 Hello and good evening. My name is Holger Muller. I'm a professor of physics at the Berkeley physics department and it is my honor to welcome you to this year's annual Emillio Segre lecture. Berkeley physics has a distinguished history marked by both world-class research and dedication to a public mission of higher education bringing it to California citizens. We are proud to be a part of the world's finest public university. Our department has a rich history that includes Ernest Olander Lawrence's invention of the cyclotron giving birth to the field of high-energy physics. It includes Robert Oppenheimer who attracted to Berkeley a generation of theorists and it includes the person we honor tonight experimentalist Emillio Segre. Each fall we celebrate Segre by bringing to Berkeley renowned experimentalists since 1987. These scientists through their research have changed the way we perceive the world. Past Segre lecturers included Nobel laureates Bert Richter, Matasoshi Kushiba, Steven Chu, Hans Bethe, Art MacDonald, Dave Weinland, Ray Weiss, and Taka Kajita. Past lecturers also include Jocelyn Bell, Millie Dresselhaus, Robert Zoclo, Xiaowei Shung, and the department member and former Chancellor Robert Birchnell. Segre received his doctorate in 1928 from the University of Rome working with Enrico Fermi and after two years in the military he returned to Rome becoming assistant professor there in 1932. In 1935 Segre became professor and director of the physics lab at the University of Palermo. Soon after his first visit to Berkeley Ernest Orlando Lawrence gave Segre a strip of molybdenum that had been irradiated in his cyclotron. In Palermo Segre and his colleague extracted from that strip a previously unknown and unstable chemical element technetium. This was the first artificial chemical element. 15 years later technetium was detected in stellar atmospheres and that proved that stars were generating new elements all the time. In the summer of 1938 Segre returned to Berkeley, continued his work while Mussolini's government passed laws that bared Segre and other Jews from universities. Lawrence offered Segre a position as research associate. Segre accepted and brought his family son and son from Italy to join him. I'm supposed to flip the slides. Okay, so here is Segre Fermi and Prashishu. Here's the discovery of technetium. We don't have Mussolini fortunately. With a war depleting the Berkeley faculty Segre became a lecturer in the physics department and in 1943 he accepted Oppenheimer's invitation to join the Manhattan Project. At Los Alamos he had at a group measuring fishing rates. He returned to Berkeley after the war. In 55 Lawrence and his colleagues designed the Bevertron to produce six GEV protons and energy sufficient to produce proton anti-proton pairs in collisions with a stationary target. Later that year the discovery of the anti-proton was announced in a paper by Chamberlain Segre, Vigand and Ypsilantes. Here's the anti-proton team. Chamberlain and Segre were awarded the Nobel Prize in 1959. Segre continued teaching and research beyond his retirement in 72. Over his five decade association with the Berkeley physics department Segre trained 30 PhD students including C.S. Wu, Herb York, Tom Ypsilantes and Herb Steiner. In 1989 at the age of 84 Segre died from a heart attack by taking a walk in Lafayette where he lived. He was an avid photographer and after his death much of his physics collection was donated to the American Institute of Physics preserving a record of physics before, during and after the war. And this year we are pleased to add Dr. Eric Cornell to the list of Segre lecturers. Dr. Cornell is a Bay Area native who remembers seeing the grateful dead at the Greek theater. He's currently a professor at Boulder Colorado and a physicist at the National Institute of Standards and Technology. His lab is located at Jiller in Boulder. Eric is an American physicist who along with Carl Wehman generated the first Bosa-Einstein condensate in 1995. Cornell, Wehman and Wolfgang Ketterle shared the Nobel Prize for this discovery. He received his undergrad from Stanford and received his PhD from MIT in 1990. He then joined Carl Wehman at Boulder as a postdoctoral researcher on a small laser cooling experiment. During his two years as a postdoc he came up with a plan to combine laser cooling and evaporative cooling to create a Bosa-Einstein condensate. As some of you might know, Eric's work is very close to my heart. Just like him I've been working in the field of ultra cold atoms and just like Eric, I've been working on testing fundamental laws of physics with ultra precise measurements. Eric's honor, I should say, Eric started that before it became as fashionable as it is now. So you're a true pioneer not just for Bosa-Einstein condensation. His lecture tonight, 14 billion years on what can be learned from the original imperfection. His talk will talk about a third and complementary way to find out new things about the fundamental laws of nature. Tabletop precision measurement. He will discuss the recent attempt to see tiny differences between the North Pole and the South Pole of the electron. Please join me in welcoming Dr. Eric Cornell. It's conventional to say it's a pleasure to be here but truly it's a pleasure to be here. I love coming to Berkeley. Something about the campus just makes me happy wandering around here. Every time I come back here I enjoy myself. I have many family in the Bay Area and so it's always a multiple function trip. Tomorrow I'll be seeing my mom in San Francisco but today I'm so happy to be here with you talking to you about my recent experiments about original imperfection. Behold we were shaping an asymmetry and imperfection that the university conceived us. That's actually not what it says in Psalm 51 but somehow it seems appropriate for this topic. So let's go back a few years 13.7 billion years before this particular Segre lecture there was a big bang and then shortly thereafter words as the creation him goes the whole universe was in a hot dense state. There were electrons, neutrons, protons, sure but there was also anti electrons, anti neutrons, anti protons. Almost exactly the same amount of both of both the matter and the anti matter. The universe expanded and as we all learned in high school chemistry when a gas expands in this case the gas that made up the universe expands it gets cooler. You can tell it's getting cooler because it goes from red to blue and it got bigger and as it got cooler something very romantic happened. Every electron found an anti electron, every proton found an anti proton, every neutron found an anti, each particle found its own soulmate. But these relationships were fraught I would say and one after another the protons and anti protons stuck together but then annihilated each other into a hail leaving nothing behind but a flash of light. And all around the universe this was happening in the mass cosmic wedding there was somebody for every everyone in fact there was back then just before all this happened one billion times more stuff in the universe than there is now and almost all of it annihilated I say almost because if you look around oh look there's an electron there's a proton there's a neutron and some of these are ones that did not find someone to connect with. And it turns out that for every billion anti electrons there was roughly a billion plus one electrons for every billion anti protons there was a billion plus one proton and so there were things left over as you can see. So who are these these final few lonely particles that no one wanted? Are there you? Yeah. Yeah so what happens then is it's actually really quite fortunate I mean it explains a lot really doesn't it you know there was a you know suddenly all but one part and a billion of the of the material in the universe disappeared but a few last few things were remaining and the electrons and protons stuck together they did not annihilate but in fact they formed hydrogen which was the sort of building block of the universe and what was nearly perfect this matching up of one billion to one billion and one to one billion was not exactly perfect it's really really fortunate that this is the symmetry this matching up was imperfect otherwise that the universe would be a very boring place there'd be nothing but light left over and that would be dull. So of this original imperfection as I like to call it we were born. Us yes but also stars and universe and the hydrogen stuck together and formed stars and this is from the James Webb telescope such a beautiful image I had to include it but this is the results of that and us as well. Okay so how can we learn about this because this was an extraordinarily important event this it was roughly a minute or two after the beginning of after the beginning of the universe an extraordinarily important event that should that meant that we're all around but it's very hard to learn about these things we can't go back in a time machine no one took any written records how can we look at things that were long ago here's a dinosaur the dinosaurs like the Big Bang happened before Facebook and so on so it was hard to know hard to keep a running track of these things sorry so the answer to this I like to connect this the metaphor is a three-legged stool one leg is is to find out about these things using telescopes and telescope like things this is a conceptual picture of a very very large telescope which collects photons this is a gravity waves gravity wave detectors are basically like a telescope looking at neutrinos coming basically whether it's real telescopes or telescope like things that look at things coming from far away I think of them as telescopes and what they all have in common is if you look at something which is 10 million light years away you don't see it the way it is now you see it the way it was 10 million light years ago so you're kind of looking