Nature Podcast

This is a transcript of the 24th April edition of the weekly Nature Podcast. Audio files for the current show and archive episodes can be accessed from the Nature Podcast index page (http://www.nature.com/nature/podcast), which also contains details on how to subscribe to the Nature Podcast for FREE, and has troubleshooting top-tips. Send us your feedback to podcast@nature.com.

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Adam Rutherford: Conspiracies, cosmic mysteries, sceptics, and conjurers on the pod this week.

Sharon L. Weinberger: It had more conspiracy theories than Kennedy's fascination. You know, it has been claimed that it could alter the weather, that it is a dust beam. One of the prominent theories is that it is a mind-controlled device. It's even shown up in a Tom Clancy novel.

Adam Rutherford: Find out what experiment that is later in the show.

Kerri Smith: We discover what really happens at the middle of black holes.

Alan P. Marscher: This was one of the great cosmic mysteries for quite sometime, since we discovered the jets in the 1970s.

Adam Rutherford: And a sceptical double-bill with the Bad Astronomy blogger Phil Plait and conjurer James Randi.

James Randi: As a Conjurer travelling all over the world, I find that the so-called psychics are using exactly the same tricks that we magicians use.

Adam Rutherford: This is the Nature Podcast, I am Adam Rutherford.

Kerri Smith: And I'm Kerri Smith. We've got a bumper show for you this week and to start us off, we hit upon an unexpected climate change culprit. Here's Charlotte Stoddart to tell us more.

Charlotte Stoddart: In recent years, the forests of western North America have been putting on a spectacular show of colour, but this beautiful patchwork of green and red tells a worrying story. The red leaves are a sign that the forest's pine trees are dying from an infestation of fungus-carrying beetles. The current beetle outbreak is more severe and covers a greater area than any other on record. And researchers from the Canadian Forest Service believe that it's turning large areas of forests from a net carbon sink to a carbon source. This means that rather than moping up human carbon emissions, as they have done in the past, these forests could contribute to global warming. Lead author of the study, Werner Kurz told me more. Nature 452, 987–990 (24 April 2008)

Werner A. Kurz: The mountain pine beetle is a native insect of the pine forests of western North America. Its populations erupt periodically into large-scale outbreaks. The current outbreak is unprecedented in magnitude and severity. It is larger than all previous outbreaks that are recorded. These large numbers of beetles attack pine trees and when they do that they bore into the cambium of the tree, they bring with them a fungus and the joint impact of the beetle and the fungus kills the tree. These trees then die and start decomposing over time and in doing so, they release carbon dioxide back into the atmosphere.

Charlotte Stoddart: The outbreak in British Columbia, which you just referred to, that's the one that you've been studying. Could you tell me a little bit more about the effects of the beetles in this particular case?

Werner A. Kurz: Yes, what we have found is that these beetles are attacking as they always do to pine trees, but because of their unprecedented numbers, they have impacted a larger area than previously recorded. This is the result of a number of preconditions, we had very large scale forest fires in the late 1800s and early 1900s and these large forest fires have set up large tracks of pine forests that are now of an age that is susceptible to the pine beetle. In combination with that, we had a series of warm winters allowing the pine beetle to spread northward and into higher elevations and the combined impact of it, a large available host area and the favourable environmental conditions have allowed this pine beetle outbreak to reach a magnitude previously unrecorded.

Charlotte Stoddart: You've estimated the impact that these beetles are going to have on the carbon balance of these forests up to the year 2020. What are you predicting?

Werner A. Kurz: We have looked at the impacts of the pine beetle on the carbon cycle and we identified two impacts. First, by killing the trees, the uptake of carbon dioxide from the living biomass is reduced and secondly, all these dead trees will then decompose in future years, thus releasing greater amounts of carbon dioxide into the atmosphere than would be the case without the beetle. In fact our analysis indicates that over the 20-year period between 2000 and 2020 the cumulative impact of the beetle is about a 270 million ton of carbon and nearly a billion ton of CO2 release into the atmosphere. In addition to that, we respond through management activities namely the salvage logging of dead trees, and in doing so, we also harvest some of the live trees, that combined impact adds another 50-million tons of carbon.

Charlotte Stoddart: To give listeners an idea of just how significant this is, can you compare it to, say, the amount of CO2 released by car emissions?

Werner A. Kurz: The annual emissions from fossil fuel burning in Canada in 2005 were about 747 million tons of CO2, so this 20-year impact of the beetle exceeds the total fossil fuel emissions from all sources in Canada in a single year. So it is a very significant amount. The beetle impact in the worst years are about 75% of the average fire emissions from all of Canada.

