hope you all have an envelope and Inside of the envelope is some bubble chamber film.
Everybody should have one piece of bubble chamber film Every image is different. This is actually film. I’m sorry What happens was that there was a very large bubble chamber at to Fermilab so what happens with the bubble chamber is you have a Compressed liquid and when charged particles go through it. They create little bubbles then when you Decompress the bubbles become large and you can actually take a photograph of it and there’s a magnetic field And so that’s what causes the particles to spin around in the picture so every event is different you all can take a look somewhere in their neutrino interactions if you can go ahead and find them but what we thought you would really like to see is where energy turns into a int matter an antimatter pair, so this happens In this picture that you have up here, you can see it right there So just tell us exactly what we’re seeing there right out of nothing which was actually a photon So that’s a little packet of energy, which is not electrically charged.
So you can’t actually see it in your detector Suddenly it converts into an electron and a positron and because we have a magnetic field What happens is that the positive charge spins one direction and the negative charge spins the other direction? So what you get is you get a little vertex and then you have the particle Traveling in one direction and the anti particle traveling in the other direction and that’s how we see Antimatter in our detectors and we know that it’s antimatter fantastic and there should be at least one in every image there’s a lot of photons that come out that actually found your electron-positron pair Find it You know when Dirac had to dismiss his own solution because he was so scared to say there’s antimatter He must be also very nervous for an experimentalist to claim. They discovered antimatter. Oh, yeah Oh, is it like? you know being an explorer run for this when when you Think you might have found something new you spend a lot of time playing with it and trying to make sure that it is exactly what it is that you you think it is and You have to look at something in many different ways Because we have a problem in Experiment with something which is called background Which is where you see things that just look similar to what at this signal that you’re looking for, right? well The example that I like to give is let’s say you are looking for women with red hair and you wanted to count the number Of redheaded women there are in the world And you go out and you count and you discover that there are many more redheaded women than you ever expected and and that’s because of lore’l So all those redheaded women where the that are not really redheaded are the background To worry about that Exactly when you’re looking for things like this including when you’re looking for antimatter So there you find the the anti electron the positron and it takes a couple decades before the next Element of the antimatter part of the world is dispersed.
It’s really easy to get an electron so they they rain down on you constantly, but it’s like right now like right now yeah, in fact if you have a banana, does anybody have a banana in their pocket, I Don’t want to hear the airing that During the hour that you’re gonna listen to us you’re that one anti-electron is gonna appear inside that banana So just to give you an idea it’s very simple to get an electron if you want something more massive like an antiproton You’re gonna have to put a lot more energy into it than you can get simply from Waiting for banana to do something interesting. So you have to build an accelerator You have to build something that will give you start out with a proton you accelerate it you go to higher and higher and energy Until you have enough energy to actually pair produce because again, you have to produce two particles. Yes There’s a equals MC squared this equals MC squared, but you also have to conserve charges You have to get both at the same time And then if you have just enough energy if you build your accelerator Just right you can produce an antiproton and when did that happen did that that was in 1955? At Berkeley and the main problem again is the the Loreal effect You get many many more particles that are produced at the same time as the antiproton So you have to actually produce an antiproton and prove that you’ve made an antiproton and what you see in the picture on the right hand side is what happens when an antiproton that interacts with the photographic emulsion as It touches the emulsion as matter meets antimatter it annihilates and in the case of a positron.
It’s not so spectacular It will go into two photons here If an antiproton touches a nucleus it basically rips apart the nucleus and these fragments Go flying all over the place and leave traces in the photographic emulsion. Right? So these are now examples of finding an Anti-electron and antiproton from them raining down in some form or another How about in controlled? experiments in the laboratory is this now something that we can do to actually Create in fact this this machine is just the predecessor of a machine. That’s now running at CERN a factory to make antimatter and again All it takes is having a little bottle of hydrogen you accelerate the protons after you have it ripped apart the hydrogen Into a proton electron go up to high enough energy you produce anti protons The real problem then is you’ve made the anti protons and as you want to study them and they annihilate so that’s not Exact options Antimatter through that process can we bring up that video of the great? Thank you, Motech so this is really a it’s a video of the world’s only antimatter factory, which is at CERN or Antiproton Factory actually and it starts out with a bottle of hydrogen you take the hydrogen you rip it apart in electric field Then through a series of electric and magnetic fields you give it more and more energy until it has enough energy to be able to smack to be smashed into a Block of iridium at that point when it hits the iridium the kinetic energy is transformed into pairs of particles and antiparticles there’s a picture of this target which I think is nice to see because it really this all stems from the 1970s 1950s 1970s.
So you really see the technology as it was at that time. This is still the same source that we’re using It’s still the same apparatus now once you have that the anti protons that are produced are moving almost at the speed of light because the protons are moving so fast and you you push Them forward and in order to actually study them you have to catch them. Yeah and catching them That’s the real hard part because they’re moving so fast. You have to first slow them down. So you need another accelerator That’s run backwards. That’s the antiproton decelerator rather than accelerator And this thing slows the antiprotons down from the speed of light down to one tenth the speed of light It’s as slow as you can go. This is practically pedestrian speed for physicists At that point you can just barely catch these antiprotons you can start hoping to catch a few but percent of the antiprotons that come out and Then how do you actually hold on to them? Right? I mean very carefully Because you have to avoid that they touch matter obviously so you’re going to be doing this in vacuum You can manipulate the trapped antiprotons once you’ve trapped them with electric fields and magnetic field So you sort of touched them at a distance while keeping them Well in the center of a series of rings these rings are all connected to batteries Each one is connected to different voltage and that allows you to create sort of potential landscapes like marbles these antiprotons will roll around in this landscape and you can raise hills move things around so Is this something that? We can create large quantities of it.
Yeah enormous quantities, I mean 10 million antiprotons in a go like what is the 10 million and type? Facility and this is really top of the line facility for a whole year You’re gonna end up with 10 to the 14 antiprotons, which is like really big numbers Except but like how many I’m just wondering like how many how many atoms why? Few more than I was gonna go up with it. 1 gram is Avogadro’s number So it’s times 10 to the 23 10 to the 20 means you’re making a tenth of a nano gram of antimatter per year, right? So so actually not that I want to be, you know the friendly competitor being here at Fermilab so in this side of the country But I I’m sure you remember the movie Angels & Demons that was there in 2009 and at that time Here in the US.
