What's the point of building bigger and bigger colliders other than the obvious fun and awesomeness of it all. It's a machine that opens up the sub atomic world. It's not just because we like to see things go boom, though of course we do, but because we want to know what happens when you pull things apart. What's inside me,
what's inside you, what's inside everything. At the root of it all is a desire to dig as deep as we can into the very nature of matter, to hope to reveal its inner workings and understand how it all comes together to make our amazing, crazy and delicious world. Is the universe made of quarks and leptons and dark matter? Or is it made of strings or shmings or bada bings? Right now we don't know. We might never know, or one day and we might build a collider powerful enough
to show us the universe's fundamental lego bricks. Then we can turned to the philosophers and ask them, hey, so what does this mean? Dude? But what if we don't get the billions to build a bigger collider? Is that the only way forward? Can we find some other clever way to get this information through the universe's back door. That's what we're going to talk about on today's episode.
Welcome to Daniel and Kelly's Extraordinary Universe, brought to you by all the tiny particles that make it possible.
Hello. I'm Kelly leader Smith. I'm a parasitologist who also studies space, and I'm wondering if today we're going to be talking about something that Daniel studies staring his day job.
Hi. I'm Daniel. I'm a particle physicist and my job is to play with taxpayer funded billion dollar toys.
Ooh, my job usually involves playing with fish bomb and I think your job might be better.
I hope nobody I've ever paid a billion dollars for fish vomit.
There are some important questions that can get answered with a lot of fish vomit. But yeah, probably not a billion dollars worth. I'll give you that. Maybe a million dollars worth. So you work at the LAC and we're going to be talking about research happening at the LAC. Is the thing that we're talking about today? Is this a question that you were working on or what does your lab do exactly? Daniel?
Mostly I take naps, in my office. Isn't that enough?
Yeah, I'm sure everyone feels great about where their taxpayer dollars are going right now.
Yeah, it's a fair question. What is Daniel actually do all day? We should have a whole episode where I talk about my research, But very briefly, in the last ten years or so, I was looking for dark matter at the Large Hadron Collider, smashing particles together, hoping to make dark matter particles which would leave an invisible signature which is really hard to pick out, and using machine learning to try to filter those patterns out from all
of the noise, which is a fun challenge. But then dark matter sort of became too popular at the Large Hadron Collider and everybody was doing it, and there wasn't a whole lot of opportunity to like do new clever stuff. So more recently I've pivoted to looking for weird, unexpected stuff. Like, we know that dark matter is out there, we should be able to see at the collider, so let's go
look for it. That makes sense. But what would be even more exciting to me is to find something that nobody expected, a discovery that makes people go, what, that's impossible, or that's crazy or huh, how could that even be something that nobody expected? And that's hard to do because you sort of have to have an idea for what you're looking for in order to go looking for it.
But we use some cool machine learning tools, anomaly detection and all sorts of other algorithms to try to make mathematical what we're looking for, what we're not looking for, and to figure out clever ways to look for it. So that's one of the things that I'm focusing on more recently, is looking for anomalies.
It's always so interesting to me the way the questions that we ask are influenced by things like, well, what are other people asking? And too many people are asking this, and so I'm going to move on to something else. And there's a lot of like social and funding things that go into the decision about what to study. I guess it makes sense. We're all humans doing work.
Yeah, there's definitely a lot of that. But I think people also underestimate how personal science is. Like people ask questions because those are their personal questions, and we all benefit from that, like the fact that some people are weirdly into fish guts, you know, we learn cool stuff about the universe. Because of that, and because some people want to stay up late looking into telescopes or get
their socks wet in the rainforest counting spiders. Because different people enjoy different kinds of activities and have different questions, we get to learn about all lots of different kinds of science. And so you know, there's no like magic sorting hat that tells people what science to do. They just follow their instincts and also, you know, look for
opportunities for sure. But I think it really reflects the sort of breadth of human curiosity, all the different kinds of science that we have, and I think that's all wonderful and delicious.
I absolutely agree limitless human curiosity. You can be interested in fish, vomits, leeches, or dark matter or anything in between, and even chemistry.
Don't go that far. You know, I was going to say dark matter fish vomit, Like maybe dark fish's vomit up dark matter vomit. That would be pretty awesome. That would be like where our research overlaps.
Oh my gosh. Yes, I hope somebody will fund the intersection of our research interests. Let's write to the NSF and find out.
But more broadly, There's something really cool about the Large A Drunk Collider, which is that it lets you do lots of different kinds of things. People have the idea that the Large A Drunk Collider is like an experiment that I do and then somebody else get the turn they do an experiment. In reality, it's the same experiment. It's just running twenty four to seven collecting very very general data, and people can ask different kinds of questions about it. People can be like, hey, dude, we find
a new particle. People can be like, hey, are the particles we've seen do they behave the way we expected? Or also like is is there anything weird in the data? You can ask all these different kinds of questions with the same data from the same setup, and so it's very general and very powerful in that way, which I love because it lets you pivot easily from different kinds of questions.
So, what is the experiment that's constantly running in the LHC. And I'm always going to call it Hadron and embarrass myself. So I'm just going to call it the LHC to avoid that.
What's embarrassing about saying Hadron is it because it's so close to another word you're afraid of saying.
Yeah it is.
That's not family friendly.
You called out Wienersmith.
It's true, the large Wienersmith collider. Yeah, what is the experiment? Essentially, it's just a big camera around a collision point. You smash particles together, and then you try to capture all the debris that comes out to get it's much information about the collision and the aftermath, so you can piece together what happened because you can't see the actual collision directly, Like when the quarks annihilate, you don't get to see that happen. You just get to see what they turn into.
So we have these layers of detectors around the collision point to take information about those particles so we can reconstruct their trajectories and their energies and their angles and all sorts of stuff and figure out what happened. And we just do that for every collision, no matter what.
