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Is the W boson too massive? · Daniel and Kelly’s Extraordinary Universe

• 0:08
  Speaker 1: Hey, Daniel, I was wondering how heavy are the fundamental particles? Oh, man,
• 0:13
  Speaker 1: is a really big range from very light to pretty massive?
• 0:17
  Speaker 1: But like how heavy and how massive? Like? How can
• 0:18
  Speaker 1: I get a handle on on these numbers? Well, one
• 0:21
  Speaker 1: way to do it is to think about electrons like cats,
• 0:26
  Speaker 1: I mean like electric cats. No, no, no, think about
• 0:29
  Speaker 1: it in relative terms. If an electron was like the
• 0:32
  Speaker 1: mass of a cat instead of its super tiny mass,
• 0:35
  Speaker 1: then how heavy would a mu want be? While mu
• 0:38
  Speaker 1: want is two hundred times heavier? Though, mue would be
• 0:41
  Speaker 1: like a walrus? All right, Yeah, that's pretty heavy stuff.
• 0:43
  Speaker 1: And your lightest quarks, the ones that make up the
• 0:46
  Speaker 1: protons and neutrons inside your body, up and down corks,
• 0:49
  Speaker 1: If the electron has the mass of a cat, and
• 0:51
  Speaker 1: then the quarks would be about as heavy as a
• 0:53
  Speaker 1: typical dog. I see, And does the light corks also
• 0:57
  Speaker 1: chase the electron? They do, actually, but it's this pretty
• 1:00
  Speaker 1: stable circle and they've been running in circles for billions
• 1:03
  Speaker 1: of you, like a Tom and Jerry cartoon. But what
• 1:06
  Speaker 1: about the top cork? I hear that one's pretty heavy? Yeah,
• 1:08
  Speaker 1: So if the electron is a cat, then the top
• 1:11
  Speaker 1: cork would be six blue whales. Yeah, that is bigger
• 1:16
  Speaker 1: than a cat. It's three hundred and fifty thousand cats.
• 1:20
  Speaker 1: Are the whales electric too, They're more positive? Hi am
• 1:39
  Speaker 1: or handmate cartoonists and the creator of PhD comics. I'm Daniel.
• 1:43
  Speaker 1: I'm a particle physicist, and I weighed the top cork
• 1:47
  Speaker 1: for my PhD thesis. Oh did you really that was
• 1:50
  Speaker 1: your Like the title of your thesis, I weigh one
• 1:53
  Speaker 1: of the fundamental particles and this is what I found.
• 1:55
  Speaker 1: Click to find out more. Yeah, so what if we
• 1:57
  Speaker 1: are very curious about exactly how much mass each of
• 2:00
  Speaker 1: these particles has? And back when I was a PhD student,
• 2:03
  Speaker 1: the newly discovered particle was the top cork, and it
• 2:06
  Speaker 1: was crazy heavy and everybody wants to know exactly how
• 2:09
  Speaker 1: heavy was it. So my thesis and post stock work
• 2:12
  Speaker 1: were like fancy statistical techniques to extract as much information
• 2:16
  Speaker 1: as possible to get the mass of the top cork. Wow,
• 2:19
  Speaker 1: it was a heavy burden. Did your thesis also weigh
• 2:22
  Speaker 1: a lot? Like? Was it a thousand pages? It was
• 2:24
  Speaker 1: a pretty massive topic. Yeah, was it printed in the
• 2:26
  Speaker 1: size of a top cork? I thought at some point
• 2:30
  Speaker 1: that I was going to collapse into a black hole
• 2:31
  Speaker 1: during the writing of this thesis from all the snacks
• 2:34
  Speaker 1: you were eating while you were writing it. As my
• 2:36
  Speaker 1: thesis got longer and longer, I thought, what is the
• 2:39
  Speaker 1: short style radius of a PhD thesis? Anyway? But anyways,
• 2:42
  Speaker 1: welcome to our podcast Daniel and Jorge Explained the Universe,
• 2:45
  Speaker 1: a production of I Heart Radio in which we put
• 2:48
  Speaker 1: the whole universe on a scale to understand exactly what
• 2:51
  Speaker 1: it's made of and how it's little bits work. Examine
• 2:55
  Speaker 1: all the tiny, little moving parts to understand how they work,
• 2:58
  Speaker 1: how much stuff they have, how they interact with each other,
• 3:01
  Speaker 1: and how that all comes together an incredible chaotic dance
• 3:04
  Speaker 1: to make the world that we know. Yeah, because it
• 3:07
  Speaker 1: is a pretty massively cool universe full of giant, incredible
• 3:12
  Speaker 1: things that defy our brains in terms of their size
• 3:15
  Speaker 1: and scale, and also the tiniest, smallest things that you
• 3:18
  Speaker 1: can even imagine. Some of these things are tinier than tiny,
• 3:22
  Speaker 1: that's right, And that feeling you get when you look
• 3:24
  Speaker 1: out into the universe that there are these really different
• 3:27
  Speaker 1: scales that like, you are so much smaller than the Earth,
• 3:30
  Speaker 1: and the Earth is so much smaller than the Sun,
• 3:32
  Speaker 1: which is tiny compared to the galaxy. That same kind
• 3:35
  Speaker 1: of thing happens also for particle physics. There are particles
• 3:39
  Speaker 1: that are a million times heavier than other particles, and
• 3:43
  Speaker 1: so we have this broad spectrum of masses. One of
• 3:46
  Speaker 1: the great mysteries of particle physics is understanding exactly why
• 3:49
  Speaker 1: that is. Yeah, the smallest of scales in our universe.
• 3:52
  Speaker 1: There's a whole zoo of particles that not only exists,
• 3:55
  Speaker 1: but that can exist and do exist sometimes in the universe,
• 3:59
  Speaker 1: and they all weigh a different amount. And particle physicists
• 4:03
  Speaker 1: really care about exactly how much they weigh because sometimes
• 4:07
  Speaker 1: our theories predict how much they should weigh, and so
• 4:10
  Speaker 1: if they don't weigh exactly the amount we expect, then
• 4:12
  Speaker 1: we know something is wrong, something is new in the
• 4:15
  Speaker 1: universe that we didn't understand, and sometimes that's a clue
• 4:18
  Speaker 1: that reveals a whole new chain of discoveries. M isn't
• 4:22
  Speaker 1: that a little awkward, though, Daniel, Like, what would you
• 4:24
  Speaker 1: do if there were a whole bunch of physicists really
• 4:27
  Speaker 1: interested in how much you wait or how massive you are?
• 4:30
  Speaker 1: I would be flattered. I'm like, Wow, I'm so important
• 4:32
  Speaker 1: to the universe. There are grants being written about me,
• 4:34
  Speaker 1: Particle accelerators being devised just to accelerate Daniel and anti
• 4:38
  Speaker 1: Daniel together. Physics paparazzi outside your house all the time,
• 4:43
  Speaker 1: trying to shoot particles at you. Wouldn't that be kind
• 4:45
  Speaker 1: of annoying? At some point over here, Daniel, over here,
• 4:48
  Speaker 1: pep pep pew, they'd be like, don't have any more chocolate.
• 4:51
  Speaker 1: We just spent ten billion dollars measuring how heavy you are.
• 4:54
  Speaker 1: You just gonna change the answer. You can't just do that.
• 4:57
  Speaker 1: Oh man, you have don't go on a diet for
• 5:00
  Speaker 1: a lot, all of that literature, you know. The truth
• 5:02
  Speaker 1: is I would hate to be the subject of so
• 5:04
  Speaker 1: much scrutiny. I'm such an introvert. That would be a nightmare.
• 5:07
  Speaker 1: But maybe you're making the point that we don't ask
• 5:09
  Speaker 1: these particles if they want to be studied, right, Nobody
• 5:12
  Speaker 1: got their consent to be part of our experiments. Yeah,
• 5:15
  Speaker 1: what if they want to keep their mass private? Well?
• 5:17
  Speaker 1: The interesting thing about particles is that they don't have
• 5:20
  Speaker 1: mass as an individual property, Like I weigh a different
• 5:22
  Speaker 1: amount than you do, and then every other person out
• 5:25
  Speaker 1: there does. But particles all basically have the same mass
• 5:28
  Speaker 1: if they're the same type. In fact, it's sort of
• 5:30
  Speaker 1: the way we categorize particles, Like the difference between an
• 5:34
  Speaker 1: electron and a muan is a muan is a heavier
• 5:36
  Speaker 1: version of the electron. But all the muans out there
• 5:39
  Speaker 1: have exactly the same mass because they're all part of
• 5:41
  Speaker 1: the same quantum field. They're all just ripples in the
• 5:44
  Speaker 1: same field. Yeah. Well, even taking a step back, it's
• 5:46
  Speaker 1: sort of amazing that you can break down everything in
• 5:49
  Speaker 1: the universe into like a short list of little, tiny particles,
• 5:53
  Speaker 1: you know, sort of like the universe is made out
• 5:55
  Speaker 1: of only five or six or nine lego pieces, and
• 5:59
  Speaker 1: it's interesting that all these lego pieces are just a
• 6:01
  Speaker 1: little bit different from each other. They not only have
• 6:04
  Speaker 1: different like charges and quantum numbers, but they weigh differently. Yeah,
• 6:08
  Speaker 1: and particle physics is all about finding those patterns, saying
• 6:11
  Speaker 1: what are these particles have in common and what's different
• 6:14
  Speaker 1: about these particles? And the reason we do that is
• 6:17
  Speaker 1: that we're hoping to reveal some deeper layer of reality.