We still have the Tevatron running. And so that was the biggest antimatter Factory in the world. Okay, and At that time I did this little calculation because that question was asked about, you know, can we really blow up? the Vatican as you know as they were telling us in this gorgeous movie and you know, Victoria Vitra and Robert Lancome has to save the Vatican So much let’s you know the law is because you brought up the film Independently of my prodding you we can now fair you show a little little clip of it. So You have that little section Extremely combustible substance called antimatter. We need to locate it immediately or evacuate Vatican City I’ve never heard of antimatter being used as such well It’s never been generated in significant quantities before it’s a way of studying the origins of the universe When I was the movie and The most amazing guy found his movies that these people made a quarter gram of antimatter and the director-general didn’t know the status And they must have spent enormous power that must have cost them billion trillion trillion dollars And the director didn’t notice it right so not a huge budget Or at CERN it actually takes the age of the universe to get enough antimatter This little calculation that it will take really a hundred Million years to make the amount of the quarter gram of antimatter It will cost the very little amount of money of five five hundred trillion dollars You know, I don’t have it in my pocket, but I can get it tomorrow And most interesting I mean I was thinking by living at CERN and going through the Swiss border many times that how they do smuggle it from CERN to the Vatican because you know This could be you were talking about this trap.
This could be of the size of a football field. So actually, the track wouldn’t have to be that big because the thing is of course, if you can work with charged particles, you need massive electric fields and massive magnetic fields, but if you transform this into atoms You can trap those and you don’t need these enormous a gram of hydrogen you can hold in a bottle about Actually, I have to make it into anti hydrogen first, that’s the tricky part I thought anti hydrogen if you do it, it will be very Extremely hard and it’s seemly unstable, correct? No It’s actually easy to easy to make the experiment but to actually keep it Safe to transport it through and you know go this is a really fascinating conversation here But if you don’t mind we’ll leave that angel name an issue to later conversation Let’s um, let’s get back to the UM the issue at hand.
So, let’s see So we’ve got we got antimatter and matter we can actually produce it in Various quantities up at the the the puzzle that we’re really focused on here tonight is how is it that the universe? Was able to create matter and antimatter and yet somehow there’s this matter left around us So so from that perspective The first person to really give us insight into this was a russian dissident Andre soccer many want to give us a rough sense and then we can have a little visual we can discuss what he told us was A physicist in russia back in the soviet union days, and he was in a pro-democracy person He was like to present many times back in those days But he came up this wonderful idea that maybe you know universe had a way of keeping matter But throwing away antimatter And so what he did is that well when universe start with a big man the huge amount of energy turned into matter But as we just heard from Janet whenever energy turns into matter, there’s also an accompanying antimatter always one-to-one Yep, if we stayed that way when any of us becomes bigger and colder and eventually matter and antimatter meet and again one-to-one They go puff and disappear Yeah So he pointed out that if there is some tiny difference between the way matter behaves and antimatter be faiths Maybe they could be tiny difference between them So if they start with a billion two billion, maybe one part of a billion antimatter turns into matter And then there’s a small difference between them when they meet pretty much everybody disappears But they remain just the tiny bit of it left ocular so your numbers were a billion say Antiprotons right today – a billion plus one proton and you had that little imbalance Leaving us one particle leftover for every billion of these guys That’s right.
You claim that would be enough if that imbalance to give rise to everything that I see in the world around So we actually live here at the expense of billion friends right gotta be really great for them So sakarov actually laid out a set of conditions that Didn’t necessarily yield a very specific theory that would yield that imbalance but a set of criteria That if you could meet would give you a shooting a fighting chance of having this scenario that who told you describe worked out So let’s just take a quick look just to get a feel for what it is that Sakarov had found so if we can look at that little sequence where we start with the big bang as you mentioned Energy is creative yields equal amounts of matter and antimatter and now we want to somehow go forward in time And pass through some process you can go on to the next slide if you would wear this black box process Well somehow give rise to this imbalance that you’re talking about that we’ll leave over just matter you can go on to the next one As opposed to antimatter.
So the question he asked is what in the world is happening inside that black box That’s the real issue and to give you a feel for what he found We’re just gonna do a little announced a little silly analogy, but nevertheless I think it give you a flavor for what it is that he found instead of talking about particles and antiparticles We’re gonna talk about instead rabbits and Anti rabbits and imagine that you have and I’ll talk you through this So please don’t advance until I tell you to advance. So in fact, this is why they gave me a little clicker I was a little bit slow on the uptake. If you can just step back if you would one slide.
That would be great So imagine you begin the equal numbers of Rabbits and anti rabbits. So in the animation is we get so we got two of them They pass through the black box and we have now more Rabbits and more anti rabbits. That means that we’re allowing the numbers of These particles or in this case these rabbits to change if you can’t change the number of protons or anti protons Then you’re dead because if you start with equal numbers, and they can’t change They’re always going to be equal numbers. But if they change in the way illustrated here, you still have symmetry You still have the same number of orange rabbits as blue rabbits, so you don’t have the imbalance that hit Oh she was talking to so if we look at the next criterion we want to now Start with the two Rabbits and two anti rabbits but want them to pass through the black box in such a way that the number of rabbits Differs from the number of anti rabbits if we could do that then we’d have the imbalance that Vitosha was talking about and that gives us a chance of Explaining why there’s matter left over the extra orange rabbits the extra rabbits as opposed to anti rabbits Now the question, let me just quickly show it in in the language of particle physics.
So imagine we have equal numbers let’s call it X matter and antimatter would pass through the black box and Somehow yield that kind of imbalance that is the goal of The black box and what theorists have been trying to do for a very long time is fill in the details of the black box To try to come up with a mechanism that allowed that to happen and clearly one of the things that needs to happen if there has to be some kind of a symmetry between matter and Antimatter and that takes us but who taught you how to comment? I want to get to that first But then we’ll talk about some of the experimental work that’s been trying to find differences between matter and antimatter that Might allow us to realize the black box, but it’s a little comment I want to make was I was happy that you didn’t use anti-human for this.
Yeah, you just arrived. It’s right I thought about humans first Climate would be an obvious choice There was a choice of color though that subconsciously Aligned with that decision Okay anyway So moving on so so Michael you’ve certainly been spending Part of your career and trying to find differences between matter and antimatter. I know you’ve done a variety experiment You just sort of go through some of the possibilty sector. So basically what you’re trying to do is look for a tiny imbalance You’re trying to see a tiny difference between matter and antimatter and by tiny It’s a part in a billion a part in a trillion who knows how small this difference can be? And so if you’re trying to measure this kind of difference with charged particles, you can do that I mean one of the experiments the the base Experiment for example at CERN is doing that by measuring the properties of anti protons as they move around inside a magnetic field But at some point you’re gonna hit some limit the systematic limit You can’t measure your magnetic field that precisely so the ultimate precision that you can try to reach is not with working with charged particles But actually working with neutral antimatter neutral systems Like atoms and atoms are really great because they’re you can use lasers to probe the atoms you can measure extremely precisely so there’s been an experiment the ALF experiment has been Measuring the light that’s emitted by anti hydrogen atoms anti hydrogen and to hide it So what is so how would you build an mm? What is it? You put two bits together It’s it’s really simple you take an antiproton take an anti-electron you put them together You’re a theorist, right? So that should be and It’s it’s taken while 10 years of hard work to make atoms that’s what we’re looking at right here That’s what the atom looks like symbolic is speaking One of the first experiments to build the anti hydrogen atom was the Athena experiment in 2002.
