(electronic music) (participants clapping) - Thank you so much, and thank
you, Daniel, for the intro, and what an absolute pleasure
it is to be back here at the Royal Institution. I've had the great pleasure
of speaking here a few times before, and for those of you
who haven't been here before, this place holds such a
brilliant scientific heritage, and hopefully, I'll be able
to show you a few small pieces of that as we go through this evening. So as Daniel said, I am celebrating having
this thing out in the world, this lovely book called
"The Matter of Everything," and so the stories I'm going to tell you tonight have been taken from this book. The difficult thing is fitting
a book's worth of stories into an hour long lecture
with demonstrations, so hopefully we'll get there. And the book and the
lecture start at the turn of the 20th century,
so from the, you know, from the 19th into the 20th century, and at this point in time, people really thought
that physics was done. This is a quote from
Albert Michelson who said, "It seems probable that most of the grand, underlying principles have
been firmly established," having only a few years earlier himself with a collaborator
demonstrated the non-existence of the ether, if you've heard of that. So this was a point in time
when people thought, well, we can just take our theories of physics, so Newton's gravity, the idea of atoms, the chemistry that they knew
about, and the equations they had that described that,
turn the handle on some maths and predict the future forever. Now, I don't think it's giving
away any spoilers that happen in the book to say that that's clearly not how things turned
out, and so the 20th century in physics was an
enormous decade of change. Now, as we go through the story today, I'm going to try and share
with you some of the stories and some of the things that
I learned as I went through and wrote this book. And I feel like we often treat
scientists and physicists, especially as like putting
them up on a pedestal, especially the theoretical physicists who I'll mention none
of tonight. (chuckles) So the reason I've just taken
off my jacket is because I want to just chill out a
little bit and bring physics down to Earth, down to the human
level, and down to this idea of how it is we walk into
a room, into a laboratory and discover new things about
the universe, and I hope you'll enjoy coming on that
journey with me tonight. Right, so in 1900,
actually, maybe I'll ask you this question, because this is, you know, an interactive kind of venue. Does anyone know what the
life expectancy was of people in 1900, roughly? - Someone's saying 50.
- Someone's saying 50, 35, yep, not- - 35. - So about 46, hopefully that's- that's in the UK actually,
you know, obviously, a well-developed nation
at that point in time. Fast forward to today, and the average life
expectancy is 81 years. The UK population in around
1900 was 30, yeah, 38 million. We're currently sitting
at about 67 million. That's not such a huge increase, right? They're pretty, you know,
they go with each other. One of the other markers
of change that's happened in the last century is
in the area of literacy, so the literacy of people
over the age of 15 years old. Now, I'm gonna give a global
statistic that at the start of, at around 1900, literacy
was at about 21% globally, and that number is now at 86% globally, which is an enormous change. And so I'm setting the scene
here a little bit to tell you how much our society and
our world has changed in the last 100 years. And one of the reflections of
that is in the GDP per capita, which has sort of been normalized
and et cetera, et cetera, to create this plot just
showing the enormous change and growth that we've had over time. Now, (chuckles) this is easy
to sort of look at and say, okay, well, clearly, you know, obviously, that was going to happen, right? And we tell this story and
we talk about innovation, and we talk about businesses,
and we talk about education. We don't normally talk about
physics alongside it, right? But tonight I'm going to try and do that, and connect these two things together. Now, if I was to ask you in
1900 what the future would look like, it would be very hard to predict, and even cutting edge
physicists at the time found it difficult to predict. So this is a quote from Lord Kelvin, who was a famous physicist at the time, who thought that, Neither the
balloon, nor the airplane, nor the gliding machine will
be a practical success." So actually, in 1900 for the
World Exhibition in Paris, someone did ask a bunch of
artists actually to predict what the year 2000 might be like from that point in time, from 1900. This is what they created. (chuckles) So you'll notice that
there's flying vehicles, but propellers were sort
of only recently invented, and so everything had a propeller or maybe some flapping wings. People's outfits hadn't changed much. Architecture, there's
at least one architect in the audience, architecture
hasn't changed much. There's no vehicles, so clearly they predicted
that incorrectly. Let's look at some other
aspects of society. So let's think about information transfer. So information transfer was
done (chuckles) electrically somehow, but the production of
goods was an interesting one. So the prediction of
the production of goods, there was of course many
factories at that time and horrible working conditions,
but they sort of predicted that you know, that automation would come from like mechanical means, right? There was no prediction of
electronic means of automation at that point in time, and
that goes for the barber as well as what's the person
who makes a suit called? Those people, tailor, thank
you, whoever said that. One of the particular
fascinations that just struck me as funny is lots of these
postcards envisioned us living under the sea. (laughing) And you could almost translate
that to where we've ended up thinking about up in space, only we don't play croquet
up in space. (chuckles) Anyway, so this was the
prediction at that point in time, and I'm not going to embarrass
you by trying to ask you what might happen in the next 100, right? But I think it's important
to come back to this idea that at this point in time,
physics looked like it was done, and again Lord Kelvin says, "The future truths of physical
sciences are to be looked for in the sixth place of
decimals," in other words, there's really nothing new to discover. Fast forward to 1895, 1896. Now in 1895, radioactivity
was discovered accidentally by Becquerel, and then in 1896, this is what a lab looked like. This is Wilhelm Rontgen's
lab in Germany in Wurzburg, and you'll notice for
those of you in the room, it looks awfully similar
to this room, doesn't it? Like, I noticed that
resonance when I was looking through my slides before,
the parquet flooring, the beautiful doors and windows. It's really a lovely environment. I think we should bring back labs that look like this, personally. Now, today, our labs
look like this, right? This is the compact Compact Muon Solenoid, the CMS detector at CERN. It's an enormous experiment. I'll talk a little bit more about this kind of thing later on. So how did we get from a lab in Wurzburg to enormous machines like
the Large Hadron Collider, and how does that relate to this question of societal change in that time? Well, let me start with this person. This is Wilhelm Rontgen
who's up on the screen, yep. He was a very shy man, but he
was good at building things with his hands, and he was a bit, he wasn't a very nice lecturer, actually. He used to speak in a really
quiet voice so that all of his students had to
sit in the front row and listen really carefully. It was really annoying, isn't it? That's how he used to speak (chuckles) so that he had the full
attention of his audience. Well, you know, in 1896,
he was playing with a tube that looked something like this, and this is a Crookes tube
from the collection here at the Royal Institution,
and at this point in time, around the turn of 1900, they