back in history last time I checked the furthest thing anyone has ever seen which is this one particular galaxy you picture you see pictured here 13.3 billion years ago oh it's 13.3 billion light years away which means that when we see it we see a picture of the universe as a part of the universe as it was when it was only a tiny fraction of how old it is today but that's it turns out as old as that thing is it's not nearly far enough to look back to to ask this question about this original imperfection another approach call it another leg of the stool is to use particle colliders you take two particles oftentimes it's a proton and anti proton you smash them together with so much energy that when they smash together they sort of simulate briefly very briefly a hot dense violent early universe this is the large hadron collider and partly in France and partly in Switzerland it's the largest scientific instrument ever built there's supposed to be a person in this picture somewhere for scale but somehow they're so small I can't even see them this is a picture of where they collide the particles together it's the largest scientific instrument ever built but it appears also apparently not able to address this question and the next larger machine won't be along for about another 30 years give or take or more maybe 30 billion dollars or more so there we need yet a third method and the third method I want to talk about is well how do we know about dinosaurs we see dinosaur bones we look for fossils can we see fossils in the modern-day world of the big bang of this in particular of this moment of this of this physics where protons and anti protons didn't exactly match up and so we're looking for this was an ancient asymmetry a tiny asymmetry between protons and anti protons here's a beautiful symmetric picture but it's not these kind of symmetries I'm talking about there are three very physics these sort of perfection so one of these is the idea that electrons are very much like anti electrons but maybe not perfectly so the other is that most fundamental particles look exactly the same in the mirror most people also if you look at yourself in the mirror you look very similar that's not true for all of us for instance when I look in the mirror I see a person who's missing a right arm it's me who knows that this is coincidence or not but I lost this arm 18 years ago and it was 18 years ago that I started this experiment it makes me think a little bit about Ahab from Moby Dick you know like chasing the white whale whatever it is I'm I'm obsessed with these things who knows we don't want to dip too deeply into these Freudian issues another ancient another important physics symmetry is that things look the same if you run the movie backwards this is not true for if you drop an egg but like if an electron and a proton bounce off each other and you take a movie of it and you run that movie looking backwards the movie looks pretty much normal you can't tell whether you're running it forward or backward but all of these symmetries aren't perfectly obeyed and they had to be in particular this thing about the movie running backward had to be wrong for there to be this asymmetry so we have this assumption and you could call it a hope or a prejudice that like dinosaur fossils these fossils won't vanish basically what I want to mean by this is we want to we believe that the laws of physics that applied one minute after the universe was born still apply and what that means is that that asymmetry has to be around today and the thing is if you look at the if you look at if you look at the physics we know about today we don't actually see that fossil we don't see in the particles we know about today in the particle physics we know about today we don't see enough of this particular kind of asymmetry the asymmetry known as CP violation or T violation that gives rise to the asymmetry between protons and anti protons we don't see it in physics today what how did that happen we think we ought to be able to look harder sometimes to find dinosaur bones you've got to dig a little deeper so that's what this talk is about and in particular we suspect that we'll be able to find this in the electron retron you can you can tell the electron is a friendly thing because we talk about him in comic sands it's got a charge of minus one it's got a mass a charged particle that spins has a magnetic moment which means it's got a North Pole and a South Pole and usually that's about all you need to know about the electron and the question is are the North Pole and the South Pole the same on the earth they're quite different you know the North Pole is sea ice and there's polar bears the South Pole is mountainous and there's penguins more or less if ever you happen to see a picture with penguins and polar bears in the same frame you know exactly where you are you're at a zoo right that's the only place that's the only place where that ever happens so the question is is the North Pole of the South Pole the electron the same and in particular is it possible that the North Pole the electron is basically a negative be charging but maybe there's a little bit extra positive charge near the North Pole little extra negative charge near the South Pole or vice versa and if that were the case like the positive cancels a little the negative and the negative adds to little the negative to the main negative and if this were like this if this is called an electron electric dipole moment if it were like this it would look very much as if the center of the charge of the electron was not exactly in the same place as the center of mass this is called an electron electric dipole moment and it's what we're looking for because if it exists it has the same kind of asymmetry the same kind of imperfection that happened way back when so it's basically a fossil and something which we can study today and do theories about today and learn about what happened 13.7 minus one minute ago 13.7 billion years minus a minute ago. All right but every time someone's gone to measure this they find that it's really really they measure the center of the electron the charge and the mass and they're really quite close to each other and in fact they don't even see them different they say it is for near as we can go there in the same place and if they're not in the same place they're different by less than 10 to the minus 27 centimeters I can't even begin to tell you how small 10 to the minus 27 centimeters is it's hard to say exactly how big an electron is but some people would say it's about 10 to the minus 13 centimeters I'm sorry to drown you in the scientific notation but this ratio basically what we're saying is compared the diameter of a virus to the diameter of the earth imagine that the center of charge of the earth and the center of mass of the earth down there you got all the way down to the very center of the earth and those two those two centers were exactly in the same place to within the diameter of a COVID virus that would be not a very asymmetric earth and that's what we're talking about if it's there at all it's less than that so it's hard to look for what I want to emphasize about this is that okay so this these new particle physics there's a very long tradition of looking for new particle physics in dipole moments it's just that it used to be magnetic dipole moments the electrons magnetic dipole moment we measure it this is like not so much it basically how strong is the magnet that that electron electrons got a north pole and a south pole that's why your your magnets stick to the refrigerator and and it's usually it's measured in these units called the Bohr magneton and the natural thing you would imagine is that it has it has one of these but when they actually measured the mass sorry the electric the magnetic moment of the electron they discovered it was not one but two for its day this was a precision spectroscopy measurements they had a very very precise spectrometer and they saw a line and they applied a magnetic field on a line broke up into two lines these were actually extremely sensitive instruments actually the this kind of spectroscopy was a big thing here in the US before physics was a big thing because we had very good diffraction gratings there was a clever guy who invented good diffraction gratings here and was kind of got us that as a country started down the road of of precision spectroscopy anyway when they measured this number two and not one it was a big deal in the particle physics of its day because the Dirac equation which was the first attempt to connect quantum mechanics and relativity quantum mechanics and relativity were hard to connect back and they still kind of hard to connect honestly but this was the you know Dirac came up with this theory and it predicted this exotic thing and it was it was confirmed by this experiment using looking at magnetic moments the next thing that came along and one of the great things about giving a public lecture is that I can say things which are so I'm not actually a particle physicist I'm not an astrophysics I'm a laser spectroscopist I'm really sort of a oscilloscope laser wrench plumber's helper kind of scientists but here in a popular lecture I can pretend to be a particle physicist or an astrophysicist and I can give these thoughts and people in the public lecture if they're in the public they won't know any better and my colleagues who are astrophysicists and particle physicists will say well Eric really got that wrong but we'll let him slide because he's trying to simplify things for the public I'm not trying to simplify things for the public this is how I understand it so anyway but and so in particular I'd get my history wrong but so I'm going to give you a little history which is basically so the the spectroscopists I mean these people who made measurements like this where they looked very carefully at the lot of the glowing light coming