Translator: Rachael Williams
Reviewer: Denise RQ So we're going to be talking
about antimatter, and, to you, antimatter
might sound like science fiction, but, what I want to get
over to you in this talk is that antimatter is science fact. I want to show you in this talk
what this strange esoteric substance is, and I want to demonstrate
why it matters to us. And what you're going to see
is that antimatter actually forms a really fundamental part
of the Universe's structure. And not just that, but its behaviour
is key to our very existence. you're also going to see that antimatter
is one of the biggest mysteries that we have in physics today. And that's because we quite
simply do not understand it. We don't have a theory that predicts it
or that describes its behaviour to us. So everything we know about it
comes from experiment. And I'm going to tell you very briefly how we form our experiments
and how much we know about it so that you can see exactly
what the matter is with antimatter or at least you will do
by the time I finish this talk. So in order to understand antimatter
we've first got to understand matter. And by matter I mean stuff. The stuff that makes up stuff around us. And the description
of this stuff, of matter, belongs to a branch of science
called particle physics. And this tells us that the Universe
is actually very simple, that all the matter,
all the stuff that you see around you is made of just a few
fundamental ingredients or fundamental particles as we call them. Twelve of them actually,
six quarks and six leptons. And just to set the scale
of the very smallest of detail that we worry about
as particle physicists, these fundamental particles
are at least as small compared to atoms as atoms are compared to you. And I say "at least"
because they're so small, we haven't actually been able
to measure their size. They're like pin pricks. Now at least when you get down
to these very, very tiny distances the Universe is simple. In fact, it's slightly
more complicated than this because this is just matter,
and we also know that antimatter exists. Each one of these fundamental particles
has an antimatter equivalent so we have anti-quarks
as equivalents of quarks, anti-leptons as equivalents of leptons. Antimatter and matter
are really, really similar. They don't differ by very much. An antimatter version of matter
just has the opposite charge and behaves like a mirror version. So if I have an antimatter version
of a negatively charged electron, it's the positively charged anti-electron. And if I have the antimatter equivalent
of the positively charged proton that contains quarks, then, that gives me the negatively charged
anti-proton that contains anti-quarks. So it's quite simple really. (Laughter) Believe me! (Laughter) Antimatter is just multiplying
the complexity of the Universe by two. OK! (Laughter) I'm glad you're with me on this! (Laughter) There's one very good diagnostic
for when you have antimatter around. And that's because when you have
antimatter meeting matter, it annihilates, releasing
enormous amounts of energy. So if I have a quarter
of a gram of normal matter meeting a quarter of a gram of antimatter, then the resulting annihilation has the explosive force
of five kilo tonnes of TNT. Wow! So you might think
that particle physicists have perhaps discovered
the next source of fuel. We might have solved
the worlds energy crisis and been keeping it very quiet because we're hoping
to make a lot of profit! If only that were true. And what stops this being true is the fact that antimatter
is the most expensive substance known to mankind. It's enormously expensive. NASA estimates it would cost
about 100 billion dollars to make just 1/1,000
of a gram of it. Wow! It's so expensive because it's so rare,
it's so difficult to produce. That's not to say,
it doesn't exist altogether, because we get antimatter in the Universe
because things decay radioactively. So in fact, bananas
are a good source of antimatter. A banana every day will release
15 anti-electrons, believe it or not! But 15 is such a small number compared to the vast number
of particles that make up a banana that for all intents and purposes, we just really almost don't have
any antimatter in the Universe at all. It's ridiculously rare. Antimatter doesn't play much part
in the Universe at the moment so you might be asking,
"What's the big deal about it?" Why am I giving you a TED talk about it?