Charlotte Stoddart: And in your paper, you argue that these emissions need to be taken into account in climate models. Is this not happening at the moment?

Werner A. Kurz: To our knowledge, none of the large-scale climate models take impacts of insects into consideration at this time. But these are important because the feedback role of insects and wild fires to the carbon cycle needs to be understood because we are currently working in a global carbon cycle system, where forests are taking up and terrestrial ecosystems are taking up a significant component of the fossil fuel emissions into the atmosphere. If insects and fires reduce forest carbon sink strengths or revert forests resources, then the rate of CO2 increase in the atmosphere will increase and this will work against human efforts to reduce CO2 concentrations. In other words, insects, fire and other natural disturbances provide positive feedback, global warming will feed future warming.

Adam Rutherford: Werner Kurz there. Coming up in just a moment, we'll be hearing from the bad astronomy blogger, Phil Plait. But first a collection of giant-looming antenna in Alaska has been generating scientific data and paranoia in equal measure, here's Geoff Brumfiel.

Geoff Brumfiel: Every now and then a scientific experiment, finds itself at the heart of a grand conspiracy theory. But few experiments have been the subject of as much rampant speculation as the High Frequency Active Auroral Research Program or HAARP. HAARP is meant to study the upper atmosphere, both for scientific and defence purposes, but it has been suspected of doing a whole lot more. Freelance writer, Sharon Weinberger, writes about HAARP in this week's issue of Nature and I spoke to her about the project. Nature Published online (23 April 2008) | Nature

Sharon Weinberger: Well, it's basically a series of some 180 antennas, basically about 200 miles from anchorage in Alaska, and it's an ionospheric heater and in that sense its nothing that unique. An ionospheric heater, it basically, the radar sent radio waves, you know, up between, at least in HAARP's case between about 100 and 350 kilometres in altitude. This accelerates or heats the electrons in the ionosphere, which allows you to, sort of, turn the ionosphere into something sort of akin to a natural laboratory. You can begin to sort of alter the things that are going on there, which in a laboratory, you know, you can't mimic these processes going on.

Geoff Brumfiel: So, I understand that the experiment, there's been a lot of, sort of, conspiracy theories about what it's actually doing and I have to say, looking at the picture, which appears with your feature, it does look like something out of a James Bond movie almost. You have all these, sort of, strange-looking antennas in this giant array. What have been some of the ideas about what HAARP is actually there for?

Sharon Weinberger: It's had more conspiracy theories than Kennedy's assassination. You know, it's been claimed that it could alter the weather, that it's a death beam. One of the prominent theories is that it's a mind-control device, it's even shown up in a Tom Clancy novel, where someone takes it over and uses it to induce mass psychosis in a Chinese village. The underlying party's conspiracies are that it is a web and that it is some sort of operational system, something that the military and the scientific community vehemently deny.

Geoff Brumfiel: Why do you think HAARP has been the subject of all these speculation?

Sharon Weinberger: You know, I have actually given that a lot of thought, because you mentioned that it looks a little bit, you know, ominous, but it doesn't look as bigger, but it doesn't look that much different than other ionospheric heaters. I think the reason why there's been so much conspiracy behind it is the origins of it, where there was this tensions that, on one hand it was a military funded project, but there were always scientific goals going along with it, and so the way that the military justified the facility, always had a little bit of sort of a moving target. I mean, the original goal was it was going to be an extremely low-frequency means of communicating with nuclear arm submarines. This testing of concept for using the electrojets, as sort of a virtual antenna to communicate with the submarines and then is that need to communicate with submarines started to go away, the military began to come up with other reasons why it should continue that. You can use ELF to map out underground facilities and finally its current incarnation with us saying they can be used to counter the effects of a high-altitude nuclear detonation. And those sort of morphing justifications, I think in some ways fed into the conspiracy that "oh! You know, they are not giving us the real reason."

Geoff Brumfiel: What's the current use that's being advanced by the military?

Sharon Weinberger: So, the idea that military has long been concerned, going back to a test in the 1960s that a nuclear weapon exploded at high altitude. While it does not kill anyone on the ground, it resulted in the sort of killer electrons that take out the electronic satellites in low-earth orbits. So, you know, in the 1960s when there was a nuclear detonation, and this happened, you know there weren't that many satellites up there. Now the number of satellites have proliferated economically, its much more important, it could have a devastating effect and the idea that a HAARP-like facility could counter this, goes all the way back to 1985, but there was basically a panel held in 2002, looking at HAARP and saying well, this could be not an operational facility that counter this, but a way to test whether we can really counter or force these killer electrons to precipitate, you knock them down basically into lower altitudes until they precipitate naturally. And this has become the focus of military interest in the facility, not necessarily the scientific interest, but specifically of the military interest.