out of hydrogen atoms they saw this and they thought oh great we could help out our friends who are doing theory of particles and relativity and quantum mechanics and then one of these these theorists said to the spectroscopists I want to tell you something very interesting about the electron I'll do this little dial I'll tell you something very interesting oh what's that did you know that when electron is like gliding along every once in a while just kicks out a photon spectroscopist no no no no I don't believe you for a second I took a bunch of elementary physics classes and if it spits out a photon that can't conserve energy and momentum you're just pulling my leg and the theory says no no it's really true it spits out the photon and the photon comes back again it only spits that for a little while and it recollects it again I'm going to call it a virtual photon the spectroscopist goes that's the stupidest thing I ever heard how could that possibly treat you and like how would we ever know and the theory says oh it's really important because it spits out all these photons and when it does it changes the mass of the electron and the specialist has changed the massive electron a likely story just a tiny effect oh no it changes enormously if it didn't do this the electron would have a very different mass and the spectroscopist says okay well what is the what would the mass of the electron would be if it didn't do this oh I don't know well can we make the electron stop doing that so we can compare the two masses no it can't do that so you're saying this has like no experimental consequences well yeah that's true so the laser sorry not the laser in those days it was the spectroscopist using grating so I'm not that interested in it and the theory said wait wait oh yeah there's one other thing you know how like recently you've been measuring these things and you did like an amazingly precise measurement down to 1% and you notice the lines weren't quite right and that when you measure the the the magnetic moment of the electron it was like 1% different from what it was supposed to be spectroscopist this is how do you even know that like no I heard you complaining about it I can explain that he says what what really happens is this thing that you call a magnetic field I just think of this magnetic field is like a whole collection of very very low energy photons and what maybe an electron will spit out a photon and after it spit out a photon it'll absorb a photon from your magnetic field and it will recollect this photon and as a consequence of that I'm gonna do a lot of math and you're gonna find out that the magnetic moment make how much the electron wants to interact with that magnetic field is changed different by about 1% okay well and they did they did the math and sure enough it was like this and this was like a very early test of what's now known as quantum electron dynamics basically quantum field theory this was what made people think like oh maybe we actually know how to do quantum field theory and then the theorist said oh but that's not all actually we can do we can do four different loops where it kicks out a photon absorbs a photon you are like totally kidding me whether it turns out to be some hundred thousands of these different of these different diagrams and if we do all that we can predict the magnetic moment of the of the electron out to like 10 digits and it turned out to be right so basically what I want to go with this is like measuring precise things about electrons in the middle of the 20th century was basically how people learned a lot about particle physics so the question is can we get still more particle physics if we did like maybe even a better measurement of the of the magnetic moment like instead of kicking out a photon what if it kicked out some exotic new particle a virtual particle just for a little while so it changed the magnetic moment of the electron and the answer is probably not the mass of the electron is pretty small and so these new particles if they exist at all are very very heavy so it doesn't work so well well what about if we use the muon people may not have heard of a muon it's a lot like electron except it's much heavier which means that yeah it talks to heavy particles better and that's true there's actually a new intriguing result that suggests that maybe you could see this but the muon is so heavy that it kicks out all these particles which are called QCD particles which are gluons and quarks and mesons and I love these things that I must want I'm not making fun of them but they're just very very difficult to understand and it makes it difficult so it's hard to know whether this you can find you know new particles new exotic new particles that can account for weird asymmetries using these experiments using the magnet the magnetic moment of the muon just because these particles are hard to calculate with that's the nice thing why we want to look at electric dipole moments because all the existing particle physics we know about would predict that the electron would have a truly fantastically small my electric dipole moment whereas there are many exotic new proposals that explain not only the electric dipole moment of the electron but also this initial original imperfection and so that's what we're about and the for many many years the result was a dude was saying if the electron has an electric dipole moment it's less than 1.6 times 10 to the minus 20 70 centimeters and that experiment was this idea of like looking thing for things very precisely in in looking for these fossils was not a new idea here in Berkeley in particular and it's very very much Holger Mueller as we know is working on it my old quantum mechanics teacher Carl van Biber was here for many years working on it I actually took quantum mechanics from Carl van Biber so if I say anything that's wrong you should take it up with your senior scientific administration you know Dima Budker professor emeritus here the late Stuart Friedman and I want to particularly mention Eugene Cummins who is a professor here for many many years a brilliant guy who I learned you know just was a very very inspirational to me and he really led this idea of measuring dipole moments particularly electrons for many years so this is now is a calendar down here this is how well how accurately we know that the electric electrons electric dipole moment is smaller than this number and you can see that starting in here starting in the in the 80s Eugene Cummins started reducing increasing this accuracy by these are like factors of 10 here so we'll call that the the common supremacy here basically something like two decades or what I mean by that is a factor of 100 in the in the accuracy of the electron electric dipole moment and two decades as in 20 years come in sort of stood astride this field I mean it was actually kind of intimidating like a lot of people didn't want to get into this because no one wanted to compete with him and at the end of that sort of towards the end of his career there was a general sense that you can't possibly get into this business by doing what he did because you did it as well as you could do it and since then the story of this of these measurements has been how can we do it in some very different way so we want basically to do something which was much better than this limit which is the limit that that gene set so many so many years ago and we had to do it in some new way so this is my group working on that and I should I call I'll use the first person just because I'm talking here but for the last 15 years and more I've been doing this experiment jointly with my my colleague Junyi I think he's the world's best atomic spectroscopist he's certainly a terrific guy and we've been working on this together for a long long time and the senior members of my group in the lab Tanya Russi postdoc Luke Caldwell Kiabun Ng have been really making the experiments that I'll tell you about work and I'll just call out Antonio V. Hill who just recently got summa cum laude working as an undergraduate in our lab and we thank very much our generous funders Junyi's graduate students you can see he's looking very sort of dreamy here and my students those students tell me that he hates this picture so I always managed to work it into my talks alright how can we measure something so very very small as that so there's one rule of experimental physics which if you want to measure something very very precisely change what you want to measure into a frequency and measure that so if you have a clock for instance that clocks are very very accurate what does that have to do with changing things well the pendulum goes back and forth why is it going back and forth is because gravity is pulling it back it turns out that measuring the frequency of a pendulum swinging back and forth that's quite a good way of measuring gravity if the gravity is stronger it will take faster gravity is weaker it will take slower and you can make clocks this is the point you can make clocks which are spectacularly accurate down to like 18 digits of accuracy and clocks which means in principle anything you can turn into a frequency you can make very very precise measurements of and so that's what we do with electric dipole moments first let's imagine how you measure a magnetic dipole moment an electron technically if you put it in a magnetic field it's got a it's got a north pole and a south pole it either points up or points down corresponds to a difference in energy and if you shine radio waves at the electron which are just the right frequency to take this energy and pop it up here the electron will flip over and if you measure the probability of it's flipping over versus the frequency of the radio waves you see some peak and that resonance peak and that resonance peak is right at the product of the magnetic field you apply in the magnetic moment that's for magnetic moment now