Transcript Sept 2007
Gareth Mitchell: From Europe's leading science university this is the official Podcast of Imperial College London.
And I'm Gareth Mitchell. Hello. When I'm here I'm a lecturer here in the Science Communication Group at Imperial and outside I present the BBC technology programme, Digital Planet. As for this podcast, it's a kind of magic as a rock star becomes one of the more famous PhD students to submit their thesis here. That's in just a moment. But also under pressure in a different way as Imperial scientists take the lead in the decade's biggest experiment.
Lily Mitchell: So I'm here in the experimental cavern and it is huge. I'd say about two times the size of Imperial's Great Hall.
GM: We chat to researchers at the heart of efforts to bring CERN's Large Hadron Collider on stream. And from the highly charged to high charges for using the roads. One of our civil engineers shares his thoughts on road pricing.
Bob Noland: Lots of people entering central London before were already taking public transport; something like 85 per cent of people entering central London. So most of the shift was people travelling around central London who would have gone through it beforehand.
GM: And we have some quick news headlines from around the College. That's all to come right here on the official podcast of Imperial College London.
Brian May explains why he swapped his guitar for a telescope
But first up an Imperial College PhD student has just submitted his thesis. And one of his extramural activities alongside being a student here at Imperial is playing in a rock band. And you might think, well, that could apply to many students. But not all of them are Brian May from Queen. But it is true, Brian, you have just handed in your thesis. It's a weighty looking tome in front of us. Just give us the title of this PhD.
Brian May: The title is A Survey of Radial Velocities in the Zodiacal Dust Cloud. It's an investigation into the movements of dust particles in the Solar System. We're actually surrounded by dust everywhere, not just like house dust or whatever, dust which is the result of various things. Probably collisions of asteroids, the remains of comets and even interstellar dust. But as you probably know we really are made of dust. Everything that we see around us has been inside a star. Dust and gas are the components of everything. It's the study of dust which is quite close to us in the Solar System, between us and the Sun and a bit further out as well towards about as far as Jupiter. And what we were doing was looking with a spectrometer looking for Doppler shifts in the light which is reflected from this dust.
GM: So what kind of insights do you get into the dust by studying it then?
BM: Well, the questions that you want to ask are where did it come from, what's it doing and what does it have to do with the creation of the Earth and the other planets? So in studying its motions we have a unique way of getting some insights into where it came from. That's the big question I suppose, you know, what's it doing there? What does it have to do with us?
GM: And I notice that in the title in of your thesis is the word ‘motion' so you're not just interested in the dust as a static entity you're actually interested in the way it moves as well then?
BM: That's right. Most of the studies of the zodiacal dust cloud that have been done have been photometric, you know, just measuring how much there is there and what's the brightness, what's the distribution? And it's an unusual technique to actually measure the velocities. Actually astronomy is full of Doppler shift investigations but it's quite unusual to apply it to this dust cloud. It's unusual because it's very difficult to do, in fact. It's hellishly difficult to do in fact.
GM: Is this partly why it took too so long to do it then?
BM: Well, yeah, maybe. I mean I had to build the instrument. I had to build a thing called a Fabry-Perot spectrometer which is a much more luminous instrument than most of the spectrometers, which are done with a slit and a grating. So it's a very specialised instrument which gives you the best chance of gathering enough photons to get some clue as to what's going on. The instrument that I built in 1970 is very crude by today's standards so I'm hoping to go back and repeat the observations with a much better system. Nevertheless, we got good enough spectra to make some conclusions. And the conclusions we drew were roughly that certainly some of the dust is in prograde orbits. In other words going round the Sun in the same way as the Earth is. Some of it probably isn't and some of it may be drifting through the Solar System. And we were able to make some estimates of the size of the particles. So in a sense it's early days with this kind of investigation. But certainly it looks like if we got more accurate measurements we would be able to answer some more questions.
GM: So it's a kind of proof of principle then? That this is a viable technique for studying this kind of dust?
BM: Yes. Fortunately we published my results in two journals. We published an article in Nature and an article in Monthly Notices of the Royal Astronomical Society. So the stuff is documented which actually makes it a lot easier for me to defend my thesis because what I can say is, look, the observations are there and they've been quoted by other people. And they were actually the first complete survey around the ecliptic of these measurements.
GM: And the back story being that this is work that you started off as a student here at Imperial College in the 1970s when you hung out with the rock band and the rest, as they say, is history. So was it that you did the observations back in the 1970s and the bit you've been finishing off writing up this thesis is actually tabulating and analysing and communicating the results?