It took almost 10 years before between making the first atom and actually being able to hang on to it to trap it because once you made it It’s neutral your electric field. Your magnetic fields are useless. It just goes off I see like for the for the antiproton you with in it with the electric opinion with with magnetic field. You hold it. Yep You’re very very strong fields. It’s very hard to hold on to these atoms But the alpha experiment managed to do that in 2010 and since then they’ve been shooting everything they’ve got at these atoms laser light microwaves anything you can do to manipulate these atoms and measure their you’re trying to basically hit it with the laser excited exact at a anti electron to jump up a little bit fall back down as it falls back down it releases some Some light some night light and you can see where that you do that with hydrogen as well You do a comparative study and you can be sensitive at one part in 100 million hundred billion hundred trillion depends how far you want to go with this and what kind of transition you’re looking at in? the hydrogen the anti hydrogen very creative very By the way the to transition these two arrows that are shown there They both lit two Nobel Prizes Ramsey on the right hand side and hench on the left hand side So it’s it’s a business where you can hope to get a Nobel Prize, which is the ultimate driver, right? This is one thing you can do you can try to look at the light and Microwave is just another form of but just so we understand this I guess what you’re saying is you’re looking at sort of the the energetic difference between those horizontal lines Exactly that’s telling you the energy of the light that’s being emitted So were there a difference between those separations you would have found the goal that you were looking for? Which is the difference between you is one difference, it might not be the one that is the cause of What we’re actually trying to understand it would certainly be really exciting and have you found any no Of course not you’d have heard about it in the news Media would have been all over this.
Now. You guys are also doing if I understand some experiments with gravity right see how So-so antimatter many people would think it must fall up instead of fall down Yeah, so tell us a little bit about the idea there is to also test the fundamental symmetry to see if there’s a difference between matter and antimatter Gravity is really hard to test with particles so again you work with neutral systems and there the hope is again that you might find a difference now that hope is even more remote than trying to find a difference in the light spectra because there’s absolutely no theory that predicts any difference or Accommodates it or could transform a difference in gravity to an asymmetry in the universe except Ito XI He’s the only one who’s managed to write a paper about it As far as I know see I’m off the Nobel Prize to write I thought it’s never get Nobel Prizes And the basic reason for that I gather is in in Einstein’s general relativity.
If we go to our most refined description of gravity gravity responds to energy, right So if matter and antimatter have the same energy then gravity seems to treat them at least on paper in exactly the same way and in fact We know that if you drop a lead brick and a plastic bottle they fall exactly at the same speed. It’s something that’s been tested extremely precisely by Adelberg a– for example way way more precisely than what we can hope to do because To actually drop antimatter the way we would like to do it like Galileo dropped. Well a lead brick from the Tower of Pisa Requires having very very cold anti hydrogen it has to have a temperature about a millionth of a degree above absolute zero and even then the best you can do is a measurement of about a percent precision so it’s gonna take many many years until we get there and This experiment underway or is it yeah, there are three experiments that are underway my experiment the aegis experiment that’s trying a different approach It’s not gonna drop atoms off a tower.
We’re actually gonna shoot them out like like cannons out of a cannon That’s our Ken balls out of a cannon and watch the para ball measure the parabolic trajectory So that’s that’s the Aegis experiments approach. There are two others The Alpha experiment has got just tell me a little bit more about this You’re gonna fire these in some manner that that is giving us a cartoon version of and you’re gonna track their Trajectories and determine whether the actual trajectory differs for a matter versus that’s right So you shoot them out at maybe a thousand miles an hour.
Sorry a second a little bit faster You can typically fly them over about a meter that’s sort of the distance that we’ve got room for and so they fly for a millisecond they drop for a millisecond and in a millisecond they drop by well a tenth of my very thin hair so It’s really really hard to measure the size thing But we’ll get there at some point. So the theorists in the group Do you have hope that that experiment is going to yield a positive outcome or do you think it’s not answer? I? Would love it to but I think it’s unlikely, right? Okay.
Thank you very much So so Janet and Toshi you guys have been thinking about a distinct kind of probe of antimatter in some sense a more subtle Probe which has to do with other particles called neutrinos, right? Janet just give us a sense of why What are neutrinos quickly and then why would they be a good place to look so neutrinos are? Among the fundamental particles that we have in the standard model One of our embarrassing problems that we have with the standard model is we have a lot of fundamental particles You would like to have your theory.
Be more elegant and but they are among the fundamental particles that we have there and they’re really interesting particles because they carry no electric charge and So as a result they are not as affected by all of the different for all of the different things that are going on around them where they may be affected by electric fields or Magnetic fields or something like that I’d like to think of them as a very quiet particle and if you’re looking for something which is very subtle It’s best to look in a quiet place. And so the neutrinos allow you to be able to look for Unexpected behavior because already they are doing things which are really very rare That’s a question about that. Just hopefully understand the main Diagnostic that we had on the table for talking about matter versus antimatter was the electric charge of the particle If neutrinos don’t have electric charge, how do we talk about? antimatter and matter So we have neutrinos and we have anti neutrinos we believe because they we have particles that decay and the particles which are Matter particles that decay into the neutrinos produce the neutrino the antimatter produces the anti neutrino That’s what we believe.
In fact, it is possible that the neutrino is its own antiparticle and in fact, this is something that Hoshi has been spending a lot of time looking at and So you yeah, so they so the reason why we think that neutrinos might actually saved us from this great annihilation after big man Yeah Is that when the big man made is the same amount of matter and antimatter? And you you want to turn a bit of antimatter into matter.
That’s some more the matter with ducks or survive, right? But if you want to change antimatter if that has electric charge There’s a plus then you can turn that into matter. That should have charged minus or minus two Plus it doesn’t happen right but if this were neutrino Neutral has charged zero and it can turn into anti neutrino with charge – Co that’s also zero So neutral is the only product I can imagine that can sort of go back and forth between matter and antimatter so that it created on this little bit of a symmetry between the two so then Neutrinos are we actually super heroes that saved us from this complete annihilation? That sounds very enticing right So let lets so that that certainly motivates us to think about this issue Now you guys have been looking at some distinctions between matter and antimatter in the neutrino sector of the world and In a probe that you’ve been using uses something called neutrino Oscillation tell us a little bit about what that is Well, first of all I need to mention that nutrition is a subtle as Janet said and they are so subtle That there are actually trillions of them going to a body every second through your body.
