The long race for the top quark

Published Jun 16, 2020, 4:00 AM

Daniel and Jorge talk about the twenty-year race to find the top quark, that came down to the wire.

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Hey, Jorgey, what's the first particle discovery that you remember?

Well, I've never discovered a particle yet.

You don't have to have discovered it yourself though to remember it. I mean, these are cultural moments. Don't you remember where you were and what you were wearing when the Higgs boson was discovered?

Hopefully I was wearing clothes, and I like how you equate physics with culture. I'm sure that there is culture within physics, but no, I was probably wearing pajamas. I'm guessing where were you.

I was there at SARN helping to discover the Higgs bows.

Though, Oh yeah, you were pressing the button.

They were trying to keep me from pressing the button too many times.

Yeah. Well, well, what's the first particle discovery.

You remember, well, I remember way back in nineteen ninety five when the top quark was discovered.

Mmm, did you push the button? Then?

No, I'm not that old. I was just in college, but I remember one of my physics professors coming into class that morning and announcing it like this was a really big deal.

Oh nice, And do you remember what you were wearing?

You know, it was college, so I was probably also in my pajamas.

Okay, I am Jorge. I'm a cartoonist and the creator of PhD comics.

Hi.

I'm Daniel. I'm a particle physicists, and I don't usually do physics in my pajamas.

What are you doing your pajamas?

Then?

I make podcasts us to stay sleeping or cooking breakfast.

Staying up late having deep thoughts about the universe.

And that's why we're here too, plant little ideas for you to stay up late thinking about about the universe. In our podcast, Daniel and Jorge Explain the Universe, a production of iHeartRadio.

That's right, our podcast in which we take you on a tour of all the incredible discoveries that science has made and all the questions that science has not yet answered.

Yeah, we like to talk about all the things we know and all the things we don't know or haven't discovered. There is a lot we haven't discovered out there, right. I feel like sometimes science gives it the impression, or people give scigence the impression that it's discovered everything already, that there's nothing left to find in the universe.

That's right. And in contrast to that, we think that there's a huge amount of exploration left to do, that most of the deep secrets about the universe remain out there for us to be found. But science is not a process where you just sort of sit at home and have ideas float into your head. It's a slow chipping away. It's a moments of discovery in long stretches without any insight. And we also like to tell you about how that happens. How do scientists actually figure stuff out?

Yeah, long stretches of sitting around in your pajamas drinking coffee is how I imagine physics gets done.

Well, you know, it's research, which means it's exploration. And when you go out to find something new, you never know if you're going to stumble on a vein of rich goal or if you're just going to be digging through rubble for decades. Yes, that's sort of the excitement of it, right, it's unexpected.

Yeah.

I always imagine mcgellan and Louis and Clark, you know, sitting around in their pajamas drinking coffee as well, so something they all haven't been comming.

I'm sure they had coffee on those ships. Come on, I'm sure nobody made it through one of those tours without drinking.

Say, discovery needs caffeine.

I'm saying, caffeine is now more widespread and the rate of discoveries is increasing, so therefore, dot.

Dot Therefore we should all drink more coffee.

We should fund coffee research, is what I'm saying.

But yeah, we like to talk about not just the signs that's out there for people to know about, but also how the science was discovered, because sometimes it is sort of this slow process and a little bit like chipping away at a rock. But sometimes these discoveries are pretty interesting and full of drama and intrigue.

That's right, because these are real people's lives and their careers. The figures you hear about in history, they were real people. They had struggles, they went to the bathroom they slept in, they had arguments, they made mistakes, and I think it's fascinating to get in the minds of those people and understand what it was like to be them before we understood the universe, before they had these insights, before they revealed new deep truths about the universe, because that helps us understand how to go forward and what it's going to be like to reveal the next deep truth about the universe.

So to be on the podcast, we have a really pretty interesting discovery to talk about. You're telling me full of leaks and lies and false discoveries and wasted millions. I feel like almost it should be an episode of Horrible Histories.

That's right, or science telenovelas. There is a lot of drama delenla And it's fun because we've been doing this series about how particles were discovering and we started way back in the late eighteen hundreds with the discovery of the electron. But you know, that's sort of like shrouded in history. Who really was JJ Thompson? What was it like to be a particle physicist back in the dawn of science? But now we're coming up to the present, moment. We're back into the most recent few decades, and so these are real people. These people are still alive. I was around when this was happening, and so it's fun to bring people up to the present and to talk about recent dramatic discovery.

Yeah. I mean, this particle we're going to talk about today was around when Friends was on the air and Seinfeld that's right, which to me sounds like yesterday. But I'm sure for younger readers it's like, what, that's ancient history.

I've read about that in text book.

Yeah, so today on the program, we'll be talking about how was the top quark discovered? Now, Daniel, is this the top quark, like the best quark? Did we save the best for last year? Or is this just sort of like the one that they was put on top?

Well, you know, this quirk has had multiple names, and you will be not impressed to discover that particle. Physicists have not agreed on how to name this particle.

Really, sometimes you went through several versions and this is what you landed on the top.

There were competing schools of thought. The top quark is the partner of the bottom cork. These quarks come in pairs, and for a while people thought that the pairs should be called top and bottom, and there was another group that thought we should call them truth and beauty quarks.

Oh my goodness. They're like, no, this one's more confusing. No, we like this one. It's more confusing.

I know.

Did we keep doing this, we'd keep adapting words from English that means something totally different and then applying them to particle physics and just like giving it a new meeting like that wouldn't be confused, you know. It's like, let's call this one the banana quark and that one the peach quark.