• 6:20
  Speaker 1: We think that probably these five or six or twelve
• 6:23
  Speaker 1: lego pieces aren't the fundamental nature of reality. They aren't
• 6:26
  Speaker 1: the most basic parts of our existence, that they're more
• 6:29
  Speaker 1: like the atoms we see that are made of smaller pieces,
• 6:33
  Speaker 1: and that by arranging the fundamental particles and studying the patterns,
• 6:36
  Speaker 1: we can get some clues as to what might be
• 6:38
  Speaker 1: going on underneath. Yeah, and as you said, physics are
• 6:41
  Speaker 1: really interested in knowing what the exact masses of these
• 6:45
  Speaker 1: particles are because I guess you want to get the
• 6:47
  Speaker 1: model right, right, Like if the model is off by
• 6:49
  Speaker 1: even a little bit, you're wrong about the universe. Yeah,
• 6:52
  Speaker 1: And because the masses tell us a lot about how
• 6:54
  Speaker 1: these particles are connected to each other. Remember that when
• 6:57
  Speaker 1: particles fly through the universe, they're new were just a
• 7:00
  Speaker 1: tiny dot flying through empty space. They're flying through lots
• 7:03
  Speaker 1: of quantum fields and interacting with those fields, and how
• 7:07
  Speaker 1: they interact with those fields changes how they move, and
• 7:10
  Speaker 1: that's part of how they get their mass. So by
• 7:13
  Speaker 1: measuring the mass of these particles we can tell something
• 7:15
  Speaker 1: about how they're touching all these other fields. So it's
• 7:18
  Speaker 1: a very very sensitive probe of the particles and how
• 7:21
  Speaker 1: they talk to the other particles. Yeah. And so if
• 7:24
  Speaker 1: we've known about these particles for a bit of a
• 7:26
  Speaker 1: long time now, and we've measured through mass. I mean,
• 7:29
  Speaker 1: if you did it for your thesis, that must have
• 7:31
  Speaker 1: been what like a hundred years ago, two hundred don't
• 7:34
  Speaker 1: try to flatter me. Last year maybe, But they've been
• 7:39
  Speaker 1: measured before, right, Like, that's one of the first things
• 7:41
  Speaker 1: you did when you discovered these particles, when physicists discovered them,
• 7:45
  Speaker 1: it was measure how much they wait, that's right, but
• 7:46
  Speaker 1: it's a long project. First you discover the particle, you
• 7:49
  Speaker 1: just know that it exists. Then you start to study
• 7:52
  Speaker 1: its properties. One of the first things you do, is
• 7:54
  Speaker 1: you said, is to measure its mass. The first measurements
• 7:57
  Speaker 1: are usually very imprecise because you only have a handful
• 7:59
  Speaker 1: of examples. You just discover this thing, is barely enough
• 8:02
  Speaker 1: data to show that it exists. But as you accumulate
• 8:05
  Speaker 1: more data and your techniques get fancy and fancier, then
• 8:08
  Speaker 1: your measurements get more and more precise, and then you
• 8:10
  Speaker 1: can start asking really interesting questions about like is the
• 8:13
  Speaker 1: mask what we expected it to be? Doesn't make sense
• 8:16
  Speaker 1: to us, Yeah, it doesn't make sense in terms of
• 8:18
  Speaker 1: the theory that you have and firm the math right,
• 8:20
  Speaker 1: and does it all hang together? Like there needs to
• 8:22
  Speaker 1: be some self consistency right, right, And it seems like
• 8:25
  Speaker 1: every time you do an experiment, you're refining that measurement,
• 8:28
  Speaker 1: like you're adding more than the numbers down the decimal
• 8:32
  Speaker 1: places of how much you how well you know this
• 8:34
  Speaker 1: the mass of them? Yeah, And there's really two different
• 8:37
  Speaker 1: ways that you can do that. One is just do
• 8:38
  Speaker 1: more experiments. You get more data, and that can reduce
• 8:41
  Speaker 1: what we call these statistical uncertainty, like the chance that
• 8:45
  Speaker 1: you accidentally measure the wrong number due to a quantum fluctuation.
• 8:49
  Speaker 1: But then later, once you have enough data, the real
• 8:51
  Speaker 1: work is in understanding the data that you have to
• 8:53
  Speaker 1: remove sources of bias because that becomes the dominant source
• 8:57
  Speaker 1: of the uncertainty. So it can take years or even
• 9:00
  Speaker 1: in decades before the final answer has come out about
• 9:03
  Speaker 1: these measurements. Most precise results are sometimes arrived at ten
• 9:06
  Speaker 1: years after the last bit of data was taken. Well,
• 9:08
  Speaker 1: we've been doing this for a while, weighing the particles,
• 9:11
  Speaker 1: and I think as in general, we've sort of feel
• 9:13
  Speaker 1: that we or if we felt that we had a
• 9:16
  Speaker 1: pretty good handle on what these particles weighed. But recently
• 9:19
  Speaker 1: there's been some big news about or maybe big error
• 9:23
  Speaker 1: about them that's right. Last week we released a paper
• 9:26
  Speaker 1: to the world about a new measurement of the mass
• 9:30
  Speaker 1: of one of the heaviest particles, a w boson. This
• 9:34
  Speaker 1: is the particle that communicates the weak force and the
• 9:36
  Speaker 1: CDF collaboration and group working at Fermilab where actually I
• 9:40
  Speaker 1: was a post doc, so I did my research on
• 9:42
  Speaker 1: that experiment, released a paper measuring the mass of this
• 9:45
  Speaker 1: thing with unprecedented precision. Like the uncertainty they claim on
• 9:49
  Speaker 1: their measurement is much smaller than anybody has ever achieved,
• 9:53
  Speaker 1: so it should be a very very precise measurement of
• 9:56
  Speaker 1: the mass. But the answer they got, the measurement they
• 9:58
  Speaker 1: made of the mass, that number was a big surprise
• 10:01
  Speaker 1: to everybody, and it made a big news. You were
• 10:05
  Speaker 1: telling me that it was all over the science pages
• 10:07
  Speaker 1: of all the major newspapers. That's right. It actually was
• 10:10
  Speaker 1: the cover of Science, which is basically the biggest journal,
• 10:13
  Speaker 1: and it was all over the news on. A bunch
• 10:15
  Speaker 1: of listeners wrote in and said, hey, what's going on
• 10:17
  Speaker 1: with this measurement? And also, hey, Daniel, I saw your
• 10:19
  Speaker 1: name on this paper. What's up? What what's up? Indeed,
• 10:23
  Speaker 1: so you're you're one of the authors of this paper.
• 10:25
  Speaker 1: I am, in fact, one of the authors of this
• 10:27
  Speaker 1: paper out of how many three hundred and eighty nine,
• 10:32
  Speaker 1: three hundred and eighty nine authors? Was your position in
• 10:35
  Speaker 1: there where you near the top or the bottom or
• 10:37
  Speaker 1: is it alphabetic? It's alphabetical, so I'm always near the
• 10:40
  Speaker 1: end of the list. Who goes after you? Mr uh xylophone.
• 10:46
  Speaker 1: We have collabrators from all over the world, so we
• 10:48
  Speaker 1: have every letter from the Hungarians whose names start with
• 10:52
  Speaker 1: two a's to Chinese collaborators whose name starts with z
• 10:55
  Speaker 1: h zough. I am not close to the end of
• 10:58
  Speaker 1: the list, m Well. I In my field, at least
• 11:01
  Speaker 1: when I was working on research, being near the end
• 11:03
  Speaker 1: means you were more senior. So that's a good thing, right,
• 11:07
  Speaker 1: It can be a good thing in our field, though
• 11:09
  Speaker 1: we have this sort of ridiculous policy or anybody who
• 11:12
  Speaker 1: has contributed in any way to building the detector or
• 11:15
  Speaker 1: running the experiment is an author on every paper that
• 11:18
  Speaker 1: uses that data, even if it comes out years later.
• 11:21
  Speaker 1: I've worked on this experiment in almost ten years, but
• 11:24
  Speaker 1: they still put my name on every paper, which is
• 11:27
  Speaker 1: kind of ridiculous. Wow, So did you get to like
• 11:30
  Speaker 1: type one word out of the whole paper or something.
• 11:32
  Speaker 1: It's kind of embarrassing. But I didn't know about this
• 11:34
  Speaker 1: paper until just a few days before the news broke. Really,
• 11:39
  Speaker 1: it's like, hey, we're including you in this paper. You
• 11:41
  Speaker 1: might win a no More prize. UM good life, f
• 11:44
  Speaker 1: y I. It's sort of silly, and it just speaks
• 11:48
  Speaker 1: to how like modern science is done in these really
• 11:51
  Speaker 1: big collaborations and the publishing system hasn't really caught up
• 11:54
  Speaker 1: to that. You know, authors sounds like a lot. But
• 11:58
  Speaker 1: in my current collaboration on a list at the Large
• 12:00
  Speaker 1: Hadron Collider, we have five thousand authors on every paper,
• 12:05
  Speaker 1: and we publish more than a hundred and twenty papers
• 12:07
  Speaker 1: every year. That means twice a week there's a paper
• 12:10
  Speaker 1: going out with my name on it. I don't even
• 12:12
  Speaker 1: know the titles of most of the papers that my
• 12:15
  Speaker 1: name is on, and some of them I couldn't even
• 12:17
  Speaker 1: explain the title to you. So being an author on
• 12:21
  Speaker 1: these papers doesn't really mean that much. Then, how do
• 12:23
  Speaker 1: you know it's good science? Like? What if they discover
• 12:25
  Speaker 1: one of them, UM was not correct? Wouldn't that look
• 12:28
  Speaker 1: bad on you? I think that's an excellent question, and
• 12:31
  Speaker 1: I think in a perfect world, everybody who's an author
• 12:33
  Speaker 1: in every paper should be responsible for the scientific content
• 12:36
  Speaker 1: of that paper. I think that we know that that's
• 12:39
  Speaker 1: not how things are working right now, and we need
• 12:42
  Speaker 1: to revise somehow the way these authorship policies work. And
• 12:45
  Speaker 1: I've actually proposed inside my collaboration that we do change that,
• 12:49
  Speaker 1: that we don't have everybody being author on every paper.
• 12:52
  Speaker 1: But there's a lot of resistance to that proposal. I
• 12:55
  Speaker 1: guess there's some politics. But on the plus side, you
• 12:57
  Speaker 1: probably get residuals and royalties right from these papers. You
• 13:01
  Speaker 1: know that in science you pay to publish, right, You
• 13:03
  Speaker 1: don't get paid to push. You get negative royalties exactly, Nobody.
• 13:09
  Speaker 1: If you go google my name, I have something like
• 13:11
  Speaker 1: more than a thousand papers with my name on it.
• 13:13
  Speaker 1: Only a hundred of those are like my actual scientific output.
• 13:16
  Speaker 1: Most of them are work done by my colleagues, and
• 13:19
  Speaker 1: I'm sure it's all excellent. Well, yeah, that's pretty cool.
• 13:23
  Speaker 1: And so this paper that your name is on was
• 13:26
  Speaker 1: big news, and in fact it was massive news. And
• 13:29
  Speaker 1: so today on the podcast, we'll be asking the question,
• 13:37
  Speaker 1: is the w boson two massive? It feels like a
• 13:41
  Speaker 1: very judgmental title here Daniel like, how can something how
• 13:45
  Speaker 1: can something be too massive? Well, it has a higher
• 13:48
  Speaker 1: mass then is predicted by the theory, and higher mass
• 13:51
  Speaker 1: than other measurements. So their new result that came out
• 13:55
  Speaker 1: is bigger than the previous measurements. It means if they're right,
• 13:58
  Speaker 1: then the w boson isn't fat more massive than we
• 14:01
  Speaker 1: thought it was and more massive than our current theory
• 14:04
  Speaker 1: can explain. Well, I'm curious to see what happened. Did
• 14:07
  Speaker 1: the w boson gain weight or with somebody leaning on
• 14:11
  Speaker 1: the scale or something, But it's a very small difference,
• 14:14
  Speaker 1: kind of right, like what was the old measurement and
• 14:16
  Speaker 1: what was what's the new measurement? So the old measurement
• 14:19
  Speaker 1: is quoted in weird units, which is why in the
• 14:21
  Speaker 1: intro we talked about cats. But the units are mega
• 14:25
  Speaker 1: electron volts, so that's millions of electron volts, and for calibration,
• 14:29
  Speaker 1: about a thousand of these m evs are about what
• 14:32
  Speaker 1: a proton ways. So the previous measurement of a w
• 14:36
  Speaker 1: boson was about eighty thousand, three hundred and seventy mtvs,
• 14:41
  Speaker 1: so like eighty point four almost protons. And now what
• 14:46
  Speaker 1: did they measure it to be? The new one they
• 14:48
  Speaker 1: measured to be eighty thousand, four hundred and thirty four,
• 14:52
  Speaker 1: So it's an increase of about sixty four of these mtvs.
• 14:55
  Speaker 1: I didn't quite spot the difference between the two numbers,
• 14:58
  Speaker 1: about I'm sure to have phisic. It's a huge difference.
• 15:01
  Speaker 1: It's a very small difference. You're right, you know, it's
• 15:03
  Speaker 1: a difference of sixty four MTV out of eighty thousand.