How does it affect me?" We think that antimatter
did play a very important part much earlier in the Universe's history. Behind me, is a picture showing you,
briefly, what happened to the Universe. We think it started over here
with the Big Bang, a tremendously energetic fireball that brought everything
in the Universe into existence. And this very early Universe
consisted not of stars or galaxies but the ingredients of stars and galaxies, the fundamental particles
that I've just been telling you about. The Universe was tremendously hot,
tremendously dense, expanding rapidly and cooling as it does so. And at various points,
matter starts clumping together to make new forms as it loses energy. So after a few fractions of a second, we get protons, and neutrons,
and then atomic nuclei. After a few hundred thousand years
we get the first atoms forming, and then we get larger things:
stars, planets, galaxies until there we are, on the right hand side
almost 14 billion years later. Although antimatter doesn't play
much part in the Universe now, we think that half the Universe
was made of antimatter at the time of the Big Bang. Antimatter fundamental particles
met matter fundamental particles, annihilated, releasing photons of light that then, through the quirks
of quantum physics could produce
new matter-antimatter particle pairs that met and annihilated. And this whole cosmic battle
between matter and antimatter continued as the Universe expanded and cooled until eventually,
almost a second after the Big Bang, the Universe had expanded
and cooled so much that there was no longer enough energy
to make more matter and antimatter and this whole
annihilation process stopped. And what remains in the Universe now is the consequence
of a very tiny difference between the amount
of matter and antimatter that existed at that point. Very tiny; I'm talking
one part in a billion type tiny. But that difference
is the reason why we're here. Because if we had the same amount
of matter and antimatter, it would all have canceled each other out and the Universe now
would just be full of light. We wouldn't have atoms,
stars, or be here either. In a sense, we are the leftovers
of those last collisions. But this is why antimatter plays
such an important role for us in physics. We want to know what made it that very slightly bit different
to normal matter to cause there to be
not quite as much of it at that point. In other words, we want to know
exactly what it is about antimatter that made evolution
of the Universe happen. This is why it's a big mystery in physics. Unless we know this,
there's no way of understanding how the Universe
got from the Big Bang to now. It's a really big problem. And more than that,
we have no understanding of it. We have no theory
that explains it or predicts it. All we know is through experiment. So what I want to show you now
is how we investigate it. There are two places
that one can look for antimatter. You might think
that perhaps there's no problem with the amount of matter
and antimatter in the Universe. Perhaps we think that we've got
a problem, but we haven't really, because there's large amounts
of antimatter somewhere we haven't looked. There's a big patch of it
perhaps out in the Universe that we haven't actually seen. And we've looked for this. We can use telescopes to look out
into the furthest Universe for evidence of the annihilation
that we'd expect to see if you have a big bubble of antimatter
meeting normal matter around it. We haven't seen any evidence yet. So we don't think, at least in as far
as we can see in the Universe, that there's any big patches
of antimatter out there. The other thing we can investigate is
the composition of high energy particles that zip through space. These are called cosmic rays, and perhaps,
most of these are made of antimatter, and that's where
the extra antimatter is hiding. Perhaps, we just never see it here,
down on Earth, in our experiments, because it's annihilated on its way down
through the atmosphere. Well, we're looking at this as well. And to study these high energy cosmic rays what you need is a particle physics
experiment but out in space. And we have one of these,
believe it or not. It's called the AMS experiment,
there's a picture of it here. It's mounted
on the International Space Station, and at this moment,
it's orbiting around the Earth taking measurements of all these particles
streaming through it quantifying them as matter, as antimatter,
and counting how many of each you get. And our hope is,
that by analyzing this data, we'll see if there's any sources
of antimatter out there in the Universe that might help explain what's going on or that might point us
to an extra pile of antimatter somewhere that could solve our problem. So far, AMS is just
a few years into its mission, and we've had the first results back. We haven't, by any means,
looked at the full data set yet. And so far, we haven't seen
anything untoward. There's no big sources
of antimatter there. There's no explanations as to why
antimatter and matter are different. So if there's no other sources
of antimatter around, we had better understand this difference if we want to understand how the Universe
got from the Big Bang to now. So we perform experiments
in the laboratory too. And the best place to do this
at the moment is at CERN, the European Center for particle physics, and it's where I work, and many of us
at the University of Liverpool work there too on the experiments. You might have heard of CERN before. It's famous for having
the Large Hadron Collider, our most powerful particle accelerator
or atom smasher if you like, based there. And this really is
a phenomenal experimental facility. It discovered the Higgs boson
a couple of years ago. You might've heard it in the news as well
because we were pretty happy about that. But what you might not realize
is that the Large Hadron Collider, or LHC, is about much more than that. So what goes on in the LHC is we have
two beams of protons, hydrogen nuclei, that have bent round