And is it like today we're just running electrons through there, or it's like whatever particles happen to be in there we're going to run into, or you know, is there like a certain combination. What do you start with?
Yeah, we just go outside and take a scoop of stuff, toss it in the collider and see what happened.
It's like, oh my gosh, you're like biologists.
We're colliding fish bombit today. No, the collider is very sensitive and very carefully tuned, so you have to put the right stuff in and tune it. Most of the time it runs protons, and so you just start from hydrogen. You kick off the electrons, you give them energy, and you separate them using their charges. You have pure protons and you collide those. The previous collider I worked at in Chicago, the Tepatron, collided protons and anti protons, so you have to make a source of anti protons a
whole other factory. That was too complicated. So for the next collider, the Large Hadron Collider is just protons and protons, but sometimes we do other stuff. Sometimes we put lead in there or gold atoms and smash them together because you can ask all sorts of interesting questions when you have like zillions of protons smashing together. It's called heavy ion physics. So yeah, the Large Adron collider is pretty flexible.
You can collide other kinds of stuff, not just protons, probably not fish guts though.
That's disappointing, but I guess we'll keep talking about physics anyway. And so is it like you know, Fridays or the gold days, or just somebody like gets a grant and that's the day you do the gold ions or whatever instead.
No, it's like ninety five percent protons. That's the main physics. And then occasionally we'll do a run with gold or with lead or something else, but it's mostly just proton proton physics. That's the bread and butter. The large Adron collider, and it's decided some very high level of committees ascerned. It is like a collection of dozens of countries, and so everything's decided by committees that take forever, and so it's very bureaucratic. Even the way we publish a paper
is very bureaucratic. We have five thousand authors on a paper and everybody gets to read it and comment on it. So you know, you put a paper through and somebody's like add a comma, and somebody else is like remove that comments. We also know add that comment, put that comments. It's very slow and frustrating, but it's also wonderful to work with people from all over the world.
You have a very nuanced viewpoint on it. That's great. I do get frustrated by those bureaucracy, like who cares about the comma, Let's just get the paper done. But on the other hand, I'm sure you get lots of great ideas you wouldn't have gotten otherwise and it was just two people working together on the paper.
Yeah, but the particle collider is very powerful and it lets you do things like look for new kind of particles directly. But also I think this underappreciated, is that there are indirect ways to discover new particles without actually seeing them. And that's the thing I want to talk about today. How we can use that potentially to see inside particles, to learn about what's going on inside the particles we think might be fundamental.
All right, well, and today we're going to be talking about how can we see what's inside the electron? And we asked our amazing listeners, who are always insightful, to tell us what they think the answer is to how can we see inside an electron? So let's go ahead and hear. What they had to say is that in order.
To see things at that scale, we would need a solar system sized particle collider. If we wanted to try to see inside of it, we'd probably have to smash other particles into it, and we just have to smash them together block we do everything else. To see inside an electron, we would need to probe it with something that has a wavelength that's smaller than the electron.
I thought that we couldn't. I thought electrons a fundamental and there's nothing in there.
Because we could crash them together with high energy particle physics, can we actually see inside of an electrons? You can't smash electrons together, so maybe you do it with neutrinos.
We might only be able just to look at the outside of it, and there might not be anything different on the inside.
I think that electrons are fundamental particles.
By colliding it with other electrons or other particles and seeing what comes.
Out, it's various quantum states. When probed multiple times with perhaps light, will generate some sort of semblance of a structure.
With a very powerful microscope and a lot of imagination, get some pliers and a set of thirty weight ball bearings. It's all about ball bearings nowadays.
Okay, I'm pretty certain Daniel's job is smashing particles together and seeing their guts when they pop out. So that's my guess. Or maybe the answer is math, but that's not nearly as exciting.
I'm imagining something like X ray crystallography, like Rosalind Franklin saw the structure of DNA, but much much more sensitive. I mean electron microscope. It's right there in the name.
Wait wait wait wait wait, I see where this is going.
Are you asking for more funds to build an even larger particle collider?
As far as I know, there's not an insight of the electron to see.
You like collide electrons together and when they hit each other, they like four minutees a big explosion, like a big like a big electronic explosion, and when and when that happens, it will there's like a giant microscope over it, and there's like somebody looking through the microscope and they like see what comes out of the explosion.
M magnets. Thanks to everybody who's sent in these answers. If you would like to play for future episodes, don't be shy. Write to us two questions at Danielandkelly dot org. We want to hear from you and we want your voice on the podcast. I love that so many people said smash them together. These are particle physicists and folks after my heart.
They've been listening to you. I think they've been listening to the show for a while. I like the one person who said it involves ball. I think a lot of really great scientific questions involve ball bearings. That was a good guess.
If you don't know, use some ball bearings, right. They can't hurt.
No, no, no, and they're always fun to play with, although I always lose them.
But these folks are basically right on the direct approach, smash it together, see what comes out. If you have enough energy, you can break the electron open. You know. That's basically the short answer, and they're right, But nobody got the indirect answer. The more subtle, the clever, the back door way to maybe see what's inside the electron without actually breaking it open, which I'm very excited to talk about.
And I'm very excited to hear the explanation because I looked at the outline and I was like, I have never heard about this before, so this will be exciting and new for me. Let's start from the very beginning. You know, we're all made of molecules. Molecules are made of atoms. Give me some more detail, what background do we need?