Like, you know, there's some physicists somewhere right now taking notes. It's like, well, that's a good one, and some peaches.

Somebody's working on like the la tech script for a miniature banana, you know, so you can work that into your equation.

I thought you were going to say that the people argue about which one should be the top and which one should be the bottom.

No, we already know that because of their charges. These quarks have really weird electric charges one third and minus two thirds, and so the ones on the top a row, the up the charm, and the top. These three quarks all have the same electric charge, and the other ones that down, the strange and the bottom all have the same charge minus two thirds, and so we know where they sit. And so top and bottom are just part of that pair. And Top isn't top because it's like the best quark, it's just the name that we gave.

It's the name of that British show Top Top Engine. Or am I thinking of top Model? What am I thinking of? Is there a reality show for particles?

America's next top particle?

The universe is next top particle?

And I wish I could get auditions from brand new particles. I mean, we had to try to smash particles together at SARN just to get hints of what new particles might be out there. If we could just like sit back and have the particles parade themselves in front of us, Wow, that would be then I could really just sip coffee and wear pajamas and just make big discovery.

We think, after all the fanfare about the Higgs boson, you know, the particles would be lining up, we'd all want to star and there's a giant media blitz.

Yeah, the particles should really talk to their agents about cashing in on that. How to monetize yourself as a particle.

Yeah, well, but anyways, this particle is pretty important. It's pretty interesting, the top Cork, and it also has a pretty interesting and illustrious and kind of funny history. And so, as usual, we were wondering how many people out there had heard of the top Cork, and more importantly, how it was discovered.

So I asked people to volunteer to answer random questions on the Internet, and I didn't tell them what I'd be asking in advance, and the rules were no googling. So here are the answers from a bunch of brave listeners willing to answer my question.

So take a moment before listening to these. If someone asked you if they if you knew what the top quark is and how it was discovered, what would you say? Some people had to say, I really.

Don't know how the top corp was discovered.

If I had to guess, like with most things, it had to do with smashing particles together.

But I really don't know, absolutely no idea. Please tell me how.

Was the top part discovered?

I don't know, absolutely no idea. It probably was the last walk to be discovered, hence that I'm top. But I don't know how it was discovered or when. I would assume eighties maybe that I have.

I have no idea. I would guess through some experiment at the LHC or certain but yeah, not sure. I have no idea how that was discovered, but I'm sure that it was discovered by a scientist way smarter than me at the LHC. I think probably in a particle accelerator.

I'm going to guess inside a particle accelerator.

Interesting question.

I hope that this will be actually something that I will learn in one of your next episodes.

I'm going to say the top quark was discovered from Quark's Got Talent Competition show.

I have no idea that, being such a specific small particle, I could suppose it was discovered using a particle celerator.

Well, I think the top quark was discovered in the early nineties, after kill Man I'd written his jag You're in the Quark book. But I don't know how the top quark was specifically discovered. Maybe there's another amusing anecdote you're going to reveal.

So I would guess either it was discovered in an accelerator or it was found in atmosphere as other particles, but I'm not really sure.

All right, not a lot of name recognition here on the top quark definitely definitely not in the of people's mind.

But somebody else had the same idea that maybe it was discovered on a reality show. Quarks got talent, I like that job.

But yeah, no, not a lot of people know what the top quark is, and so maybe Daniel, that's how we should start. Tell us a little bit about the top quark. Why is it interesting?

Well, the top quark is especially fascinating because it's different from the other quarks. So remember, you know, matter is made out of electrons which orbit the nucleus, and then the protons and neutrons inside the atom, and those protons and neutrons are made up of quarks, upquarks and down quarks specifically, So the upquarks and down quarks are the ones that like make up me and you, and lava and ice cream, all the stars in the universe and all that stuff. But there are heavier quarks out there. If you collide particles together at really high energy, you can make these other quarks, which are heavier they have more mass to them. They don't last very long. They like to decay back down to the lighter stable quarks. But you can make the charm and the strange quarks. Whole episode about strange matter that has strange quarks in it, and if you pump even more energy into it, you can make the bottom quark and then the top quark. And the top quark is weird because it's so much heavier than all of the other ones, like the light quarks, up, the down, the strange, all these way about as much as a proton or less, but the top quark is like one hundred and seventy five times heavier than a single proton.

Really, so wow. Yeah, and a proton is filled with other quarks, so it's like many times heavier than a regular.

Yeah, it's many, many times heavier. And that's what was so surprising about it. That's why it took so long to find, because it was shockingly massive. Even to this day, we do not understand why the top quark is so darn heavy. We think it's probably a clue, a window into something else that's happening in physics, some special role it might play in mass or in generating matter, but we really don't understand it.

Well. You would think that it is the easier it is to find. That's usually kind of the rule. But I guess maybe my question is, you know.

Because wait, because you're imagining that you're like chasing these things on the savannah or something, and if it's heavy, it's like.

What's funny? Is the elephant in the room? I guess maybe maybe that's a bad analogy because elephants in the room are hard to see.

Have you ever caught an elephant? It's not that easy.

Yeah, I don't have a lot of personal experience.

I guess no, it's actually the opposite. It's because if it's really massive, then it takes a lot of energy just to make it. So it's harder to make these particles because you have to concentrate more energy into a really small space. So it takes more technology and frankly more money just to build a bigger accelerator to make these things.

Oh, I see, because you guys, don't. I guess you don't discover these in the sense that you find them. It's not like you're mixing chemicals in the lab and it's like, oh, there it is it's like you have to make them to discover them.