if you want to care if you care about the electric dipole moment you just add an electron electric field to your magnetic field and you'll shift the resonance and you can do the experiment twice once with the electric field pointing along the magnetic field once with it pointing against it you measure the difference of those two resonance lines the magnetic field drops out and what's left is just the electric field times the electric dipole moment conceptually it could hardly be a simpler experiment but you've converted into a frequency this very sensitive thing you converted from a geometrical thing like center of mass center of charge how are you ever going to measure those things those are hard to measure frequencies were good at measuring so that's the point is you convert geometry topography into frequencies and you're halfway there but you're not that not maybe not halfway because it's still really hard and what makes it hard well how if you want to make a really good measurement what do you want to do first of all you want to apply the most humongous electric field you can apply so as to split the lines because this number if it's not zero it's really small then you want to have what's called a long coherence time basically look at the clock ticking for a long time see if you look at a clock ticking for a long time you can measure its frequency really well that makes it makes it easier to turn that the turn that to tell those two frequencies apart and then you want to watch the electron flip over many many times because then you can average and you can find the center of these resonance lines really really well you get a figure of merit big electric field big coherence time lots of electrons flipping over within some limited amount of time say the lifetime of a graduate student some finite finite unit of not lifetime graduate career of a graduate student although some people say they feel like they've been in graduate school their whole life so so big problem you want to apply a big electric field to electron you all learn what happens if you apply a big electric field to a charged particle goes boom flies away so there was a guy named Pat Sanders who figured out what to do with this you actually take the instead of using a bare electron use an electron which is already attached to an atom and turns out for some complicated relativistic reason having a very very heavy atom with lots of protons and it makes the effect larger so we do that the other thing to get a really big electric field is you use a molecule it was actually the last time I took chemistry I was in high school but the one thing I learned about is some molecules stick together because they have a positive atom and a negative atom and you can imagine that right in the spacing between a positive and negative atom there's really big electric fields and that's what we do so in the spacing between what for us we use a fluorine which is a very negative atom and half name which is a very heavy atom right in between here the electrons experience is extremely large electric field all we have to do is apply a very small electric field just a few volts per centimeter and it will make the molecules stand up straight and then in the laboratory the electrons feel much larger electric field such as there is between the molecules so it's kind of like multiplying the magnetic field by a factor of a billion by going from by using molecules which is a big big win for us we use an ion trap our molecules are charged and these are supposed to represent electrodes I'll show you a picture of the electrodes but we put electric voltages on them and the fields from the voltages push the molecules in and keeps them sort of confined to the center of this trap and but you might think okay but the thing about thing about working with them in an ion trap is that you've got all these electric fields which are pushing the ions around and the electric fields are changing and there's weird magnetic fields how could you possibly do a precision measurement in the middle of there to do that we use the molecules the molecules have a wonderful property which is the molecules we use this sort of represents how how what direction the molecules are spinning in the molecules we use come in pairs of what are called parity pairs parity doublets with with them arranged sort of symmetrically with the molecule pointing up and down or anti-symmetrically with them pointing up and down positive or negative parity if we apply an electric field these things just a few volts per centimeter these the natural states what are called the energy states the eigen states molecules become states of the molecules pointing along the electric field or against the electric field and then we apply a little magnetic field to to separate out these energies and then if there's an electron in theirs feeling the big electric the electron spin feels the big electric field in there and you can see that this energy difference is slightly different from this this energy difference if we measure those two frequencies and take the difference everything cancels out the magnetic field in the lab the electric field in the lab only thing that's left is the big electric field inside the molecule and the dipole moment so it's sort of a way of cancelling out all the noise all the garbage all the things we don't care about by doing a differential measurement yes measuring a frequency but measuring two frequencies that if we subtract them all the junk cancels out and only the thing we care about is left but we do need to apply a an electric bias field that is basically an electric field to the molecule to make it stretch out in the laboratory and you know if you if you have an ion and an ion trap and you apply an electric field to it it will fly out so like here's a here's our molecule half neumann flurry we apply electric field that will stretch it out nicely but you need to check this out ready I'm sorry this is this is really advanced PowerPoint skills we'll do that again yeah so that doesn't work so how can we apply the electric field in the lab to this ion and it turns out we can take a trick from people who make heavy ion storage rings here's that same accelerator or a heavy heavy a large accelerator the ions travel around this huge circle and basically everywhere along here there's a magnetic field pointing into the screen and as the molecule goes zooming around that magnetic field causes the these cars are causes the heavy ion to go around in a circle from that heavy ions point of view it's kind of as if there's an electric field always pointing in so if we were to do an experiment like this the ion would constantly feel an electric field but it wouldn't go very far at least it would be trapped inside this huge ring here so I thought well this is a great idea and we can do it in Boulder here's Boulder there are the mountains recently we had a snowfall and so this is about the same scale and so I went to the I went to the Chancellor actually if I had gone to Bob version he totally would have said yes but I went to the Chancellor said listen I've got this great idea it's gonna it's gonna be great it's gonna be Nobel prizes galore and we're gonna build this big ring and the Chancellor said well yeah but looks like we'd have to tear down the football field I said right but he didn't think that was funny and he said no I said well I could scale it down no I said well what if we just put it on the lawn outside of July so I could there's this grassy space just outside of the building I could totally build a big ring there and only cost 30 million dollars he said no so then we built a really tiny storage ring we'll have to zoom in to see the scale yeah it's a millimeter across so that's the one we built there was a little bit of a let down but okay and it's actually not really storage ring at all we just apply a rotating electric field and it rotates in such a way that before we apply electric field before the molecule has a chance to go anywhere we've rotated electric field around so it's pointing the other action it keeps rotating around and the molecule travels around in a circle about a millimeter across so it's the world's smallest heavy iron storage ring but it rotates the electric field rotates around rapidly enough that it traces out a very small circle but slowly enough that the molecule stays aligned locally the electric field we just have to do this spectroscopy in the rotating frame but any given moment in the laboratory everything's all lined up we had to learn how to do that but it wasn't too bad this is what the experiment actually works like for scale there's a pair of needle nose pliers there's eight separate fins which are made out of out of titanium and the spacing between them is about 20 centimeters about 10 centimeters excuse me and we one by one we make each one alternately positive and the opposite one negative so it causes the electric field to rotate around and we drive that around turns out about almost a million times per second the electric field goes spinning around and around and the ions are trapped in the middle we apply other electric fields whose purposes are to keep the ions kind of right halfway in between all the different fins how do we so we we want to watch it there we want to listen to it go tick tick tick and measure the frequencies how do we how do we make it tick how do we listen to it tick we use lasers here because this is a public lecture I'm gonna skip a few things because we use 10 lasers and each laser is really really important my students it used to be that the students would name the lasers after X's and the lasers were always sort of it was very sort of personified like is like this laser exemplified this particular unsympathetic trait of some former partner and that just got to be too edgy and so we stopped doing that and now we may we still use sort of a sort of we sort of reified lasers