were very common objects. Now, this one has a particular
use, but around that time, they were used to study
electricity and gases pretty much. And so he had these
tubes in his laboratory, and one day he was using it
and he noticed a screen glowing across the other side of his laboratory, a fluorescent screen. Now, Rontgen had a trained
mind in experimental physics, so instead of just sort of
saying, "Oh, I didn't expect that, I'll just ignore that and go back to what I was doing," he
paid attention, right? So he switched the tube off
and the light went away, back on, the light came back on. Oh, okay, so he got
curious, so he thought, oh, I wonder if I put
something between the tube and this screen, whether it
was still glow, and it did. He put some wood there and it did. He put some rubber and it did. He sent it through the door to the next part of his
lab and it still glowed. And then he put some metal
in front of the tube, and it stopped the glowing. And so he realized he'd found
something completely different from the glow that happened
inside this glass tube, and he was observing
something completely different from that, and so he put his hand, as all scientists want to. We're always, we just stick
our hands in there, you know? That's how we work. (chuckles) So he stuck his hand in between
the tube and the screen, and what he observed was that
he could see the dark bones of the hand, but not
the flesh around them. And then he grabbed his wife, Bertha. He spent about seven weeks
in the lab, by the way, investigating this, and Bertha, his long-suffering wife,
would bring him food. He didn't tell anybody what he was doing. He worked very much alone. He didn't even like having assistants, which is a rarity even in those days. He was a bit of a recluse, but we've already said he
was a bit of a strange man. And so he stuck Bertha's
hand in front of the thing, and he took a photograph,
and this is the photograph that he took off her hand and her ring, showing that he could see
the bones inside the hand, not the flesh, and this of
course is, as you will all know watching this is the discovery of X-rays, which we now know and love. Now, very quickly,
Rontgen told the medical, local medical society about that, and this is a photograph of
him presenting his discovery to the local medical society in Wurzburg. And he decided very quickly,
instead of patenting his idea, he would sort of hand over this concept to the medical profession
and let them develop the medical application of that. And very quickly, we had,
you know, the following year, people using X-ray tubes like this one, this one actually does
produce X-rays, by the way, on battlefields to remove
shrapnel from soldiers' bodies, and we had it used, you
know, almost immediately, because these things were so common in different labs around the world. It was so common, in fact,
that even artists had it. This is a photograph taken two weeks after Rontgen's discovery
by some photographers. And so very quickly we
get not just an impact in the medical profession, but we also get even a whole new type of photography and of understanding of anatomy, which came from some of
these beautiful photographs. This one's from Austria. And this happened literally
in two weeks, right? So once someone has the
idea and communicates it, it's spread like wildfire. So X-rays still weren't very
well understood at that point, but he could determine from
his experiments that they, you know, they didn't quite
move around like normal light, but they kind of acted
like a type of light, and now we know that they
are high energy form of light that can travel through objects. So what happened over time with
that is an interesting story because over many, many years,
and now I'm talking decades, we get from the very
first version of X-rays and some very rough, you know, hand X-rays to what we now know and love and use as a first line medical treatment
technology in hospitals, which is the CT scanner. And that took the coalescing
of X-rays and advanced, you know, X-ray tube technology, it took the advancement of computers, which we'll talk more about,
and it took, you know, a bit of clever mathematics
and someone working at EMI, that's a record label
if you've heard of it. That's why it was the
Beatles record label, but they also created
different technologies. And so this guy, Godfrey
Hounsfield in the 1970s, set about trying to combine
these technologies together to take images inside the human body where you could actually
see in three dimensions, and it was quite a journey. He had to actually, to test his device, he had to cut out the brains
from cows in abattoirs and carry them across
London in a paper bag to put them on his test machine, which, sorry if there's any vegans
in the audience. (laughs) But it was remarkably
successful, and it actually went far beyond what Rontgen thought
was originally possible, because originally, you would
think if there was something in the way as you're making an image, that you'd never be
able to get around that. But actually, with the three
dimensional reconstruction of modern CT scanners, we can
see in detail the soft tissues and different tissues and things,
and so this is really used millions and millions of times a year now in hospitals all around the world. So a few things to point
out about this is that the physicists themself had no idea what this could be used for, right? And then also it took decades for the multiple different
inventions and technologies to come together to realize
what we would now call an innovation of a CT scanner
or medical technology, and this is important
to keep in mind as we go through our story about
the timescale involved. Now, my next story involves
almost exactly the same type of apparatus, but it happened
here in this theater. In fact, the announcement of
this discovery happened here in this theater, and this
is really where our story of particle physics begins,
and it begins with this man, JJ Thompson, who was the director of the Cavendish Laboratory
in Cambridge at the time, and he wanted to explore,
after Rontgen had discovered X-rays, he wanted to
explore what was happening inside the tube because
it was making this glow, but still no one knew the
nature of the cathode rays themselves, and so he
designed an experiment, or I should say he designed
it and somebody else made it, because Thompson was
famously completely useless with his hands. (laughs) Rontgen was very good
with his hands, right? Thompson, not so much, and so he had to employ the
services of a glassblower. And one of the things that
I learned through writing this book was actually how
skilled and detailed it was, and how difficult it was to
actually invent the apparatus that I'm talking about
to do the experiments, 'cause you might get the
impression that anyone with half a brain at that
point in time could, you know, make a world leading discovery. So before I tell you what Thompson did, I want to show you this video. (flame hissing)
There we go. So this is Les Gamel. He's a scientific glassblower
at the University of Melbourne in Australia, which is one
of the institutes I work at. He's just retired, actually,
through the pandemic, so he no longer blows glass,
but just pre-pandemic, I got in there and asked
him to show me how it works. And so what he's doing there
is he's using some gases to create the flame, the torch, and he's heating a glass cylinder. You can see it glowing red (flame hissing) when you pull it away, there we go. And now what you might not
see so clearly is in the side of his mouth, away from
the camera, he has a pipe. So he's blowing into that
pipe, and you'll see him, there he goes, he's
blowing in and coaxing it with a metal iron to
create a bulb or a bubble in the middle of the glass tube. (flame hissing) Give him a minute. (flame hissing) So this sound you're hearing, this whooshing sound would've been- There we go, he's created a glass bubble. (flame hissing) So this would've been a sound
that you heard all the time in science labs back in the