That's right, You have to make them. You have to create the environment in which they can exist, because if you just look around you, everything in the universe is sort of too cold to make any quarks except for the upquarks and the down quarks. Those are the stable ones that can't go lower into any lighter quarks because there's nothing below them on the ladder. So to make anything above it on the ladder, you have to create special conditions. So, yeah, we're making these things. And you know, that's what happened sort of in the nineteen fifties that we first created the tools, the accelerators that we could use to create these conditions to make heavier quarks. And we talked about in the podcast when we talked about how the charm cork was discovered, that in the fifties we found all this crazy new slew of particles and when we slowly understood that these were just different combinations of a few light quarks, the up, the down, and the strange, all put together in different ways like lego bases.

Yeah, and I like how you talk about creating the conditions, because it's literally like you need to create pure energy, like you have to put enough energy in one place that all these particles can come out of that kind of ball of pure energy.

Yeah, and it's an amazing way to do exploration. It's not like we go out and find these particles. We just create the energy and there's some quantum mechanical sort of almost magic that happens there. Because if you create the energy, then nature turns that energy back into mass. Because energy, just like that is unstable. Nature likes to convert it into particles, and it can convert it into any of the particles on its menu, which means you don't need to know what's on Nature's menu in order to find something new. You just have to create enough energy and then Nature will roll a dye and say, okay, this time that energy is turning into bottom quarks. This time that energy is turning into charm quarks. And as long as you're above sort of the energy cost of making that particle, then it can be discovered. You do it often enough, you will see it, which is why we can go out and explore the fundamental nature of the universe just by staying in our pajamas and running our particle accelerators here at home.

Just sit back and roll the die over and over twenty times a second.

Yeah, much more than that. We run this forty million times a second because we want to see rare things. Heavy things are rare, and so the more time you roll to die, the more likely you are to see something weird and new.

It's a lot of pajamas. I guess My question is, you know you found this, you found this particle, and you decided to call it a top cork, But you know, how did you know it was a quark? Like what makes a cork a cork? And what? How did you know that this one was like the other quarks that you found?

Yeah, well we sort of looked for it because there was a hole in our ideas. We had found five corks so far, the up, the down, the charm, the strange, and then the bottom. And that was in nineteen seventy seven that Leon Letterman found the bottom cork, and there was sort of like a hole there four of the quarks you could pair off together, up and down, charm and strange and then.

Like I guess, pair pair it up in what way? Like they're the same but with a different charge. And then that's how you pair two of them together.

Yeah, they're up and the down or in the first generation they're the lightest one, so you sort of sort them by mass. The charm and the strange are heavier, but they have the same charges as they up and the down. They're like the second generation we call them. And then a in this third generation of quarks was the bottom cork, and we were like, well, where is its partner? Shouldn't it have a partner. We're always looking for patterns in particle physics. We're always looking for trends to help us understand what's coming next. And then on the other hand, we had six kinds of leptons, right the electrons, the particles that whizz around the atom. There are also six kinds of those particles. So we thought, well, if there are six leptons which form nicely into three pairs, and then there are five quarks, that's weird and they form two and a half pairs. It's just very suggestive. It's like if you write this periodic table of particles on paper, there's a hole there, you say, well, is there a particle that feels in that hole? Let's go look for it. So we sort of knew what to look for before we found We thought it probably did exist, and we went looking for it.

I feel like maybe you set yourself up. You're like, we'll call this fifth one the bottom cork, and who knows if there's a sixth one the twink wink, it's probably the top called the top cork.

Well, yeah, and a lot of discoveries in part article, physics work this way that we see a pattern in our data and then we think, you know, this would make a lot more sense if there was one more particle. That's the way it happened with the Higgs boson, right. The theorists they saw this pattern in the data and they thought the universe would make more sense if you had one more piece, because it would all click together. And that's really powerful. That tells you that, like, wow, you've understood something deep in the universe. If you can like call the next discovery, if you can say, I see a trend and it means this is going to be the next thing we can find.

All right, let's get into how it was discovered, and let's see if the drama involved here can top the history of the other particles. But first, let's take a quick break.

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All right, we're talking about the discovery of the top cork, and Daniel, you were telling me that this could very well be an episode of Horrible Histories and physics because it's full of drama and intrigue and a lot of twist and turns in this story. So maybe step us through and set it up. First of how you would look for a particle.

So the way to find new particles is really just to spend money, Like you need to create the conditions where the particle can exist. The more energy you put into this tiny, little collision, the more likely you are to find a big, heavy, fat particle. And the way to do that is just and more money to build a bigger accelerator. So there's nothing limiting us from building accelerators like the size of the Solar system to discover crazy new massive particles other than money, Like it would cost a good jillion dollars, right, and back in the day before we discover the top quark, before we knew it was so crazy heavy, nobody ever imagined it would be so massive. Nobody ever thought it would take so much time and money and such a big accelerator to discover. So they were sort of thinking smaller.

Right, because the other quarks they were all sort of in the same range.

Yeah, they were all in the same range. Like the heaviest one we'd ever found was the bottom cork, which is five GeV about five times the mass of the proton. So the theorists got to work and they said, well, we're very sure the top quark exists, and we're also very sure that its mass must be around ten or fifteen GeV. They had like very convincing arguments. They were so sure that it was right around that range, you know, and theorists they can come.

To because they were just connecting the dots kind of like the lightest core started about one GeV and then and the next bigger one is about one point six and the next one is five, and so they kind of extrapolated like, oh, it's probably about ten.