Actually. Does anybody feel that? If anybody does I recommended to go to see a doctor tonight So, you know you don’t feel them Right, they’re so shy so for experimental eyes like Janet. It’s incredibly hard to study them because you can catch them very easily But fortunately neutrinos do something really really amazing First of all, they come in what we call three flavors so they come with like strawberry chocolate and the pistachio Yeah, but why the Newton is describing some space they what strawberry chocolate? Do what I have a debate on So the thing is that when you have less is strawberry neutrinos They’re going through space then it starts to turn into chocolate and that’s what people discovered So can we bring it forward go to the animation just one question because I love analogies obviously Can you hold off on that? Not just yet.
Just you hold that for one second I think about these neutrinos and and the flavors that you’re using to describe them in. What physical ways would they actually? potentially differ from yeah so let’s say the chocolate flavor neutrino can produce an electron and straw be a flavor of the Neutrino can put you sort of heavier version electron called muon so different flavor of neutrinos when they interact with matter Produces different kinds of particle. How about the new trainers themselves? Would they all have the same mass or what about that? You know new stress is a really weird thing so they do have mass and that’s a great discovery That was awarded Nobel Prize couple years ago, but at the same time they are sort of a mixed up in a strange way Yeah, so if we take one neutrino, it’s a mixture of three flavours.
It’s a very very strange particle So if you have one of these in your hand it could at one in the same moment be a combination, right? That’s right And that’s one of the weirdnesses of quantum mechanics that things can sort of be a mixture of here and there the mixture is spinning this way and that way a mixture of Being chocolate and strawberry. That’s right. Yeah. All right. So so take us through what you were gonna describe. Yeah. That’s right So let’s say Homer Simpson orders a strawberry chocolate and he’s waiting at the counter Guys, thank you. And then why did they I scream is coming towards him It starts to turn into chocolate and complete now with the chocolate and starts to interact into strawberry Now back completed strawberry what was doing back and forth eventually, they’re gonna be mixed up like this, right? So what he’s gonna find is the mixture of chocolate and strawberry and what experimental state is that they were just looking for? strawberry neutrinos So the detector that was very good at detecting that kind of arena but not the chocolate and then they’re waiting for strawberries arrive But when they actually got the nutrients in the hand They were very surprised because they thought half what the more lost And they don’t have them lost because half them in turn the chocolate they couldn’t taste right.
So the homo was shocked, right? So he’s bitterly complaining about that And this is called neutrino oscillations that as the neutrino travels through space Its identity can actually shift between these three possibilities. Right, right So given that neutrinos can do that. How would you go about? Determining if anti neutrinos might behave differently because after all that’s where after a difference between matter and antimatter nutrients an antigen is now Jana you’re doing an experiment as I understand that that is aimed at Trying to find that kind of a difference want to take this for those ideas. So the way that you do this is you actually begin by running a beam that only has Neutrinos and you look for a neutrinos to do their little dance and change from one type to the other and then you run The experiment again, but the next time you go ahead and you make anti neutrinos so first Let me tell you a little bit about how we make a beam and then I’ll tell you how you do the difference between this so think So you make these as an accelerator for example at Fermi National Accelerator Laboratory which is a place that you can go and visit if you want to it’s open to the public and people are very welcome to Visit it.
And again, we begin with hydrogen and it we put a big voltage across it basically like a lightning bolt and out comes the protons and the protons travel along our Accelerator and we want to have those protons go faster and faster And so what we do is we have them surf They surf on a radio frequency wave but very much like a surfer in Hawaii might be surfing if you catch the bigger and bigger wave you go you get more and more energy you go faster and faster and you approach the Speed of light so these go around the ring. They come out they run into a target the target when the proton set the target There’s an explosion of particles that come out and some of those decay to neutrinos those neutrinos We want to send to a detector. That’s very far away. So there’s plenty of time for them to do their little dance So we have to send them through the ground actually that means you have to send your neutrinos under the ground and It will go through the earth and it will show up from an accelerator.
That’s outside of Chicago It’ll show up in a gold mine in South Dakota. That’s the plan and how It’s about a thousand thousand kilometers and so during that time the neutrinos will do their little dance and You would start out with neutrinos that were one particular flavor and at the end. Hopefully you see another flavor in your detector Now that’s if you’re going to make a neutrino beam What you want to do is you want to have all of the particles that decay To neutrinos be pointed forward into the earth towards your detector And so if you take a look at your bubble chamber picture again You notice that the the matter is spinning in one direction.
The antimatter is spinning in the other direction that’s because there’s a magnetic field so If I want to pick out matter All I need to do is put on a magnetic field and that sends any antimatter I create going off some other direction not pointed in the direction of my detector and so the particles that are going to decay to produce neutrinos then go off and Decay and produce the particles that I would like to look at now if I want to switch All I have to do is reverse my magnetic field Now all my matter will go off in one direction and my antimatter will go toward my detector a battle decay into the neutrinos that I’m actually looking for in my detector and the neat thing about this detector is actually it is really the The descendant of the bubble chamber we think of it as a sort of an electronic bubble chamber that we’re building It’s a state-of-the-art detector and it is going to be 40 kilotons So it is a ver very large detector that we have to build It will be One of the largest of this type of detector looking for this question once we’ve actually built it, but there is actually an experiment running Today in Japan that is working on the same ideas And I suggest that all of you pay attention and about a week because we’re having a big conference It’s called neutrino 2018.
It’s where we present all of our results and We suspect that a big result is going to come out of from the group from Japan Although I I don’t know what it is secret. Yeah, I don’t know what it is. I really don’t know The doors are locked in the audience So as of today just to get the experimental stage repairs the experiments that you guys have been involved with has it yielded any asymmetry so that’s So there are hints of an asymmetry that are coming from this experiment that was running in Japan Two years ago at the same big conference. They showed a little bit of a difference and So we suspect that they will be showing a bigger difference at this next conference And I think it will not quite meet the level that we use in science to kala discovery Which is why I think we need this experiment that we want to run at Fermilab But it looks like it is likely that the anti neutrino does this little dance differently? From the neutrino and if that’s true, and this kind of thing was happening in the early universe You can actually get matter Antimatter, let me ask you a question about that because just to be clear as many people perhaps already know there have been Signatures of an asymmetry between matter and that had been on the table for some time.