Yeah? Yeah, And I just love this question because I love like looking at the stuff around us and wondering, like how it comes together? What's the recipe for my coffee? What's the recipe for those fish guts? How do we end up in this universe? You know? And to me, unraveling with things are made of is really like looking at the matrix, you know, finding the source code for the universe. It's something really deeply satisfying. So it's no surprise that I am a particle physicist instead of like
a rainforest spider ologist. But I hope other people out there also find that exciting. And we get to live in a time when we have unraveled so much of nature. You know, thousands of years ago people were like, I don't know, maybe there's four kinds of stuff, who knows. But you know, we figured out what used to summarize, like, Okay, we're made of molecules, we're made of atoms. That took us thousands of years to figure out. It's just like
obvious high school chemistry by now. But it's also hugely revealing about the way our universe works, you know, and it tells you something already really powerful, which is that you have a huge complexity of stuff, right, Like how many different kinds of things are out there in the universe? Ice cream and blueberries and mushrooms and fish guts and planets, so many things. Maybe infinite numbers of kinds of things.
Definitely a huge number, even white chocolate unfortunately, but yeah, there's a lot of stuff out.
There, hey said fish cuts, Okay, don't be redundant. The amazing thing is that you can build all of that with like one hundred atoms, right, It's kind of incredible. You put those hundred items together in different ways, and you get lava, or you get kittens, or you get hamsters, or you get whatever. It's incredible that this huge complexity is built out of simplicity, and the complexity comes from
the arrangements of the stuff. I think that says something really deep and powerful about the nature of our universe. And so I want to dig deeper, but I want to past for a moment and like appreciate how far we've come, even just when we get to the atom, right, because the universe could have been different. It could have been that like everything's made of its own kind of particle and there isn't simplicity, or as you get lower,
there's more and more kinds of stuff. And so I'm grateful that we live in the universe where as you dig deeper, things seem to get simpler. And it's tantalizing because it tells you like, ooh, maybe keep going. There's a really simple hints they're waiting for you. It's all forty two.
And as someone who studies behavior, I also think it's awesome that we live in a time where you can get a bunch of nations together to agree that we're interested in the fundamental nature of the universe and we're going to invest in something like the LHC. It's just I don't know. I think it's an amazing time to live for a lot of different reasons.
Yeah, it is, And so for anybody out there who happens to be in the US Congress, for example, I think funding for particle physics is great for lots of reasons. One is the huge return on investment in terms of transforming the nature of society economically and militarily and all that stuff. But also just for the sheer knowledge, you know, like it's worth it anyway, Let's dig deeper. So we have molecules. Molecules are atoms, is like roughly one hundred
kinds of atoms. Inside the atom, of course, is the nucleus and then electrons. Nucleus is made of protons and neutrons, and so now we have structure inside the atom, right, and don't take that for granted. There's an amazing correlation between the structure of the atom and the behavior of the atom. All this complexity we're talking about, all the fascinating different behavior like why are metals metallic, and why something's active and something's inactive. That all comes from the
structure of the atom. And you could almost have guessed it if you looked at the periodic table you said, oh, look at these different kinds of atoms. Why there are so many different ones, and why are there patterns here? You could have guessed that it comes from internal structure. That the atoms weren't themselves fundamental, meaning they weren't just made of their own stuff. They were made of something smaller.
So we had a very strong clue already when you look at the periodic table that there was more structure deep down, and it's amazing that when we dig in we find that structure and we're then able to explain all of those patterns we saw, right, It's incredible.
I feel like you just said that chemistry is important, and I'm feeling a little uncomfortable. But we talked about this. There was a listener question about why is carbon so important for life forms and that did come out of a long discussion about, you know, what we can learn from the periodic, So it's important even if it's chemistry.
Now I would say it's redundant. All you need to know is the structure of the atom, and chemistry you should just follow naturally from that if you knew what you were doing.
It's always about physics.
Exactly anyway. So now let's dig inside the nucleus. Right, we have the protons and the neutrons. Protons and neutrons we know are made of smaller particles. They're made of quarks, and the mass of the proton is fascinating, you know, like basically the proton is the mass of hydrogen. That's what the hydrogen is, basically just a proton. So fix that in your mind is like the unit, and in particle physics we use units of GeV giga electron volts
to talk about mass. It really is GeV divided by the speed of light squared, but we just set the speed of light to equal one because otherwise it's such a pain in the butt. Anyways, So the proton has a certain mass. And if you dig into the proton and you ask, like, well, the proton is made of
the quarks. Does that mean I can get the proton mass by adding up the mass of the quarks the way you feel like if you take your car apart, the mass of the car is equal to the mass of the parts of the car, right, Well, that's not true for the proton, and this is going to be very important later. The proton's mass is made of things with much much smaller mass. Like you add up the mass of the quarks that make up the proton, you get like a few percent of its mass. So where
do the rest of its mass come from? Or? Remember mass is not stuff, right, Mass is internal stored energy, and there's a lot of energy between those quarks holding those quarks together, and that energy inside the proton contributes to the proton's mass. The same way, like shining a photon into a box of mirrors makes that box more massive, even though what you've added hasn't added any actual mass
on its own. So the proton is pretty massive, but it's made of very low mass stuff, and a lot of its mass doesn't come from the mass of the things that's made out.
Of this mass is internal stored energy thing. I remember you blew my mind when we were talking about that in the Where does Energy Come From? Episode? So if folks want a bit of a deeper dive into that concept, they should check out that episode.
Yeah, exactly, So we've zoomed it now inside the protons and neutrons, and protons and neutrons both made of quarks, just different arrangements. You got upcorks and down quarks and two upcorks in it. Down makes one of them to down quarks and up and makes the other one. Honestly, I don't even remember which is which. I can never keep that straight, but you can look it up.
I don't bother memorizing stuff like that either.
I often remember this stuff, but I feel like if you confuse it too many times early on when you're learning it, then it's forever scrambled in your brain, and I will never be able to snangle them and always have to look it up.
And this is why I'm never going to try to say hadrawn, because I've gotten it totally confused. If there are some people in my life where I said their name wrong so many times, I will never be constantly I'm going to say it right where I'm just like, hey, I've known you for five years. I don't want to mess it up now that we're face to face.