• 15:07
  Speaker 1: So it's very very precise. Issue is that the theory
• 15:10
  Speaker 1: predicts it to be eighty thousand, three hundred and fifty
• 15:13
  Speaker 1: seven with a very small uncertainty of about six. So
• 15:17
  Speaker 1: the old measurement was eight three hundred and seventy and
• 15:21
  Speaker 1: the new measurement is eighty thousand, four hundred and thirty four. Again,
• 15:25
  Speaker 1: I'm catching the difference. I feel like it's maybe like
• 15:29
  Speaker 1: maybe we can put it in terms of percentage. It's
• 15:31
  Speaker 1: like point one percent different, maybe less. Yes, So the
• 15:34
  Speaker 1: difference between the old measurement and the new measurement is
• 15:37
  Speaker 1: less than point one percent relative to the ws mass
• 15:41
  Speaker 1: M And I guess that sounds like a little but
• 15:43
  Speaker 1: to a physicist that's um massive. Shall we say it's huge? Right,
• 15:47
  Speaker 1: because if it doesn't match the theory, then there's either
• 15:50
  Speaker 1: something wrong with the experiment or something wrong with the theory. Yeah.
• 15:53
  Speaker 1: The key thing is not how big is this difference
• 15:56
  Speaker 1: of sixty four mtvs relative to the WS mass. That's tiny.
• 16:00
  Speaker 1: The key is to compare the difference to how well
• 16:02
  Speaker 1: we know these numbers. The difference is sixty four mtvs
• 16:05
  Speaker 1: in the measurement, the uncertainty is ten mtvs. So like
• 16:09
  Speaker 1: they are very certain in this new measurement relative to
• 16:11
  Speaker 1: the other measurement. So like the uncertainty is one sixth
• 16:15
  Speaker 1: of this difference. All right, well, um, it's a big
• 16:18
  Speaker 1: result and made all the news and and a lot
• 16:21
  Speaker 1: of people ask you to come on the podcast and
• 16:23
  Speaker 1: explain it, right, that's right. Folks were wondering what this
• 16:25
  Speaker 1: meant for physics. Did it really break science like all
• 16:28
  Speaker 1: those psyclon journalism headlines said, And so they wanted us
• 16:31
  Speaker 1: to talk about it. Oh, man, I hope it didn't
• 16:33
  Speaker 1: break science, because then we have to return it is science,
• 16:37
  Speaker 1: have a warranty on it, or wait, we can return
• 16:39
  Speaker 1: it was usually we were wondering how many people out
• 16:43
  Speaker 1: there had heard of this headline and knew what it meant,
• 16:47
  Speaker 1: what the difference between the W bosons mass could mean.
• 16:50
  Speaker 1: And so, since this was a late breaking news event,
• 16:54
  Speaker 1: instead of asking our cadre of Internet volunteers, I just
• 16:57
  Speaker 1: walked around campus here at you see Irvine to see
• 17:00
  Speaker 1: had undergrads heard the big news about the w boson? Yeah?
• 17:03
  Speaker 1: And so you went out there into the campus and
• 17:05
  Speaker 1: you ask people if they had heard of this interesting
• 17:07
  Speaker 1: measurement and does it worry them? Here's what people had
• 17:10
  Speaker 1: to say. Have you heard of the w boson? Only
• 17:13
  Speaker 1: heard boson but not w um? What do you think
• 17:17
  Speaker 1: it means if scientists discover that the w boson is
• 17:19
  Speaker 1: a little heavier than it's supposed to be? I don't care.
• 17:22
  Speaker 1: Have you heard of the w boson? What do you
• 17:25
  Speaker 1: think it might be? Probably a policy in place for
• 17:29
  Speaker 1: like an environmental aspects. And what do you think it
• 17:33
  Speaker 1: would mean if scientists discover that some particle is heavier
• 17:36
  Speaker 1: than it's supposed to be. Not so good? That's um
• 17:40
  Speaker 1: not so good to be honest. And I've heard of
• 17:42
  Speaker 1: the boson, not the w boson. Whatever. What do you
• 17:45
  Speaker 1: think it means if scientists discover that the w boson
• 17:48
  Speaker 1: is a little heavier than it's supposed to be. I'm
• 17:50
  Speaker 1: not sure. Does it make you worried? Yes? Have you
• 17:54
  Speaker 1: heard of the W boson? What do you think it is?
• 17:58
  Speaker 1: Boson and shape? Look at you? And what do you
• 18:01
  Speaker 1: think it means if scientists discover that it's heavier than
• 18:04
  Speaker 1: it's supposed to be? Have you heard of the W boson? No?
• 18:10
  Speaker 1: If you have any guess what it might be? Now
• 18:12
  Speaker 1: my first year? No? Um, what do you think it
• 18:16
  Speaker 1: means if scientists discover that some particle is heavier than
• 18:19
  Speaker 1: it's supposed to be, it's more like charged. I don't know.
• 18:23
  Speaker 1: Do you know what the w boson is? Have you
• 18:25
  Speaker 1: heard of it? What do you think it might mean?
• 18:28
  Speaker 1: If scientists discover that it's a little bit heavier than
• 18:31
  Speaker 1: it's supposed to be, maybe it might be a bad thing.
• 18:34
  Speaker 1: Does it make you worried? Kind of? But not really
• 18:37
  Speaker 1: since I don't really know what it is? Thank you.
• 18:40
  Speaker 1: What do you think it means if the W boson
• 18:42
  Speaker 1: is a little heavier than it's supposed to be, the
• 18:46
  Speaker 1: interaction length is a little shorter, Does it make you worried?
• 18:51
  Speaker 1: M hm no, it makes me excited, all right. The
• 18:56
  Speaker 1: question is do you know what the W boson is? No?
• 18:58
  Speaker 1: I do not you have to guess what you think
• 19:01
  Speaker 1: maybe a science law. I don't know. And what do
• 19:05
  Speaker 1: you think it means? If scientists discover that a particle
• 19:07
  Speaker 1: is heavier than it's supposed to be, it just didn't
• 19:10
  Speaker 1: find it correctly last time? No, I don't you have
• 19:12
  Speaker 1: to guess? What do you think it might be? Something
• 19:15
  Speaker 1: with either physics or chemistry? Okay? And if scientists measure
• 19:21
  Speaker 1: a particle and discover that it's more massive than it's
• 19:23
  Speaker 1: supposed to be, what do you think that means? Maybe
• 19:26
  Speaker 1: there's something else smaller than that particle. That's possible if
• 19:30
  Speaker 1: it's bigger than we think it is. Okay, the w boson,
• 19:36
  Speaker 1: I'm not familiar. If you have a guess a particle particle? Cool?
• 19:41
  Speaker 1: And if scientists measure a particle and discover that it's
• 19:44
  Speaker 1: heavier than it's supposed to be, what do you think
• 19:46
  Speaker 1: that might mean? It's something unstable or that it's not
• 19:52
  Speaker 1: functional in a normal manner? All right, Not a lot
• 19:56
  Speaker 1: of people have maybe heard of this. Nobody had any
• 19:59
  Speaker 1: idea of what I was talking about. Um, some people
• 20:02
  Speaker 1: thought it was some sort of policy or some particles
• 20:05
  Speaker 1: shaped like a W. I was kind of surprised. I
• 20:08
  Speaker 1: thought the w boson was a little better known than that.
• 20:10
  Speaker 1: It's only famous in certain circles a certain scales, like
• 20:15
  Speaker 1: if you're really small, the w boson is big. Yeah. Well,
• 20:19
  Speaker 1: I thought the w boson is going to get a W,
• 20:21
  Speaker 1: but it looks like I got an L instead. Well.
• 20:24
  Speaker 1: It's interesting because this time you went out into the campus,
• 20:27
  Speaker 1: which is more of a maybe general audience than the
• 20:29
  Speaker 1: one that you find online, because online you sort of
• 20:31
  Speaker 1: get a lot of listeners of this podcast. Yeah, and
• 20:33
  Speaker 1: I think that listeners the podcast probably have an idea
• 20:36
  Speaker 1: of what the w boson is, but maybe don't necessarily
• 20:40
  Speaker 1: understand why it's important to measure its mass and what
• 20:42
  Speaker 1: this new measurement means and if we can believe it. Well,
• 20:45
  Speaker 1: I guess to start with for those of us who
• 20:47
  Speaker 1: don't know what a w bozon is, Daniel, can you
• 20:50
  Speaker 1: explain it to us? Yeah, as you described earlier, we
• 20:52
  Speaker 1: know that the world around us is made of tiny
• 20:55
  Speaker 1: little particles and stuff that makes up you and me
• 20:57
  Speaker 1: and the table in front of us. It's not smooth
• 20:59
  Speaker 1: and continue us like it seems. It's more like a
• 21:02
  Speaker 1: mesh with these little points of matter connected by forces,
• 21:05
  Speaker 1: and so we've discovered but the little points of matter
• 21:07
  Speaker 1: are made out of time, the little bits of stuff,
• 21:10
  Speaker 1: and we call those matter particles fermions, like quarks and electrons.
• 21:14
  Speaker 1: But there are also the forces that tie those things together.
• 21:18
  Speaker 1: And those forces you can think about as communicated via field,
• 21:21
  Speaker 1: like an electric field from an electron. You can also
• 21:24
  Speaker 1: think about them as communicated via particles. So we call
• 21:28
  Speaker 1: these force particles like ripples in those fields. And so
• 21:31
  Speaker 1: for example, when an electron pushes against another electron, you
• 21:34
  Speaker 1: can think about that is like ripples in their electromagnetic fields,
• 21:37
  Speaker 1: or exchanging virtual particles. In this case it would be
• 21:41
  Speaker 1: a photon. So every force that you know about has
• 21:44
  Speaker 1: a particle associated with it, Like the magnetic field has
• 21:48
  Speaker 1: the photon, the strong force has the gluon. The weak
• 21:51
  Speaker 1: nuclear force, the weakest of all the forces we know,
• 21:53
  Speaker 1: actually has three of these particles, the W plus, the
• 21:57
  Speaker 1: W minus, and the Z. So there's sort of like
• 22:00
  Speaker 1: heavier versions of the photon for the electroweak force, right,
• 22:04
  Speaker 1: And I think this is something that maybe confuses a
• 22:06
  Speaker 1: lot of people, or at least it confuses me. You know,
• 22:08
  Speaker 1: this idea that you know when you take high school physics,
• 22:10
  Speaker 1: or you know, even college physics. Do you sort of
• 22:12
  Speaker 1: think of forces as just the some invisible things, like
• 22:15
  Speaker 1: you know, the Earth is pushing me down through some
• 22:18
  Speaker 1: invisible force, or you know, a magnet repels another magnet
• 22:22
  Speaker 1: through some invisible force. But you're saying that, actually, what's
• 22:25
  Speaker 1: going on. It's like they're exchanging sort of invisible particles
• 22:29
  Speaker 1: when something is pushing against something else. It's a bit
• 22:32
  Speaker 1: of a subtle question. We did a podcast recently about
• 22:34
  Speaker 1: what is a particle? And one way to think about
• 22:37
  Speaker 1: how particles push against each other is that each particle
• 22:39
  Speaker 1: creates a field, and that field pushes on other particles.
• 22:43
  Speaker 1: So when two electrons come near each other, each one
• 22:45
  Speaker 1: has an electric field that pushes on the other particle.