Anyone want to speak to that Situation. So the problem with all of the ones that we have seen so far So we have we have seen evidence of this in what’s called the quarks The quarks are what actually makes up the proton and the neutron They’re the other two another type of fundamental particle, but they’re the effects that we’ve seen we have seen differences But the effects we’ve seen are are too small to explain the level of Matter antimatter asymmetry and the theory with that is it definitely too small that can’t be leveraged into yeah, I agree with that So so when people discover this tiny difference between behavior matter and antimatter back in 1964, actually Yes People try to explain this by coming up with all kinds of theories for that And then there were experiments one at Stanford another one in Japan They were in sort of head-to-head competition for about 10 years and they proved in the end that no You can understand why that happened but the reason how that happened was not enough to explain the difference between madinat jumeirah in the universe at the level of one billionth of a billionth So is this way so Miss and Miss by a factor of a billion But the thing about but I think is really interesting is our understanding of particles comes from looking at patterns and we see all of these different patterns and what we have found is that if you find a pattern in the quark sector like something is is a very Small effect and you look in with the neutrinos you’ll discover that it’s a larger effect So one example of it has to do with this kind of flavor changing right, and it looks like this may also be holding out for the the difference between neutrinos and antineutrinos So you guys are kind of artists they do the opposite.
I know you can’t divulge and perhaps you really don’t know but So the differences that are hinted at in the neutrino versus antenna treated do you think that would be enough to explain the matter/antimatter Asymmetry, the connections are a little bit tricky so I can pass those connections over to one of the theorists you guys Want to comment on? Yeah, so as we’re talking about today So you want to see that the matter rabbits and antimatter aunty rabbits behave differently, so that’s one thing we need But another thing we need is that we start with the same number. Yep, and turn antimatter into matter, right? That’s why there’s a imbalance between them do and nobody has seen that kind of thing the matter turning into antimatter Or antimatter tuning into matter. So people frantically looking for such a thing also by doing experiments mostly underground Yeah, and there’s actually I think slide for that Which that mutant double beta decay.
Yeah, so we can look for a process actually This is a super chem you can experiment in Japan but anyway, this is the process that you produce a anti neutrino from some radioactivity process and if that anti neutral can turn into Neutrino and which would require it to be its own anti, right? That’s right So that’s only possible because the neutrino has no weight active charge, right? Yeah, then you have a process which otherwise wouldn’t happen so people looking for this special process that you produce anti neutrino that turns into Neutrino and any interacts with electron at the end of the day Yeah, and nobody has seen that yet because it is cannot happen even once in 10 to 20 60 years So it’s way beyond the age of universe, right? That’s why nobody has seen this but if you have ten to the twenty seven of this stuff Maybe it can happen once a year here. So let make sure I just fully understand this So so the blue things I gather here are protons and the proton itself is undergoing a process Where an electron and an anti-neutrino? Is being emitted, that’s a neutron? Yeah, that’s that nutrient.
Sorry neutrons of that yeah, so so on the left-hand side that is Quite conventional compared to the right hands. That’s right. So on the left-hand side of the story the neutron turns into a proton and Spits out electron and antineutrino. Yep, and another Neutron does the same thing So in the end is spits are two electrons in two anti neutrinos Yeah, and of course, you don’t see neutrinos, but you can tell that something is missing So, you know, they are actually neutrinos made in this process But if the Antonina can turn into neutrino, that’s what we hope to see Yep, then you know nutrient restructure disappear from this and All you see is two electrons coming out right and by looking at the balance of energy You can tell that nothing is missing there. It’s only just two electrons then you would say aha Anti neutrino can really turn into neutrinos See, this is actually a laboratory experiment where you could literally in some sense have direct evidence. That’s right That’s right off matter turning to antimatter and vice-versa.
So where does that stand this this? Well again people looking for this I mentioned this is such a way of process. There’s a machine that’s relevant to that This is the rori Yeah, so this is this is right. Now the experiment that is got the the best limit on neutrinos double beta decay So we have not seen it. And so what happens is we have to set some kind of a limit and what it is is it uses an element which is called tellurium, which is An element that we believe will be a good place to look for the neutrino list of lead.
Okay, and these are crystals They’re very large crystals that they’ve grown and it’s a beautiful experiment right so far Right, so so so we know what we need and There are hints as you say and next week. Maybe we’ll have new insight into that Let’s now turn to cosmology So these are laboratory experiments things happening today, which may give us insight into a difference between matter antimatter Yeah How do we leverage this? into a theory that Sort of a start at the Big Bang and take us to today So before before going to cosmology just to comment on on these searches for the difference between meant matter and antimatter I think we’re at the point in the development of particle physics when you look in the neutrino sector It sort of seems more likely from what we know that there will be these effects there. I mean, some people have hinted to that it’s It would be surprising if they’re not there so the way Physics has developed in the last few decades and people people had all sorts of other ideas about how to produce the matter/antimatter Asymmetry in the universe more matter than antimatter But I think as we understood more deeply the structure of the theory the processes that are possible the most plausible explanation is that it’s simply The natural structure in the minimal standard model that will do everything It’s not what like you really have to add lots of ingredients it’s already all the ingredients are sitting there and it took people a while to appreciate that and So you think that ultimately that’s where the explanation that seems the most economical and likely explanation So I agree with you that neutrinos will most likely have this asymmetry root in between neutrinos and antineutrinos right what I’m not totally convinced is that Even if that is shown that it would be in any way proved that the neutrinos are responsible for the matter/antimatter asymmetry in the universe and I say that with a heavy Heavy breath because you know Fermilab is who is paying me so but the truth is that Maybe we are going into that direction later on but There are many mechanisms that we can that we fear is have thought of to try to explain what it is in this black box that you were put in there and of course, there are some Explanations that are more plausible than others The neutrino explanation or the one related to neutrinos I think is it’s beautiful its elegant It’s most likely partly there But I think it would be most likely inconclusive so Although that doesn’t mean that we have to do the experiments at Fermi to understand the essence of what are the properties of neutrinos because you know, we don’t know the neutrino world is so different of what we are used to the rest of the particles in the standard model that for example we don’t know if there are more neutrinos than all the nutrients that we have seen and So we don’t know how they behave really.
So even if we put aside this idea that neutrinos antineutrinos most likely will Behave a little different from each other And still maybe that’s not the whole story there still. We need to learn a lot about what these enigmatic particles do and so You know in the next decade here in the United States we have we are building with international collaborations the most impressive neutrino experiment and I hope he toshi at least with Yeah So I know that I know that Neil you’ve got some as some very iconic views on what the solution may be I like to get to in just a moment but Marcella Can we? Maybe explore a little bit of the work that you’ve been doing to try to fill in that black box Try to fill in our understanding of that process that takes us from Matter/antimatter symmetry to asymmetry, what are the ingredients that you envision? Okay, so I I could say there are two possibilities.