but now they're all named after animals from the Chinese zodiac so we have like rabbit and horse and cow and so on the cow is our really big laser you know and and eventually we got to a point where we actually had two we got to a point one time we had 11 lasers or we actually had more than 12 lasers they weren't all on use at any given time so we started to invent lasers which seemed you know we have both sheep and goat you know we have mouse and hamster you know we got but it got very complicated I'm not going to tell you a lot about it but we do make the molecules right inside we we we write we can't you can't buy these molecules from a chemical company we actually make them inside of our vacuum chamber we shine a laser and we evaporate some hafnium and we combine it with we make to do the chemistry we combine it with sulfur hexafluoride we make hafnium fluoride it travels into the center of our trap we ionize it with lasers and we trap them in here we do many many lasers to adjust the internal states and get the molecules just where we needed to it's kind of complicated so I'm going to skip over a few steps here oops there's some more good steps yep I'm going to skip over those two the room is a diet room full of a very very large number of lasers and they all shine into a spot way back there and inside a little vacuum can there is is the is the experiment I showed you earlier we had we use various sorts of tricks which I'm again I'm going to gloss over a little bit but again where we're doing differential measurements we measure one frequency which is about a hundred hertz the another frequency which is has the opposite sensitivity to the electrons electric dipole moment is about a hundred hertz plus or minus 30 or 40 microhertz so it's it's very very similar frequencies these very small frequencies are what we're trying to measure let's see if we got here we do something called Ramsey spectroscopy which means we start by preparing all of the all of we have two samples of molecules one sample of molecules is pointing down one sample of molecules is pointing up these two samples of molecules are both in our trap at the same time all swimming around together so they occupy exactly the same space in the trap we measure at the same time which means that many of the sort of errors that would confuse us like maybe the magnetic field is changing over the time maybe the electric field is not always exactly the same these errors tend to cancel out we take some of the population to put them over here we let it wiggle back and forth a little time and then it wiggles back and forth at the frequency of the clock ticking tick tick tick tick about a hundred times per second then we get rid of all the atoms over there goodbye and these molecules are actually all overlapping but some molecules are pointing one direction some molecules are pointing the other direction when we hit with them with a laser and they fly apart we break them apart and they fly apart in different directions and then just the half new ions we accelerate them on to a detector and we see two separate clouds of ions I realize I'm skipping a few steps here I'm not trying to give you a flavor don't worry if this doesn't fully make sense we see two separate clouds of ions which correspond to the molecules that were pointing down or the molecules which were pointing up and if we see a large population that corresponds to a tick if we see a small population that corresponds to a talk as we go as this time goes by these things wink on and off these things wink on and off we measure tick tock tick tock and we plot them this is the upper population going tick tock here the lower population going tick tock this is right at the beginning 1500 milliseconds later one and a half seconds later they're still going tick tock tick tock we know how many tick tocks we missed in between here there was just 100 times one and a half seconds so 150 ticks and tocks in between there and we can fit that to a particular frequency and we can extract the frequency of the ticking and talking very precisely and we can compare those two frequencies and it's the difference that tells us about the electron-electric dipole moment all right I seem to I'll we spend a lot of our time trying to understand if we've made any mistakes because it's really easy to mess these experiments up so we'll do things like put the molecules on the trap and we'll apply a little extra positive voltage on one side a little extra negative voltage on the other side and then we can move the molecules from one side of the trap they're basically the center of the trap the trap is 10 centimeters across we'll move them like half a centimeter one half a centimeter one way half a centimeter the other way a couple centimeter maybe half a centimeter up and down we'll measure various frequencies inside there and ideally these all should be exactly the same but we learn about what's going on and we we were able to interpret all of these different frequency shifts and use them to understand about any possible imperfections any spatial inhomogeneities any any any problems with our electric or magnetic fields eventually we come to understand just about everything that's going on inside our trap that's what we spend a lot of our time doing there are two currently there's for the last 10 years or so there have been two leading experiments one is called Gila which is us one is called Acme they're the competition we love them but they're the competition so when I say Acme it's okay if you if you hiss it's like no actually there may even be several people who are graduates of Acme here in the audience so we really do love them but they are after all our competition and over the years we had many ways do are very similar experiments we use a heavy metal fluoride molecule they use a heavy fluoride metal fluoride molecule we both have very therefore very large electric fields we use ions which are relatively easy to trap but because the ions don't like to be close to each other we we don't have we can't count very many ions the Acme people use neutral molecules and they can which you can jam a lot more neutral molecules together and so they count many more molecules than we do we use a trap so we have a very very long coherence time they sit in the trap for more than now up to about three seconds Acme has a beam line so they look for it only for maybe a thousands of a second so they have much broader resonances which is not so good but they have much better signals of noise given how different all these things are it's surprising how very similar our results are we have to work at a rotating frame of reference which is complicated and the Acme people don't have to do that coming soon from around the country there are other experiments which are going to use trapped neutral molecules and basically those new experiments will be combining the best of both worlds but they're still several years away last time we looked at this plot we saw the the common supremacy here where they were for roughly 20 years he held he held the record a group from imperial college originally led by Ed Hines really were for a long time leading the way on using this is like the first of the molecule experiments and they actually made a small improvement by middle of I guess this was just after 2012 or something like that just ever so slightly better than genes genes measurement then along came Acme the Harvard Yale group it's no longer the Harvard Yale group it's the Harvard Northwestern Chicago group professors have a way of shuffling around and they did a factor of 10 better then along came Jill and Ness we were just about the same and these two measurements together it looks at 10 to the minus 28 but what I want to make clear is that it's not that we measured the electron electric dipole moment to be 10 to the minus 28 centimeters we actually measured zero we said it's zero plus or minus 10 to the minus 28 centimeters so this is a limit not a measurement and but it was a limit which was such a good limit that it had a very uh you might say I mean had a very sinister effect because at the same time as Harvard and Yale were setting these limits the large Hadron collider was looking for all sorts of new exotic new particles called supersymmetric particles and they didn't see anything and so together the Harvard and the Harvard Yale group and this group were sort of accessories to the murderer of what was known as the minimal supersymmetric model of particle physics may at rest in peace but for a long time this was a very popular idea there was no experimental evidence for it but it was still very lovely now there's you know considerable experimental evidence against it so uh that was fine but uh still didn't solve this problem of maybe okay maybe we don't have supersymmetry but we still have this problem what happened to this asymmetry in the very beginning of the universe the Harvard Yale group added another factor of 10 which really was uh really felt like we had to get going so uh we recently have finished the experiment which is now even a little bit better than that and i um in order to we took 600 hours of data and we took that data blind what that means is as we collected the data we told the the computer to lie to us take all the numbers and add like a random number and don't tell us what the random number is the reason we did this is that we didn't want to fool ourselves there's something of a tradition in the precision metrology world of people fooling themselves and being over overly influenced like people would be measuring the the charge of an electron this is you know through the 20th century the measure charge electron all these measurements were you know they were done by different groups probably they were a little it's possible we don't know but they may have been influenced this line shows the current value they may have been influenced by these previous