Geoff Brumfiel: And what about the scientific interests in HAARP. Tell me a little about all that?

Sharon Weinberger: Well in some ways, what has worked out almost amazingly well or surprisingly well for the facility is that the scientists are interested in this question. You know, may be not to the point of whether you can technologically do it, but the scientific processes, the mechanisms underlying this, how lightning and aurora precipitate electrons, you know, how this all works is of interest to the scientific community. So luckily there is some convergence there. You know, there are of course other things that you can study with ionospheric heater. So, this is not to say that the scientific interest is divergent with the military, but the scientific community also gets a lot more out of it. This provides a facility where they can do other tests. I mean, they are paying sort of a huge bill to maintain a scientific facility and so it has benefits for both sides.

Kerri Smith: Sharon Weinberger harping on to Geoff.Jingle

Kerri Smith: Later on, we'll be solving a cosmic mystery rather than spreading conspiracy theories. But now it's off to Imperial College, London, where Mike Hopkin has been testing the waters.

Michael Hopkin: They say you are what you eat, but now it seems that you can also tell a lot about someone from what their body throws away. That's the message of a new study analyzing urine samples from more than 4600 middle-age people in China, Japan, Britain, and the United States. The aim was to search the samples for hundreds of metabolic products, to see which ones are associated with high blood pressure and also how different national diets, from burgers to sushi, influence the production of these compounds. Here's researcher Paul Elliott. Nature advance online publication (20 April 2008)

Paul Elliott: The idea was to have very detailed information on dietary intakes. So for each individual, we saw them each four times and we asked each of them on each occasion to give us a very detailed dietary history of what they had eaten in the previous 24 hours. So, we have a very detailed dietary history and we measured blood pressure on each of those occasions for those individuals and the idea was to look at individual level of what that particular person was eating and also what they were excreting in their urine, again we collected 24-hour urine collections on each individual. In relation to their individual blood pressure, in two different settings as you say, in East and West.

Michael Hopkin: The study found new molecules, or biomarkers that have not previously been linked to high blood pressure, and it underlines once again, how some national diets are healthier than others.

Paul Elliott: Well, we know there are, as you said earlier, well known dietary differences in terms of the total fat contents of the diet and the carbohydrate content of the diet between East and West, so clearly we saw those differences. But we also found quite marked metabolite differences between groups related both to the gut microflora to some dietary variables including amino acids. We know for example that the Chinese and Japanese are closely related genetically, but in terms of their metabolism and the excretion of metabolites, that we were looking at in the urine, they were very different, and they map very differently when we looked at those data. And for example, when we looked at Japanese who are living in America, compared to Japanese living in Japan, Japanese living in America looked more like Americans in terms of the metabolites that they excrete in the urine than they did like Japanese. So, overwhelmingly we are looking at environmental factors, particularly related to diet, that is distinguishing between the different groups.

Michael Hopkin: The technique could potentially be used to study a wide range of other health problems and as Paul Elliott's colleague, Jeremy Nicholson explains it's an approach that actually tells us about what's going on in the body, unlike other methods that only look at genetics.

Jeremy K. Nicholson: For instance, you might have a thousand metabolites measurable in your urine and I might have a thousand, but they wouldn't necessarily be same thousand, and that's one of the things that comes out. There are some metabolites that you get in Chinese people, and you don't get in British people. The metabolites that come out of these studies, give you particular pathways to focus on that link to the disease risk factors.

Michael Hopkin: The samples were first collected 10 years ago and they should be useful for years to come, potentially helping in studying other widespread problems such as obesity, says Paul Elliott.

Paul Elliott: Generally, I think it has got very wide applicability. Within our own study, we are also interested in obesity and we have very good measures of height and weight, body mass index and certainly one of the next studies we will doing, we will be looking at how the metabolism affects obesity and again we are not looking just at disease and non-disease people, which is commonly done. We have population samples and we have this sort of full gradation from thin to fat people in both East and West and of course the obesity epidemic has really taken off in the USA and is beginning to take off in an informal way in the UK and hasn't yet really taken off in the Eastern zone. So, these are extremely interesting contrasts.

Michael Hopkin: And that means that all the effort involved in collecting the urine samples will have been worthwhile, including the entire Chinese village who are asked to contribute to the study.