You remember my name though, right?
Hey?
You putting you on the spot.
It's Whitson right.
In French they call me Wittissan. I was actually one time waiting for an aployment at a bank in France and they came out and said Monsieur Wisson and I was like, that's not me, and calling him and calling him. I was like, who is this moron? We're going for your appointment already.
Your whole never would come with me, oh.
Exact, oh simla. Anyway, I go to.
Doctor's appointments, including to the like obgyn, where you think that people would be comfortable saying the word wiener. It's always like when they call people out from the waiting room it's like, oh, uh, you know, miss Smith, Miss Jordan, Miss god Luski, uh Kelly, would they get to me? And nobody wants to try to say Wiener Smith, even at the Obgyn. But anyway, that's all right, I go buy anything. It's all fine.
Maybe they think you're Bird Simpson, you're playing a brank on them.
Yeah, maybe nobody would actually do that. We did one We went to go pick up our turkey for Thanksgiving it Whole Foods, and they called to the back, the wiener Smiths are here for their turkey. And then fifteen minutes later we hadn't gotten the turkey, and I was like, hey, could you call them in the back and see what's up. They called back and they said, what about the turkey for the Wienersmith's. And I heard the person on the walkie talkie go, oh oh gosh, you were serious. So
then we got our turkey. All right, I've gotten us off track, daniell get us back on track.
Please, that's right. So we're zooming inside of matter inside your frozen turkey. You have molecules and atoms, and those are made of protons and neutrons and electrons, and the protons and neutrons are made of quarks. So we've zoomed all the way down, and everything that you've ever tasted or eaten or thrown at your family members on Thanksgiving is made of quarks and electrons, right down to this very basic Two kinds of quarks and one kind of
electron can make basically everything. So the particle physicists cookbook has three ingredients. And the most amazing thing, the most mind blowing to me, is that everything in the universe is made of the same ratio of that stuff. It's like one proton to one neutron to one electron, which means the same numbers of quarks and electrons in everything.
It's just the arrangement of stuff. But you know, we're never satisfied just knowing that it's not like that's the answer, and so we're always interested in the question of like, is there something deeper? Is there something inside the electron? Is there something inside the quarks? And we haven't talked about it today and probably won't, But obviously there's a huge chunk of the universe dark matter that's not made of quarks and leptons, So we know there's other kinds
of matter out there. Definitely not the end of the story.
Well, and you said leptons, which we haven't talked about yet. What is elepton? Is a lepton like a quark, but it jumps a lot. I'm stretched.
No, it's a particle that's slept in. No electon, Sorry for the terminology. There's a category of particles that the electron belongs in, and the electron has cousins the muon and the towel that make up the other leptons. But we can also do say quarks and electrons because that's what makes up the matter that we are made out of.
There are other quarks out there, and there are other versions of the electron out there, the muon and the towel, but our kind of matter is made out of two quarks, the up and the down, and the electron.
Got it, Okay, So after the break, we're going to talk about why we think that digging into the electron is worth it doing. Do we have any evidence to suggest there's something else making that up? And we'll discuss that after the break and we're back. Okay. So we've dug into protons and neutrons. We know that there's quarks that are making them up. Do we have any indication that if we dig farther into electrons we will find that electrons are made up out of something.
We have no really direct smoking gun, right. What we do have is a sort of history and some hints that encourage us. Recall when we were talking about the periodic table. We saw all these patterns in the periodic table and we were wondering, could that be explained by internal structure? Could these actually all be made out of smaller bits? And the patterns come from how those bits arrange themselves and come together naturally, from the different ways
that they can click together, or whatever. And now we know the answer is yes. So we can also look at the current list of particles that we don't know what's inside and ask are there patterns there? Are there unexplained phenomena, things that seem suggestive that maybe these are built out of the same smaller bits. The answer to that is, oh, yeah, absolutely, there are huge, obvious, screaming patterns that suggest very strongly this is not the final answer.
And if you were to find something fundamental making up electrons, what would you name it?
The white son? Of course?
The what toll exactly?
So yeah, I hope I'm around to do that, and I suspect the particle physics community would overrule me, and that happens occasionally, you get overruled, like the electron discovered by JJ Thompson. He didn't call it the electron. He wanted to call them corpuscules, like little bits of matter. But people are like, yeah, no, we're going to go with electron.
I mean, as long as they don't name it like A or B, like what was it Jupiter's rings? It needs to be something exciting. But okay, all right, so tell me more about these tantalizing patterns.
Yes, So we mentioned earlier that there's more than just the electron, right, the electron has cousins. There's the muon in the towel, so there's three kinds of electrons. The electron also has a partner, the new trino, which isn't part of our matter, but it's part of the universe. It's something the universe can do. So in total, there are six of these lepton particles, the electron, muon, TAW,
and then the three neutrinos that correspond to them. So that's interesting and you might ask like, well, why are there three these particles are all so closely related that muon is just a little heavier than the electron. The toaw is even heavier. It feels like you patterns in the periodic table. There's like three columns of these particles. So that's already very interesting and suggestive. It makes you wonder, like, are there three ways to click together their internal bits?
And this is how it happens, three ways for some string inside of it to vibrate. And that's just one of the really interesting patterns. That whole pattern of like six particles three pairs of two is also reflected in the quarks. We talked about the quarks the up and the down. That's one doublet of quarks up and the down go together. There's a copy of that doublet the charm and the strange, very similar to the up and the down, but heavier. And then there's another copy of
that doublet the top and the bottom. So all in all the quarks have six and it breaks into these three columns of two particles exactly the same way the leptons do. So you have this structure which is interesting and suggestive, and then you have it repeated in another set of particles. The amazing thing is that the quarks and leptons are very different. The quarks feel the strong force, the leptons don't. The quarks make up the nucleus, the
leptons make up the stuff that orbits around it. We don't actually know what the relationship is between quarks and leptons, yet there's this very strong symmetry between them. It's like if you go into a suburban street and you see, like all the houses on the left have this one floor plan, all the houses on the right have this other floor plan, but they're similar. You might be like, oh, okay, well this is obviously built by one company and they
got two floor plans, right, it's the same deal. It's like the universe can do this or it could do that, and probably they're built out of the same bits, you know, Like, for example, the charge of the proton is plus one and the charge of the electron is minus one. Those two things cancel exactly. For that to happen, there has to be some relationship between the quarks and leftons. Can't just be chance that the quarks add up to make plus one and the electron adds up to make minus one.