• 22:48
  Speaker 1: Totally equivalent, mathematically and philosophically. Acceptable way to think about
• 22:52
  Speaker 1: it is, instead of feels, to think about particles being exchanged.
• 22:55
  Speaker 1: An electron comes by another one and it shoots a
• 22:58
  Speaker 1: photons at the other electron. On I think like photons,
• 23:01
  Speaker 1: I mean I don't see light. I don't see like
• 23:03
  Speaker 1: bright flashes of light between electrons. Well, these aren't things
• 23:06
  Speaker 1: that you see, right. You can't see a photon unless
• 23:08
  Speaker 1: it hits your eye. These are photons that are shot
• 23:11
  Speaker 1: back and forth between the electrons, and sometimes there are
• 23:14
  Speaker 1: a special category of particles we call virtual particles that
• 23:18
  Speaker 1: don't follow all the same rules that normal real particles
• 23:21
  Speaker 1: that you observe do. If you're interested in the subtleties there,
• 23:24
  Speaker 1: we have a whole podcast episode about what are virtual particles? Right,
• 23:28
  Speaker 1: It's interesting that, like you know, the force that one
• 23:30
  Speaker 1: magnet pushes on another magnet is basically the same thing
• 23:34
  Speaker 1: as the light that hits your eyeball from the sun. Right.
• 23:37
  Speaker 1: It's it's sort of hard to square the two, but
• 23:39
  Speaker 1: they're the same thing because one feels tactile and the
• 23:41
  Speaker 1: other one feels visual. But they're the same thing. They
• 23:43
  Speaker 1: are the same thing depending on your definition of same thing.
• 23:47
  Speaker 1: They're all part of a larger phenomenon, which is electromagnetism.
• 23:51
  Speaker 1: There can be different aspects of it. It's like saying
• 23:53
  Speaker 1: our electric fields the same as magnetic fields. Well not exactly,
• 23:56
  Speaker 1: but there are two sides of the same coin, and
• 23:59
  Speaker 1: so in that sent they are the same. Every force
• 24:01
  Speaker 1: that's applied via electromagnetism is communicated via electromagnetic fields, and
• 24:07
  Speaker 1: all information that moves through electromagnetic fields you can think
• 24:11
  Speaker 1: of as photons, like every ripple in those fields, every
• 24:14
  Speaker 1: piece of information with the field, was one way and
• 24:16
  Speaker 1: now it's another way that you can think of as
• 24:19
  Speaker 1: a photon M. And so the photon is basically the
• 24:22
  Speaker 1: thing that carries force, or the electromagnetic force, and so
• 24:25
  Speaker 1: the W boson is one of the things that carries
• 24:29
  Speaker 1: the force for the weak force, which is one of
• 24:31
  Speaker 1: the fundamental forces. Exactly, the weak force is one of
• 24:33
  Speaker 1: the fundamental forces. And it actually has three of these
• 24:36
  Speaker 1: particles that carry its forces, which seems weird, like why
• 24:40
  Speaker 1: does it need three? It's busier, you know, it needs
• 24:42
  Speaker 1: more staff, it needs three sort of because we've already
• 24:45
  Speaker 1: done some unification, like we found the W plus, we
• 24:48
  Speaker 1: found the W minus, we found the Z, and we realized, oh,
• 24:51
  Speaker 1: these are actually all part of the same thing. Originally,
• 24:54
  Speaker 1: people found the Z and the W separately and they're like, oh,
• 24:57
  Speaker 1: these are different phenomena until scientists put them together into
• 25:00
  Speaker 1: one idea called the weak force. And so those sort
• 25:03
  Speaker 1: of fit together very nice as part of the same force.
• 25:06
  Speaker 1: So we have those three particles, the W plus, the
• 25:08
  Speaker 1: W minus, and the Z that we now call carriers
• 25:11
  Speaker 1: of the weak force, the force particles for the weak force. Okay,
• 25:15
  Speaker 1: so this one is a force particle. Does that mean
• 25:17
  Speaker 1: that we're not actually made out of W bosons or
• 25:21
  Speaker 1: is it somehow sort of these things trapped inside of me.
• 25:24
  Speaker 1: It's another great philosophical question, right there are w bosons
• 25:27
  Speaker 1: inside you right now, because there are particles that are
• 25:30
  Speaker 1: feeling the weak force. Right some particle potassium, for examples,
• 25:33
  Speaker 1: decaying radioactively right now from the banana that you just ate,
• 25:36
  Speaker 1: and that's happening via the weak force. So there's a
• 25:39
  Speaker 1: W inside you right now. Are you made up of
• 25:42
  Speaker 1: w's is a little bit harder to say, Like, you're
• 25:44
  Speaker 1: made up of the matter that's inside you, but a
• 25:47
  Speaker 1: lot of your mass actually comes from the energy and
• 25:50
  Speaker 1: the bonds inside that matter, Like your matter comes from
• 25:53
  Speaker 1: your protons, but the mass of the protons mostly comes
• 25:56
  Speaker 1: from gluons inside you. So I would say that you
• 25:59
  Speaker 1: are made up of those matter particles, and also the
• 26:02
  Speaker 1: force particles definitely need them to make up Jorge M. Yes,
• 26:07
  Speaker 1: and that's important for sure, especially um bananas. So then
• 26:11
  Speaker 1: is the W boson helping keep me together? Is this
• 26:15
  Speaker 1: something that sort of helps things you know, stay as
• 26:17
  Speaker 1: one piece or does it only happen when things decay
• 26:20
  Speaker 1: or things break down. The W boson is part of
• 26:22
  Speaker 1: the weak force, and it's really really weak, and so
• 26:25
  Speaker 1: it doesn't play a role in holding together quarks into
• 26:28
  Speaker 1: protons and neutrons, and it doesn't play a role in
• 26:30
  Speaker 1: terms of holding the atom together like electrons surrounding the nucleus,
• 26:34
  Speaker 1: and so it doesn't really play a role in holding
• 26:36
  Speaker 1: things together. It mostly plays a role when things break down,
• 26:40
  Speaker 1: When a neutron decays into a proton, for example, that
• 26:43
  Speaker 1: happens via the weak force. M I see, all right, well,
• 26:46
  Speaker 1: but it's still important because, you know, it tells us
• 26:48
  Speaker 1: a lot about how things breakdown, which is kind of
• 26:50
  Speaker 1: an important process in the way the universe works. And
• 26:53
  Speaker 1: it's also important because it's a cousin of the photon.
• 26:57
  Speaker 1: The WS and the Z are actually very closely related
• 27:01
  Speaker 1: to the photon. They're just sort of like heavy versions
• 27:03
  Speaker 1: of the photon. And the way that we group those
• 27:06
  Speaker 1: three particles together, the W plus W minus and the
• 27:08
  Speaker 1: Z into the weak force, we can actually include the
• 27:11
  Speaker 1: photon into that, making a quartet of force particles that
• 27:14
  Speaker 1: all fit together really beautifully, and we call that unified
• 27:17
  Speaker 1: force the electro weak force, where we combine electromagnetism and
• 27:21
  Speaker 1: the weak force into one idea. I see. So it's
• 27:24
  Speaker 1: only famous because of its cousin. That feels a little
• 27:27
  Speaker 1: nepotistic there. It's part of the entourage of famous. It's
• 27:32
  Speaker 1: the guy who gets the water whenever the the photon
• 27:36
  Speaker 1: doesn't roll without the woveson. Alright, Well, it's one of
• 27:39
  Speaker 1: the fundamental particles, and it's important because it's in particle interactions,
• 27:43
  Speaker 1: and it helps define our theory of the universe. And
• 27:46
  Speaker 1: so recently scientists measured it to be different than we
• 27:49
  Speaker 1: thought it was. And so let's get into that measurement
• 27:52
  Speaker 1: and what it could mean. But first, let's take a
• 27:54
  Speaker 1: quick break. All Right, we're talking and discreetly about the
• 28:09
  Speaker 1: w bosons mass Daniel. I guess there's a lot of
• 28:12
  Speaker 1: interest in knowing how much this thing weighs. Do you
• 28:14
  Speaker 1: think the ws out there are blushing? Can? Can't? Do
• 28:16
  Speaker 1: they have color? Do they have color charge for them
• 28:20
  Speaker 1: to turn red? No, you're right, they are colorless. They
• 28:23
  Speaker 1: are colorless. They're they're colorless. Maybe they don't care. All right,
• 28:27
  Speaker 1: So there was a big headline recently that the mass
• 28:30
  Speaker 1: of the Dewey boson is heavier, is more than what
• 28:33
  Speaker 1: we thought or what the theory predicts. And so Daniel,
• 28:37
  Speaker 1: I guess maybe a more basic question is why does
• 28:39
  Speaker 1: the force particle need mass? War isn't it just transmitting forces?
• 28:42
  Speaker 1: It doesn't need mass, And a lot of the force
• 28:44
  Speaker 1: particles don't have mass, right, the photon doesn't eight gluons
• 28:48
  Speaker 1: and none of them have mass. But this particle has mass.
• 28:50
  Speaker 1: It doesn't need mass, and we think back in the
• 28:53
  Speaker 1: very early universe it didn't have mass, but then it
• 28:56
  Speaker 1: got massive because of the Higgs boson. Interesting, so it
• 29:00
  Speaker 1: doesn't neat mass, but it somehow has mass, and it's
• 29:03
  Speaker 1: all because of the Higgs boson. It's all because of
• 29:05
  Speaker 1: the Higgs boson. Exactly. Remember how the photon and these
• 29:09
  Speaker 1: particles fit together beautifully into this nice quartet, and they'd
• 29:12
  Speaker 1: be this very nice symmetry. For those of you interested
• 29:14
  Speaker 1: in the mathematical details, it's a gauge symmetry where you
• 29:17
  Speaker 1: can like rotate these particles into each other and it
• 29:20
  Speaker 1: preserves all sorts of interesting properties. That only works if
• 29:23
  Speaker 1: these particles are all massless, if none of them have
• 29:25
  Speaker 1: any mass, And we think in the very early universe
• 29:28
  Speaker 1: that was true, and the W and the Z had
• 29:30
  Speaker 1: no mass, and they flew around the universe just the
• 29:32
  Speaker 1: way the photon does. And in fact, we think the
• 29:34
  Speaker 1: weak force was much stronger because it's particles weren't so massive,
• 29:38
  Speaker 1: so they could fly further and interact more. But then
• 29:41
  Speaker 1: the Higgs boson came along and it broke that symmetry.
• 29:44
  Speaker 1: May have heard the phrase electro weak symmetry breaking, that's
• 29:47
  Speaker 1: what this refers to. It made the ws and the
• 29:50
  Speaker 1: z s very heavy, and it left the photon massless.
• 29:53
  Speaker 1: M Yeah, I guess it's kind of weird to think
• 29:55
  Speaker 1: of a force particle as having mass because first of all,
• 29:58
  Speaker 1: um that means it's it's slower, right, like it can't
• 30:01
  Speaker 1: go at the speed of light. And two does that
• 30:03
  Speaker 1: mean that it's like costs you to exert a force,
• 30:06
  Speaker 1: you know, if you have to use mass or where
• 30:07
  Speaker 1: does that mass come from? If you are pushing one
• 30:10
  Speaker 1: thing from another with the weak force, it definitely costs you.