values and sort of afraid to make a measurement which was too different i don't know anyway at some point it popped over similarly massive electron someone made it much much better but you know maybe they were a little shy about going to what's now known to be the right value these these sort of trends and experiments aren't necessarily evidence that people were sort of sociologically influenced but they're but they're did not but they're they definitely suggest that it's not that physicists are dishonest people i for instance am a very very very honest person but i'm also a person a human being and you know human beings want things they're influenced and like measuring a non-zero electric dipole moment would be a very big deal it would be a huge thing in my in my career finally amounting to something you know that'd be good so that's the sort of that's the sort of thing that like you know influences people and so you can say well i'm not going to be influenced by that but then you could like that what's very easy to do is to be so committed to not influence letting that influence you then you go the other way right and so it's very very hard to find like not to allow something to push you one way or the other but if you tell the computer just straight lie to me okay don't tell me what the number is and you collect all the data and you can look at the data and based on other things about the data like how well the apparatus was working that way or how well it wasn't working you can include the data in your final average or not without being influenced by the number so we took 600 hours of data and it takes much more than 600 hours of data to take 600 hours of data because the machine only works on really good days this took many months to collect all of these data and these aren't uh this we subtracted the the average from it because we don't actually know what the average is but you can see the data follow this very beautifully smooth symmetric thing just the just the width you might anticipate we spent a lot of time studying the systematic errors and we think the systematic errors are pretty small but the central value is still blinded oh wait a minute the central value is not blinded it was blinded until four days ago so four days ago we looked at the answer i have something to confess i really really really wanted to come to the segre lecture the the university of gene commons and to tell you the answer and i actually know the answer but the problem with doing an experiment this large is that you have colleagues we call them collaborators and we all got to vote about when we were announcing it and i feel as the senior person on this experiment i should get to decide that wouldn't you think so and since i want to tell you i should tell you yeah that's what i thought too i was outvoted um and um this is the price you pay for doing physics as a sociological activity everyone else said what we really should do what would be better is if we wait till we finish the paper and we've submitted the paper and then we'll go ahead and we'll put it on archive and that will be the right thing to do and they're right it's just that i wanted to come here and tell the answer and um well there it is but i can't tell it to you but we can tell but i can tell you but i can tell you what it might be this by the way is the um the acme measurement this is the 2018 our collaborator our sorry our competitors measurement they measured in units of electron centimeters four plus or minus 10 to the minus 30 uh e centimeters remember the gene commons limit was 10 to the minus 27 so this is like more than 200 times better um it's traditional in this business if you get a measurement like this one which is more or less consistent with zero you report the answer is consistent with zero but then you add sort of absolute value error bars saying we think the absolute value is less than and they said less than 11 times 10 to the minus 30 okay so on this plot our error bars are more than a factor of two smaller i can't tell you exactly where that dot is but i can tell you the error bars are much smaller and i just would just want to review with you like what are some possibilities like it could be it's right around here and if it were that would be very interesting right because we could put uh we could we could associate with that a smaller upper limit is be smaller by more than the factor of two of this and there are theorists who are trying to explain the original asymmetry that you know is responsible for us and a consequence of almost every time a theorist tries to explain that he or she ends up predicting a particular value for the electron electric dipole moment which depends on their particular theory so we measure this a smaller error bar we can use it to murder theorists i'm not theorists theories and murdering theories is what we're all about right it's that's like i i i i i i murder a theory in the morning i'm set for the day i feel great um so that would be good or we could measure this number this would be an interesting number about eight uh eight's interesting because or nine say because it's in reasonable agreement with the acne folks the acne folks will say yeah we we believe your number but because the error bars are smaller because it's shifted over this way it would be four standard deviations away from zero very very unlikely to be a statistical error would be a big deal right or we could measure minus eight which would be a this would be a touch awkward because yes it would be four standard deviations away from zero but it'll also be really really far away from acne the acne group and we we would have to have many many heart to heart conversations about about this it would be it would be so and it's um the answer is one of those but uh just in case and it's a way of hedging our bets whichever one of those it is we'll definitely want to make a better measurement you know um we'll want to have smaller error bars either so we can know the non-zero value more accurately and also have it be better and better more and more strong statistical evidence or uh or we want to have smaller error bars because we want to overwhelm the skepticism which we might encounter from the acne people or because we want to have a smaller limit well we definitely want smaller error bars after this so we've already started on the next generation experiment this is the group working on the next generation experiment uh and you can see it's a modstrosity every four every time you count four of these little circular chunks of metal here that's a separate trap so we're going to do the experiment on like 15 times in parallel so we're bringing in parallel processing if you want to think about it like this so it's going to be we're going to have much better statistics uh the ions are going to actually be shoveled along here into a region of very low magnetic fields and low temperature where we'll get longer lifetimes it's going to be a marvel it's going to be great um and it's already being assembled we had an extremely tense moment when we constructed the whole thing and slid it inside the vacuum chamber this was like we had huge arguments about what's the right amount of coffee before you do something where if you drop it it's going to set you back six months some people said a lot of coffee some people said not too much coffee so some people were like visibly trembling and other people were almost falling asleep but we got everything inserted in there it's working we've seen our first when instead of using hafnium fluoride we're using an even heavier molecule thorium fluoride and we've discovered we've detected the thorium atoms and the thorium the the thorium fluoride molecules and the thorium atoms around the outside after the photo dissociation effect and we've started to use lasers to cool the rotational temperatures this is for my friends in the amo physics community we're using lasers to rotationally kill this this was these j equal one j equal two j equal three we cool the j equal two molecules when we turn on sheep that's a member of the chinese zodiac it's but also it moves the population over over here so things are coming along um we hope that experiment will be yet another factor of five or so better but it won't be around won't be finished for several more years meanwhile we're hoping as i as i expand we're hoping to understand uh this original asymmetry uh and contribute to a third leg of the stool um which is which includes telescopes accelerators and precision measurement and with that i i thank you for your attention and i'm very happy to answer questions i wasn't kidding i would be filled to answer questions and uh there are particularly be very happy to answer questions of uh students or younger people or not even professors like there is no such i'm i love questions which are totally off the wall so i'd be thrilled from all of us thank you i rake for the lecture yeah who wants to ask the first question yes over there so what are the odds that there actually is um symmetry in the matter and antimatter but there's just some like spatially separated cluster of antimatter sitting somewhere in the universe oh there's a really interesting question um the odds of that are if the idea is like well maybe just in the part of the universe we can see or like one thing i can tell you is that it's um in the we think of stars as being quite distinct from each other and galaxies as being quite distinct from either but there's interstellar and even intergalactic dust and if one star was made of matter and the next star over was made of antimatter the dust that came off of one star would fall onto the other star and we'd see the annihilation of that's happening we see flashes of gamma rays coming even between galaxies so what we know is that all of the galaxies we can see because we see one galaxy we see the next galaxy we understand next galaxy we never see flashes of gamma