day, which was something that I sort of discovered
through this process. And in a moment when
he's ready, there we go, you see has pulled the
side away and he separated the two ends of the tubes, and
so what he's left with there, there we go, is a glass bulb. (flame hissing) Now, this one he did just
as a practice to show me how he actually did it,
and it's quite astonishing, and it cools down so quickly. You can see, look, the
color's gone already. There we go, so he did
that one to show me. Some of the other things
that he's created are on the right hand side
of the picture there. This is his lab, which I
love, 'cause it's just like, it's a real working
lab, it's full of glass. So just to make the point that we think that nowadays we do
this like very detailed, very complex engineering work, but actually back in the day,
it was much more artisanal, and if I was a physicist then, I would've had to learn
how to do this myself, breaking glass again and
again in order to create the apparatus that was needed. So let me come back to
JJ Thompson for a minute. So there was two things
that Thompson wanted to ask about these cathode
rays, and he had a theory that these cathode rays
were a type of particle. Now, this was not held by his
contemporaries in Germany. In Germany, they thought
that this tube was glowing because there was a
form of light in there. But he thought that it
might be a type of particle, and if it was, then he should
be able to measure two things. One was the charge and the
other one was the mass. And in fact, what he
really wanted was the ratio of those two things, the
charge to mass ratio. So he used a tube like this, but it's the one shown
in the picture here. And this is actually in the,
if I've got a laser pointer, this one is actually in the
Science Museum in London, if you'd like to go and see the original. That's my photograph
of it, and inside here, he was able to apply magnetic
fields and electric fields in order to bend the beam around. And to measure firstly the charge, he would put it onto a
device like this one. This is called an electroscope. And let me just, actually,
let me show you how this works because this will become
important in a moment. So this is actually an
original electroscope from the Royal Institution Collection. I think it was owned by James Dewar. And apparently they've never
before used a collection item to actually show a
demonstration in this theater, so I have the great honor
of being the first person to actually try and use a
heritage object to do a demo here. So let me, if I can get this sorted out. So I've got just a Perspex
rod here and this cloth, which hopefully will
charge the Perspex rod up. So this is called an electroscope,
this device, and it just, it has sort of this
metal plate on the top. There's a metal rod
coming down, and hanging off the metal rod is
two thin leaves of foil, and that would usually be a
bit of gold, or this one looks silver in color, so it might be, I dunno, some other thin,
highly ductile metal. And when you charge up the
electroscope, there we go. I'll just leave that placed on there. Hopefully you observed that. The people in the front hopefully can see. What happened was this,
the leaves did this. Yeah, yeah, they splayed
apart, and so by measuring, so you could charge up one
of these, and when you put something that was charged onto the plate in a version of this, over
time, the leaves would fall back down toward each other, and if you sort of measured
how long that took, you could measure the charge
that was being deposited onto the electroscope,
and eventually they put sort of meters on them
so that you could call it an electrometer, right? To actually measure it over time. So I'm very glad that that
worked from the collections. Thank you Charlotte, who's
our collection manager, for bringing it up. So this is the kind of equipment that JJ Thompson was working with. Now, what he found was
that these cathode rays had a normal electric charge of
a negative electric charge, but they were 2000 times
lighter than the hydrogen atom, which was the lightest thing
they knew at that time. What he discovered was the
electron, as we now call it. And Thompson announced and
did this series of experiments showing the charge and the
mass and the different bending with the electric and magnetic
fields in this very theater, perhaps at this very desk
that I'm standing at, so it is quite an honor to stand here and explain his experiments
poorly, I'm sure. (laughs) Unfortunately, I don't have
his exact device to show you the exact experiments, but
it's quite an astonishing thing that with such a simple
apparatus made from glass, and a simple electroscope
made from sort of a wooden box and some bits of metal,
that you could discover the first subatomic particle, the first particle smaller than the atom. Right, now, Thompson didn't
think this would go anywhere, and in fact it wasn't very well received, the idea that there were
particles smaller than atoms. He said, "At first there
were very few who believed in the existence of these
bodies smaller than atoms. And I was told long afterwards
by distinguished physicists that had been present in
my lecture that he thought I'd been pulling their leg." (laughs) Now, in fact, 20 years later he came back to the Royal Institution
and gave another lecture about the industrial
applications of these electrons, 'cause it turns out that they
were incredibly important. So first of all, he understood
that in these tubes, the electrons were being
created by the filament or the cathode at one end. And when he studied light bulbs that, say, Thomas Edison was creating
for lighting households, he found the same thing, that light bulbs also generated electrons through a process called
thermionic emission. And this all came together
with a person called Alexander Fleming a few
years later when he took an invention of Edison's
Edison had set aside, where Edison noticed that if
you put multiple electrodes in a light bulb, you can
control the flow of current that comes out of it. Now, Edison couldn't see
a use, he set it aside, he didn't understand it, he
didn't try to understand it. In fact, he was quite scathing
about the kinds of scientists like Thompson who wanted
to understand such things. But Fleming managed to bring
together Thompson's work and Edison's work and
created the these devices which looked kind of like
miniature robots, (chuckles) which are called Fleming valves. Now, the important thing
about a Fleming valve is that it is the very first electronic device. And Fleming realized that
this could be sensitive to a radio signal coming in, and if you put a radio signal in, it can switch on and off
an electrical current. This might not sound like
much, but it is underpinning the entire radio, telecommunications, and early computer industries, so electronics, as opposed
to electrical devices, which we'd had previously, electrical devices work
with currents and wires, but electronics now works
with electrons moving through vacuum or through the
air, and so this invention, which came off the back of
Thompson's understanding, completely revolutionized
our world, completely, right? We would have no computers,
we would have no radar, radio, long distance telecommunications, any of that without this invention. Okay, so let's move on from there. So one of the other
things I learned as I went through this story, and I'll
talk about this a little bit as we go through, was that
there were more people involved in these experiments
than I thought at first. And this is a photograph of Ernest Rutherford's research group, his first research group in Montreal. Now, Ernest Rutherford was
a student of JJ Thompson. He was a New Zealander,
he was massively tall, massively boisterous, full
of energy, and used to speak so loudly that he'll disrupt
the electrical apparatus in his laboratories. Some of the students eventually
built a light up sign about this big above their
table of experiments that said, "Talk quietly please," like