So there's definitely some connection there. But we don't know what it is. So all of this to me are very obvious clues. And in one hundred years, when we know what's inside the electron and the quarks, people will be like, God, it was so obvious. How did you not see it? Right? But right now we don't know.
We know that we have these patterns, and it could be that the universe is just this way, that all this stuff is fundamental and the universe has made it of these complex bits with these weird patterns, and there is no explanation, but I refuse to believe it. I think that everything out there should be explained.
So if we've got you know, three different kinds of neutrinos, they've got up and down quarks, charm and strange and top and bottom charm and strange was a good naming thing. When we break the electron into its component parts, do we expect there to be two parts then, to match with what we're seeing with the neutrinos.
Yeah, good question. We don't know. There could be made of two things, could we have three things? Could just be made of itself. Whatever is down there is going to be very different from what we've seen before. And you know, when we saw the proton, it was made out of three things. And it's interesting it's made of three things because of the way the strong force works. There's three colors, and one way to get a balance
is to have all three colors, you know. It's not just like a plus charge and a minus charge is red, green, blue, and if you have a red, green, and a blue, it comes together to make a color neutral object, which is stable. So one reason why the proton is made out of three is for that reason, because of the structure of that force. So we don't know what force is holding together the quarks or the electrons, and that's what would determine how many pieces there are and how
they interact, you know. And so it could be that the electron is fundamental. It's just made of itself, and when the coders of our simulation put together the universe, they started with electrons and that's it, and there's just nothing else inside. But it could also be that it's made of smaller stuff. The frustrating thing is that you can never prove that something is fundamental, right. You can prove it's not by breaking it open and seeing what's inside.
But all you can do is not to discover that it is made of something. That doesn't prove that it is fundamental, right, just shows that, well, maybe it's fundamental, or maybe it's stuff that's so small you can't see, or it's bound together so tightly you can't break it open, so you can never actually prove that it's fundamental.
The universe can be very frustrating that way.
And it might also be this is really philosophical, that there's nothing fundamental, like maybe the electron is made of something else, Schma electrons and those are made of something else, but electrons and those are made of something else, is made of something else. And your instinct is, well, there's got to be something at the bottom, right, it's got to be a bedrock layer of reality. And maybe but that's just a philosophical hunch, you know, we have no
evidence that there is. There are theories out there in philosophy that the universe could just be an infinite ladder of particles with no bottom, right, it just goes on forever, which would be great for particle physics because like infinite funding, right, just keep.
Digging infinite nobels. Yeah, there go, there you go.
But that could be our reality, right, it's possible, but there also could be a bedrock, and that's what I hope for. I hope that we get someday to some set of particles that's so simple, so basic, so obvious and beautiful that we think, okay, this must be it. It would make sense for the universe to have this beats fundamental, because it'd be very unsatisfying if the answer is what we have today. The answer is, well, there are twelve matter particles and there are five forced particles,
and that's just it. They're seventeen and that's the basic elements of the universe, and that's what we start from. And like, really, come on, it's got to be simpler than that. We have this tendency towards simplicity, and I just hope that the march continues, but there's no guarantees, so.
I gotta be honest. Before you and I started talking regularly, I also held out hope that they were like simple, beautiful, elegant answers. And then you told me about the weak force. That was the moment for me where I'm like, I don't think any of this is gonna make sense. We're just gonna have to keep buddling our way through. But hopefully I'm wrong.
So I ruined your view of particle physics. Used to think of it as like a shining cathedral of simplicity and beauty, and then you're like, man, this is a mess that's.
All held together with zip ties and duct tape in there. I don't know what's going on, but it is.
Yeah, But you know, at least now we understand why the weak force is a mess. They used to just be like, gosh, this is kind of ugly, and now we see, oh, it was beautiful and it was shattered by the Higgs boson in this precise way, and that's at least satisfying, and we can explain it, and we can hark back to an earlier day in the universe before it all got messed up. Something satisfying there, and I hope we get that kind of explanation.
All right, sounds good. I'm sure the more I learn, the more satisfied I'll become. That's so nice of you, You know, you make a strong effort to be interested in biology. We're both supporting each other here. So let's talk about the methods that are currently being used to try to break electrons into smaller pieces. If that's a thing that exists.
Yeah, all right, So the most obvious thing is what the listener suggested, which is like, hey, let's smash it open, right, Take two electrons or an electron and a positron, doesn't really matter, point them at each other, give them a lot of energy, and bounce them off each other. See what happens. Like This method works also for things like toasters. Right, want to know what's inside your toaster? Take two toasters,
throw them at each other at really high speeds. You're gonna have a shower of stuff that comes out, and you can sift through the debris and be like, oh look there's two springs and there's two handles, and oh okay, this must be what the toaster is made out of.
An ouch just should have unplugged it first.
That's a long extension cord. And there's something fundamentally different about the way it happens or quantum particles, but the spirit is the same. I mean, if you smash two toasters together, you're not destroying parts of the toaster and converting their math into energy and trains meeting them into something else. The bits that come out of the toaster collision are the same bits that went into the toaster collision. In a quantum collision, you can annihilate the particles like
eve an electron and a positron. They can annihilate into a photon and then turn into something else. Crazy. What comes out isn't always what went in, right, So you're not always learning about what's inside the electron if you annihilate it.