in a big circular path and accelerated to enormous energies until they're going
at almost the speed of light. And then they're brought into collision
at four points around this circular ring when we build experiments. What happens in a proton-proton collision is that, for a tiny instant of time,
in a tiny area of space, we recreate those very hot conditions
of the very early Universe. That means we create matter
and antimatter as fundamental particles. And our experiments act
as gigantic three dimensional cameras that take snapshots of what goes on. We record this information, and then,
we analyze it at our leisure offline and try and work out what's going on. One of these four experiments
is of particular relevance in our search to understand antimatter. It's an experiment called LHCB, and we work on this
at the University of Liverpool. In fact, we built
some of the particle detection kit contained in the experiment. I will show you a picture of it
when my PowerPoint recovers; here we go. It's a silicon detector. The silicon is this grey part,
this grey semicircle you see behind me. It would fit into the palm of your hand, and it can detect the position
of charged particles passing through it to within a tenth
of the thickness of your hair. It's incredibly precise, and it was built
just a few tens of metres up the road in the ground floor
of the Oliver Lodge Laboratory just opposite Abercromby Square. Because you may not know this, but Liverpool University
is one of the world's centers for making this type of equipment, and we've built this for many, many
particle experiments around the world. This detector makes it possible for us to isolate the samples
of matter and antimatter that we need to study them. OK, so what have we found? Well, we've made measurements of matter,
we've made measurements of antimatter and, as I've said, we don't have
a theory that predicts them, but instead, we have to somehow reflect this difference in behaviour
between matter and antimatter, in our theory, if we're going to have predictions
that reflect reality. And, very stupidly, we've got one number
that does the job in our current theory. So our idea is, if we make a measurement, we can compare it to a prediction
where we don't know that number and extract a number for it. And if we make another measurement
of matter and antimatter, we can do the same thing. And again, and again, and again. And then we can compare
the numbers we get out to see if we're getting
a consistent picture. And this very colorful plot behind me
shows you the state of the art of everything we've found. Every colored band here shows you
how different matter and antimatter can be from a different type
of experimental measurement at a different experimental facility
around the world. What's really compelling and remarkable is that all of these colored bands
overlap at a single point which is the apex of that triangle. And what that means is
that there's one number, one common number, one common difference
between matter and antimatter that can explain what we see
in all of our experiments. Wow, that is great! (Laughter) If you're a particle physicist
it's really great! (Laughter) Because what it means is that, even if we don't have
a deep understanding of antimatter, the fact that we can describe it
in this common way, is giving us a clue somehow, in ways we have yet
to comprehend as to its nature. And what we can do is to take the amount of matter
we think there is in the Universe, take this difference
between matter and antimatter, and in our calculations
wind the clock back, to the beginning of the Universe, and see how much antimatter
there should have been. And if we do that, we don't see
half a Universe's worth. If we do that, we see a galaxy's worth. And this is the matter with antimatter. Because whatever we've seen experimentally does not account
for this huge difference needed to explain how the Universe evolved. This is the state of our
understanding at the moment! (Laughter) But it's not so bad, because we think even if we can't yet understand what
makes antimatter that little bit different from studying the particles
that we know about, we think that perhaps the answer is contained in the behaviour of particles
we have yet to find and study. Particles that are associated
with "new physics", new phenomena. Particles that are predicted by a theory that takes our existing
understanding and deepens it, and perhaps answers
some of our other open questions: what is dark matter, for instance? How does gravity behave
at very small scales? And so we think that perhaps,
by finding evidence, that these are a better
explanation of the Universe, we can then explain antimatter because some of our candidate
replacement theories can accommodate this difference
between matter and antimatter that we need and although we haven't seen any evidence
of what it might be yet, 2015 may provide the answer. Because what happens next year is that the LHC will restart
providing us with data, but at higher energies
than we've ever been able to make before. Almost twice the energy that we've been able to run
experiments at up to now. And this is important because this enables us
to look at the Universe in a regime where we have never studied it before. So we hope we can make measurements
of matter and antimatter that may suddenly not agree
with our theory at all and illuminate where we might find
that ultimate answer. We hope we might find evidence
for these new particles that might be associated
with deeper understanding and explain more of the Universe. But to be honest we don't really know. And we don't really know because we've never looked
at the Universe in this place before. It's incredibly exiting
because we really could find anything. And that's what makes this
such a wonderful adventure. And whatever happens, whatever we find,
we know thar 2015 onwards, we are going to learn
more about the Universe. And hopefully, that means
we are going to learn more about what exactly
the matter is with antimatter. Thank you. (Applause)