Yeah, But you know, they made their arguments sound very confident, Like when you go to a funding agency and you're like, look, I want one hundred million dollars to build this collider. You want that funding agency to think we're going to find it, like we're right about where this is. Because if you build it and your accelerator is not big enough, then you just find nothing. Right, You've explored a little bit of territory and found nothing. That's very disappointing. So you want to make your accelerator big enough that you're sure you're going to find this thing, but not too big because then you're wasting money, right, So it's a balancing act. So they were very confident we were going to find this thing if it was like ten or fifteen GVA and.

This So take us back what year was the first, I guess project to try to find this top corp?

So the bottom cork was found in seventy seven, and so in the late seventies and early eighties, people thought, well, this must be right around the corner because the charm cork was in seventy three. So we were like finding a new particle every few years. People were like getting into a rhythm of it, right, And so they thought, you know, in the early eighties like sequels.

It's like avenger sequels every three.

Years, that's right. And so in the early eighties they looked for it in Hamburg at this accelerator called Daisy, and they looked for it up to about twenty five GeV. And it was very surprising that they didn't see it. I mean they were surprised that they didn't see They were like, what, we thought it was going to be maybe up to fifteen, and we looked all the way up to twenty five, and it's not there. That's crazy. So that was the early eighties, and of course the theory community that had very confidently said it must be around ten or fifteen, they said, oh wait, hold on a second, we have a new calculation. Now we're very sure it's around thirty.

Cheap.

What's the what's the latest number, what's the biggest number. They haven't found anything. Twenty five. Oh well, then I think it's a thirty exactly exactly.

And that's the game in theoretical physics. They're always predicting things to be just around the corner, and they're very confident in their predictions every time, you know, and you're thinking, like, well, why this factor of two and not a factor of three, They're like, you know, two is a more natural number.

It's a more natural number for us to get funding. Yeah, all the other numbers don't work out.

And so then the Japanese built a collider and they were going to be able to see it up to around thirty GeV and so, you know, they spent a lot of money on this thing. It was called Tristan, and it ran for about ten years, and it didn't find anything.

We're talking about like hundreds of millions of dollars.

Right, yes, and a lot of time and a lot of people's work. And they were very certain, like they thought they were buying a discovery. You know, the Japanese government thought, we are going to discover the top quark. It's going to secure our place in the history of particle physics. But they came up empty and they didn't find it. Wow, And so then of course, you know, the theory community is like, oh, you know what, it turns out it's going to be around forty gv?

Did I say thirty and forty?

And so this game continued for a little while. At Stanford they looked for it. They could see it up to about forty five gv. And the reason these accelerators had different capable was just because they had different amounts of power. They had more money to build them longer, to push the particles faster, to make more energy in these collisions, and so Slack was able to slack. That's the accelerator at Stanford was able to push it up to about forty five GV.

I like how the name the acronym just says slack. It's like, a are they slackers? They did? They voluntarily picked up.

I don't know. Everybody I know who went to Stanford is a bit of a slacker.

In a good way, right, in the best possible way as possibly. But I guess my question is what does it mean to not find something? It's like you run the machine and you get all these bazillion collisions and you get all the stuff coming out, and then you don't see what you thought you were going to see, or you don't find anything.

Yeah, you don't see what you thought you were going to see. Like, if the top works exists, then we already understand how it should be made and how it should decay, so we know how to look for it. Now there are other things that could also look like that. Remember we don't actually create the particle and then get to look at it. It lasts for like ten to the mine is twenty three seconds, and it turns into other particles, which turn to other particles, and then they make these splashes in our detector. But we're pretty good these days of figuring out like, Okay, given this splash and the detector, it looks probably like it was a top but you can never know for sure. You can't say this event was a Higgs boson, this one was a top quark. What you can do is you can count. You can say, well, there are other ways to make the same kind of splashes, the same patterns, but we know how often that happens. We expect to see maybe ten of those, and so if instead we see fifty, that tells us, oh, we see more of these specific kinds of splashes in the detector than we expected without the top work, and so we think that the top quark is there, and you can see it in lots of different ways, like the top quark should decay in this way and in that way and in this third way. If you see them all together, you sort of build confidence in the story.

I think it's amazing to me how dependent this is on the the theory. You know, It's it's not like you're looking through rubble and saying and finding a pearl or something. It's like, you know, you really relying on the theories to tell you exactly what to look for and where to look, and you know they're they're also kind of you know, theorizing, and they're not sure, and so you could be totally looking in the wrong place or looking for the wrong thing.

It's amazing that it ever works. Yes, and there are certainly some discoveries you could never make if you didn't know what to look for, Like, you know, could we have found the Higgs boson if nobody had thought of it random? It's a pretty subtle signal. Yeah, it's a pretty small effect. And so you can imagine another universe where you delete Higgs and everybody else who had similar ideas from history, and then what experimentalists discover it. And there are times that experimentalists have found particles before they were conceived of, before anybody had the idea of them. And you know, that's my personal scientific fantasy is to find a new unanticipated particle, a particle that makes the theorists go, what that can't be true? What are you talking about? If that exists, then we got to erase all these other things we thought we understood. And that's, you know, that's the goal, is to crack open the deep mysteries of nature and find something surprising.

All right. So it sounds like up until the seventies and eighties that people had looked up to sixty GeV and found nothing. But so then this is where the plot thinkets. Yeah, so now the stern gets into the game, the Europeans sort of step it.

Up, that's right, And so the Americans had it up to a forty five GeV and everybody felt like, Okay, this thing is around the corner, Like it's ridiculous that we haven't found it yet, where like four times the mass we thought it should be, we were certain it should be, and so the next collider is definitely going to discover it. And so cern turned on the collider in the early eighties called the SPS the super Proton Signatron, and this was run by a guy with a really big personality, Carlo Rubia, and he ended up winning the Nobel Prize using this collider and this detector for discover ring the W boson and the Z boson. And he's a famously huge personality.