So, say you smashed two toasters into each other, and you expected to see like screws and springs and stuff like that. We don't even know what we should expect to see when you break the electron. And so if you know, things we had never seen before came out of the toaster, like fish cuts, fish guts, exactly, how would we even know what to do with that? And so, like, how do we know what to look for or how to measure it if we've never seen it before?
Yeah, good question. It would be amazing if we discover this fish all the way down.
I'm skeptical.
The simplest version of what we do is that we start at low energy and we know what we expect to see. Like, if you shoot two electrons at each other at fairly low energy, they're going to bounce off each other in a way that's similar to what happens if you shoot two baseballs at each other. They're going to bounce off, and you can calculate the angles they're going to come out at and the energy. And they're quantum particles, so you can't predict an individual one, but
you can predict the distribution. And so if you have what we call elastic scattering, which means you're not breaking the particles open, you know, changing the configuration they're just bouncing off each other is very predictable. So you start with that and you see the distributions you expect, the
angles that you expect, you're like, okay, that's cool. And then you increase the energy, and like with baseballs, at some point when you increase the energy, you're going to get what we call an inelastic collision, which means the baseballs shatter or they stick together, or something else happens. Right, And it's an energy threshold because the baseball's help together with energy, right, it's bound together. And if you have
a high enough energy, you can break those bonds. If you don't, you don't, So below some energy threshold, you're not probing inside the baseball. You're probing the baseball behavior itself, but above some energy, it's inelastic, and then the distribution changes. Yeah, maybe a baseball comes out, but first of all, it's mangled. It looks different, and the angles look very different. Like if you collide to baseballs and they stick together, they don't come back out at you in the same way.
Or imagine if you're doing it, like you throw a baseball at a wall, and if you throw it low energy, it bounces off, it doesn't break the wall. Throw it high enough energy, baseball just doesn't come back right. It just goes through the wall. So that's very different. And so that's what you look for to see. If you're probing inside a particle, you shoot it at higher, higher and energy, and you look for deviations from the distributions you would expect from elastic scattering to see that you're
starting to do inelastic scattering. You're starting to probe maybe what's inside the particles instead of probing the particles as a whole.
We found an energy at which we can shoot electrons at each other where it looks like we're transitioning from elastic to inelastic scattering.
Unfortunately not yet, but This is exactly how we discovered the structure of the proton. We shot electrons and protons at each other, and a low energy they bounce off elastic scattering. At higher energy, you start to destroy the proton, and what's happening is the electron is now interacting with the quarks inside of it, and so at some energy you start to just get like shrapnel from the proton and it's definitely not elastic scattering, so you can tell
you're doing inelastic scattering. For people who want to learn more about these experiments, they're fascinating and amazing. They're called deep in elastic scattering, so you can google that. And if you get to high enough energy, you actually start to see elastic scattering from the things inside the proton.
And that's, for example, how we know we have three quarks inside the proton, because you shoot electrons at the proton and you start to get elastic scattering as if there are three tight little dots of objects that you're interacting with. Because at high enough energy, the bonds of
the quarks are irrelevant. If your energy of your probe is larger than the energy of the bonds between the quarks, you're just shooting it at three quarks and sometimes they bounce off and exactly the way you would expect from elastic scattering between electrons and quarks. So it's this incredibly beautiful transition from elastic to inelastic to then three times elastic scattering. It's really amazing.
That must have been so cool to realize that you, instead of a proton, now have three other things that have popped out and be like the answer is three.
Yeah, I don't know.
That sounds really cool to me.
It is really cool, but for a while people didn't believe it. They're like, okay, well that's cool and that's clever, but that's just mathematics, Like is that real. And for a long time people call these partons like parts of the proton, and nobody believes that they were like actually physically real things inside the proton until somebody predicted, like, okay, well if these things are real, these quarks are real, they should be able to do other things also, like
make other states bound together. And somebody predicted one of these states. And the day they saw this in the experiment, is this new state made of just these quarks together. That's when everybody started to believe Okay, quarks are real. It's called the October Revolution. It was a very yeah,
absolutely in physics. And a guy I worked with tells a story about his father who's also a particle physicist, getting a phone call that day in October and like leaping out of the shower naked and dripping wet because he knew he was going to be exciting news to take that phone call. So sometimes there is drama in particle physics. And so that's what we saw for the inside the proton. We know the proton has structure, and that's how we know, and we can try the same
thing shooting electrons at each other. But so far we've seen no structure.
And have we gone up to what you would consider to be very very very high energies doing these experiments, Well.
We've done the highest we can, right. The large hadron collider is the highest energy collisions of protons and protons, and before that we had a high energy electron collider. You know, we built these things as large as we can. The limitation is just money, Like, there's no fundamental limitation to building a bigger collidse. We know how to do it. It just costs a lot of cash. You got to build a tunnel, you got magnets, you got little accelerating modules.
We could, in principle build one that circumnavigates the moon or you know, the galaxy or whatever. You just cost a zillion dollars, and even I think that's probably not a good way to spend to your cash. But it's awesome sort of to think that, like we could just buy this knowledge of the universe, Like it's out there, we're in the candy store, we have the money in our pockets. We're just like, hmmm, I feel like that Snickers bar is too much money.
Maybe we should figure out what causes cancer.
Yeah, exactly, save some kids from dying. Exactly. So one approach is like, just build bigger colliders. But the problem is we don't know how big it has to be, Like until you see the inside of the electron, you
have no idea. Is it right beyond our capability if we build it a little bit bigger we see it, or is it going to require a solar system sized collider or a galaxy sized colider or use black holes or just like a revolution in collider technology, so we don't need to make them so big and expensive something are working on that, So it's an exploration game the same way. You don't know when you land on an alien planet is going to be all dust and rubble? Or are the aliens waiting for us? And you want
to land on as many planets as possible. We don't know when we build a collider, are we about to see inside the electron? Or is this thing way too small and we're not going to see anything. You just don't know, all right.