• 30:13
  Speaker 1: To create ws and zs is harder than it is
• 30:16
  Speaker 1: to create photons. That's why it took us longer to
• 30:18
  Speaker 1: discover them. At colliders. The WS and disease were only
• 30:21
  Speaker 1: discovered in the eighties at certain we had enough energy
• 30:24
  Speaker 1: and colliders to make them. And then if you don't
• 30:27
  Speaker 1: have enough energy to make them, you can make them
• 30:28
  Speaker 1: as virtual versions where you like borrow the energy temporarily
• 30:32
  Speaker 1: from the universe to make this heavy particle. But the
• 30:35
  Speaker 1: heavier the particle is, the less likely you are to
• 30:38
  Speaker 1: be able to borrow that energy. So to like borrow
• 30:41
  Speaker 1: enough energy to quantum fluctuate a w out of the
• 30:44
  Speaker 1: vacuum is much less likely than it is for lower
• 30:47
  Speaker 1: mass particles. Is that where the name weak force comes from,
• 30:51
  Speaker 1: because it's sort of like it's really hard to do,
• 30:53
  Speaker 1: so nobody ever uses it. Kind of that is why
• 30:57
  Speaker 1: the weak force is weak, because it's particles are massive exactly,
• 31:01
  Speaker 1: and it also means that it doesn't have a lot
• 31:02
  Speaker 1: of range, right, Like if something has mass, it eventually decays,
• 31:06
  Speaker 1: and so like you can't shoot a boson from here
• 31:09
  Speaker 1: to the Mars because it's not going to get there. Yeah,
• 31:12
  Speaker 1: the universe likes to spread out its energy. It doesn't
• 31:14
  Speaker 1: like to have a lot of energy density in one particle,
• 31:17
  Speaker 1: and so if a particle can decay to less mass particles,
• 31:20
  Speaker 1: it will so The reason your electrons are stable is
• 31:23
  Speaker 1: because there's nothing lighter than an electron that they can
• 31:25
  Speaker 1: decay into. But a W can decay into things, and
• 31:28
  Speaker 1: so it will very quickly. Like a W naturally lives
• 31:32
  Speaker 1: for ten to the nineties twenty five seconds. What so
• 31:35
  Speaker 1: you have ten to the minus twenty five seconds to
• 31:37
  Speaker 1: measure its weight. We'll get into the details. But you
• 31:41
  Speaker 1: can't actually weigh w's directly, and you can't see them directly. Well,
• 31:45
  Speaker 1: all right, well that sounds like a perfect transition here
• 31:47
  Speaker 1: to talk about how you do measure the mass of
• 31:49
  Speaker 1: a force particle if it's so hard. Well, the first
• 31:52
  Speaker 1: thing to understand is that you don't measure its weight, right,
• 31:54
  Speaker 1: you measure its mass. The difference there is that weight
• 31:57
  Speaker 1: is the force of gravity on an object, or mass
• 32:00
  Speaker 1: we think of as an inherent quantity. Although you can
• 32:02
  Speaker 1: get into whole philosophical questions about what is mass and
• 32:05
  Speaker 1: where does it come from? The mass is something that
• 32:07
  Speaker 1: you have even if you're not in a gravitational field. Right,
• 32:09
  Speaker 1: So you would weigh different on Saturn than you do
• 32:12
  Speaker 1: on Jupiter than you do on Earth, but your mass
• 32:15
  Speaker 1: is the same. So that's the quantity we're interested in
• 32:17
  Speaker 1: your trying to measure not how much it weighs on Earth,
• 32:21
  Speaker 1: but like how hard it is to get it accelerated,
• 32:23
  Speaker 1: or how much energy it costs to make this mass? Right, yeah,
• 32:26
  Speaker 1: how much inertia it has? How much it been space.
• 32:28
  Speaker 1: The other problem is that you can't really use gravity
• 32:30
  Speaker 1: to measure these things. Like if I asked you how
• 32:33
  Speaker 1: massive is that bag of onions, you would put it
• 32:35
  Speaker 1: on a scale you would use gravity. You would say,
• 32:37
  Speaker 1: I know how much gravitational force there is on it,
• 32:39
  Speaker 1: so I can deduce what it's massive. Now I would
• 32:41
  Speaker 1: just mash it against another bag of onions. Physicist, you're
• 32:46
  Speaker 1: a natural physicist, now exactly, make some freakasy or something exactly.
• 32:51
  Speaker 1: And so the reason we can't do that with particles
• 32:54
  Speaker 1: is that they don't weigh very much. You know, these
• 32:56
  Speaker 1: amounts we talked about earlier are tiny, and so the
• 32:59
  Speaker 1: gravity pactional force on the w bson it exists, but
• 33:02
  Speaker 1: it's basically impossible to measure even though the w is
• 33:05
  Speaker 1: one of the most massive particles, And so instead we
• 33:09
  Speaker 1: don't measure its weight, we measure its mass. All right, Well,
• 33:12
  Speaker 1: then how do you measure its mass? Well, we would
• 33:14
  Speaker 1: love to measure its mass by seeing like how it moves,
• 33:17
  Speaker 1: so we can measure it's inertia, right, But we can't
• 33:19
  Speaker 1: do that either, because, as we said before, the W
• 33:22
  Speaker 1: doesn't last for very long. When we make it in
• 33:24
  Speaker 1: our colliders, it lasts for ten to the minus twenty
• 33:27
  Speaker 1: five seconds before it decays into other stuff. And so
• 33:30
  Speaker 1: because we can't ever see the W directly, all we
• 33:33
  Speaker 1: can do is look at that other stuff the W
• 33:35
  Speaker 1: turned into and try to reconstruct what its mass was, right,
• 33:39
  Speaker 1: because I think the other particles that do fly for
• 33:41
  Speaker 1: a while, you can see like how much they bend
• 33:43
  Speaker 1: in a magnetic field and things like that, and that
• 33:45
  Speaker 1: kind of tells you it's momentum, which tells you it's mass,
• 33:48
  Speaker 1: right exactly. So you use equals mc squared and you say, well,
• 33:51
  Speaker 1: the mass of the W boson is getting converted into
• 33:54
  Speaker 1: the energy of these other particles it turns into. If
• 33:57
  Speaker 1: you have some particle that's really heavy but you can't
• 33:59
  Speaker 1: see it directly, it doesn't last very long. It turns
• 34:01
  Speaker 1: into other particles that you can see. Then you can
• 34:04
  Speaker 1: measure the energy or the momentum of those particles, and
• 34:07
  Speaker 1: from that energy you can reconstruct how much mass the
• 34:10
  Speaker 1: original heavy particle had because its mass is getting turned
• 34:13
  Speaker 1: into the energy of those particles. Be like trying to
• 34:16
  Speaker 1: see how much Daniel whites and ways by weighing your kids.
• 34:20
  Speaker 1: Sort of, It's more like measuring the brightness of a
• 34:23
  Speaker 1: nuclear bomb and using that to figure out how much
• 34:25
  Speaker 1: fuel there was, Like what was there before things broke apart? Exactly?
• 34:30
  Speaker 1: If I took all this energy that was released and
• 34:33
  Speaker 1: asked how much mass is that equivalent to, then you're
• 34:35
  Speaker 1: weighing the mass that was converted into energy. So that's
• 34:38
  Speaker 1: what we're doing with the W. We're seeing the parts
• 34:40
  Speaker 1: that fly out the decay products of the W. We're
• 34:43
  Speaker 1: measuring their energy or their momentum, depending on the particle,
• 34:47
  Speaker 1: and we're using that to figure out how massive the
• 34:49
  Speaker 1: W must have been. Well, that sounds straightforward, but there
• 34:53
  Speaker 1: are difficulties, right, It's tricky. It is tricky, and one
• 34:56
  Speaker 1: reason is that the W doesn't always decay to visible particles.
• 35:00
  Speaker 1: The way they measure its mass is when the w
• 35:02
  Speaker 1: DK is to a muon and a neutrino, and the
• 35:05
  Speaker 1: MU one you can see it flies to a detector.
• 35:08
  Speaker 1: It bends in a magnetic field. You can measure that
• 35:10
  Speaker 1: bending so you can deduce the momentum of the muan.
• 35:13
  Speaker 1: The neutrino, however, flies right through your detector and you
• 35:15
  Speaker 1: can't see it. It's invisible, So that makes the problem
• 35:18
  Speaker 1: a little harder. Yeah, I guess you need all the
• 35:20
  Speaker 1: pieces to get a good rectorate measurement of what the
• 35:23
  Speaker 1: thing looked like when was put together. Right, if you're
• 35:25
  Speaker 1: missing a piece, then you're not gonna be able to
• 35:27
  Speaker 1: tell how much the thing. Wait, originally it makes it harder.
• 35:30
  Speaker 1: You can do a better measurement if you have all
• 35:32
  Speaker 1: the pieces, but even if you have half the pieces,
• 35:34
  Speaker 1: you can still make a measurement. Like imagine you could
• 35:36
  Speaker 1: only see half of a nuclear bombs explosion. The fact
• 35:39
  Speaker 1: that you know you're seeing half of it means you
• 35:41
  Speaker 1: can extrapolate to the other half. Right, as long as
• 35:44
  Speaker 1: you know what you're missing, you can guess what might
• 35:46
  Speaker 1: have been there. So they measure the mass the w
• 35:49
  Speaker 1: just by seeing one of these particles that flies out.
• 35:52
  Speaker 1: But then do you sort of need to know what
• 35:55
  Speaker 1: the missing particles parts are, right, And that's where your
• 35:58
  Speaker 1: models come in. That's where a lot of our models
• 35:59
  Speaker 1: come in. And that's where a lot of the really
• 36:02
  Speaker 1: careful experimental work comes into figuring out how to do
• 36:05
  Speaker 1: this very very precisely. Yeah, because there's a lot of
• 36:08
  Speaker 1: like uncertainty, right, and so you need a lot of
• 36:11
  Speaker 1: data to make sure that what you're measuring is correct, right. Yeah.