You’re under this much dearest to my heart So I will go second on that one. Okay, so the first one has to do with theories grand unified theories and the idea that maybe we can think I mean, there are some Hints, okay. What is a grand unified theory? I’m going there So they all be quiet No, please No, so the idea is that we know that there are three forces the non-gravitational forces You know, it’s the electromagnetic force. That means that particles with the same charge repel each other particles of opposite charge attract each other We know that they are what we call strong forces those are the forces that keep the protons together to form the atomic nuclei and they have to be strong because the protons Themselves have positive charges so they repel each other And then the last one is what we call the weak force and the weak force is what allows for Radioactive decays, okay, but of course this means that a proton becomes for example a neutron and a positron and a neutrino on the side and Those should be weak because otherwise all the atoms that we know will disintegrate We need to have mostly stable atoms.
So we have these three forces three Or three it depends We can get into another phase. Yeah. Yeah, and another film we can get into another film the reference. I’m not in America. Yeah So These three forces we think then there may be the possibility that they unify at some early Or early epoch in the history of the universe and they become like we see here this got great Grand unified theory. So I talked about Roman Electra weak and weak and strong and maybe sometime Close to the beginning of the use of the universe or after the Big Bang. They were actually one mega force one Unique force and then as the universe cooled down then these forces became different and are the ones that we see today So that’s a grand unified theory So you saying that the strengths of the forces actually depends on the distance over which? they’re measured aside and I guess distance is getting smaller that way so this graph is a Section so on very very small distances which means very high energies the three non-gravitational forces Their strengths seem to converge and there is this data as this theory that we’re looking at right here Well, depends how you look at it the best of the eye of the beholder, correct? There are some indirect evidence and this is closer to your fields, I’m trying to be nice So there is some Circumstantial evidence as you would like to say that this may happen and if that’s the case We probably would need to have some extended symmetry of space and time.
Let’s call it supersymmetry string theory They’re there one quite Strong hint would be if you could see proton decay Okay So proton so far. We have looked for a proton the case and in fact, we have we will look at this experiment from Fermilab in to South Dakota One option there would be the dispute enormous and high detectors will also look not only for neutrinos and antineutrinos being different but also for decay of a proton into some Lighter particles and for example a positron and that’s like a fairly generic prediction of fairly generic prediction so far Fortunately, maybe we have not seen proton decay and we know that protons leave at least a hundred thousand billion Billion billion years, which is a lot a lot maybe they belong So we can set limits like that because we get them out of experiments like for example The super-k experiment the image of Super K was put up just a few minutes ago And maybe they’ll buy a more Super K.
And so it’s it’s an experiment that is twenty-five kilotons within the active region that people look at and It’s filled with water So you can actually see the people going around in the little boats as they’re cleaning the light detection devices That are all around the outside And and it’s filled up with water Actually i-i’ve on an experiment that was actually filled up with oil rather than water So I wasn’t allowed to go in a little boat because if you fall out you sink and oil But this experiment is the experiment that has set the very best limits on proton to cage gives that number that huge Lifetime right because there’s so much water in there that you can you can set excellent limits on that So you have to have an enormous detector in order to be able to do this so if you so you have this theory then what’s the next going back to the Matter/antimatter asymmetry so proton seems to be stable so far and we are searching for hints of how to prove some Desire and fight theories but within this grav unified theories because we have this this mega force or these United force There are other particles that are behaving a bit different from the ones that we know Today, correct and these particles exactly could be doing Something interesting.
So turning you know, the blue and orange rabbits in different side when they go to the box so they were basically there are two things they can be doing they are actually making an asymmetry between the the blue and the orange rabbits and They are also capable of basically Going on in one direction so that basically once you went from one side and you have this asymmetry Between the orange and the and the blue rabbits. It’s not possible for them to recombine and come back and create these universe at the gut scale so that would be an interesting possibility And it is there and of course we have seen we have women theorists all together Brian included we have worked a lot of possible grand unified theories They behaved different for example, if we will actually observe proton decay we will have some input about how these models could be the other the Downside of this is that it would be kind of hard to really have Gain, an irrefutable proof that this is the reason why the matter/antimatter asymmetry is different.
So in my opinion Or at least the thing I have been working for the last 20 years, so I obviously like it Is I’m sure you have Heard about the Higgs boson or the god particle, correct? I don’t see you, but I’m sure there you are all saying. Yes So So the Higgs is mysterious, correct? And let me just say in a second one to two phrases about the Higgs So there is a Higgs field and Higgs boson. The Higgs field is an invisible field of energy that is That permeates the whole universe and you would say, ok. That’s really not a good thing to convey. But just think about the Magnetic field of the earth. That’s also an invisible field Ok That of course is only permeating the region around the earth and it’s generated by the earth itself when it spins around its own axis We know that the invisible Higgs the invisible field of the Magnetic field is there if we just take a compass, correct? We will know with the Higgs It is an invisible field that it sources itself.
It doesn’t need anything else Ok And it’s everywhere and the reason we know is there is because we know that It gives masses to all these particles with having were talking about the quarks. Ok Maybe with reception of the neutrinos I won’t go into there So you must all the particles that form all the matter that we see today are the basic particles like quarks and electrons And they and it stops them from moving at the speed of light so that the universe as we know it today can work this happens at basically this happens at 1/10 of a billion of a second after the Big Bang and this is when we see that these are bubbles of Higgs on and kicks off at that moment in in the epic of the universe the Higgs starts turning on Okay, and gives mass to all these particles that we are talking about the quarks and electrons, okay So this is somewhere where it says Hicks turns on that’s there.
Okay So all what we were talking before was close up to the bit, man So this kind of the latest explanation that we have in mind for when the matter/antimatter asymmetry Actually start appearing even though it’s 10 to the minus 10 seconds that’s late on the scale Because you know we are Earlier is the big past. Sorry win, of course There are two things why I’m very excited about these possibility first of all because if you look there it says David Ronn and CERN and slack and of that.
So these are the energy is that we are proving today with colliders so this means that if these things happen if we are recreating the this instance after the Big Bang at energies or at moments that are The moments when the Higgs turn on then we can really explore if this matter antimatter Asymmetry was also connecting with this idea. Okay, let me just make sure I fully understand so you’re saying that there’s sort of exotic configurations that involve the Higgs field that can somehow Assure a symmetric configuration of matter and antimatter to an asymmetric one afterwards Yeah, and you think that in principle, this is true.