Well, so we've talked about direct methods of trying to figure out if electrons are made of smaller parts. Next, you are going to tell us about the indirect method that you queued up for us as a super exciting thing earlier in the episode, And when we get back from the break, we're going to learn all about it. We're back and during the break I asked Daniel if the indirect method required bigger colliders, and he said the answer is no, which means maybe this could be the
key with existing technologies for figuring it out exactly. I'm super excited. How do we do this indirectly?
Yeah? So, particle physicists loves smashing stuff together and they love making bigger and bigger colliders, and that's all fun and everybody would prefer to do it's a direct way. It's the most fun, it's the most obvious, it's the cleanest, the data is beautiful. But hey, it's expensive, and you know, it's hard to build new colliders, and so we also try to be resourceful and we try to find other ways to discover things without having to build the collider
to make them directly. So we have these indirect methods of discovering things. Essentially, if we can see the influence of some new particle, for example, on the particles we already are able to make in the collider, even if we don't have enough energy to make that new particle,
that can still influence the particles we have. So for example, before we discovered the top quark, we were pretty sure it was there, and we're pretty sure we knew where it was, like how much mass it had because of the way it influenced the particles we were able to
make at the lower energy colliders. So we can play this indirect game of seeing the influence of new particles out there on the particles we see to discover new particles without like having the energy to make them, but we can also do something similar to see inside the electron using a very clever trick of studying the Higgs boson. So you remember, the Higgs boson is the particle it messes up the weak force, but also it gives mass to all the particles, like it gives mass to the electron,
for example, by interacting with it. So without the Higgs boson, the electron would have no mass. It would be a speed of light, massless particle, similar to the photon, but with charge. Of course, once you have the Higgs boson in the universe, the Higgs and the electron interact, and so the electron that we see is not the pure electron. It's the electron interacting with the Higgs field, and that
interaction is sort of like a big pulsing ball. The energy is sliding back and forth between the electron field and Higgs field, back and forth constantly, and that basically counts as internal stored mass of this thing, this thing which is a combination of the electron in the Higgs field. We talked in the Charge episode about how fields are coupled together sloshes back and forth between them. That's what's
happening with the electron field and the Higgs field. So the thing that we see is not really a pure electron. What we call the electron is actually a combination of the electron field and the Higgs field, and that thing has energy inside of it because of this interaction, and that's where the electrons mass comes from. Still with me, So I'm.
Trying to connect what you just said and thinking about what we were talking about before. So is this interaction going to give us more energy than you would get if you were just smashing electrons together. No, that's not what we're going for. We're just expecting the interactions to be different in a way that is formative.
Yeah, exactly. You can't use that as a source of fuel to like push things further or anything. But what's really fascinating is that the electron has a different mass than the muon. For example, right, muon is the cousin of the electron. Muon has a lot more mass, interacts much more strongly with the Higgs boson, and so the Higgs boson interacts with the muon more intensely. So the
muon has more mass. And that's really interesting because it means that by studying the interaction between the Higgs boson and a particle, you can understand how much mass it should have. Like if you knew the strength of the interaction between the Higgs boson the electron, you could predict the electrons mass. You'd be like, Okay, I know how much these two fields couple together, so I can calculate how that little pulsling ball of energy should be and
I can predict the electrons mass. Right, And the same way, you know, Okay, the muon interacts more strongly with the Higgs, so we should have a higher mass. And the top quark crazy interaction with the Higgs. Huge mass for the top quark. Top quark is like two hundred times the mass of the proton, which is much more massive than the electron. So enormous variations in the amount that the
Higgs boson interacts with this stuff. So say you knew how the Higgs boson interacts with these particles, you could predict their mass, and then you went out and you measured their mass, and what if you saw a discrepancy. What if the Higgs boson interacts with the electron and it should give it a mass of like zero point one. But you go out and you measure the mass and it's point five where it's ten point zero, then you'd be like, hold on a second, the electron has more
mass than it's getting from the Higgs boson. We think the Higgs boson is giving the electron a certain amount of mass, but we can go out and measure it in the universe it has more mass than that. What could that mean. Well, we've seen that before, haven't we.
The proton is made of three quarks, and those quarks get their mass from the Higgs boson, But the proton gets most of its mass not from the Higgs boson, but from the interaction of the quarks, and so in a similar way, if you measure the mass of the electron and it's heavier than you can explain with the Higgs boson, that means that it's got some energy inside of it, some bonds that are holding its bits together. That its mass is not just coming from the Higgs boson.
Its mass is coming from the interaction of the things inside of it, which means there are things inside of it. Haha, look at that, ha ha.
But that doesn't tell us how many things are inside of it, or the nature of the things inside of it.
Don't throw cold water on our discovery. Oh my god, we just had an aha moment. We revealed something about the universe, and now you're not sad.
Now I'm excited. I'm excited. I'm just trying to figure out how excited.
I should be. No, you're totally right. The indirect method is not as exciting as the direct method. It tells us that there is something inside of it, and you can tell us something about the nature of those bonds. But you're right, it doesn't tell us what it is. It doesn't show it to us, It doesn't give it to us to play with.
But has this been done?
So this is what we're working on. And this is something we can do with a large hadron collider because we can study the interaction of the Higgs boson in various particles. Who The way we do that is by measuring how often the Higgs boson turns into those particles. Like you create a Higgs boson, does it turn into a pair of bottom quarks or a pair of top quarks, or a pair of electrons or a pair of muons.