BM: Yes, more or less. Although in fact I did most of the analysis in those days as well. I've reinterpreted some of it in the light of what we know now.
GM: And the obvious question, I know everyone is asking you this, so why now? Why come back and finish this PhD? Because I assume that you're not, well, maybe you are; are you setting out now to be a career scientist or are you still Brian May the musician but this was unfinished business for you scientifically?
BM: I think I'm just Brian May the curious mind really. I really have a passion for unusual things. And this was unfinished business in the back of my mind for 30 years I suppose. And I'm thrilled to be able to have the opportunity to go back and tie things up so I can hold this tome in my hand. But it's more than that because this opens some doors. And we've already discussed the fact that I'll stay on and hopefully do some more observations. And it's the observations which I love. It takes you to the most beautiful places in the world and it brings you close to the Cosmos I guess.< p>GM:And what are the parallels between doing this as a scientist and your work as a musician? I mean as you go about finishing a thesis like this was it a little bit like finishing off an album, you know, there's some point where you've just got to let the album go and do that last over-dub and then send it off and get it cut? Was it a bit like that with this thesis, just knowing when to finish it?
BM: Very much so, yeah. You've hit it on the head, yeah. I had to really chuck everything out of the window. I mean I had to stop doing almost everything to finish the thesis at some point. Having made that commitment I really had to go for it. And there were some difficult times. But, yes, very much like an album. Very much like a piece of music because you want it to be perfect and you want it to be everything that you dreamed it could be. But at some point you have to stop.
GM: I'd imagine you have a reputation for being somebody, you know, you must be a perfectionist and the rest of the people are saying, come on, the album is done Brian. Just leave it. Move on. Is that what you're like as a musician and what you're like as a scientist?
BM: That's probably a fair comment, yeah. I'm usually the guy who's in there till five in the morning tweaking things, yeah. There's a kind of push-pull thing that goes on because you have to have perspective. You have to have an overview. So you have to step back quite often. But there are times when you have to step right in and look at the detail and the little nuances which make all the difference. So you have to have an incredibly adjustable zoom lens I think to make the best of anything really, art or science. That's my feeling.
GM: What's it like to be back here after what must be quite an interesting career break for you?
BM: It's very curious. I feel a bit like that book by H. G. Wells called The Sleeper Awakes. I don't know if you've ever read it. It's not a very well known book. But the guy sort of goes to sleep for some reason and wakes up a hundred years later and has to deal with all the changes. It's a bit like that for me because it looks pretty similar, a lot of it, and I walk around and I see a lot of the same landmarks. And I walk into the same physics building and the same lecture theatre is still there.
GM: It's hardly changed a bit has it?
BM: But there are subtle differences. There are pictures on the walls. There are all these clues that an awful lot has happened since I've been here. There are pictures of the heads of departments and a lot more pictures around the place. It's also a lot more student friendly. There's a lot more of a campus than there used to be. It used to be a bit of a cold place, Imperial College. You tended to go out for your entertainment. But now there's a real feeling of community here. It's odd. It's very odd. And of course I'm a bit of an oddity here, you know, I can't really blend into the background. People look at me in a very strange way a lot of the time.
GM: Any invitations from the Rock Music Society then to join in?
BM: I've had various invitations but again I've resisted everything up to now because I didn't want to get too embroiled in enjoyable life because I wanted to do the job. I thought it would get in the way if I was too visible.
GM: So what's your biggest achievement then Brian? Is it this thesis in front of us or Bohemian Rhapsody? There's a question.
BM: It's hard to compare really. Bohemian Rhapsody really is a triumph for Freddie. Yes, we all contributed. Yeah, I'm really proud of what I contributed to it but that has to do down as a Freddie masterpiece really. I don't know. I have a strange feeling that in a hundred years' time people will probably care about the music more than the zodiacal lust. Zodiacal lust? There's a Freudian slip. But for me they're both important. I love the fact that I can reach into both areas and enjoy them. I'm actually excited, very excited, by music and by astronomy. And for the first time in my life I'm able to actually contribute to both. I'm in a very fortunate position.
GM: Well, it's lovely to have you back Brian. Thank you very much.
Brian May and his zodiacal dust right here on the official podcast of Imperial College London with me Gareth Mitchell. And still to come, how best to manage Britain's crowded roads and when is walking a better and safer option?
Headlines from around the College
Right now though let's have some quick headlines from around the College.