this elaborate sign. (chuckles) And he would still walk in
and like hang his wet coat on something and electrocute himself. So Rutherford was a bit of a character, but he loved building
simple kinds of experiments, as do I, actually. Now, you'll notice someone in this picture who you might not recognize, right? And this is the first person
in this research journey that I went on who
really jumped out at me, and I don't think it takes much for me to point out who she is. (chuckles) This is Harriet Brooks. She was Rutherford's first
research student at Montreal, and she, together with
Rutherford and Frederick Soddy, a chemist, did some
foundational experiments in understanding radioactivity. Now, during her time at
Montreal, she was proposed to, and she was told at that
point that if she was going to become married, she
would have to quit her job, because she was, to support
herself, she was teaching physics at one of the
women's colleges there. And so of course, she protested,
and other people protested on her behalf, not of course, actually, that wasn't taken for granted, but she protested, and it didn't work, so she broke off the engagement. This is how committed this
woman was to doing physics. Now, she was one of seven children, and she could not be
supported by her family, which was unusual, actually, in the history of women in physics, that she wasn't actually from
a particularly rich family. She had to support herself,
and had been doing so through scholarships, 'cause she was a very, very good student. So what happened later in
her career is after making some amazing discoveries,
and she went to the UK, and she worked with Thompson
who kind of ignored her, 'cause he was busy with other things, but she sort of moved
back and forth, Canada, back to the UK, worked with
Marie Curie for a while, and then at the grand old age
of 31 was approached again for marriage by a different
man who she'd known when she was in Canada, and at that point, she actually, the societal
pressure was so strong that she actually got engaged,
had a couple of children, and had to quit her work, and
never worked in physics again, which is probably why
we've never heard of her. But in Canada, she's now quite well known, because in around the 1980s people realize the contributions that she had made. And I want to read a
little bit from the book around radioactivity and its importance, because this work that Rutherford did in Montreal helped us understand that radioactive elements
have a half life. That means over time
everything is changing. Elements are transmuting from
one type to another over time, so nothing in nature is static. Even the elements we
call, even the elements that we say are stable,
well, that just means that their measured lifetime
is longer than the age of the universe as we know it. But they are still, eventually, everything is going to change, and this is quite a large mental shift, but it also created the
ability for us to understand the world in a way we'd
never understood before, because if things change over time, that gives you a clock, right? And so what Rutherford realized
quite early on was that this could be used to
understand the age of the Earth and the age of other things on the Earth. So as well as revolutionizing
our understanding of the age of the Earth, which we now know is close
to 5 billion years old, let me read some of the other
things that we know about because of this understanding of the transmutation of elements
and radioactive half lives, and what we call radiometric
dating techniques. So we know that the Shroud of
Turin is a medieval forgery, and we can put a date
to the Dead Sea Scrolls. We know homo sapiens migrated
out of Africa, not once, but over multiple periods,
and we know how they spread across the globe because
we can date human remains like 14,300 year old ones
found in a cave in Oregon. In archeology, we can put
a time scale to objects, not just locally, but can compare them over different countries
and even continents, letting us build a story of
the pre-history of the world. We can date ice as far back as one and a half million
years old to understand the ancient climate from ice falls, and it's also thanks to
radiometric dating that we know when dinosaurs roamed the Earth, and the date of the asteroid which appears to have wiped them all
out 65 million years ago, which is a theory that went out of favor and is now back in favor,
by the way. (laughs) Going further back, we can
identify the first evidence of fossils that might be
animals, which is a kind of early sea sponge found in
the 665 million year old rocks in the Trezona Formation
of South Australia, and I could go on, but
the amount of things that we culturally take for granted of knowing in our society,
either about pre-history, history, or our culture, or art, or archeology is astounding,
and a lot of it we know purely because we understand
that elements can transmute one to the other because
they're radioactive, which was an enormous change in the world. Right. So the next experiment I
have for you is one that's very close to my heart, and
also inspired the lovely balloon on the front of the book. So I showed you the electroscope before, and you will have noticed over time, those of you who have been
observing very closely, 'cause I know you're
scientists who like to observe these things, that the
leaves that were splayed out very far have fallen back down
and are touching each other. Now, this might be because
the air in this one isn't very well insulated, et cetera, et cetera, but this was an effect
that was observed again around the turn of the 1900s, that even when there wasn't
a radioactive source present, an electroscope, an electrometer
would discharge over time. And what that meant was
that they must be a source of radiation around them
that they didn't know about or that they weren't
bringing into the room. Because when a radioactive source decays, it decays into charged particles, and those charged particles
will then discharge the electrometer or electroscope. Now, people went in search of
this extra source of radiation because the obvious place
it must come from is from the Earth, because
all the radioactive sources that we had, including
those that were found by Marie Curie and Pierre
Curie were milled and refined from the materials of the Earth, right? They're very, you know,
maybe very small percentages, but radioactive materials
exist on the Earth naturally. And so people took
electroscopes and they went up the Eiffel Tower, and they
went down into the ocean, and they went into rail
bridges under the ground, trying to detect this
extra source of radiation, and they couldn't find it. It was no good, basically, but part of the problem
was their equipment. Now, if I told you I was going
to take this electroscope and I was going to take
it up in a hot air balloon and measure things with
it, you'd laugh at me, because clearly, these leaves
are going to wobble around, and it's clearly not an
appropriate instrument. So in about 1910, a Jesuit priest named
Theodore Wolf invented a better version, and it looked like this. It had a microscope on the side, and inside instead of a couple of leaves, it had some wires instead. Now, I know this seems like a small thing, but it made the device much more robust. And so he wasn't the first person to go up in a hot air balloon, but
Victor Hess was the first person to do this well, and he took a couple of these Wolf electroscopes and he did six balloon flights very
high up in the atmosphere. He went up further and further and further up to about 5,000 feet
in the end, actually. And what he found was this,
that as he left the Earth, the amount of radiation he
was detecting decreased. That's what he expected, but
as he went further and further up into the atmosphere, the amount of radiation he
was detecting increased again, and it just kept increasing
the further he went up. And what Wolf had discovered
was cosmic rays, that is, a source of high energy charged