• 36:14
  Speaker 1: You want to see a lot of examples to make
• 36:16
  Speaker 1: sure you're not seeing anything weird, any random fluctuations. And
• 36:19
  Speaker 1: in the latest measurement they had four million examples of
• 36:23
  Speaker 1: w boson is decaying either to an electron or into
• 36:26
  Speaker 1: a muant. But that's not really the problem. That challenge
• 36:29
  Speaker 1: these days is not getting enough examples of ws. They
• 36:31
  Speaker 1: think they have enough. The challenge is making sure there
• 36:34
  Speaker 1: aren't biases. Like when your muan flies through its magnetic
• 36:38
  Speaker 1: field and you're using its curvature in that field to
• 36:41
  Speaker 1: measure its momentum, are you sure you know exactly how
• 36:44
  Speaker 1: strong your magnetic field is, as one of your magnets
• 36:48
  Speaker 1: that makes that magnetic field slipped by one millimeter in
• 36:51
  Speaker 1: the thirty years since some grad student installed it, how
• 36:54
  Speaker 1: would you know? And so it's that level of scrutiny,
• 36:57
  Speaker 1: that level of detailed understanding required to a precise measurement
• 37:01
  Speaker 1: of the mass of the W right because I guess
• 37:03
  Speaker 1: if your instrument is off, all of your results are
• 37:06
  Speaker 1: going to be off, right, Like if there's a blur
• 37:08
  Speaker 1: in your microscope, you're going to think that, you know,
• 37:11
  Speaker 1: what you're measuring has a blur in it, exactly. And
• 37:13
  Speaker 1: that's why this measurement has taken so long. You know,
• 37:16
  Speaker 1: they stopped collecting data in two thousand and twelve and
• 37:19
  Speaker 1: this measurement came out. Now, it took them ten years
• 37:22
  Speaker 1: to understanding gory detail exactly what does that magnetic field
• 37:25
  Speaker 1: look like? How does the detector respond? They did things
• 37:28
  Speaker 1: like looking at cosmic rays muans from space to see
• 37:31
  Speaker 1: how they fly through the detector to understand exactly where
• 37:34
  Speaker 1: every piece of it is down to the micron. Wow,
• 37:37
  Speaker 1: that would sort of drive me crazy, right if you
• 37:39
  Speaker 1: have to worry about, you know, your experiment, which is huge,
• 37:42
  Speaker 1: but you have to worry about it down to like
• 37:44
  Speaker 1: the particle level, Like are all the particles in my
• 37:46
  Speaker 1: instrument okay? Or are they somehow being you know, shaped
• 37:50
  Speaker 1: or moved by some cosmic fourth. Yeah. And it reveals
• 37:53
  Speaker 1: something cool about these experiments, which is that there are
• 37:55
  Speaker 1: very different kinds of physics you can do. There's the
• 37:58
  Speaker 1: folks who are like, let's look for an exciting signature
• 38:01
  Speaker 1: or something new that if we see it, we know
• 38:03
  Speaker 1: it's there, and it's like a big press release. And
• 38:05
  Speaker 1: there are other folks are like, I want to very
• 38:07
  Speaker 1: carefully understand this one particle to gory detail. Even if
• 38:11
  Speaker 1: it cars ten years of super fine understanding of how
• 38:14
  Speaker 1: the detector works, it's just sort of like a different
• 38:16
  Speaker 1: way to do science. And so I imagine that people
• 38:19
  Speaker 1: have been working on this for you know, decades, and
• 38:22
  Speaker 1: they've been refining this measurement of this one particle, and
• 38:25
  Speaker 1: they've got some new results out a few days ago.
• 38:28
  Speaker 1: That's right, they did, and their answer shocked the world.
• 38:31
  Speaker 1: All well, let's get into this massive shock, this massive
• 38:34
  Speaker 1: discovery about the w boson and what it could mean.
• 38:37
  Speaker 1: But first let's take another quick break. All right, I know,
• 38:53
  Speaker 1: so who got to tell the w boson that it
• 38:55
  Speaker 1: weighs more than it should? Well, maybe the w boson
• 38:57
  Speaker 1: is like you. It doesn't read science, so it doesn't
• 39:00
  Speaker 1: know you're gonna say. It's like me, who doesn't care
• 39:03
  Speaker 1: how much their way. Hope you could all be so lucky.
• 39:06
  Speaker 1: Maybe the w is listening to this podcast, and this
• 39:08
  Speaker 1: is how it's finding out. Oh no, that would be awkward. Sorry,
• 39:12
  Speaker 1: you look great, boon. So they did the big measurement.
• 39:16
  Speaker 1: It's sort of it's a new measurement, right, or it's
• 39:18
  Speaker 1: something they've been measuring for a long time and only
• 39:20
  Speaker 1: just now they published the results. Yeah, and if you
• 39:22
  Speaker 1: might be surprised to hear that this is not a
• 39:25
  Speaker 1: measurement that's coming from CERN, it's not from our new
• 39:28
  Speaker 1: fancy collider, the Large Hadron collider that discovered the Higgs boson.
• 39:32
  Speaker 1: This is from the previous generation. The last champion, the
• 39:35
  Speaker 1: Tevatron just outside Chicago, which has the energy of about
• 39:39
  Speaker 1: one seventh the Large Hadron Collider and turned off in
• 39:42
  Speaker 1: two thousand and twelve. But they've been biding their time
• 39:45
  Speaker 1: and working carefully on this measurement for ten years, having
• 39:49
  Speaker 1: just released it. Wait what they did their measurement back
• 39:52
  Speaker 1: in twelve, and they've been just processing the data for
• 39:56
  Speaker 1: ten years. The last collisions were in two thousand and twelve.
• 39:59
  Speaker 1: And yes, they have been processing the data and analyzing
• 40:02
  Speaker 1: it and thinking about how to bring down these uncertainties
• 40:04
  Speaker 1: and measuring the location of the detector and calibrating it
• 40:08
  Speaker 1: and double checking it and double checking those double checkings
• 40:11
  Speaker 1: and then hiring somebody else to independently cross calibrate those
• 40:14
  Speaker 1: double checkings. Oh, I see, Like, if you find that
• 40:16
  Speaker 1: there's a bias in your instrument, you don't fix the instrument,
• 40:19
  Speaker 1: You just fix the data to account for it. Well,
• 40:21
  Speaker 1: they spent the last ten years developing these tools to
• 40:24
  Speaker 1: measure the w boson and to get the answer. They
• 40:26
  Speaker 1: didn't know what the answer was until very recently. We
• 40:28
  Speaker 1: do this thing in particle physics where we blind ourselves
• 40:31
  Speaker 1: from the answer to avoid biasing ourselves. We don't want
• 40:34
  Speaker 1: to change the way we're analyzing the data to get
• 40:37
  Speaker 1: the answer that we want or the answer we expect.
• 40:39
  Speaker 1: So they actually added a random number to all of
• 40:42
  Speaker 1: their data so that nobody who was working on the
• 40:44
  Speaker 1: analysis would know what answer to expect. And they only
• 40:48
  Speaker 1: unblinded it. They only removed that random number in just
• 40:51
  Speaker 1: about a year and a half ago. Wow, that's wild.
• 40:54
  Speaker 1: So they like corrupt the data so a little bit right,
• 40:57
  Speaker 1: so that you don't like look for the like, you
• 41:00
  Speaker 1: don't manipulate your analysis to get the answer. You're like,
• 41:04
  Speaker 1: you're supposed to work in your analysis independent of what
• 41:06
  Speaker 1: the data says. And we're not worried about like explicit
• 41:08
  Speaker 1: manipulation where people are like fudging the results. We're worried
• 41:11
  Speaker 1: about like subtle biases. For example, if you get the
• 41:14
  Speaker 1: answer you expect, you stop looking for mistakes, whereas if
• 41:17
  Speaker 1: you get the answer you don't expect, you keep looking
• 41:19
  Speaker 1: for bugs. And so what happens is people just leave
• 41:22
  Speaker 1: bugs in if they cancel each other out, or they
• 41:24
  Speaker 1: leave bugs in if they've given the answer they expect,
• 41:27
  Speaker 1: which might not be the right answer. With his history
• 41:29
  Speaker 1: and particle physics of experiments confirming previous experiments, and then
• 41:33
  Speaker 1: we discover later, oh, all those experiments were actually off
• 41:37
  Speaker 1: by a big factor, and then the result jumps. So
• 41:40
  Speaker 1: we have to be very careful because we only have
• 41:41
  Speaker 1: one shot at this right. You can't run the collider
• 41:43
  Speaker 1: for ten years again with one data set. You have
• 41:47
  Speaker 1: to do it right in an unbiased way. So we
• 41:49
  Speaker 1: hide the answer from ourselves to avoid being biased by
• 41:52
  Speaker 1: what we expect to see. M M. That's wild. It's
• 41:55
  Speaker 1: will that you would do the experiment and then just
• 41:58
  Speaker 1: kind of sit on the data or working for ten years.
• 42:01
  Speaker 1: You know. I think as part of the public, you're
• 42:03
  Speaker 1: sort of used to this idea of like scientists in
• 42:05
  Speaker 1: a lab and she's measuring something and she goes, yourek,
• 42:08
  Speaker 1: the results are there, but here it's like they do
• 42:10
  Speaker 1: the measurement and then ten years later it's like, oh,
• 42:12
  Speaker 1: hey we found something. Yeah, well, most of the people
• 42:15
  Speaker 1: left this experiment. This experiment used to have like five
• 42:17
  Speaker 1: scientists on it in it's heyday, and then the large
• 42:20
  Speaker 1: hage On collider turned on and almost everybody moved over
• 42:23
  Speaker 1: to the LHC to work at CERN. But a few
• 42:25
  Speaker 1: folks stayed behind because this measurement would take a long
• 42:28
  Speaker 1: time and a lot of really careful work, and they
• 42:31
  Speaker 1: thought it was worth it. So there's just like a
• 42:33
  Speaker 1: few folks left and most of the lights are off,
• 42:35
  Speaker 1: and they're like wrapping up the last little bits of
• 42:37
  Speaker 1: science you can do with this data, right right, And
• 42:39
  Speaker 1: I guess it's tough because it's not like you can
• 42:41
  Speaker 1: ask them to do it again, right, not like, oh,
• 42:43
  Speaker 1: you found this that's interesting. Can you run it for
• 42:45
  Speaker 1: me again and see if we find it again? You
• 42:48
  Speaker 1: can't because the thing is like ten years old. It's
• 42:50
  Speaker 1: been decommissioned for ten years. M it's in pieces, literally,
• 42:53
  Speaker 1: like it doesn't exist anymore. They've built a museum where
• 42:56
  Speaker 1: it used to be. Wow, all right, well what did
• 42:58
  Speaker 1: they find? What was this exp remant that they did?
• 43:00
  Speaker 1: So the experiment is the collision of protons and anti protons.
• 43:04
  Speaker 1: So the experiment uses the Tevatron collider, which smashes protons
• 43:08
  Speaker 1: and anti protons together at two trillion electron bolts and
• 43:13
  Speaker 1: that's one seventh the energy of the large Antron collider,
• 43:15
  Speaker 1: and it's different from the LHC. And then it's protons
• 43:18
  Speaker 1: and anti protons instead of protons and protons, which is
• 43:21
  Speaker 1: what the LHC collides. Really you can make anti protons, yeah,
• 43:26
  Speaker 1: and it's hard, which is why they didn't do it
• 43:28
  Speaker 1: for the late C. But at the Tevatron we fabricated
• 43:31
  Speaker 1: anti protons by smashing particles and basically a big blob
• 43:35
  Speaker 1: of rock and filtering out the anti protons that come
• 43:38
  Speaker 1: out the other side. Not very easy to make them,
• 43:41
  Speaker 1: or to store them, or to insert them and accelerate them.
• 43:43
  Speaker 1: It was a huge piece of work, and kudo to
• 43:45
  Speaker 1: the accelerator engineers at Fermula who made that work. Yeah,
• 43:48
  Speaker 1: it's pretty cool. I guess they're very ordinary, right, because
• 43:50
  Speaker 1: they're very anti everything. They're not protons exactly. There antons antons. Well,
• 43:59
  Speaker 1: I guess what I mean? Is is this an experiment
• 44:01
  Speaker 1: similar to the large hadron collector? Like, is is it about,
• 44:04
  Speaker 1: you know, spinning protons around in a ring and then
• 44:06
  Speaker 1: you spin anti protons I guess the other way in
• 44:09
  Speaker 1: the same ring, and then you bring them together. It's
• 44:11
  Speaker 1: similar in idea to the l e C. You have
• 44:13
  Speaker 1: a ring, you're accelerating particles around it. A few points
• 44:16
  Speaker 1: around the ring, you smash those particles together to create collisions.
• 44:20
  Speaker 1: So here you have protons going one way and anti
• 44:22
  Speaker 1: protons going the other way. And so you need two
• 44:25
  Speaker 1: different rings because you don't want the protons and antiprotons
• 44:28
  Speaker 1: just smash together except at the heart of your detector.