Imperial researchers who've taken the lead in the largest ever trial investigating the effect of blood pressure lowering drugs in the very elderly have stopped the study early after finding significantly reduced mortality in those receiving treatment. The patients in their 80s were given either a placebo or a blood pressure reducing drug called and ACE inhibitor. In line with previous studies the ACE inhibitor reduced stroke and other cardiovascular problems. But contra to earlier research those taking the drugs also lived longer. The doctors leading the trial say that the results bode very well for particularly elderly patients with high blood pressure as ACE inhibitors reduced stroke and helped them live longer.
And staying with affairs of the heart but this time on an emotional level. A turbulent romantic life can damage your health. That's what Professor Martin Cowie of Imperial's Faculty of Medicine told the Daily Mail newspaper recently. He was speaking at an event to launch the Heartfelt Emotions exhibition at the new Wellcome Trust Centre near Euston in London. According to Professor Cowie falling in and out of love is stressful, taking its toll on our bodies as our pupils dilate, our palms get all sweaty and adrenaline courses through the body. The burden is actually similar to that suffered by stressed workers for whom the pressure is sometimes enough to lead to fatigue and flu like symptoms. So be warned.
Well, I don't know about breaking hearts but if it's breaking news that you want from the College before it even gets into the newspapers just visit our Press Office website. You can do that at imperial.ac.uk/news.
Tejinder Virdee on the biggest experiment on Earth
Right then, well now to the massive particle physics lab CERN which is due to switch on its Large Hadron Collider within the coming months. As the lab and the scientific community at large brace itself for the world's biggest science experiment in the quest for the most fundamental of particles, Imperial College is taking a lead in making it all happen. Science Communication MSc student Lily Mitchell has been speaking to some of the Imperial team involved.
Tejinder Virdee: The most elegant theories we can write contain massless particles. We exist. We have mass. If our theories only used massless particles it cannot describe the nature as we see it. So what is the origin of mass, if you like? How do particles get mass?
LM: Professor Tejinder Virdee of Imperial College is the spokesperson and lead scientist of the CMS and he explains how the Higgs might be the missing piece which completes our current understanding of physics.
TV: We have theories. I go into a bit of jargon. Two of the forces. One is electromagnetism. The other one is weak interaction which is the interaction that powers the Sun. Now, we know they're quite different phenomena but we call them unified because at high energies we cannot tell the difference. Now, forces are transmitted by other particles. For example, the electromagnetic force is transmitted by the light particle of the photon. And the weak in teraction is transmitted by part icles called the Ws and Zs. Now, the W and Z particles have a very high mass. They have a mass of a hundred times a proton. So we have a theory which has on the one hand a photon which has no mass and on the other equivalent heavy photon, if you like, with a mass of a hundred times the mass of the proton. Why are the masses so different? There must be some mechanism which gives mass to particles. More specifically, gives mass to the Ws and Zs and leaves the photons massless. This is what the origin of mass problem is, if you like. So one of the conjectures is that there is a field which pervades the Universe and the field is called the Higgs field. It is a quantum field and particles interact with this field and acquire mass. It's as if you take a ball and you pass it through treacle and you see it move very slowly. So there is some resistance to motion and that we can ascribe to something like mass if you wish. So the particles actually interact with this field and acquire mass. The strength of the interaction with this field: higher the strength, higher the mass. Since this is a quantum field the quantum would be the Higgs-Boson. We then go look for the Higgs-Boson. So if we find the Higgs-Boson we know that this field exists and that's how mass is generated.
LM: Claire Timlin, a PhD student now based at CERN, tells me how the accelerator and the new CMS detector at CERN are designed to allow scientists to hunt down the Higgs.
Claire Timlin: It was Einstein that told us that mass and energy are related through his famous equation E=mc². So the Higgs turns out to be a very heavy particle in particle mass terms and in order to create it in our detector we need to create a lot of energy. So in order to do this we take particles and we accelerate them to very high energies and then we smash them together, essentially, and create new massive particles. So this is the way that we can create the Higgs particle. And at the LHC, the Large Hadron Collider at CERN, we have enough energy and enough collisions going on that we can create lots and lots of Higgs particles if they exist. But an extra point to say is we don't actually detect the Higgs particle itself. We detect the particles that the Higgs decays to. What we have to do in our detector is start to look for signals of the decay particles of the Higgs. So I'll just go into one example of one decay channel that the Higgs-Boson goes to. The Higgs can actually decay to two photons. Now, this is a rare decay but it is a very obvious signal because what you see in your detector are two very high energy photons going off in opposite directions. So this is why CMS, the Compact Muon Solenoid, which is the detector I work on, has a very good calorimeter for measuring the energy of electromagnetic particles such as photons. So if the Higgs is there and if it is in the mass range where it decays to two photons we should be able to see it. And not only should we be able to see it we should be able to measure its mass very, very precisely.