particles coming from space that had never been observed before. And he had no idea what it was or how it was being generated, and one of the lovely things is, even now, to tell you the truth, we
don't know how it's generated. (laughing) We're still learning about it. But these charged particles
would come raining down from space, and were
detectable in his experiments. And we now understand
that most of these are high energy protons which come into our atmosphere and collide, and they generate other
types of particles, which I'll talk more about. And at this point, his story
collides with somebody else working in Cambridge, someone who is very
interested in meteorology, who's called CTR Wilson, and you can see him sitting
down there on the right. His first level was actually meteorology, and he had built a chamber out of glass, and the original version in
Cambridge I've photographed here where the chamber could
expand, and as it did so, it created clouds, and
he'd actually built it to try and study clouds in the laboratory, 'cause that's what he was interested in. But what he found was that
when he put an X-ray source up against the cloud chamber,
he could see the radiation from the X-ray source,
and so he redesigned the whole experiment to be able to see radiation for the first time. And we've got a couple of
cloud chambers over here, and fingers crossed they're working. That's why I've got two
for redundancy. (chuckles) So I've got a couple of
things to show you over here, because it is quite an astounding
thing to be able to see with your eyes for the very first time, the effects of radiation. Now, let's have a quick look at this one. If we could bring the
house lights down, Tom. Let me pop a light on. All right, this one's behaving badly, so I'll start over on this one. Have we got the, yep,
we've got the camera up. So okay, I wanted to show you this one, but it's not currently working so well, because this is another original
object that we have here. I was talking about radiation before, and Marie and Pierre Curie. Well, in 1904, Marie and
Pierre Pierre Curie traveled over here to this very lecture theater, to the Royal Institution
to talk about radiation, and they brought with
them a source of radium that they had refined
themselves in a container. And Charlotte the archivist
has given me the lid of that container, which still
has a low level of radiation. And that is what, that's
the object you're seeing actually sitting inside
the cloud chamber there. Now, sadly, because it's
taking a little while, I don't think we're gonna
see much on that one at the moment, but we'll see. Tom, if you want to come and play with it, if you are around, feel free to come and
try and reset that one. This is a real live experiment, so it doesn't always work first time, and I'm going to try to
show you this one instead. So okay, so first of all, what I'll point out that you're
seeing here is you can see some sort of cloud-like
stuff trailing down, right? I'm pretty sure you can see that. So what is happening inside
this chamber is there's a vapor of alcohol, which
is falling toward the bottom where I've got dry ice, and dry ice is about minus 70 degrees, and so it's creating a
temperature gradient. And so the vapor falls down to
the bottom and forms a layer that's called a super saturated state. And what that means is the
alcohol vapor really wants to condense and form clouds, but it needs a little bit of energy to do so. (chuckles) Thanks, Tom. And so if you watch this very carefully, if I can actually hold
it stable, there we go, you can see just occasionally
a little cloud trail. There we go, there's a
few, there's a big fat one. And now you'll see also
some thin, wispy ones that come through. Now, I'll point out
here that I do not have a radioactive source
in this second chamber, so what we are seeing here,
if we see tracks, there we go. There's one, another one. What we're seeing here if
we see tracks is actually the cosmic rays that Victor Hess created, or perhaps some radioactive decay of, say, radon gas in the air in the theater, or of some elements in the
Earth which are coming through. But some fraction of these are
going to be from cosmic rays. I'm gonna sit it there and let it. I actually could watch it all day. It's quite mesmerizing. One of the astonishing things
really is that you can build a chamber like this at home
if you can order some dry ice from a cocktail maker or a supplier. It's actually quite easy. It's just a, it's propanol, by the way, the type of alcohol that's used. And you're welcome,
we'll leave them running, so you are welcome if you're
in the theater to come down and have a closer look afterwards, especially at this second one there. Did you, yeah, you need
to wipe some alcohol off just to, it was a bit sort of saturated. Yeah. (chuckles) All right, so we'll get that one reset up. So hopefully what you'll be able to see. So this one we're looking at cosmic rays, but hopefully, if you come
down at the end of the lecture, will be able to look back
over at this other one, which hopefully, by then will
be showing some nice tracks from the radioactive source
that I've put in there. Okay, if we can bring the
house lights back up again. Thank you. This is why we always have
redundancy in case one of the real experiments
doesn't work. (chuckles) The thing is that they're
quite temperamental. If they get too saturated,
they lose their state. Now, this is actually a
later version invented about the 1930s which uses this
so-called diffusion method, whereas Wilson's original one
used a pressure difference, which is what happens sort
of if you open a bottle of soft drink and you see
that cloud in the top. It's sort of the same effect. Okay, so what happened
with the cloud chamber? Well, there was an incredibly
adventurous journey that happened after the
invention of this device, because now that you
could see and photograph the passage of charged
particles for the first time, you could just look at the
tracks that we were seeing. So those short fat ones
were alpha particles. Long, thin ones are probably electrons. And then when they started
taking these chambers, putting them in big magnetic
fields and leaving them and photographing them
for a long, long time, what happened was they
found other particles that they weren't expecting that played no role in ordinary matter. And the first one of those
is called the positron, which is like the electron, but it's the anti-matter
version that was found in 1932. And then just four years later, they took one of these on the
back of a big flatbed truck up a mountain in California, and in these inhospitable
conditions, you know, it's really cold and
windy and stormy up there, they left the thing running
for about six weeks on end, taking photograph after
photograph after photograph, poured through all of these
pictures and then found another new type of
particle called the muon, which was like the heavier
version of the electron. And this sort of revolutionized
our understanding of physics because if you think about
the fundamental particles that make up nature, we
normally talk about atoms. Inside the atom, there's the nucleus, which by this point they knew about, the electrons around the outside, and inside the nucleus
is protons and neutrons, and later, we found what those protons and neutrons are made of. And here we have particles
that don't make up the matter around us, right? They're completely different. And there was one theorist
called Isador Rabi who reacted to the muon discovery by
literally just saying, "Who ordered that?" (participants laughing) Like, it was so unexpected. Now, at the same time as this, it was really annoying to
take a really, you know, like, unpredictable chamber up a mountain, or let alone up in a balloon
or up even higher altitudes and take measurements with it. So instead, there was a
different invention using photographic plates or
photographic emulsions made by a woman named Marietta
Blau, who I'm guessing most of you have never