• 44:30
  Speaker 1: But you can't actually use the same magnets because protons
• 44:33
  Speaker 1: going one way it bent the same as anti protons
• 44:36
  Speaker 1: going the other way. So that was a clever trick.
• 44:38
  Speaker 1: And so you smash a bunch of these a lot,
• 44:40
  Speaker 1: and then you look at kind of what comes out
• 44:42
  Speaker 1: of it, right, and mostly what happens when you smash
• 44:44
  Speaker 1: protons and antiprotons is a big flash and a lot
• 44:47
  Speaker 1: of quarks flying out. Because quarks are created by the
• 44:49
  Speaker 1: strong force which is the most powerful force, and so
• 44:51
  Speaker 1: it's the most likely thing to happen. The weak force
• 44:54
  Speaker 1: is very weak, and so it's interactions are much rarer.
• 44:57
  Speaker 1: But sometimes what happens is you get a down cork
• 45:00
  Speaker 1: from one particle and anti up cork from the other,
• 45:04
  Speaker 1: and they come together to make a W minus. Where
• 45:06
  Speaker 1: you might get an up cork from one side and
• 45:09
  Speaker 1: anti down cork from the other come together to make
• 45:11
  Speaker 1: a W plus. That happens very rarely in billions of collisions,
• 45:15
  Speaker 1: and you filter those out and you get a few
• 45:17
  Speaker 1: million examples after running from like ten years. Wow, and
• 45:22
  Speaker 1: so how long did they run this experiment? This data
• 45:24
  Speaker 1: set is about ten years of running that ended in
• 45:27
  Speaker 1: two thousand and twelve. Wow, wait they ran it for
• 45:30
  Speaker 1: ten years and then it I guess that makes sense
• 45:32
  Speaker 1: now it took him ten years just to go through
• 45:34
  Speaker 1: all that data. Well, it takes ten years just to
• 45:36
  Speaker 1: get the data, just like do the collisions and find
• 45:39
  Speaker 1: those ws, and then another ten years to analyze it,
• 45:42
  Speaker 1: to go through it and to get the answer. So
• 45:44
  Speaker 1: from start to finish, it's twenty years. It's ten years
• 45:46
  Speaker 1: of data taking and ten years of data analysis and
• 45:49
  Speaker 1: how long to build the thing that wasn't mean also
• 45:51
  Speaker 1: like ten years, right, Oh yeah, that was ten or
• 45:53
  Speaker 1: fifteen years. They started that even earlier. That's back when
• 45:55
  Speaker 1: I was a baby. So this whole projects like as
• 45:58
  Speaker 1: long as my lifetime. That's wild, Okay. So then you
• 46:03
  Speaker 1: look at the brief from this these collisions and somebody
• 46:06
  Speaker 1: you pieced together the measurement of the w Boson mass,
• 46:09
  Speaker 1: and I guess what did they find? So what they
• 46:11
  Speaker 1: found was not what they expected. All the other experiments
• 46:14
  Speaker 1: in the world has measured this, The LHC has measured it,
• 46:17
  Speaker 1: Other experiments that Tetron have measured it, experiments from other
• 46:20
  Speaker 1: colliders have measured it, and they all came up with
• 46:22
  Speaker 1: an answer of eighty thousand, three hundred and seventy. That
• 46:25
  Speaker 1: was the previous best measurement of the w boson mass okay,
• 46:29
  Speaker 1: eight three seventy, eight three seventy. And people were pretty
• 46:32
  Speaker 1: happy with that number because it agreed with what the
• 46:35
  Speaker 1: theorists predicted. The theorists go into their offices and to
• 46:38
  Speaker 1: sit down with calculations, and they say, the W boson
• 46:40
  Speaker 1: sometimes interacts with the Higgs and with the top and
• 46:43
  Speaker 1: we know the mass of those particles, how heavy should
• 46:45
  Speaker 1: the w B, and they do all their calculations and
• 46:47
  Speaker 1: they come up with a number, and their number was
• 46:50
  Speaker 1: eighty three fifty seven. So the old measurement was eight
• 46:53
  Speaker 1: three seventy and the expectation from the theorists was eight
• 46:56
  Speaker 1: three fifty seven. Those are pretty close. People were pretty happy. Yeah,
• 47:00
  Speaker 1: and like you said, it came that three seventy came
• 47:03
  Speaker 1: from multiple colliders, right, Like you know, they measured it
• 47:06
  Speaker 1: in Geneva, they measured it in Japan. And now this
• 47:09
  Speaker 1: new measurement was four thirty four with an uncertainty of
• 47:13
  Speaker 1: just ten. So not only is it like sixty mtb
• 47:16
  Speaker 1: above the theory, it's like above the other measurements with
• 47:20
  Speaker 1: an uncertainty of just ten. So the result is shocking,
• 47:24
  Speaker 1: not just because it's so much heavier than the previous measurements,
• 47:27
  Speaker 1: but because it seems so confident. They're like, oh, yeah,
• 47:29
  Speaker 1: it's heavier, and we're very sure it's heavier. Well, as
• 47:32
  Speaker 1: we've learned from us politics, being confident doesn't mean that
• 47:35
  Speaker 1: you're right, though, doesn't it. Yeah, Well, there's a difference
• 47:40
  Speaker 1: between physics and politics, and this is one of them.
• 47:42
  Speaker 1: It's kind of an interesting scenario. So you're saying that,
• 47:44
  Speaker 1: like the theory predicts through fifty seven, most of the
• 47:48
  Speaker 1: people who have measured this measured this to be three
• 47:50
  Speaker 1: seventy and they were all independent, right, with different colliders.
• 47:53
  Speaker 1: But now this new measurement is way higher. Wouldn't you
• 47:57
  Speaker 1: just say, like, there's something wrong here? You it? But
• 48:00
  Speaker 1: this measurement is also the most precise of all the
• 48:03
  Speaker 1: measurements we've made. This one claims to have the best
• 48:07
  Speaker 1: handle on all of these details that affect the mass
• 48:10
  Speaker 1: of the w. So on one side of the room
• 48:11
  Speaker 1: you have a bunch of imprecise measurements saying one value.
• 48:14
  Speaker 1: On the other side of the room you have one
• 48:16
  Speaker 1: very precise measurement claiming something else. And so it's a puzzle. Yeah,
• 48:20
  Speaker 1: I mean some someone must be wrong kind of a right.
• 48:24
  Speaker 1: And it feels like this one's out there in the
• 48:26
  Speaker 1: corner of the room by itself, whereas everybody else is
• 48:28
  Speaker 1: on the other side. If somebody could be wrong, or
• 48:31
  Speaker 1: it could be random chance, and you can ask the
• 48:33
  Speaker 1: question like, well, what's the odds of a random fluctuation?
• 48:36
  Speaker 1: You know, these are quantum particles we're talking about. Sometimes
• 48:38
  Speaker 1: as new ones end up a little faster in the
• 48:40
  Speaker 1: w looks a little heavier. That can happen. There's always
• 48:42
  Speaker 1: statistic but they calculated what are the odds of the
• 48:45
  Speaker 1: w boson having the mass the theory expects, and then
• 48:47
  Speaker 1: see DF measuring this, and those odds are one in
• 48:50
  Speaker 1: ten to the twelve. So it's very unlikely to be
• 48:54
  Speaker 1: like a random fluctuation, right, Yeah, I mean, I'm sure
• 48:58
  Speaker 1: that's what they got, But I guess there's a skeptical
• 49:00
  Speaker 1: you know, engineer, you could you know, if you're out
• 49:02
  Speaker 1: there in the middle, in a corner of the room
• 49:04
  Speaker 1: by yourself, maybe late there was something wrong with the
• 49:06
  Speaker 1: equipment or something. What's the certainty that they didn't make
• 49:09
  Speaker 1: a mistake. It's a bit hard to pull apart. Like,
• 49:11
  Speaker 1: on one hand, I know these folks. They are the
• 49:14
  Speaker 1: most careful scientists I've ever met, the kind of people
• 49:17
  Speaker 1: where if you show them a result and there's one
• 49:19
  Speaker 1: tiny little part of it that doesn't make perfect sense,
• 49:21
  Speaker 1: like what's this wiggle over here, they will not let
• 49:24
  Speaker 1: it go, and they will go down a rabbit hole
• 49:26
  Speaker 1: for months to understand it. It It can be very frustrating
• 49:28
  Speaker 1: to work with these people because they are so detail oriented,
• 49:31
  Speaker 1: and that's why it took them ten years because they
• 49:33
  Speaker 1: did so many insane cross checks just to make sure
• 49:37
  Speaker 1: they didn't mess at all up. So they have a
• 49:38
  Speaker 1: lot of credibility. On the other hand, their result disagrees
• 49:42
  Speaker 1: with everybody else, and so you've got to wonder if
• 49:44
  Speaker 1: there's something that they haven't understood. And one area to
• 49:47
  Speaker 1: look at is like this claim of their precision. They're
• 49:50
  Speaker 1: claiming this measurement of four thirty four with an uncertainty
• 49:53
  Speaker 1: of about ten. Some people have wondered whether that estimate
• 49:55
  Speaker 1: is accurate, if in fact, they really understand those uncertainties
• 49:58
  Speaker 1: as well as they think they do. And it's not
• 50:00
  Speaker 1: about them making a mistake in any one cross check.
• 50:04
  Speaker 1: It's about how to arrive at this small uncertainty and
• 50:07
  Speaker 1: then what that means. For example, they had many sources
• 50:10
  Speaker 1: of uncertainty, how do they combine all of those two?
• 50:13
  Speaker 1: I mean, if you have two uncertainties of five MTV,
• 50:17
  Speaker 1: what's the chances of getting a ten MTV fluctuation? The
• 50:20
  Speaker 1: answer depends a lot on whether those two sources tend
• 50:23
  Speaker 1: to fluctuate together or tend to cancel each other out.
• 50:26
  Speaker 1: And now we're talking about understanding how likely a sixty
• 50:30
  Speaker 1: MTV fluctuation is with lots of sources of uncertainty that
• 50:33
  Speaker 1: are all around five MTV. To say that you know
• 50:36
  Speaker 1: how likely that is means you think you understand the
• 50:40
  Speaker 1: rare events really well and whether they fluctuate together or
• 50:44
  Speaker 1: cancel out. So I think the result is probably right,
• 50:48
  Speaker 1: but the uncertainty might be underestimated, or the calculation of
• 50:53
  Speaker 1: how unlikely we are to get this big a deviation
• 50:57
  Speaker 1: might be a bit overstated. So in that case, the
• 51:00
  Speaker 1: result might not really be in that much tension with
• 51:03
  Speaker 1: the other results or with the theory results. Right. Well,
• 51:06
  Speaker 1: I mean, I'm not trying to, you know, throw down
• 51:08
  Speaker 1: under work. I'm sure they're top notch and they're amazing scientists.