I mean, and he has two Nobel Prizes.

Well, he got one for the discovery of those the W and the Z. So he was sort of riding high. He was like, hey, I am, you know, basically god of particle physics. And they saw some interesting things in their data around nineteen eighty four, and they started putting stuff together and Carlo Rubia sort of got out ahead of his skis and before people really looked at this data very carefully, he went and called up a reporter for the New York Times and said and claimed discovery and said, hey, we found this.

Yeah, he said, it's like, it looks really good.

Yeah, he said, it looks really good. And then they wrote a paper and they claimed discovery of the top quark at around sixty GeV and you know, of course that was not correct. The top quark was not there. And I talked to some folks who are around at the time and part of that experiment, and one guy in particular who worked for Rubia, and his job was to go through the data and verify that everything looked good. And on his first day he could tell him very soon that things were very sloppy.

Oh I see.

He looked back at the data and it didn't look the way it was described, and the record of what had been done didn't seem to match up with the results they were getting, and so there was just sort of like a lot of sloppy work there. I think there was a bit of a rush, like an anticipation. People were, you know, I'm sure it's there. So if we claim discovery, even if the data is not quite right, we're sure that the data will eventually back us up.

I wonder how that phone call went, Like did he call the public line at the New York Times. It's like, Hi, my name is Carla Ruvia. I think I discovered a particle.

This is you know, he was a celebrity and he's still a big figure and his son is a big figure in particle physics today. So this is like if Stephen Hawking calls the New York Times. You know, then they pick up they want to hear what he has to say. And so he was making a big claim and it's kind of embarrassing because they had to walk it back. Right, This is they did not discover the top quark despite their claims.

All right, So CERN kind of crashed and burn here, and that's when and more people get into the.

Game, that's right. And that's when the Americans picked up the race. And we had a collider outside of Chicago at Fermi Lab. It's called the Tevatron, and it was the most powerful collider in the history of human science at the time, and so it picked up the race. The CERN didn't see the top quarker and they left the limits at about sixty nine GV. We knew that if it existed, it had to be heavier, but about sixty nine GV and.

I guess people believed each other. Like if you were at the Tevatron and Stern says, we can't find it out to sixty nine, you sort of assume that they were right. You don't do you go back or do you go back and check?

You definitely go back and check, absolutely, because if they missed it yeah. I mean that's the point of having these independent experiments is to check each other. And also, you know, there's a lot of antagonism and rivalry between these experiments, like they want to find it and they want to scoop the other one. I mean, scientists are all about scooping other experiments. That's one thing I think the public doesn't understand about science. It's not a monolithic enterprise where we all sit down together and decide what we're going to announce, right. You know, That's why it's impossible to have like scientific conspiracies for very long, because the data reveals the truth. And some scientists out there, if you're bsing with your results, if you're covering up something, some scientists out there is going to get some data that shows you're wrong, and they are going to show you're wrong, and you're going to be embarrassed. Yeah.

Yeah, I think the same way too. It's like scientists would wish nothing more than to prove each other wrong. And so if you have something like climate change where ninety eight percent of scientists agree, you know, you know that those ninety eight scientists are trying to disprove each other. So the fact that they agree is must mean a lot.

Yeah, And you know there's also international politics here, because the torch is passing back and forth between Europe and America. Started looking for it in Germany and went to Japan, momentarily went back to America with slack then cern thought they were going to win it. And then the Americans come in with their new accelerator, and you know, they seem like they're poised to find this thing. So there's also a lot of national pride.

All right, So the Americans have the football the running. Will this be a Bruce Willist movie where America wins at the end. Let's find out after the break.

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Hi, I'm David Eagleman from the podcast Inner Cosmos, which recently hit the number one science podcast in America. I'm a neuroscientists at Stanford, and I've spent my career exploring the three pound universe.

In our heads.

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More because the more.

We know about what's running under the hood, the better we can steer our lives. Join me weekly to explore the relationship between your brain and your life by digging into unexpected questions. Listen to Inner Cosmos with David Eagleman on the iHeartRadio app, Apple Podcasts, or wherever you get your podcasts.

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All right, Daniel, we are We are in the middle of this drama that's unfolding about the discovery of the top quark. And the Germans failed, the Japanese failed. The people of California case California is kind of like a different country.

The nation state of California.

We failed as cern didn't couldn't find it up to sixty nine giga electron volts. But now there's a new collider called it Tevatron outside of Chicago that thinks they get to football and they make a run for it. But the drama is not over.

That's right. Tebatron very powerful collider. It had the potential to discover the top quark up to about two hundred GeV So there was like a lot of territory there that the Tevatron could discover. But it was not just a happy party. It wasn't just like that Tevatron is just one group. They set it up like a competition. They set it up. They had two separate groups with their own detector competing to find this thing.

Wow, and that's new too, right, that's like none of the other teams have done that. It's like putting your kids to fight against each other.

Yeah, it's a bit like a reality show. Some of the other accelerators, like Tristan had multiple experiments, but some of them only had one. But it's you know, it's a bit controversial, but I think it's good because it motivates people, you know, it keeps them honest. And also, if you're going to make this big discovery that people have been looking for for now twenty years, you really want to have independent information. And so we're here by now in the very late eighties and the early nineties, and we had two experimental collaborations. One was called c DF and the other one was called D zero. There was some friendliness between them, but also there was a lot of animosity.