heard of, I think, yep. So she was working in Vienna
unpaid, and she invented this technique using thick
photographic emulsion. She worked with Kodak and
Ilford and other big companies to develop them. She developed this technique
of being able to leave, instead of a chamber which
you had to photograph all the time, she'd leave
these thick photographic plates up at altitude in the
mountains for months at a time, and then she could take them away and she could process
them, and by doing so, she actually found some
quite remarkable things, including the image here, which
they referred to poetically as a star of disintegration, which is where a high energy
charged particle is coming in and the nucleus of an atom
is decaying and throwing out tracks in all different directions. So Marietta Blau was a
pioneer of this technique. And there was another woman in
India at the time who picked up this technique and used it as well. But because we ran into
World War II at this point, her emulsions, her supply of
emulsions was not very good. But Bibha Chowdhuri, who I'm
guessing you've never heard of, 'cause I hadn't, she's one
of the people I learned about in writing this book,
actually found another type of particle similar to a muon,
but slightly heavier again, and it's a type of particle
that we call a pion. And now anyone, there's a
couple of particle physicists in this room, so this
will make sense to them, but to anyone else, it just
means we were discovering more and more and more particles, right? But one of the important
things about Blau and Chowdhuri and some of the other
women that I've mentioned, including Harriet Brooks, not Marie Curie, 'cause we know and recognize
her work very well, 'cause she won the Nobel Prize, the important thing
about these women is that their stories weren't written
down, weren't recorded, and they really weren't acknowledged for the work that they did. And one of the difficulties
I had in writing this book, in writing their stories
back in for their amazing discoveries is that we don't know anything about their personalities
or their lives, actually, because it just wasn't recorded
and it wasn't written down. But let me tell you what
happened after the discovery of things like muons, because
this is, as I've said, I've talked about
changing the world, right? So one of the amazing things that happened with muons is we've developed over time, taking cosmic ray muons and
using them in technologies to do things which we couldn't do before. And one of the things that
they did was to use them as like a giant X-ray scanner
through enormous objects 'cause they can travel a long way through meters and meters of rock. And in a project called
Scan Pyramids in Egypt, they actually discovered a new room in Khufu's great pyramid in
Giza using this technique. So the muons can travel
sort of straight through and be detected mostly using Marietta Blau's emulsion technique, and this is what a detector
like that looks like, and they don't just use it for pyramids. They're now using it for
volcanoes as well to actually see the magma and the changes
in magma in volcanoes. So instead of, you know, we
are used to having X-rays of sort of small objects
in bodies and dogs and things like that, but
now, understanding cosmic rays and having the technology
means that we can actually use naturally occurring radiation sources, which are around us all
the time to measure things which we simply wouldn't
have known how to do before. So just to summarize,
this space of 20 years, we had this huge overhaul in
our understanding of physics, and along the way in the book as well, we get the development
of quantum mechanics at the same time, right? And it all ties together, so we understand that the atom was no
longer the smallest object, that some atoms weren't stable over time, and that that change was
an inherent part of nature, that the atom was mostly empty space, that light acts like
a particle and a wave, in fact, all of matter acts
like a particle and a wave, that we're living in a violent shower of high energy particles
coming from space, and that the universe is
far richer and more complex than we originally thought. So this was a huge change
that happened at the start of the 20th century, but
it actually continued. That trajectory continued
massively, because at the end of the 1920s, Ernest Rutherford, who by then was the president
of the Royal Society, decided he needed to dig
deeper into the atom, because he still didn't understand what was at the heart of the atom. They knew that there was an
atomic nucleus at that point in time using another experiment called the Gold Foil Experiment that some of you will have heard of. So he presented to the
Royal Society this ambition that he wanted to have available
for study a copious supply of atoms and electrons
with an individual energy far transcending that of
the alpha and beta particles from radioactive bodies. Now, there's one way to get
particles up to high energies, and it's what my field is. I work in particle accelerators, and that is exactly
what he was asking for. And to get a particle up to a high energy, you need a high voltage. And they calculated that
the voltage they would need to split open the nucleus of an atom was about 10 million volts. Now, if you've walked under
a pylon that transports our electricity at 300,000 volts, you'll realize how frightening
10 million volts was. And at the start of the 1920s, most homes didn't even
have electricity, right? So at this point in time,
requesting 10 million volts for a physics experiment
was pretty wild, right? And the only person, one
of the only people working with those kinds of
voltages was Nicola Tesla, and this is what it looked like. I don't know about you, but
I don't want to go in there and do a detailed experiment
anywhere near that thing. (chuckling) And there were people all
around the world using things like Tesla coils. In Germany, they were trying
to harness the lightning until one of the researchers
fell down the ravine that they'd rigged up their
experiment in and passed away, so that experiment didn't go any further. And other people were using
things like transformers. And there was this race to
develop the first machine which could get up to a high enough energy to split the atom, and along the way, quantum mechanics changed the
game, because along the way, there was a Russian
researcher called George Gamma who came along to the Cavendish Laboratory where Rutherford was working
in Cambridge at that time, and worked with them, and
together they understood that they might not need 10 million volts. They might be able to do it
with just a million volts or even lower, and at this time, they were well along the way of developing their first particle accelerator, which is the one on the left
here by two main researchers called John Cockcroft and Ernest Walton. And Walton, who was
the student by the way, did most of the actual building
and most of the actual work, which for some of my graduate
students in the audience, they'll feel a resonance
with that experience. And at the same time in the US, Ernest Orlando Lawrence was
coming up with a different idea for a particle accelerator
called a cyclotron. But actually, these guys in
Cambridge, they won the race, and they split the atom for
the first time in April 1932, using what is effectively
a series of transformers. And I want to point out to you
how they did the experiment, because again, like when
I learned about this, it was quite incredible
to find out the reality of what experimental
life was like in 1932. So you can see underneath
the vertical tube, which is actually the
accelerator where protons start at the top and they travel down and they go through a
voltage in the middle, and then they travel down to the bottom where they're meant to hit
a target of usually lithium or something like this to study whether or not it's with the nucleus. And underneath there
you can see a detector, otherwise known as a human, (chuckling) watching a scintillating screen, very similar to the one