Paul Elliott: I guess, once everyone is doing it then everyone understands what it is, but you have people carrying around jars of urine, about their everyday purpose, so it is quite an interesting event, I guess.

Michael Hopkin: Not a bad effort for something that most people don't think twice about flushing away!Sound of water flushing

Kerri Smith: Paul Elliott and Jeremy Nicholson of Imperial College, London. And speaking of London, last week arch-sceptic and conjurer, James Randi, aka The Amazing Randi, was in town. So Nature showed him some British hospitality in the form of a few pints at a local pub. Charlotte went along to catch up with him.

Charlotte Stoddart: Every couple of months Nature Network, the social networking forum for scientists, holds a drinks event in a London pub. This evening we're in the Rugby Tavern and we are honoured to welcome a very special guest, well-known magician and investigator of pseudoscientific claims, James Randi. Hello James!

James Randi: Hello there! We are sitting outside the pub let's say and we're freezing, but the noise level inside is a little bit of a competition to us.

Charlotte Stoddart: Well, that's right. There are lots of people here tonight inside and enjoying themselves. Now James, you are normally based over in Florida.

James Randi: That's correct, yes.

Charlotte Stoddart: So what are you doing here, this side of the Atlantic, in the UK?

James Randi: Well, I had been invited over here to consult contracts, possible contracts to do a series about the Million Dollar Challenge that the James Randi Educational Foundation offers and brining it to the UK, liable liable so to speak, it should be very interesting.

Charlotte Stoddart: So tell me a bit more about your foundation and this million-dollar challenge.

James Randi: Well, the foundation is an educational foundation and we are devoted not to debunking, no, just investigating so called things of the paranormal, occult and supernatural and we tried to bring a little bit of enlightenment to the public in general and information about what these things really are or not. There is a widespread belief all around the world that there is a supernatural world, a paranormal and occult world. I rather doubt that and I'm willing to be shown -- I'm a million dollars worth of willing to be shown, because we offer this prize.

Charlotte Stoddart: And has anyone come close to winning the prize money yet.

James Randi: Well, it's like being pregnant. You can't come close to it. You either are or you are not. So, we designed the rules and the protocol in such a way, with the agreement of the person who is answering the challenge, we designed it in such a way that it's extended up, at the end of the test you will know yes or no, whether they succeeded or failed. And so far they all get exactly what would be a chance of expectation.

Charlotte Stoddart: Now James, I hope you don't mind me mentioning your age, because you are in your 80th year now.

James Randi: Right!

Charlotte Stoddart: So I'm just wondering what it is that keeps you going, keeps you travelling and talking about science?

James Randi: Well, it's not the expectation, as some people have thought that I'm going to find a genuine psychic. My expectation after 80 years of into this is that there probably isn't such a thing as a psychic power. Now I don't say there isn't and I never claim there is not such a power. I am really saying I am an investigator and I am willing to be shown, but it is a very active field and I find that people all over the world are either being deceived or deceiving themselves about belief in the paranormal.

Charlotte Stoddart: You started off life as a magician, so how did you become more interested in the paranormal and pseudoscience and investigating these areas.

James Randi: Well, as a magician, that is a conjurer more correctly. As a conjurer, travelling all over the world, I find that the so called psychics are using exactly the same tricks that we magicians use, mis-directions and the half statements and what not. It's rather distressing to see this sort of thing done because they are in effect vultures working on the gullibility and the need and the sensitivity of these people who need some answers, are not going to get them from the psychics in my opinions.

Charlotte Stoddart: Now you've come along to these drinks tonight with Sid Rodriguez and you are both part of a sort of growing band of people who are investigating paranormal claims and homeopathy and that kind of thing. Could you just tell me a little more about this sceptic community?

James Randi: Well, its rather surprising that you know, I travel to foreign countries all the time and not too long ago in Denmark, I was walking on the street and I heard a shout from across the street, "Mr. Randi!" and a fellow came running through traffic and shook my hands, smiled at me. He said I am sceptic too and I looked him up and down, I said, "I doubt that," just to keep in character, you see. But there is a sceptical community all around the world now which is growing bit by bit and there are sceptical organizations. Now scepticism is not cynicism. Cynicism is a different thing altogether. We are honestly sceptical and I think justifiably sceptical about claims that we encounter. Homeopathy is one of the silliest claims that you can possibly entertain as possibly being real. People are taking homeopathic medicines and they don't know unless they study it that they are getting zero dosage. A friend of mine actually calculated the effect that with the sleeping pills that I take at every one of my performances. I always swallow a huge handful of sleeping capsules and I always survived, as you may have noticed. He calculated one time, that in order to get at least one molecule of caffeine because that is the active ingredient in a sleeping capsule and don't ask me how that is, I would have to eat 16 average swimming pools, full of pills, that's a big dose.