Really, you know, cdo So they're all working the same place, like eating at the same cafeteria.

Yes, they're all eating at the same cafeteria, but they have their own detectors. So fermilab is a big ring. It's like four miles around where the protons swing around and smash into each other and the protons collided, are four different places around the ring, and CDF had one of those places. They had their own collisions, and D zero had a different place when they built their detector around that other collision point. So they would go off to their own detectors and work during the day, and then you have lunch together and you know, try not to growl at each other too much over their sandwiches to.

Poison the other cafeteria food.

Yeah, and you know, there's something of a cultural difference here because CDF was earlier, Like they got funding first, they got built first, they started collecting data before D zero was even finished, and they had sort of the fancier universities, you know, Harvard and mit, Yale, all these Stanford, all these big famous universities. They were on CDF, and dzero sort of came along later. It was a scrappier, it was cheaper, it was late in the game, and so you had the sort of different culture and different personalities and CDF was very hierarchical and D zero was a bit more wide open in terms of the culture of these.

I feel like you're sending it up here. Who is the clear underdog?

Yes, exactly, Like there's.

The Ivy League, you know, slotty dude or who has all the money and attention, and then there's this crappy, scrappy business.

This is definitely Bob's College of Knowledge versus the Ivy League for sure.

Oh man, all right, well, if this was a Hollywood movie, I would know who to root for it. But who knows this it science?

Yeah, exactly, Well, maybe we'll make a Hollywood movie about this story. So they turned the accelerator on, it starts to run, and by like late nineteen ninety three, CDF had some interesting hints. They like they had some events that looked like maybe top quark. But it's hard to say, right, there are ways that you can mimic what the top quark looks like. You can't take a picture of the event and say, with one event, I found it, here's the one. You need enough statistics, you need to say, you know, the background looks like ten, but there's an uncertainty of one, and I found twenty and that's very unlikely to have come from this background.

Is that the number that you typically need just like twenty times you have to find it, and that's it.

What you need is you need to calculate the chance for the background to fluctuate to look like the signal like the background is other ways to make the same signature, and your detector that looks like a top quark, and you know there's fluctuation. Quantum mechanics is random. You do the same experiment one hundred times, you get a different set of splashes and your detector. So what you calculate is the probability for there to be no top quark and for your data to look like top quarks.

If you roll a dye, you know you're going to get a four it's certain number of times. But if you roll the die, keep rolling the die, and you get four a lot more than one sixth of the time, then you know it's like a there's something funny about that.

Die exactly, And before you're certain that the die is biased, you want to roll it a lot of times. You don't just roll it and get four once we're like, oh, the die is biased, right, because that could happen randomly, exactly. And so CDF saw a few events which looked interesting and looked weird, but you know, everybody was primed to discover this thing, and so they tried to also be really skeptical and unbiased on the statistics. We decided we were not going to declare we'd actually discovered this thing until the chances they were a fluctuation were less than one in millions.

Because they learned from Carla Rubia what happens if you claim discovery too early?

Yes, e embarrassing. It's embarrassing. And particle physics I think because of that experience with Ruby and the top quar, Etcern is now very very conservative. They're terrified of claiming discovery and then having to walk it back, and so they only claim discovery when they get to this five sigma threshold, which is when the odds are millions against it being a fluctuation.

Yeah, all right, so CDF, the Snotti Ivy League favorite to win, find something, but it's not enough.

That's right. In ninety three they had some hints, and then in nineteen ninety four they had, you know, a nice little collection events that seemed unlikely to be just background. It seemed it smelled like top quark, and there were a lot of rumors swirling around the community, and there was an agreement at the lab. You know, these two different groups, CDF and D zero, And the agreement was, if you're going to go public, if you're going to claim your discovery, you have to tell the director of the lab first and give the other experiment two weeks to sort of scramble together to say something. At the same time, they wanted to present sort of a unified message.

What really Yeah, but wasn't it a competition, Like what's the incentive then, or do you get to claim to be the ones who discovered it?

Well, it is a competition, but also, you know, Fermilab didn't want like racing press conferences. You know, if these two groups really are going to discover it about the same time, then they wanted a unified statement. If one was really far ahead, then two weeks was not going to give anybody enough time to like really catch up. But they felt like it was a sort of a you know, a gentleman's agreement, like we'll let you know if we're about to call the New York Times.

Oh, I see, And then then what would happen Like press release would go out and would say CDF found it and it's confirmed by d O D zero.

Yeah, J zero, that's the idea. But you know, in ninety four D zero really didn't have very much, like they had one interesting event they had found, but you know, they had really just turned on. They didn't even have access to the earlier data because their detector didn't even exist for those first runs, so it was really just CDF on its own. And in about nineteen ninety four CDF told the Fermi Lab director, they said, look, we have twelve events that look like top quarks. The chance of fluctuations about one in four hundred, which is not enough for discovery. It's like it smells like top work, it seems like topwark. A lot of arguments inside CDF about what exactly to claim, but finally the conservative group inside they said, we are not claiming discovery on a one four hundred chance. But they put this paper out because they wanted to sort of like stake their name on.

Really they put it in what did the papers say that we found something but we don't know. Yeah, you its really good.

Yeah, it looks really good. But you can't use the word discovery unless you have reached this statistical threshold for significance. Right, And at the time, d zero was like, well, we don't have enough, Like, we have some interesting stuff, but our data looks more like background than CDs data. Their fluctuation probability was one in forty, so they didn't Their data was not nearly as converceed.

But the information from CDF maybe told them where to look, yes, or were they both looking at near the same you know, kind of energy level.