that Rontgen would've used back in 1896 in his
lab to discover X-rays. And so one morning after much
trial, and things breaking, and things not working,
and then rebuilding the entire machine in a different room, this is, you know, four years
later, something like that, Walton is alone one morning,
he's a student, right? So he is like warming up the machine, he's at his control desk,
and the thing gets up to a couple of 100,000 volts
and it seemed pretty stable. And the Cockcroft was
away doing something else, 'cause he had a million jobs. And Walton thought, okay,
well, I'll dial up the machine, and I'll pop a target in
and I'll turn it on it, and I'll just see if anything's happening. And so he steps away
from his control desk, and he crawls across the floor. Now, there's hundreds
of thousands of volts in this room, right? He crawls across the floor
and into this little box that he's sitting in, in this photograph, and he pulls the curtain past
him, and he sees on the screen flashes, more flashes than
he ever thought possible. The screen was lighting up with flashes, and what that meant was that the protons coming down
were hitting lithium, and it was splitting apart
into alpha particles. And even though he hadn't
trained for very long, he could recognize an
alpha particle in this box. And so for the first time
he was, oh my goodness, what am I, seeing? He knew he was seeing something special. He called in Ernest
Rutherford and John Cockcroft and others, and Rutherford,
being the tall guy that he was, he climbed into this box
with like his knees up around his ears and he watches the screen, and he's like, "Those are alpha particles. I should know, I was there
when they were invented." He basically found them for the first time earlier in his career. And so for about a week as
they did more experiments and wrote it up, there
were only about four people in the world that knew that
the atom had been split. And this led to incredible advances, some of which I'll tell you
later about the applications of machines like this,
of particle accelerators. And some of those
applications also happened with Ernest Lawrence,
with this other machine, which was circular, which overcame this sort of 10 million volt
crazy voltage requirement by reusing a voltage again and again. But despite that, as they
worked harder and harder, the machines got larger
and larger and larger, and there were more and
more discoveries coming from cosmic rays, but
at this point in time, particle accelerators
were still not really used for anything other than some detailed nuclear physics studies. They hadn't discovered any new particles using an accelerator. And then World War II broke
out, so we get to this point, we get to these big labs. They've started to generate new types of radioactive elements that
they could use in medicine, which Ernest Lawrence
did with his brother. Everything was sort of going wonderfully, and then the world
changes entirely, right? And most of the physicists that I've talked about were involved, especially the US based ones were involved in the war effort in some way. Many of them were involved
in the Manhattan Project. And one of the people
who was asked to join the Manhattan Project but refused was a woman named Lisa Meitner, who again you might not have heard of her, but she did some foundational work in understanding nuclear fission. But her name was left off the key paper because she was Jewish
and so she had to flee, and so her collaborator could
not admit that he was working with her, and she refused to
join the Manhattan Project. She refused to have
anything to do with a bomb. And while we know what came after that, and we know what physics was capable of, when there was large amounts of resource and putting all of these people together in one or a number of places
with a mission to do something that they did not even know
was possible at the time. And I should say many of
the physicists who worked on the atomic weapons
project didn't even know really what they were trying to achieve, let alone did they think it was possible. And this changed the world, obviously, but it dramatically changed
how physicists approached what they did. They realized that physics
was political, right? This was no longer just a
search to understand nature, that what they were finding
could dramatically change the world for better or for worse. And there's some stories in
the book about how that changed the views of some of the
physicists, and they're becoming much more pacifistic
after the war, actually. And so with this knowledge
that the US now had, especially even Winston
Churchill was sort of saying, "Well, the US now is at the
forefront of this knowledge. Let them act up to their
level of responsibilities, not for themselves, but for others, and then a brighter day may
dawn upon human history." This is a dark period in
the history of physics. So I wish I could allocate
it more time here. I can't, but it changed
the approach entirely. But what did come of it
was our understanding that if you put together
large amounts of smart people and give them a very
difficult problem to solve, that they can solve it. And so after World War II, we get the emergence of big science, big scientific projects,
big scientific laboratories, especially in the US, and
that led to discoveries of many new types of particles. At one point, there were
about 200 different types of particles that they
were struggling to classify and understand how they were fundamental. It wasn't just the weapons that came out of World War II, either. One of the other big inventions
that came out was radar. And I don't have time to
tell this entire story, but we start with a couple of
people trying to invent radar. We get someone who's trying to
invent particle accelerators, who teaches them how to do it. Yay, we have radar, but
as a result of this, these two brothers, Russ
and Sigurd Varian team up with Bill Hansen, the accelerator person, and they invent very compact
particle accelerators that can then be used
for cancer treatment. And so it seems a
completely roundabout story, but the whole story is in
the book, and actually, their company Varian and Co. was the first publicly floated
company in Silicon Valley, predating what we would now
call Silicon Valley, actually. But this activity towards
particle accelerators and radar in that area seeded the
high technology background and the concentration of
highly technical people that would then become Silicon
Valley later down the line. And now these machines, these particle accelerators are
used in many different parts of the world for many
different applications. But the one you'll probably
come across if you ever come across an accelerator is in a hospital for cancer treatment using radiotherapy. And so the growth in the
applications of these machines over time is just phenomenal. Everything from the lithography
that creates the chips in your smartphones to
materials processing to create shrink wrap, to treating cancer, to understanding the
origins of the universe, it is really quite phenomenal. So by the '60s even, we know
that the atom has a nucleus, that these big science
laboratories are bringing new opportunities, that
we can now create isotopes with many uses, including
tracers for medical imaging, that these new particle
accelerators can create lots of new different particles that play no role in ordinary matter. We get these particles called
strange particles that acted in very confusing ways,
and slowly but surely, people started to piece
together the different particles and forces in the universe
through this kind of experiment to generate what we now
call the standard model of particle physics, which is so elegant that you can write it on
a T-shirt. (chuckling) And of course, there were
many questions that came along about those nuclear forces
and how they worked. And I just want to
highlight one other person, and if I have time, do
one more quick demo, who is part of this story,