You could actually recreate it in in Switzerland. You could actually Learn about the details of the theory. Yeah, so that it will prove it or not the same way that you know, the Higgs boson is The proof that the Higgs mechanism is right, correct? but we only saw we don’t we can’t see the whole mechanism but we see the bottom which means that What we fear is thought is the right answer same way here. We will measure some properties Related to this moment of the Higgs turning on maybe at the LHC maybe at Large Hadron Collider maybe in future electron posse accelerators of the future but this is amazing because Now we have you know, the Higgs is turning on at this moment these These bubbles that we soft turning on actually very rapidly respond and the whole universe as we see today is all heats turn on Okay, and at this moment when there we are at the boundary when this is happening It’s what we think that there are two things happening one that the Higgs as we were saying Talks differently to matter and antimatter Okay and the other one is what you are saying that our process is that Taking advantage of the Higgs talking differently to matter and antimatter they come and basically they can Turn this asymmetry that the Higgs is capable to make in a real net asymmetry of matter antimatter That is here today and these processes I was told don’t say that word But they’re called Fatherís is a Greek word that means slippery.
It means what slippery slippery slippery slippery Slippery process that is happening there another less valid on process. That’s better So it’s a slippery process and this is libery process. We need that the same moment When the Higgs turns on This is slippery process has to very rapidly turn off so that all their symmetry we have created is not wash out And this is what I think could be the most exciting explanation for this matter antimatter Asymmetry and you can ask me if it works in the standard model and I can answer Does it work in the standard? No And again by standard model you’re talking about the ingredients that we know exist through experiment and the equations that we’ve written them support actors, but but Obviously, you know, I wouldn’t be so excited if that would be the end of the story obviously, okay? the point is that As you know Because you like super strings if you like the purse strings you like supersymmetry could be in reality The point is that we do expect that there would be maybe additional symmetries in nature or maybe additional forces That we call dark forces because we want to connect them with the idea of dark matter.
Okay. And so so the point is that With what with the main ingredients that we put there all these particles along and the Higgs is not enough Because what happens is first of all the Higgs Does not have a sufficient difference in the ways it talks to matter than antimatter So we need to have a bigger difference. Okay, and the second point is that this? slippery process as I was talking about they actually Turn, do not turn off Sufficiently rapidly. And the reason we know that is because we have measured the Higgs boson mass to be 125 times the mass of the proton So this this turning off of this slippery process that is essential to conserve the asymmetry that we have generated This is directly related to how much the higgs mass value is and we have done these calculations And we know that the Higgs mass is about three times too heavy or too large.
Sorry In order to allow this to happen But if we have supersymmetry or we have another dollar sectors that only talk to us through the Higgs Then it’s an amazing possibility To have this matter antimatter asymmetry be an trigger at the same moment where the Higgs turn on Very early in our universe. So so Nia when you hear that I Imagine that that you said, that’s an interesting idea which no doubt is yes, but from knowing you all these years you like things to be as tight and as minimal as possible in some sense you have Your own idea. So you want to give us some sense of where yeah so I mean I I was also a huge enthusiast for these ideas and I think Probably the audience has gained the impression that after correctly that off over the last 30 to 35 years The whole field of theoretical particle physics has been exploring All kinds of avenues most of which involve adding more so we add more particles We add more fields.
We had more symmetries. We even add more dimensions of space And more objects like strings and membranes and so on So we’ve been elaborating all kinds of thing under which we’ve seen none of which we’ve seen. It’s been a strange 35 years. Yeah Exploration the basis for it had a very good foundation, which is that adding more things did work for a certain period in the history of physics, I mean people Initially started with with the electron and then they constructed colliders and they found muons and towns You know some more and more particles were discovered when you did more experiments So it was only natural to think that adding more wood would somehow continue to be successful But the truth is the last 35 years.
It’s not succeeded. There hasn’t been a single Successful prediction of some natural phenomenon. So just from my own point of view I have been Attracted by the idea that perhaps We’ve seen all the particles we’re ever going to see so if you could show the next slide You know one one Fashionable idea which has come out of particle physics and string theory and supersymmetry is that there is a multiverse You know when you start adding more and more and more things to your theory you very quickly find that you have so many theories You’re you’re drowning in theories and possibilities and the multiverse is the ultimate sort of drowning in in possibilities And so I’ve never found it very appealing because if you show the next slide the observations have gone Consistently in exactly the opposite direction when we look out.
So here we are in the in in the center of the observable universe Sitting in our solar system and as we look outward In space. We’re also seeing back in time to the bit towards the Big Bang itself And as we look outward, we see the very large-scale structure of the universe as it was very very early after the Big Bang and The observations are reveal a stunning simplicity You can describe the large-scale structure of the universe with essentially one number Which tells you the level of fluctuation that came out of the Big Bang. So the universe is basically the same in all directions as far as we can tell Everywhere in space was the same and And these tiny fluctuations which you can characterize with a single number because they’re the same on all scales to to good accuracy This time of the single number describes the whole structure of the universe so you can say the the universe is simpler The universe is the simplest thing in the universe But you know, the large-scale universe is the simplest thing in the universe.
They’re very paradoxical so In in and by the way this dark energy that has been mentioned a couple of times Plays a huge role in this because the dark energy is making the observable universe finite so in in principle you could imagine that the universe became more and more complicated as you went to large scales and And this would continue indefinitely and and so the multiverse picture is like that there’s an infinite infinitely variable universe, but in fact the observable universe Due to dark energy is finite because anything further than a certain distance is Being carried away so fast by the expansion that we will never ever ever see it So all of these facts are sort of pointing Towards the possibility that we live in an extremely simple universe, which is self-contained Brizzy and Possibility it’s the only thing there is this may be the most likely Universe and and by the way, I feel the multiverse picture Which came about as I said because of this gigantic exploration of possibilities Misses a point about quantum mechanics, you know quantum mechanics Also, the world can go through any number of histories and possibilities But what happens is that one variant usually one of them is the most probable, right? That’s why classical picture of the world works occasionally You can create interference between these paths and see quantum phenomena, but general one Possibility dominates so my current perspective is probably there is one Dominant probability and this and this is it That’s the one we live in so if you go to the next slide, what what is that? possibility And this relates directly to what you’ve heard about earlier matter and antimatter So if we talk about the creation of the universe, you know is there anything in nature which is somewhat which involves creation where something comes out of nothing and matter antimatter is the prime example that you If you switch on an electric field the electric field pulls an electron one way It pulls the antiparticle the other way because they have opposite charge and joke so even if you have no particles if you turn on an electric field You will create a part that if it’s sufficiently strong you will create a particle antiparticle pair out of Out of nothing again that’s equals mc-squared energy and the electric field can just and it creates matter and antimatter in exactly equal amount so next slide So this is how we look at this from the outside Okay, so we’re looking at these two particle two particles appearing as an external observer We measure this process in time.
