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Professor Brian Cox

Brian Cox OBE is particle physicist, a Royal Society University Research Fellow and Professor at the University of Manchester.  He also works on the ATLAS experiment at the Large Hadron Collider at CERN.  He is the author of two best selling physics books with Professor Jeff Forshaw and co-host of the Sony Award winning radio series ‘The Infinite Monkey Cage’ with Robin Ince.  However, Brian is probably best known as a science presenter on hugely successful programmes such as Horizon, Stargazing Live and the Wonders series.  He was also a member of chart topping pop group D:Ream in the 1990’s.


There’s something about looking up at the stars, at the night sky, I’ve always found fascinating.

On becoming interested in science

It’s hard to remember what particular, or the particular causes of me being interested in science were, because I’ve always been interested.  I think it was astronomy.  There’s something about looking up at the stars, at the night sky, I’ve always found fascinating, then reinforcing that was certain people, certain physicists and scientists that I saw on television, in particular Carl Sagan who came along when I was twelve years old in 1980 with Cosmos which was, it’s hard to believe now that someone would put thirteen hours of science documentary on television over thirteen weeks.  I mean, thirteen weeks is a long time and so once you become engrossed in that, then every week Carl Sagan is on television that you can watch.  And that absolutely reinforced, it made an indelible impression, from that point there was absolutely no debate.  

Actually before that I don’t think there was any debate in my head either about what I wanted to be.  Certainly astronomy, I used to avidly watch Horizon when it was about astronomy or space exploration.  I vividly remember the Voyager spacecraft setting off on their journey to Jupiter and Saturn and then Uranus and Neptune.  I remember the Apollo Soyuz docking in 1975, um, so you know, I was interested from the age of four or five certainly.  

But it needs reinforcing certainly.  A lot of children are interested, as I was, in other things as well.  I was interested in dinosaurs.  Anyone who’s got little children will know that.  I was interested in Egyptology, again, anyone with little children will know that.  There’s all these things that seem to fascinate children.  Ancient Egypt, dinosaurs, astronomy, space exploration, it’s always the same things, so I suppose there’s an element of reinforcement somewhere.  You need to see something on television or you read a book or you meet someone and that’s actually important I think.  That informs a lot of what I do now because I genuinely believe that if you put ideas on television, so let’s talk specifically about the ideas that I want to talk about, or I find interesting, which is science, so you put science on television, that plays a big role I think in, if not lighting the spark then at least reinforcing a particular interest amongst children and I think that the more scientists and engineers we have in our society the better.  

And it’s not just my opinion.  You can look at research that suggests we’re short of scientists and engineers in this country (Great Britain) and so it’s important.  So I think it’s an important thing to give due credit to those moments of inspiration.  In my case it was Carl Sagan in Cosmos, I think that finally cemented my career as a scientist and therefore I think there should be more programmes like that on television.

On my work in particle physics

Well for years, actually twenty years now, I’e worked in an area of particle physics called diffraction, which some people think is quite arcane, but it’s actually fundamental.

There are four forces of nature, gravity by far the weakest, it doesn’t concern particle physicists at all.  The other three forces are electromagnetism, and the strong and weak nuclear forces.  And diffraction is, in the way I study it, is associated with the strong force.  So you have to think about what happens when you collide say, two protons together, which is what happens in the Large Hadron Collider.  And what happens if they interact strongly, is they exchange a particle called a gluon, and that carries something called colour charge, and ultimately that means that the protons fall to bits.  So you smash two protons together – protons are big bags of stuff, they’re large objects for a particle physicist – so they come through, they interact by the strong force and they fall to bits.  But, there‘s another form of interaction, by the strong force, which is called diffractive scattering.  And the way we understand it now is some configuration of these particles called gluons gets exchanged and we call that configuration, the pomeron, which, there’s actually been no, as an object, as a concept, this idea that protons can bounce off each other and stay intact has been known for many decades – it was actually known before the theory of the strong force, called Quantum Thermodynamics was built.  So it’s a fascinating interaction, that protons come along, they can, they can bounce off each other, exchange in this thing called a pomeron, which is some configuration of all these things called gluons, which, which conspire together to have the quantum numbers of the vacuum, that’s the interesting thing, so basically nothing gets exchanged in some sense, except that they get deflected.  So this has been studied for decades and decades and decades, so I worked on that for many years.  

I don’t know why I started actually, it was just an area.  This is often what happens when you start doing a phD, your supervisor has, has an area of interest and this was it, and I worked on it in a place called DESY which is the Deutsches Elektronen-Synchrotron in Hamburg, which is no longer operating, but that collided electrons with protons.  And the particular, bizarre in some sense area I worked on was when an electron comes along, a photon, which is like a particle of light comes off it and in certain circumstances those photons can be thought of as having a structure – which is bizarre when you think about it – a particle of light, you know you just think about those as individual, a stream of particles called photons, but actually they can behave like they have a structure, which they’re composed of quarks and gluons and you can write it down, it’s a way of modelling the way that they interact.  And so this photon floats off the electron with all it’s structure, a pomeron gets exchanged between the photon and the proton and you get this strange interaction with lots of particles around here, lots of particles around here and none in the middle because nothing’s basically got exchanged apart from energy, and you, and you can explore it.  So, so with that very long answer, things that I explored, the um, I suppose it is a fundamental property of the strong force which is one of the four fundamental forces of nature, and it’s the way it behaves in these strange interactions; the pomeron.  

Which I think someone told me that we should make little toys and sell them, cause it does sound like something you would give a three year old for Christmas, a pomeron.  I haven’t explored that yet.