No.

That was a very important clue because remember CERN left the game around sixty nine gvs and then people thought, well, the top must be like one hundred. It couldn't possibly be much more than one hundred, right, so people were focusing their search around one hundred and one hundred and twenty. It makes a difference because as it gets heavier, it changes how it case the other kind of particles that can turn into. So this gave D zero a clue. And then in the summer of nineteen ninety four, D zero got very very lucky.

Really so wait, so they were both looking so CDF was looking in the higher energies and D zero was not. But now they got a hint that CCF was was looking at the higher energy. So now they were both looking at the higher energy. And then then they got more data.

And then they got more data because the accelerator group discovered that one of the magnets had been put in wrong, so like what exactly it was turned ninety degrees from where it was supposed to be, and so the accelratory.

Degrees not like point zero one degrees. She really messed it up.

Somebody really messed it up.

You know.

They had one of these Ikea drawings for how to assemble a particle accelerator, and it's hard to get that stuff right.

You know, I feel like tevatron is does sound like an Ikea name.

Yeah, And so what they did was they discovered this and they fixed it. They rotated the magnet, and then all of a sudden, the accelerator was working much better. It's very important that these magnets are arranged correctly because they focus the beams, and the more you can get those beams down to really small locations so the two beams of protons overlap, the more collisions you were going to get. They hadn't noticed this before. They hadn't well, they had noticed that it wasn't working as well as they hoped. But you know, this is not like downloaded from the internet. And running on your laptop. This is something nobody had ever built before. This is cutting edge technology, so you know, you never know how these things are going to operate, but it often takes a few years for the engineers to figure out, like how to make this thing really hum You know, you got to kick it here and twist this knob and flip that button three times, and then it's really going to sing. And so that's what happened in the summer of ninety four.

I feel like this in the next part of the story, is you're going to tell me that this magnet that was discovered that was wrong was discovered by this upstart intern called Daniel Whitson who was working there at the time.

No, I was in college at the time. I didn't even know about particle physics at the time I was I was still thinking I was going to do lasthma physics, so I was not involved at all. Found somebody found it. And the reason it's important in the story is that all of a sudden, the data started coming in much more rapidly, so it didn't make much of a difference anymore that CDF had been there early, that they had access to data that Zer didn't have because now there was like an avalanche of data and so this verse few percent of the data now irrelevant. So DZ are basically caught up to where CDF was in terms of how much data that had access to because the flood.

Games and they both share the same colliders, so it's like everyone's getting more data.

Everyone's getting more data. Exactly, they have different collisions. Actual collisions are different statistically independent, but they share the collider. They're drinking from the same river, all right.

So now now there's lots of data, and so who makes the first claim.

So in January of nineteen ninety five, D zero showed some results at the Aspen Winter Conference, a very important conference in particle physics. But they didn't look great. There was more convincing evidence of the top quark than they had before, but they hadn't yet like re opt demize their analysis. They were still doing their calculations the old way, and so their results were like, you know, one in one hundred and fifty chance of fluctuation. So people thought like, huh, that's weird. You know, the zeros has all this new data, but they haven't yet like really optimized how to look at it. So CDF was like in top Speed. They were like they were racing. They were sure they were going to find this thing. And they had a bunch of really smart people and they worked really hard and they had a great result. And this is in February now of nineteen ninety five. They had a result which is basically totally inconsistent with just background. It looked like top quark. Top quark was the only way to explain it. The chances of it being a fluctuation were now like one in a million.

So they did it.

They did it, but they had to tell the director. They couldn't just go to the New York Times and claim discovery. They had to calm the role lab director and say we're going public in two weeks.

They had to follow the rules.

They had to follow the rules. So then from a lab director calls Dzer and says, by the way, CDF has found the top quark. You guys got I.

Wonder if that's the phrase he use. He's like, oh, yeah, did you guys win out to the bathroom so huh yeah, Oh, by the way, your brother, your sister just found the top quark.

Yeah. Well, d zero had been working furiously of course, because they had this new pilot of data and they were working to improve the way they were analyzing it. And so I'm very curious to know, like what it was like to be on that experiment in those two weeks. Did anybody sleep at all? Did they stay up all night? Because the option was discover the top quark alongside CDF or be left in the dust? Right, wow, So nobody's like on vacation, nobody's like, you know, taking a break to watch a movie or whatever. This is like these two weeks. Yeah, these two weeks define your scientific legacy, right, and so but they did it, and they came out with a really strong result just in.

Those two weeks. Were almost there anyways, right.

Yeah, Well, there's a lot of discussion here. There's a lot of grumbling from old folk who are on CDF that they shouldn't have had to tell d zero and that only because they gave the zero the clue that it was there, that the zero scrambled something together.

And then this, you know, when you're on the giving side, they complained, but if they were on the receiving side of it, they would be grateful.

And then you know, you talk to people who are on D zero at the time, and they're like, no, we were totally on track. We had this thing, you know, we were going to be ready anyway. We were about to pick up a call on the phone to call the director.

Also, I also had that idea.

Yeah, exactly, exactly. There's a lot of this. And so then in the end it was March second, nineteen ninety five. They had a press conference together, a joint discovery press conference. Theation submitted papers the same second, like they synchronized their computers. Really, they submitted their papers in nineteen ninety five and discovered and claimed discovery of the top quart.

So that each of their papers said that they found it together, or just both papers said we found it at the same time.

Yeah, each independently wrote their own papers saying we discovered the top quarks. Another two papers published on the same day, so they have equal precedence that have independent evidence for the top quark, each with a background fluctuation probability around a million or more.