LM: So there's the theory now where's the action? Right, so here I am at CMS. I'm above ground at the moment. I've just been handed my yellow hard hat and we're at the top of the lift and we're going to descend 150 metres underground to where the detector is located. So I'm here in the experimental cavern and it is huge. I'd say about two times the size of Imperial's Great Hall. Within the cavern the detector is currently being assembled and there's a flurry of activity with engineers and scientists working together. I got the opportunity to climb up into the middle of the cylindrical detector because the innermost element, known as the tracker, had not yet been installed. Dr Costas Foudas accompanied me and described why many self detectors are needed and how they will reveal what events have taken place.
Costas Foudas: You see you're trying to detect different types of particles. So what you're seeing there is designed to detect electrons or photons.
LM: You're pointing out a ring of crystals?
CF: Yeah, this is a ring of crystals. So if photons go through they'll stop right there, the electromagnetic calorimeter. If on the other hand pions go they will go most likely thorough this and stop at the next level.
LM: And what is the next level?
CF: This is this brass ring that you're seeing which is the hadronic calorimeter. So this is where you can tell which particle is which. So if you see energy deposited in the electromagnetic calorimeter and nothing in the hadronic this means most likely it was an electron or a photon. If you look in the tracker an electron will leave a tracker; a photon would not. So by combining all these three you know if it's an electron or a photon. The whole thing is to tell you which different particles go through so you can identify where the decay products of the Higgs are.
LM: The stupendous computing power installed at CMS sieves out those collisions that are worth investigating further in the search for the elusive Higgs.
TV: This is where we make the trigger of the experiment. So there are bunches of protons. Each bunch contains about a hundred billion protons and these bunches cross every 25 nanoseconds and 20 pairs of protons interact. So there are 40 million crossings occurring and we have to reduce that to a hundred thousand. That happens here. The way we reduce it is to look at energy, high energy, going at 90 degrees from the beam line, if you wish. That tells us that we've had a head-on collision.
LM: I met Tiziano Camporesi who is the Global Commissioning and Run Coordinator and has the task of getting this massive project live for the second quarter of next year.
TC: CMS is composed by something like eight different parts. These parts have been working as a federation until now and now they have to start to work together. And so far so good.
LM: The good thing about CMS is that it is a general purpose detector so if it does not detect the predicted Higgs it certainly will find whatever it is that generates mass.
GM: Lily Mitchell reporting there from CERN on the Imperial scientists doing there thing to track down the elusive Higgs-Boson.
Bob Noland uncovers the unforeseen effects of traffic policies
So now let's talk about transport to finish off this podcast. Obviously an issue close to many people's hearts, especially those who use the roads a lot. I'm speaking now to Dr Bob Noland who's a reader in transport and environmental policy and he also heads the Environment and Policy Research Group within the Centre for Transport Studies within the Civil Engineering Department here at Imperial. Bob, just give us a sense of what your primary interests are in terms of transport.
BN: Probably my primary research area is to look at how transport policy impacts on people and on transport in terms of environmental impact, safety impact, economic impacts.
GM: One of the many things that you're interested in then is the idea of a congestion charge. And I could imagine there are probably as many different definitions of the congestion charge as there are people that you'd ask for definitions of them. How would you define it?
BN: Well, ideally a congestion charge is a charge on travel that charges people for travelling in the most congested time periods such as morning peaks or evening peaks or various areas that are highly congested. And the idea behind that is to give an incentive to travel either at another time of day, take a different route or go to a different area or perhaps not travel at all or even take public transport or cycle or walk.
GM: And does the research suggest that a congestion charge does what it suggests it should do which is to relive congestion?
BN: I think the evidence is they've had a traffic reduction in central London so on those grounds it's been relatively successful. However, most people entering central London before were already taking public transport; something like 85 per cent of people entering central London. So most of the shift was people travelling around central London who would have gone through it beforehand.
GM: And alongside congestion charge another aspect of managing traffic on Britain's roads is whether you widen existing roads. What effect does that have? Does that make the roads easier to travel down or do you just have more people using them and so the net effect is pretty much the same amount of congestion?