• 51:11
  Speaker 1: I guess maybe the maybe the question that is on
• 51:14
  Speaker 1: my mind is like, well, what could have been wrong
• 51:16
  Speaker 1: with the other measurements? That would you know, what could
• 51:19
  Speaker 1: be the reason this one is so different? What could
• 51:21
  Speaker 1: have been wrong with the other measurements? You want to
• 51:22
  Speaker 1: cast out on their qualities as a scientistic what I'm saying,
• 51:27
  Speaker 1: I'm saying is this new measurement is doing that, and
• 51:30
  Speaker 1: what are they saying could have been wrong with the
• 51:32
  Speaker 1: other ones? Well, so they're not analyzing the other ones
• 51:34
  Speaker 1: and criticizing them. They're just coming up with their measurements
• 51:36
  Speaker 1: saying here's what we got. And they did a lot
• 51:39
  Speaker 1: of really important and impressive cross checks, like they used
• 51:42
  Speaker 1: the same method to measure the mass of the z
• 51:44
  Speaker 1: bos on those z ways about these mtvs, and just
• 51:48
  Speaker 1: as a cross check, they're like, let's measure the mass
• 51:50
  Speaker 1: the z and they got its spot on, agreeing with
• 51:52
  Speaker 1: everybody else. So there's a lot of reasons to believe this,
• 51:55
  Speaker 1: but as you say, it disagrees with the other measurements,
• 51:57
  Speaker 1: and we don't understand that. The truth is, we don't
• 51:59
  Speaker 1: understand and the discrepancy between these experiments, there's two different
• 52:03
  Speaker 1: important discrepancies. There's this new CDF result is different from
• 52:06
  Speaker 1: what the theory expects. It's also different from the other measurements,
• 52:11
  Speaker 1: and those are two things that we don't understand. I
• 52:13
  Speaker 1: see nobody's saying nobody's wrong, anybody's wrong. They're just saying like, hey,
• 52:17
  Speaker 1: I know you guys did this, but this is we
• 52:18
  Speaker 1: did this, and we worked hard, and this is what
• 52:20
  Speaker 1: we found. Let's let's all sit together and figure it out.
• 52:23
  Speaker 1: So now we sit through it and try to think
• 52:24
  Speaker 1: about it and try to understand where things could have
• 52:26
  Speaker 1: gone wrong, or if this one's right, what it means
• 52:29
  Speaker 1: about particle physm Right. Yeah, I was gonna say. The
• 52:31
  Speaker 1: science headlines were not so measured. They're like, oh my gosh,
• 52:35
  Speaker 1: did we break science as everything we thought was right
• 52:38
  Speaker 1: as it turned out to be wrong? Right, It's that's
• 52:40
  Speaker 1: sort of how this has been kind of portrayed in
• 52:43
  Speaker 1: the media, right, like maybe we've been wrong all this time. Yeah,
• 52:45
  Speaker 1: the most exciting way to read this is, Wow, this
• 52:48
  Speaker 1: new measurement is right, and it means that the theory
• 52:51
  Speaker 1: is wrong. That means that the prediction of the w
• 52:53
  Speaker 1: mass to be lower than what CDF just measured means
• 52:56
  Speaker 1: that those predictions are wrong, which means that all those
• 52:59
  Speaker 1: fancy calculation is about how w bosons and mid virtual
• 53:02
  Speaker 1: top corks and Higgs bosons those must be wrong, which
• 53:05
  Speaker 1: means there's something wrong in our theory of particle physics.
• 53:08
  Speaker 1: If this new measurement is correct, I see, and so
• 53:12
  Speaker 1: I guess what specifically could have been wrong with our
• 53:16
  Speaker 1: clearly wrongular theory about the universe that this measurement exposes.
• 53:19
  Speaker 1: The great thing about these kind of measurements is that
• 53:21
  Speaker 1: they're very general probe like, these masses are sensitive to
• 53:25
  Speaker 1: the existence of basically every particle out there. Remember the
• 53:28
  Speaker 1: muan gm is to measurement we talked about recently. You
• 53:31
  Speaker 1: did that really cool cartoon about the reason that's so
• 53:33
  Speaker 1: powerful is because it's sensitive to the existence of all
• 53:35
  Speaker 1: these other fields out there that it can interact with.
• 53:38
  Speaker 1: And the W mass is the same way. When it's
• 53:40
  Speaker 1: flying through space, it's sensitive to the existence of new
• 53:43
  Speaker 1: particles we don't know about that might change its mass.
• 53:46
  Speaker 1: So what this means is there might be other particles
• 53:49
  Speaker 1: out there that make the W mass different from what
• 53:52
  Speaker 1: our calculations assume. Our calculations use the existence of all
• 53:55
  Speaker 1: the particles we know about, but if there are more
• 53:57
  Speaker 1: particles out there, you would get a different W I see. Yeah,
• 54:01
  Speaker 1: it's sort of like the zoo analogy, right, Like, you know,
• 54:03
  Speaker 1: we have this Zoo diagram of all the particles, but
• 54:06
  Speaker 1: if something's off, maybe it means that, you know, the
• 54:09
  Speaker 1: panda is sprouting off a little rabbit on the sign
• 54:13
  Speaker 1: and the nobody had noticed before. Yeah, Or if you're
• 54:15
  Speaker 1: feeding the panda three square meals a day and it's
• 54:17
  Speaker 1: still gaining weight, maybe somebody sneaking at some snacks and
• 54:20
  Speaker 1: you weren't. Whatever, maybe some some physicists who are overly
• 54:25
  Speaker 1: interested in its weight I've been snagging or helping it out, yeah, exactly.
• 54:29
  Speaker 1: Or maybe the clever pand is sneaking out of its
• 54:31
  Speaker 1: cage at night and helping itself to the vending machine.
• 54:33
  Speaker 1: There you go, mystery solve. But I guess it's sort
• 54:37
  Speaker 1: of points to this idea, and I think probably the
• 54:39
  Speaker 1: reason that it got so many headlines is that, you know,
• 54:41
  Speaker 1: everyone is interested in this idea of like, you know,
• 54:44
  Speaker 1: we have this model of the universe. Maybe we've been
• 54:46
  Speaker 1: wrong all along and it's a little solahous, but it
• 54:49
  Speaker 1: has happened in the past, right, It definitely has happened
• 54:52
  Speaker 1: in the past. And you know, there are two different
• 54:54
  Speaker 1: ways to discover something new about particles in the universe.
• 54:57
  Speaker 1: One is like actually see some new particle like the
• 55:00
  Speaker 1: Higgs boson, and be like, look, here's something new. We
• 55:02
  Speaker 1: found it. Another way is to just do a bunch
• 55:04
  Speaker 1: of consistency checks between the particles we do know and
• 55:07
  Speaker 1: see if they all add up, because if they don't,
• 55:09
  Speaker 1: it means that there must be some particle out there
• 55:11
  Speaker 1: playing on the field. That you're not aware of. So
• 55:14
  Speaker 1: it's a little bit more indirect, but it's also a
• 55:16
  Speaker 1: little bit more general, So it's a nice way to
• 55:18
  Speaker 1: cast a wide netancy. Is there something new out there?
• 55:21
  Speaker 1: And we would love to discover something new because it
• 55:24
  Speaker 1: would help us understand all the open mysteries of particle physics. Yeah,
• 55:28
  Speaker 1: and I guess it sort of takes a little bit
• 55:29
  Speaker 1: of courage to do that, right, Like if you know
• 55:32
  Speaker 1: that everyone is saying one thing, right, they have this
• 55:34
  Speaker 1: measurement of the w boson it's matches the theory. You know,
• 55:38
  Speaker 1: it takes a lot for sciences to go like, hey,
• 55:40
  Speaker 1: I'm measuring it to be different, to just sort of
• 55:42
  Speaker 1: stick your head out there and say, hey, maybe it's
• 55:44
  Speaker 1: different than what everyone thought it was. And you know,
• 55:46
  Speaker 1: they've known about this result since November twenty twenty. That's
• 55:50
  Speaker 1: when they remove that random number and actually saw the
• 55:52
  Speaker 1: answer for the first time. And they kept it to
• 55:55
  Speaker 1: themselves in a very small circle of folks while they
• 55:58
  Speaker 1: worked for a year and a half and just double
• 56:00
  Speaker 1: triple check all of their double checks before they went
• 56:03
  Speaker 1: out there in public with it. And I'm sure as you,
• 56:05
  Speaker 1: as one of the authors, got to double check it right. No,
• 56:08
  Speaker 1: I wasn't even aware about this until two weeks ago,
• 56:10
  Speaker 1: so they kept us to a very small circle. Otherwise,
• 56:13
  Speaker 1: you know, it would have been on the podcast a
• 56:14
  Speaker 1: year ago. Folks would have been the first to hear, right, right, Yeah, Daniel,
• 56:20
  Speaker 1: what's what's going on there? You though you have connections?
• 56:22
  Speaker 1: We should have been ahead of this story. No, I
• 56:24
  Speaker 1: got the paper a few days before it was released,
• 56:26
  Speaker 1: everybody else under embargo. Yeah, and I guess you also
• 56:30
  Speaker 1: never know what's going to capture the imagination of the public,
• 56:33
  Speaker 1: right and the newspapers. Right. Sometimes I feel like, you know,
• 56:36
  Speaker 1: some these discoveries are seemed like they're the amazing and revolutionary,
• 56:39
  Speaker 1: but hardly anyone notices. Yeah, you can never tell what
• 56:42
  Speaker 1: people are excited about. But particle physicists at least are excited.
• 56:45
  Speaker 1: You know. The day after this was announced, there was
• 56:48
  Speaker 1: a flood of new papers put out by theorists explaining
• 56:51
  Speaker 1: this new result. They have some model where the Higgs
• 56:53
  Speaker 1: boson is made of other smaller particles it's not fundamental
• 56:56
  Speaker 1: and that explains the w boson. Or they have a
• 56:59
  Speaker 1: model with some new crazy particle they call a sweet
• 57:02
  Speaker 1: no particle like a weird supersymmetric version of the w
• 57:05
  Speaker 1: boson and now it explains this. So now that we
• 57:08
  Speaker 1: have this new result, the theory community is going wild
• 57:11
  Speaker 1: coming up with ways to explain it. Well, I guess
• 57:13
  Speaker 1: that's sort of how signs works. You know, it's in
• 57:15
  Speaker 1: a continual process where people are coming up with new ideas,
• 57:19
  Speaker 1: new measurements, and you gotta, you know, don't take the
• 57:23
  Speaker 1: established facts as established sometimes exactly. And if you trust
• 57:27
  Speaker 1: what you've done and you double checked everything, and you've
• 57:29
  Speaker 1: got to come out there with your answer even if
• 57:31
  Speaker 1: it flies in the face of other measurements, because hey,
• 57:34
  Speaker 1: maybe you're wrong or maybe they're wrong. History will sort
• 57:36
  Speaker 1: it out, all right. Well, best of luck to the
• 57:39
  Speaker 1: scientists working on this, and then I guess stay tuned
• 57:41
  Speaker 1: to see who is not right. But you know who
• 57:44
  Speaker 1: has the most to say about what's the mass of
• 57:48
  Speaker 1: the w boson? That's right. We'll keep working on it,
• 57:50
  Speaker 1: will make measurements of it at the Large Hadron Collider
• 57:53
  Speaker 1: and and at future colliders, and eventually we will know
• 57:56
  Speaker 1: the truth. Yeah, we will know if Daniel was actually
• 57:58
  Speaker 1: working on this or not. To be surprised even to himself. Well,
• 58:02
  Speaker 1: we hope you enjoyed that. Thanks for joining us, see
• 58:05
  Speaker 1: you next time. Thanks for listening, and remember that Daniel
• 58:15
  Speaker 1: and Jorge Explain the Universe is a production of I
• 58:18
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• 58:25
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