We measure it in space and and and that’s what we see we see these two particles appearing by the way the blue part of the the Positron or and the electron and the red part the electron those are classical Parts of this process literally just this particle flying off to infinity. The gray part is very quantum The the particle you see the particle if you if you think about what’s going on at that time It’s not going forward in time. It’s traveling through space at a fixed time. That’s actually not allowed Classically, okay, nevertheless it happens. But so I want to point out. That’s the quantum part the gray part ok next picture Now, let’s look at it from a different point of view Let’s instead of thinking about two particles. Think about one Because one of the deepest insights which occurred in the 30s and 40s Physicists called Zuckerberg and then Feynman.
Was that what is an ante? What is an anti-electron? What is an antiparticle an Anti-electron has the same charge as an electron. Why because it’s actually the same particle The only difference is that it’s going backwards in time and So this was a very profound principal Feynman actually built his whole machinery For particle physics on that insight and so from that point of view Forget about the antiparticle on the left. Think only about the electron imagine I had an electron which went backwards in the external observers time, but forwards in its own time Which goes along? its path Right, then it would have been the anti-electron it went back in time went through this quantum region and emerged as the electron so that picture is beautiful mathematical a very precise picture of how a Particle antiparticle pair is created actually just one particle that’s going backwards and forwards in time So that that is the closest analogy we have in nature to the to the formation of a universe, so if we keep going This is the scenario which we recently proposed, is that the Big Bang Was just such an event Where from one point of view say we’re an external observer We’d say an anti universe came out one side and the universe came out the other But that’s actually not the deepest point of view.
The deepest point of view is that it’s all a single thing and You can regard the left-hand side as going backwards in time towards the Big Bang just as the anti electron was going was the electron going backwards in time and the right hand side is the As the universe going forwards in time. So in a sense the universe causes itself You can mirror image this picture if you like and it’s exactly the same We could not tell which of these two we lived in And so where would you put the beginning of the universe in this way of thinking about it? There really isn’t one It just is.
It’s you see the important point is the gray region in that particle picture was quantum It’s not classical at that point. It doesn’t satisfy our classical notions of There being a single time for example, so in this picture in the middle of the picture, that’s the blurry part That’s the quantum part. You shouldn’t say, you know, the universe wasn’t started By an external agent at a definite time. No the The blurry part is where we don’t even know what time is okay, so one amazingly you can describe all this just as you can describe with perfect precision the creation of the electron-positron pair you can describe this, but you need to use quantum gravity and When you do this this picture seems capable of producing the matter/antimatter asymmetry in the universe The U is different than the U bar But the difference, you know We see a universe full of more matter than antimatter Because we’re looking at it going forwards in time if we were going backwards in time on the other side we’d see exactly the opposite and If I were living in his antimatter part, yes, do I get younger can no my gray hair back yet Wow.
No, no No, you know you don’t know When so in terms of you can think about it as one causing the other But actually when the universe becomes classical you have to identify the U and U-bar. There’s no distinction between them There really is no distinction. So how would I decide if time is going forward? That’s the direction in which in the universe is getting bigger and which galaxies are forming and you can see that’s the same Whichever side you’re on No, no no, no Time exactly the classical parts of this picture the you and the you BA are identical So you see that we’ve gone And I just want to end this fascinating conversation going back to Michael, you know, we we’ve Been out in two grand unified theories.
We’ve been firing neutrinos through the surface of the earth we’ve been watching a homer and his ice cream cones and so forth, but But the antimatter is actually with us and we use it. Right. I mean, they’re actually applications for antimatter We’re still trying to explain this asymmetry and maybe Niels got it, maybe more so and maybe there’s some other ideas But but we actually use it. Can you just give us some like concrete application? Yeah, so everybody’s favorite application is of course to use antimatter’s fuel for spaceships And this is a fact in the future far in the future.
It will happen There is a beautiful image that was supposed to be flashed up now actually if I just say the word which I don’t want to say enterprise No interesting application I had something more down-to-earth in mine Okay, we can talk Star Trek on our way out But I was actually thinking about more more concretely. Of course the example with the banana is a very good one Yeah, because you won’t go where I want you to go, but that’s fine because that is actually what positron emission tomography The banana emits positrons automatically in humans, you can inject positrons in a way antimatter by injecting Radio isotopes And then you can accumulate them in the organ of your choice Which is the bladder but also occasionally in tumor Tissue and so by watching where these annihilations happen as the anti electrons are produced.
You can actually look inside the body So it’s a very very useful application Sort of down to earth not so exciting as I have to say the cosmological implications Feel so exciting right? I mean antimatter We’re actually using a zig zag Gnostic tool and it may be the key to understanding that perhaps our universe is part of a much Different picture and a bigger picture than the one that we would have anticipated So we’re going to be waiting for next week to hear And you know well, maybe they’ll let me end on the following question So imagine we come back here at the I don’t know. What are we 2018 you come back at the 2025 World Science Festival just very quickly. Will we have the antimatter matter? Asymmetry of the universe solved by then or are we looking at something? That’s you know, so you Just give us a what you think I would say it We may come to the point that well Neutrinos are indeed plausible explanation for this we may have discovered by then that the neutrino can turn into a neutrino Yeah, so we can we suffer them.
Yeah by then. We may have discovered the neutrinos antineutrinos can change the flavors a different way So we can distinguish them then it’s pretty plausible then that okay. They are the superheroes. Yep So I have to agree with him and I just want to point out to you that You know, I 25 years ago. We thought that neutrinos were massless and that they you know we understood very little about them and we now understand a good bit more and I think by the time we get to 2025 there is a real chance that we could understand them as part of matter antimatter asymmetry But I like to say that they go from zeroes to heroes I I definitely hope that we won’t see any difference by them because I’ve got a bet a case of champagne Riding on the fact that matter and antimatter behave the same way Well, I think that, you know only five years ago We didn’t know that the Higgs was turning on at all Now we are sure it does and so that would be for me you know exploring what will come from this Large Hadron Collider and there is the plan of Increasing the energy to twice what it has there is plans in different regions in the world from China to to Europe to many other places to Japan Where we are trying to think about new tools new accelerators to study better Not only the Higgs but also for example we don’t know if this is sterile neutrinos are and we can even have a handle through the Experiments that Janet was talking about or maybe also by in different regions of parameter space By looking at them at colliders Extra neutrino by that time also could be even more energy Check us out on your yeah.
Yeah, so I think I really feel that in the next 10 or 20 years We could see a complete revolution in physics It won’t be more of the same It won’t be more it will probably be less but a better understanding of one. I’m not going to take that personally No But a deeper understanding of what we already know exists and My suspicion is that when we solve the problem of the Big Bang singularity, which is the ultimate puzzle and the dark energy which is the equivalent puzzle in the future, then these other phenomena are going to be explained as Side effects of the bigger theory well fascinating conversation ladies and gentlemen, please