rays you know intense gamma rays coming from the boundaries so we know that everything we can see and we can see out to about 14 billion light years is the same stuff now well 13.5 billion light years on so it could be like right next to that there's another chunk of universe which is all antimatter and so on yeah we can't i can't rule that out um that's possible yeah all i can tell you all i can really do is talk about the universe that we're our sort of the universe that we have any chance of ever seeing we're never going to see that part of the universe that's that's flying away from us too fast how about the next question yes star um hold on um sarah has a microphone for you how does the asymmetry the original asymmetry compare between protons electrons and neutrons like was it all the same one in a billion or is there like variations between them no there were not variation okay neutrons are another story but protons and electrons we we know that the number of protons and neutrons and protons and electrons are very very very precisely the same number because the universe is not charged if the universe were charged crazy things would happen so even back before when there was a billion and one and a billion one even back there the universe was neutral so um that part if it's if it was a billion and a billion and one protons then it was a billion and a billion and one electrons too that to quite to much higher precision than that to many more digits than that yeah it's a neutral universe here's a question in the front here comes a microphone so sorry to get in so late i was working in the election um what is your best bet for whether it's tableton or not which um are particles and it's may be covered may have been covered uh are the best candidate to looking in the mass spectrum for uh dark matter all right what do you think of specifically what do you think of the tabletop very light axions okay so the question asked to do with dark matter which is uh not what this talk was about but which is a super super interesting talk in in astrophysics and cosmology uh we know that when we see galaxies well there's various different ways we know that most of the matter in the universe isn't even protons isn't even electrons it's something else altogether something which gravitates because we see the galaxies spinning around each other faster than the galaxies would spin around each other than if they were just made up of hydrogen atoms that they were just made up of ordinary stuff uh so it's quite clear that it's dark matter it's also quite clear no one knows what it is the question was me little eric what's my best guess for what the dark matter is and i don't know i really don't know i um i am a humble molecular spectroscopist and uh this is i you know i love to think about these things but my understanding i mean you might not tell it from my talk i hope you can't tell it from my talk but my understanding of many of these things is kind of at the scientific american level really i don't know i i i don't know i don't think that anyone else it's a great question and i and um there are many many different experiments around there looking for it but i would not want to be the person who has to handicap those experiments for the bedding line in los vegas and the front there's there's one over there so my question is could we look at this sort of a symmetry for other non-elementary particles like quarks with fractional charges um okay yeah so the about this asymmetry for for things with fractional charges it's hard to see the asymmetry is the thing with fractional charges because we can't see the things with fractional charges it's the the nature of things that these fractional charges are confined and so um that into what are called uh you know hadrons right they're basically protons and neutrons and and those things all stuck together and so that's kind of what we're it's kind of what we're stuck with there are there are other particles like um you know mesons which are like one one one two quarks stuck together and that's allowed uh but they don't live very long and so it's very hard to say much about them because at the precision level there are things beyond electrons like muons or tau particles they also don't live very long so the things that stick around long enough to measure are people have tried to do this on muons neutrons people there's an extensive effort to look for electric dipole moments and neutrons uh that actually predates even the measurements of of electric dipole moments going back to the days of norman ramsey and continuing even now and i didn't talk about it just because it's a whole nother field motivated by very similar these similar they same considerations just in a different sector people also look for dipole moments and various cp violating physics in in larger atomic nuclei like the the mercury nucleus and the the radium nucleus and things like that experiments which have a lot in common with these but then also a lot different um but they address a lot of the same physics and it's nice to have all of these things going on it would be nice if all of them came up with some non-zero values because you could put all of that together and actually start to tell a coherent story about what's going on with the physics of course it would also be nice to see a whole zoo of new particles coming out of accelerators but that really no joke that could be i say 30 but that's probably would be the optimistic number years away um it's it takes a long long time to find the money for them and build them and there's a significant chance that they will never will be never will build another big one that's just a yeah Derek um are there any other manifestations of an electron electric dipole moment other than this asymmetry like could there be something in solid state physics or some other manifestation yeah well if it were if it were really big you'd start to see like interesting effects in atomic spectra like you know just like things would change but it's not that big um this is not exactly what you asked but it gets at what you asked a little bit there are people of i think particularly Larry Hunter and Amherst college who have tried to look for these inside solids because solids can have magnetism they can even have something much like magnetism sort of ferroelectric effects inside which can exaggerate uh these things and so it could possibly you would get an enormous signal to noise the problem with solids are there any condensed matter physicists in the audience this is really this is this is a little delicate um so i'm an atomic physicist i'm a molecular physicist solids are icky they're full of like dirt and impurities and crystal dislocations and all of these things break symmetries and that doesn't mean you can't do this kind of physics and solids but you just have to be very careful to do it so for instance Larry Hunter extremely talented scientist wasn't able to make that work so for tests of some of these symmetries solids aren't perfect on the other hand they bring you Avogadro's number worth account rate and so that's a huge trade-off and so if you could figure out how to solve that i know that there's a group in in Canada which is taking building their own designer solid out of frozen neon and in which is or frozen argon i can't remember one of those and which makes it we can make a very beautiful pure solid and putting putting things into it and using that to study again electron electric dipole i know it's not exactly your question is more like well what would be the cool things that happen in the regular world maybe if the electron had electric dipole moment and the answer is it's already so small that the answer is like nothing really i think here's a question please here we go seems strange to me from your kind of your first slide that there's this one extra proton and antiproton and so on there's there's an asymmetry why did it favor matter or is that just nomenclature it's just nomenclature um it's only nomenclature what we call matter is the stuff that's left over absolutely there's no reason why we couldn't call we there it would be perfectly reasonable to say the entire universe universe is made of antimatter and not matter you know it was kind of like think of benjamin franklin he figured out there was two different kinds of charge and he had to call one positive and one negative and ever since then we've done that he could have flipped it around and probably would have been better honestly because you know electrons are much more important than protons and every most everything around see i'm showing my biases but electrons really are much more important than protons they should be the positive ones but it's too late and it does seem reasonable to me that as people we would call the stuff that we live in the good stuff and everything else the anti stuff i mean it's okay another another follow-up naive question yeah if we've been left with this one in billion uh antiproton and an electron do they annihilate no they don't um well you know and anti uh and antiproton and electron it's even hard to get them close together because they're they're both negative um but if even if you could get them close enough together they don't annihilate electrons because there's um there's these various quantum numbers that are conserved so even if you could like get an electron to smash into an antiproton i guess you can do that actually they don't you might cause the antiproton to break up at the little fragments of antiprotons but no it wouldn't annihilate okay last question suppose you'd had some anti-neutrons left yeah can you make a nucleus out of anti-neutrons and protons um oh that is a really interesting question my belief um there's going to be some particle physicists here who are going to laugh at me i hate when they laugh at me um can i answer a different question instead a different question instead is what