BN: Yeah, this has been a controversial issue for a long time. And there was a study in the UK back in 1994 or so that suggested that if you widen the roads you get more traffic on them and mainly that this had implications on how we assess the roads. The theory is we increase the capacity, we're reducing the cost of travel since the main cost is your travel time. So we expect to see an increase in travel over the long term and eventually you get the same levels of traffic on that road which might be just as congested as before. So your benefit is partly more people travelling. Perhaps travelling when they want to rather than at off peak times. But then again you get these economic effects in terms of where businesses and residencies may locate. So in some cases it may mean that you get more opportunities to develop plots for housing that's further out. So maybe the benefit is people can buy a larger house at less cost but their commute may be just as long.
GM: And some of those benefits may translate into wider economic benefits?
BN: Perhaps. It's possible. But then we have to also look at the external costs such as environmental costs associated with getting people further out and perhaps travelling more than they did previously.
GM: And I'm glad you mentioned the environmental aspect there as well because I know that one other research area that you have an interest in is pedestrians; I assume the most environmentally friendly form of transport. What benefits are there to more people walking to their destinations instead of jumping into their cars?
BN: There's been a lot of research in this over the last 10 or 15 years or so. And one of the benefits is that you can think of a city that has a lot of pedestrian activity as being a more exciting place to be to engage in activities as opposed to a city that's just car based. And what tends to happen, and in some work we've done work here is looking at how some of the traffic policies, mainly how we set signal timings and such. These tend to favour the cars. So we want to get all the cars moving through the network very quickly and we ignore the pedestrian. So the pedestrians are sitting there on the side of the road or sometimes in the middle of the road in one of these cattle pens waiting to cross. So an interesting question there is how does this affect exposure to pedestrians? So the traffic engineers say if the traffic is moving by quickly that's a good thing because of the various dynamics of how the engine operates were such that you might get a reduction in emissions. But if you start looking at exposure it's actually better to move the pedestrians out of the way, away from the traffic, more quickly. So get them through the system quicker and let the cars stop at the light a bit longer.
GM: And so how much of an issue is that in road design or in urban planning? Is there a drive now to try and get more people walking?
BN: Well, certainly in London there's been a big drive for that and a lot of interest in how they can change signal times as such to favour pedestrians over vehicles.
GM: Bringing all this together then what does it mean ultimately for climate change?
BN: That's a very difficult question. Everyone has their little pet solution, whether it's a technology solution. We're hearing a lot about bio-fuels these days as the solution. There's potential there but there's still a lot of problems with various approaches. People are talking a lot, at least in the US, about corn based ethanol as a bio-fuel but that has a lot of problems in terms of whether it really reduces your carbon emissions. There are other feedstocks that might be more effective. And a lot of research is going into those sort of technologies. A few years ago hydrogen was what everyone was talking about but that has lots of problems because for the most part you've got to burn the coal or pull the hydrogen off coal to get essentially through various processes and that generates carbon. There are other approaches that people need to start thinking about. The first one is how we design cities to try to reduce the need for travel. So that feeds in with a lot of these policy approaches to try to get people to take other modes of travel, other modes of transport, more public transport, perhaps walking more. And one issue that people tend not to talk a lot about is speed, speed reduction. And that's an area that I'm quite interested in getting into. It's understanding that a little bit more. Because it's actually a very effective policy to reduce carbon emissions.
GM: Do you mean speed reduction in terms of what is often known as traffic calming then? Just putting measures on the roads basically to make people drive a bit less quickly?
BN: Traffic calming is definitely one in a residential neighbourhood. That certainly has lots of safety benefits. There's some questions in terms of how that affects particular emissions based upon how people drive through traffic calming areas as well as perhaps how that affects the efficiency of the vehicle. But for safety it's certainly a good policy. But certainly on motorways the speed limit is 70 miles per hour in the UK. It's a bit higher in a lot of European countries. It's a bit higher in the US now, in some states at least. And reducing that speed limit to 60 mile per hour could get you several per cent reduction in your carbon emissions, which is significant. It's all these little things that tend to add up in what drives our carbon emissions. But we're looking at the economic trade offs here and it would probably be quite difficult to have motorways that are only 30 miles per hour.
GM: Yeah, it might be a bit politically unacceptable.
BN: Although a lot of them are when it's congested.
GM: Bob Noland there pretty much wrapping up for this month. We'll have plenty more for you in our October edition. The official podcast of Imperial College London is available on the first working day of each month and is a co-production of the Science Communication Group and the Imperial College Press Office. Ozgur Buldum is the man who wrote this theme tune. It's called Lila and you can hear more of Oscar's work at ozgurbuldum.com.
So thanks for listening but from me Gareth Mitchell it's goodbye for now.