The rate at which it interacts with these particles determines how often it turns into those particles, so electrons very very low mass, low interaction with the higgs, very rare. To see higgs turn into electrons very difficult, but you run the collider long enough, you'll see it and you'll be able to measure that, and then we can compare that to the mass of the higgs. So we don't have that number yet because the higgs decase to electrons
very very very rarely because they're so light. But we're starting to be able to measure that for other particles. So we've measured it for the top cork and for the bottom cork, and those numbers are as we expect. So the higgs boson de case to the top cork in a way that suggests that all of its mass comes from the higgs boson. I mean, you would have heard about it already if we discovered something inside the quarks. So far the number is don't indicate that there's anything
inside the top cork or the bottom cork. We haven't been able to probe the other particles because they're lower masks and therefore the higgs the case to them more rarely. But that is something we can do, and we have ten more years to run this collider and get all
that data and analyze these things. And I just think it's cool that we have sort of these backdoor methods to be like, well, let's look to see if we can figure out if there is something there before we actually build the collider to break it open and show it to us.
Yeah. So say you had an electron a muon what is a tau town?
Good?
Right? Towh man, it was so cool question stuff.
I'm rounding you up to any of plus.
All right, thank you? Great? Oh yeah, okay, So you've got these three things and you interact them with the Higgs if the answer for their mass differs in some predictable way, like you know, one is always twenty five percent higher than the other, and then the other one is another twenty five percent beyond that, could you guess how many there were in there, like you know, there's probably three, and then there's an additional one in this one and an additional one in that one, Like could
you get a handle on like the relative numbers of things that way?
Yeah, that's exactly the game we'd love to play. You know, look at these things, look for patterns, look for clues. If we saw this, there would be instantly a zillion theories explaining it, you know, to match all those numbers, which would be really fun. And you know, we need that kind of inspiration. We need this kind of data to give us a clue to come up with these ideas. There are lots of theories of electron compositeness, you know, things that could be inside the electron, but nobody's any
idea if any of them are true. Maybe the most famous is string theory. String theory says all the particles are just string oscillating in different ways, which is cool and very beautiful, but strings are so tiny that we could never see them with a direct method, like we would need a ridiculous collider to see strings. And you know, not everything that's inside the electron could be seen even with this indirect method, because it has to couple to
the Higgs boson. In order for this to work, it has to directly get its mass from the Higgs boson the constituents of the electron. It could be that the constituous electron don't get their mass from the Higgs boson, and the electron itself is some like effective approximate description of it, and it gets its mass directly from the Higgs boson, unlike the proton, for example. So there are ways that this could fail, but it's an exciting way to see inside the electron anyway.
So is this the kind of thing where, like tomorrow, the news could be saying, oh my gosh, using the indirect method, we are now sure that the electron is made up of stuff. You said something about a decade's worth of data. Is this the kind of thing where we're gonna need ten years to figure it out? To see a signature, We're gonna.
Need a while. This is hard. You're measuring something that's very very rarely happens, and then you want to measure very precisely, which means you need a bunch of examples. But this is what we're good at, you know, we are good at using machine learning to extract this information from the data to get the most juice out of the dollars that we have spent on it. And you know, this is what particle physicists do. We're blocked by this wall, so let's see if we can find a way around it.
And I'm impressed with the cleverness. I mean, I didn't come over this. Yeah, somebody else thought of this, and it just goes to show you the ingenuity of humanity. You know, there are questions we have, and we will always push to find the answers, even if it seems impossible or impractical or ridiculously expensive, we will find a way to get there.
So you said that the LEDC right now mostly has protons shooting around. So are we even collecting the right kind of data to use the indirect method right now or is that happening at like a different collider.
No, proton shooting around is a good way to make Higgs bosons. One thing that LEDC is really good at is making Higgs bosons. It was built to discover the Higgs, but it was also built to discover lots of different versions of the Higgs, because we didn't know in advance how much mass the Higgs would have, and so exactly the best way to make it. So proton collider is really good at discovering things you don't know much about, because it can make lots of different kinds of things.
Now that we know more about the Higgs boson, people are talking about making a Higgs factory, which is a machine that makes zillions and zillions of higgs. It's like perfect for making higgs, and it does it by colliding muons actually, so you make beams of muons because muons interact with the higgs more than the electrons do. This is a good way to make lots of higgs. It's really hard to make muon beams because muons don't last very long that the k back into electrons. But people
have figured that out. So that's one thing on the docket for the next colliders. Maybe make a big muon collider higgs factory so you can study these things incredible detail. So that'd be exciting, but of course you know that cost a few bill Yeah, yeah.
I would like to make a discovery there where people can say, like, well, we need to make more Wienersmiths, make more higgs. Like that's a person and that's just so great that his name has become, you know, used in that way. But anyway, maybe one day they'll be wanting to make more Wienersmiths, but maybe not.
Maybe one day, And I hope that in a one hundred years or a thousand years, people know more about the structure of matter and they can talk about the fundamental bits and you can smoke banana peels on the roof and talk about why the universe is made out of squiggly ons and what that even means and why are the two of them? And you know, to me, these are fun philosophical questions and we don't even get to ask them yet because we don't know what those
answers are. And I hope to live long enough to see some of that.
Yeah, but it's cool that we live in a time where you can devise the experiments to ask these questions that we've gotten this far down the ladder. So I'm excited.
The ancient Greece would be very impressed.
I hope, I think so. Yeah. I mean, even though this isn't about fish cuts or fish vomit, I still think this.
Is very cool in a way. It is about fish cuts because it's about all of us.
That's aw man. That was poetic, really poetics modern days.
Saga over here, all right, all right, thanks everyone for going on this journey with us into the dark heart of matter and understanding what makes up our uni and what we know about it.
And if you have a question about the universe, you can send it to us at Questions at Daniel and Kelly dot org. We look forward to hearing from you. Daniel and Kelly's Extraordinary Universe is produced by Iheartreading. We would love to hear from you, We really would.
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