what new people can do and have done is taken anti-electrons and antiprotons and stuck them together you're saying yeah this is old hat stuck them together to make anti hydrogen and that was super cool they did that in cern um so which is not exactly your question so people have made anti hydrogen and in principle they can stick that all together and make you know anti water or anti whatever but it would be difficult i don't actually i have my guesses but i hate to say wrong and stupid things i'm not sure whether you could get an anti neutron and a positive a proton and make some sort of hybridized deuterium sort of neither anti nor nor nor neither anti deuterium nor deuterium that's a great question i have my guesses but i think i want to keep him to myself i think i love the question don't know the answer a couple of people in the back have been waiting for a while whoever i can't i i see somebody here i see someone way back there and then we'll come here keep raising your hand we'll get back i think that gentlemen with a mask in the back has been waiting for the next so i don't understand most of what you said oh i'm sorry i'd like to ask you this question yeah it's a either or or both either or both what is it about what you've just described that's important to me in my life or what is it that's what is it that's important in your life in the advancement of the physics where does this fit does this fit on the practical scale my life okay so theoretical stuff yeah i mean there are multiple different answer i'm going to give you like three different answers as many as you got yeah i it doesn't it doesn't uh what this will never do is like help you design a better transistor like there's a lot of things that physicists do that will help you make a better this doesn't happen to be one of them it's just too small effect to be particularly relevant to like commercially useful things that said i myself would i don't know if i want to say i would find comfort or just interest or just i would love to know to me it seems to me it seems like an important question a question i'd like to understand just as a person this particular question i'll say that i don't and doesn't basically my my left like my life better or worse i just find these sorts of things interesting and like helping understand why we're here at some level um but there's another answer that i want to give you which is um why should why should we pay for it um it's these experiments are much much cheaper than building an accelerator but that doesn't mean they're actually cheap um that lab i showed you had three quarter million dollars of lasers in it and if you pay taxes uh out here in the audience then you bought them and i thank you um actually some of it came from foundations so some cases it was bought by uh very rich people who have passed away and were generous but um those are foundations but a lot of the money came from taxpayers and that i have a very specific answer for i know why the government wants to fund this and it's because um it's not because of the answer but it's because of the what people have to do to get the answer basically the students in my lab who can answer these problems are students who could do just about any freaking technological thing you could possibly name these are very very very difficult experiments the students who can do these things are all around technological badasses when they graduate they are hired they are in very enormous demand into this country's high tech industry in particular these days it's uh the quantum information industry which is booming and they can't hire my students fast enough and the postdocs before there were other they were gubbled up into other high tech industries and our cto's ceo founders just all around company technological superstars in many many companies and so it's basically so much of the american economy is driven by that high tech part and you can't it's not like specific training to a particular uh industrial need which is a fine thing to do it's rather uh generalized training how to like solve extremely difficult technical problems and my students who are in industry now are mostly doing and nobody is doing this right no anything remotely like this so it's not the specific skills they learned it's the sort of overarching free swinging technological confidence to to accomplish things um that i i feel like in difficult experiments like this you do this and you come out with that so that's kind of the product uh for uh for the american consumer for the american taxpayer i know that's not exactly the question you asked but i do get that question sometimes but i'm curious yeah um and obviously you thought about it yeah yeah no it is thank you thank you my pleasure the next question will unfortunately have to be the last one we have uh maybe a younger person asking a question great so the uh initial part of the talk was the difference between matter and matter in the universe and then you brought in the electro dipole moment but are they connected can you have one without the other can you have a zero electron a dipole moment and still have generate matter and anti matter difference that's a terrific question and um the answer is it's not completely clear um it's it turns out what people can do not me but the particle theorists what they can do is they can what they try to do is they construct mathematically consistent explanations for everything everything that we see it turns out that it's very difficult for them to construct an explanation which accounts for the early universe and doesn't also predict uh these dipole moments i say difficult but not impossible but they have to tie themselves into pretzels to do it um and so that's what's sort of motivating this it's like okay like you might be able to come up with like you know some sort of you know deus x moxina come down and dial this number down to zero or something like that but it's not super easy and so that's the connection it's not a rigorous connection in the sense that this one theory already explains everything because there are multiple candidate theories what most of the theories have in common is that they predict both um it's hard because these these two things really are very strongly connected at a theoretical level but not emphatically connected i guess is how i put it yeah okay last one okay hi uh so on your slides um i think in the beginning when you're talking about the uh the the annihilation of the uh anti-matter and the um matter um it seems like it's uh like the pictures only depict that they only like uh started annihilating when it cooled down of it yeah did i misunderstand and uh that's correct yeah uh why did it happen okay it's not that they don't um that they don't annihilate when they're hot it's that when they're very hot they smash together so hard like the the protons say the proton and the entry proton smashes together and they have so much energy when they smash together they could annihilate or they could actually generate more like you can take a proton and antiproton and smash them together and have more than two particles come out uh and so those two things are kind of in balance in a in a statistical mechanical balance you're sort of balancing the there's some um basically what you're trying to do is maximize entropy is the way to put it and as you cool down um entry becomes uh less important and and the annihilation becomes more important so um at the high enough densities and high enough temperatures it's a sort of equilibrium the the forward and backward going processes are just as likely and you cool down then then only the decay problem becomes more likely so yeah no it's not like it suddenly turns on like a switch um the annihilation is always there but it's more like the turning off of the generation of new of like smashing together and creating more particles so beforehand it was like annihilation smashing creations like it's like in the middle of an accelerator right exactly in the middle of a center where all kinds of stuff is happening and and as you cool down and a density in particular is a density goes lower one is favored over the other so that and it doesn't happen in a second you know it happens over what was then 10 of the lifetime of the universe or something like that but i don't know exactly but something along goes is when it sort of went from lots of stuff to little stuff yeah basically does okay uh does one pair of of annihilating um particle anti particle pair uh can you can you get multiple like other pairs when when it's hot or is it like violates conservation laws so as you say it again can you get okay so um can you get like um like when when they annihilate really hot can you get multiple other pairs uh from from the annihilation or is it uh does it violate conservation laws no it doesn't i mean you can you can have a a proton and an anti proton crash together and in principle you could have they could annihilate and then they release a lot of energy and out of that energy could come two protons and two anti protons that's a perfectly reasonable thing to happen or a proton an anti proton a mason and anti mason or those all those sorts of things are are allowed the only thing that can't change when they collide together is like the sum of the call it like the matter like baryons and the anti matter like baryons that that's that that's the number that's conserved as they smash together um but and then you can go from one and minus one and get zero or you could go from one and minus one and get two and minus two yeah that's absolutely possible and as you get colder it's more likely to have one and minus one to come together and get zero and then all that's left is photons like the energy has to go somewhere and photons are sort of the candidate for that stuff as the density goes down okay let's thank you for the fabulous discussion and eric for an absolutely fantastic lecture