and her name is Helen Edwards. So by the 1970s, 1980s, of course, women are accepted into physics. They're still not as prevalent
as men, but this woman, Helen Edwards is a remarkable
accelerator physicist. She works in my field. She worked in my field. She passed away a few years ago, and she was the mastermind
behind the biggest accelerator before the Large Hadron Collider, which was called the Tevatron. And what she needed to mastermind was the first superconducting
accelerator, which we needed, because we needed accelerators to breach higher and higher energy without
becoming infinitely large. So to have stronger
magnets, they had to use an entirely new technology
which had to work at liquid helium temperatures
in order to produce very strong magnetic fields
to confine the particles, and she's someone who sort of
oversaw this whole process. So very quickly, if we
have time, Tom? (chuckles) Tom has been hopefully
cooling down a little piece of superconductor, which is
almost like a ceramic material. The type is, it's called
yttrium barium copper oxide, the one we have here today. This one works at liquid nitrogen instead of liquid helium temperatures. The key thing with a
superconductor, it's in the name. Normal conductors have
electrical resistance, so they heat up if you try
and put a very strong field, electric current through them, but a superconductor does not. It can be in a state when it's very cold, where it will actually keep
electrical currents flowing without pumping in more electricity. And this is both the trick to reaching very high magnetic fields,
but it's also the trick to reducing the energy consumption of these very large particle accelerators where otherwise the losses
would mean, well, I mean, the electricity bills are
high enough, right? (laughs) And when this machine was invented, that was actually a very important thing. So I'm going to get out a
piece of the superconductor. We've been sitting in
liquid nitrogen here. It's been bubbling away. And it also, the superconductor also has sort of some slightly strange effects, which hopefully I'll be able to show you. Put it on there, there we go. So because of this weird thing
where they can have currents run through them infinitely, if you put them near
magnetic field like this, it creates its own field to
push back against the magnets that are on this track
here and sort of traps the magnetic field
inside in an opposing way to the one I've put it in, and that means it can actually float
above the track here. And this, by the way, is
something which is really used. Superconductors levitating
above tracks is really a technique which is used
for incredibly fast trains, because of course, there's
no friction involved. We've got here, which Tom has
prepared a little version, which is not a train, but it's a boat. I'm going to see if I can- Isn't it sweet? I'm gonna see if I can
get that one working. There we go. Hey. Oh. (participants clapping) Flipped over. Presumably, the trains in China
do you not do such things. Let's see if I can just get
it there a bit more stably. Oh, of course, friction, there we go, something on the tracks,
leaves on the tracks. People watching me in
Australia will have no idea what I'm talking about, but
everyone in the UK knows. (laughing) All right. So okay, but the point with the Tevatron, the superconductor was
that in order to create this enormous particle collider, they actually had to commercialize
this wire technology. And the commercialization
of that that happened through the Tevatron project is the reason why we can now use superconducting magnets in other applications including trains, MRI scanners, which is a huge one, and potentially, infusion
reactors in the future. And the biggest manufacturer
of superconducting wire and magnets in the world,
Teledyne, their CTO, I think it is Robert Marsh, says that "every program in superconductivity that there is today owes
itself in some measure to the fact that Fermilab built
the Tevatron and it worked," and it is quite in incredible. And the Tevatron also helped us understand the different pieces of the standard model of particle physics, at
the end of which in 2011, Helen Edwards was the one
who switched the machine off. Now, for the sake of time, I'm going to rush through to the end here, but there's so many other ways in which these enormous experiments
have affected our world. And there's one that I would
be remiss not to mention, which is that Tim
Berners-Lee working at CERN with the predecessor to the
Large Hadron Collider was the one who actually
invented the worldwide web, which if we now talk
about using the internet, we actually talk about
using his inventions. So hopefully, you can see
that by bringing together this collection of fundamental particles and these equations, which
we now understand to be how our universe works
on a fundamental scale of particle physics,
we've also been working on the cutting edge of
technology, and as a result, even though what we are
doing with no application in mind is very much curiosity driven, it's had an enormous impact in society. And that culminated most recently
in 2012 with the discovery of the final piece of the puzzle,
which was the Higgs boson. But despite all of this, nine in 10 people do not think
the world is getting better, and this was before Trump and COVID and everything else, right? (laughing) And I'm just gonna skip over that one, but one of the key things I
learned through interviewing all of my colleagues in the
field about this is when I asked them what people could
learn from this experience of particle physicists
working together to overcome these enormous barriers
in enormous experiments, I expected them to say
lots of different things, and they all said the same thing. They all said that people
can learn how to collaborate. And I think therefore,
what I didn't realize when I was writing this book
is that I was writing a book about hope of how we might
be able to work together in the future to overcome
the enormous challenges that now face us. And in studying collaboration, these are the key things that
come up about what works. And so these are some takeaways for you, which is to talk to people who
have different mental models or ways of knowing, to avoid
clustering around people who agree with us, especially
in problem solving, but also that probably
applies to social media, to seek out people who
have different backgrounds and disciplinary expertise, so multidisciplinary
interdisciplinary work is key to good collaboration, and to engage with diverse team members in collaboration and problem solving. And so some of the three,
well, I really distilled all these experiments over 120 years down to three key things that I
think all of us can take away about how we can use
this search for knowledge to change the world going forward, and one is to ask good questions. The other one is to build
a culture of curiosity where people are allowed
to ask these questions and are supported in it,
and the freedom to persist. Now, I know I'm standing
here wearing a T-shirt with particle physics
equations on it, but I think, especially given the
week we've had in the UK with all sorts of comments
about girls and physics and all this rubbish, what
I want us to acknowledge and remember is that there's
more than what meets the eye in terms of these experiments, right? So I want to show you, I was
gonna do this out the back, but for the sake of time,
I've done it live on stage, this T-shirt that I've made,
which highlights these people, these women who I've talked
about mostly in this talk who were behind this story of discovery. So creating environments
where people can thrive, all people can thrive, I think
is really going to be the key to unlocking those future discoveries which are going to
change our world in ways that we cannot even yet
imagine in the next 100 years. And I will finish there,
because I'm overtime, and take some questions. Thank you so much for your attention. (participants clapping)