I'm picturing it like a Hollywood movie, right, I'm picturing the press release, and I'm picturing the fancy folks at CDF looking bitter and and like they were upstage, and then I'm picturing the zero physicists, you know, scruffy, they're wearing sandals, they having shaved, and they're feeling pretty happy in high fiving each other.

Yeah, I think there's a lot of that. I think there is a lot of that. And you know, I wasn't around at the time. And the professor who came into my class that March morning in nineteen ninety five very proudly showing this paper he was on D zero. I went to Rice and I was on the D zero experiment.

What was he wearing?

He was a finished guy. Actually wore the same thing every day. So we used to joke like, did he have like a closet full of those shirts that was just the same shirt every day. We didn't know it was a quantum mechanical question. But you knew how to dress, you know. It was a nice button down shirt, button all the way to the very top.

Yeah, he knew exactly how to dreads. That's why he never change.

He was really he was a really nice guy. He's the guy who got me into particle physics.

Oh wow, and here we are, and here we are. They found the top quark. Does it in March second, nineteen ninety five. What was I doing in nineteen ninety five, Danny?

You were probably drawing cartoons up at ten.

I was a Georgia Tech. Yeah, I was a junior sophomore. H I was probably in my pajama.

Probably. Well, it's a you know, it's a crazy long saga because they started looking for this thing in the late seventies, expecting to find it at any moment, and then for basically the next twenty years they thought he was going to be around the corner, around the corner, around the corner, and then finally they did actually find it. So it was a real moment of triumph for particle physics, but also a moment of head scratching because this thing is one hundred and seventy five times heavier than the proton. It weighs as much as the nucleus of a gold atom, and that's really weird. You know, anytime you see something in particle physics that doesn't fit into a pattern, you ask why, because often those questions lead to ideas that lead to like pulling back a layer of reality and seeing what's underneath. And it's been you know what, twenty five almost thirty years since we found the top quark, and we still don't know why it's so heavy. We're still studying it at the Large Atron Collider, trying to figure out what it means if the top quark is so massive.

Because it's weird, right, because it weighs more than you know, it's a basic particle of nature, but it weighs more than all of these complex build atoms.

That's right. And remember when we were talking about particles in their masses, we're not talking about like different sizes of particles. It's not like the top quark has more stuff to it. These are points in space. Each point just gets assigned a certain amount of mass based on how much it's slowed down by the Higgs field. So you might say, well, doesn't that just mean that this thing interacts with the Higgs field more and that's why it has more mass. Yeah. Sure, you just transform the question into why does this one interact with the Higgs field more? Why does the upquark interact very little with the Higgs field and the top quark align? What sets that knob? And that's a question we have no clue about the answer.

I feel like it's also more expensive than gold. You know, has anyone figured out, like how much money was spent to find for sure this quark that divided that?

No, that's good, that's a good point. Yeah, you know, a ring made out of top quarks would be.

Very expensive and also kind of explosive and no good for your finger.

No, and lasted about ten to the minus twenty three seconds, So not a good investment.

All right, Well, I think this is I was. I was glued to my seat, Daniel, and I'm a little exhausted now all this drama.

Well, you know, the funny thing is that that was the last discovery of that century, and then we didn't discover a new particle until the Higgs Boson in twenty twelve, and.

So the Higgs boson has kind of also this kind of drama about it. Right. There was a famous documentary movie called what's it called Particle Fever Particle Fever, yeah, yeah, and which shows you these two groups trying to find the Higgs boson and a lot of this drama as well. It's a pretty good movie.

Yes, and you know, Carlo Rubia plays a big role in the discovery of the Higgs boson, and yes, and in sabotaging the Americans attempts to discover it. Oh well, we'll tell that story in another ATISO, a sequel. We'll do it in three years. But we never know when the next discovery will come. Will it be another twenty years before we find a new particle? Or tomorrow when I open my laptop, Well, I'll get an email from my students saying, look at this weird bump in the data. You never bring me some coffee. I need my discovery pajamas. Where are I discovery pajamas?

Oh? Oh no, dang it, are gonna beat us? They don't wear pajamas.

All right?

Well, I think this again points to you know, how much there is does discover? You know, we never know. We never know what's out there beyond what we can see with our telescope or with our colliders. You know, it's like we're blind to a huge part of the universe. There's a huge unknown out.

There, that's right. We just keep chipping away at this rock, hoping to discover fascinating fossils underneath, hoping that there's something for us to learn. But you never know. That's why research really is like exploration. We're not reading textbooks. We're trying to write them and we don't know what's coming next, and the only way to figure it out is to just go out there and tap, tap, tap and see what we learned.

To make sure you have your magnets on the right way and that you'll be good.

Follow those akia diagrams very carefully.

All right, Well, we hope you enjoyed that. Thanks for joining us, see you next time.

Thanks for listening, and remember that. Daniel and Jorge Explain the Universe is a production of iHeart Radio. For more podcasts from iHeart Radio, visit the iHeartRadio app, Apple Podcasts, or wherever you listen to your face it shows when you pop a piece of cheese into your mouth, you're probably not thinking about the environmental impact. But the people in the dairy industry are. That's why they're working hard every day to find new ways to reduce waste, conserve natural resources, and drive down greenhouse gas emissions. How is US Dairy tackling greenhouse gases? Many farms use anaerobic digestors to turn the methane from manure into renewable energy that can power farms, towns, and electric cars. Visit US Dairy dot COM's last sustainability To learn more.

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I mean neuroscientists at.

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Daniel and Jorge Explain the Universe

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