On the theory of the one electron Universe

Well, the, one of the great mysteries – I say mystery, it’s a property of nature –  um, it’s a fundamental property of sub – atomic particles, is that at the basic level they are the same, identical, strictly, and that matters actually, cause it, it effects the way the statistics of the particles um, operate which effects the way they behave.  So, so, they, they’re absolutely, fundamentally identical.  Um, way back in the nineteen, I think it was the nineteen forties actually, Richard Feynman, talking to his supervisor Hans Bethe, suggested that the reason for this, particularly in the case of electrons, same as the other particles as well, was that there’s only one.  And he said that, well, is it possible that there’s this one electron, wandering backwards and forwards in time.  So if you imagine our reality as it is now, is it’s a kind of a sheet, then you could imagine this thing, zigging backwards and forwards going zig zig zig zig like that and so you see all these instances of the same electron crossing our reality as it were, just time and again, time and again, time and again, so they’re all the same particle.  It’s sort of a, it doesn’t help you in anyway that, and so it’s sort of faded away I think, as an idea.  

It’s a lovely idea but the fundamental point is that every electron is identical.  And what that means when you start doing the statistics of quantum field theory which describes how particles interact and behave, is that one electron there and one electron there is identical to swapping them round.  And this has a very, and there are actually two ways of performing that swap, which leads to two kinds of particles called fermions and bosons which have a different property called spin and that difference, which all comes from this identical statistics has real consequences for the way they behave.  An example would be the Pauli Exclusion Principle which is the reason you can only get, ah, if you imagine an atom with electrons around it the the electrons sort of pile up into orbits so they don’t all drop down into the lowest energy orbit around the nucleus.  If they did that you wouldn’t get any chemistry, chemical bonding, you wouldn’t get molecules and so we wouldn’t exist.  What happens instead is they have to stay way from each other.  You’re not allowed, strictly, to have two of these things in the same, strictly speaking, what we call a quantum state.  Or you can imagine it as these energy levels, or orbits if you would like, so you can’t have two electrons in the same orbit.  Now there’s always caveats in physics.  Basically you can have two electrons in there of the opposite spins right, but essentially you can’t have two electrons in the same quantum state, the same box if you like.  

So that means if you have a carbon atom with six electrons around it then they pile up and you end up with four of them in a higher orbit that want to bond with other things.  That’s why carbon can form other molecules, like carbon dioxide, or it can form long chain molecules so you get amino acids and proteins and all the molecules of life, that fundamentally comes from this behaviour of electrons which can be traced back all the way to their statistics and the way that when you swap them around you essentially do the sums which actually describes the behaviour.  So it’s a very important property that these things are identical and has very important consequences.  As I say without that, molecules wouldn’t exist, so an example of that is the Pauli Exclusion Principle.

On explaining physics to a mainstream audience

To take a recent example, the Higgs mechanism, the mechanism by which particles get mass, that’s a relatively easy thing to describe.  It’s mind blowing, the idea that in every cubic metre of space if you calculate, perhaps naively, the amount of energy taken up, the so called binding energy in the Higgs Field, per cubic metre, there’s more energy than the sun outputs in a thousand years.  Per cubic metre, which is a ridiculous thing to say.  By the way, why that doesn’t curve space-time in a ridiculous way which would actually cause the Universe to explode if you just work it all out naively, why it doesn’t do that is not known, so there are huge questions about the Higgs, but the idea that a vacuum is full of these things, of the Higgs Field, and matter gets its mass by interacting with it is actually something you can talk about.  And the reason, I think, is there’s a nice story to tell.  The theory’s been around for almost fifty years and everyone’s had a lot of practice in understanding it.  So whilst the mathematics of it are relatively difficult, although you teach it to undergraduate students so it’s particularly problematic, but anyway the actual ideas are quite simple.

I find that when I talk to audiences in talks, or on television, about the Higgs Mechanism, people understand it.  It seems, it feels understandable although it’s a rather bizarre story. But what they often say, and I’ve seen this said many times, about many physicists explaining things, is they get it while you’re talking about it and then the moment that they walk out then they can’t repeat it the pub although they try.  Although I’ve seen that said about comedians as well.  I think I’ve seen Eddie Izzard do a great part of his act on the fact that people try and tell his jokes and his jokes, you know, they make absolute sense at the time but the moment you walk out and someone in a  pub tries to tell the joke it all falls to bits.  And I think it’s the same with science a lot of the time.  And the reason for that of course is you’re using a shorthand and so to really understand the Higgs Mechanism and how it works you’ve got to sit there and do the maths, but you can still tell a story about it and I think that’s very important actually.

And it’s interesting the, I suppose it’s almost one of the problems about, or the challenges of communicating modern science is that really, to deeply understand it, you have to do mathematics.  Certainly physics.  Mathematics is the language of nature at the most fundamental level we know.  So if you’re talking about fundamental physics, language is not the appropriate language.  For some reason, it’s either a great mystery or obvious and I’m not sure there’s any grey area.  For some reason mathematics is the language of nature.  It could be that we live in a Universe that’s structured in a predictable way, obviously, I mean there are structures like planets and stars and light and civilisations in the Universe has to, well civilisation, there’s only one that we know of in the Universe, and so the Universe has to behave in a predictable way, there are patterns underlying nature and mathematics is the language of patterns, it’s the language that’s used to describe patterns.  So I’ve seen people say that that’s the reason.  That mathematics is a good guide however there’s a very famous essay by a physicist called Eugene Wigner called The Unreasonable Effectiveness of Mathematics in the Natural Sciences, and the key word there is unreasonable.  So you could also look at it that there’s some deeper mystery there, there’s something we’ve yet to understand about the Universe that, ah, means that the Universe is described in this language of mathematics.  Whatever the reason, it is, so therefore any explanation using language, the English language let’s say is going to be deficient in some way.

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