Charlotte Stoddart: It is. So, it's not going to be a homeopath, who wins your prize.

James Randi: No, I very much doubt it.

Charlotte Stoddart: James, thank you very much. I know there are lots of people, upstairs in the pub, who would like to talk to you. So we'll go back to the drinks now.

James Randi: Thank you so much and I am frozen! So get me into the warm.

Charlotte Stoddart: Let's get into the warm. Thank you.

James Randi: Thank you. Bye Bye!

Kerri Smith: James Randi, charming Charlotte at Nature Network's London Drinks Evening and you can join your local Nature Network, by going to http://network.nature.com

Adam Rutherford: Now one of Randi's fellow sceptics is Phil Plait, an astronomer, best known for his blog Bad Astronomy. He was in town this week as well, before a visit to CERN, and he stopped by to give us his opinion on why space science needs funding more than ever.

Phil Plait: In my country, the United States, science is under attack for many factions. You've probably heard that far right religious groups are attacking evolution and trying to subplant it with factually challenged mythology that if successful will no doubt push the US back to the Middle Ages. But on both sides of the Atlantic, scientific research is under attack from the government. The people in charge have the ultimate anti science weapon -- funding withdrawal and in both the US and the UK, the governments have used it. I am an astronomer, so while I am concerned about science in all fields, my personal stake is in the skies, literally since space travel is so critical to astronomy. When US citizens comment about the money spent on space travel, they commonly ask why spend money in space, when we need to spend it here. Well, I have an answer for that, actually two answers. First, we have enough money to work on problems both here and in space. We just don't seem to choose to. Twelve million dollars an hour is spent in Iraq. The US government chose to do that instead of fixing many more problems at home. By contrast, NASA is less than 1% of the US budget, so it's best to pick your fights wisely here. Second, we need to spend money on space exploration, to make life better here on earth. Satellites found a hole in the ozone layer, letting us know we are damaging our ecosystem. Weather prediction via satellites is another obvious example, as well as global communication, TV, global positioning satellites and much more. Space exploration may even save us from an asteroid impact and if all else fails, spreading our seed to other worlds may eventually save the human race. Simply put, the more we explore other planets in the universe around us, the more we learn about the earth itself. I have no problems with more esoteric, more philosophical reasons, as well. Its the very nature of humans to explore and of course we could spend our lives looking no farther than the ends of our noses or we can look up, look out to the skies, see what wonders are there, marvel at exploding stars, majestic galaxies, ring worlds, and perhaps planets like our own. That gives us beauty and joy in our world and it adds a depth and dimension that we might otherwise miss. Space exploration, any science exploration is cheap, not exploring is always very, very expensive.

Adam Rutherford: Phil Plait on the Podium and you can read his excellent blog at http://www.badastronomy.com.

Kerri Smith: Our final report this week wouldn't have been possible without some of that funding for space science. Using a vast array of telescopes spread across the globe, an international team lead by Alan Marscher at Boston University have been peering into some of the most violent phenomena in the universe. Black Holes, which lie at the centre of most galaxies, are famous for sucking in everything that comes near them, but certain types called blazars also emit jets of light powered by the gas and dust they hoover up. Scientists have theories about how these jets form, but couldn't look far enough into the blazars to find out whether they were right. Now Marscher and his team have come up with the goods. He started by explaining exactly what a blazar is. Nature 452, 966–969 (24 April 2008)

Alan P. Marscher: The centres of many galaxies may be even all massive galaxies contain black holes that have masses that range from around a million times the mass of the sun to as much as 10 billion times the mass of the sun. Black holes are objects that are so compact that their gravity is so strong that nothing can escape from them once it falls in, not even light. But the term black isn't exactly correct, whilst material falls into the black hole, it encounters frictional forces, as it spirals around and that heats up the gas and it also twists up magnetic fields and that causes all sorts of radiation to be emitted. In a blazar, we see radiation coming from jets that are expelled from the regions around the black hole and the speed of this out-flowing ionised that is charged particles approaches the speed of light and when matters go in that fast, it beams all of its radiation into the forward direction, sort of like a halogen flashlight beam. And so if we happen to be fortunate and the beam is pointing almost exactly in our direction then we see a blazar.

Kerri Smith: Wow! And that's what happened in this case, isn't it. You've made some observation of a jet coming from a blazar and its coming directly towards us?

Alan P. Marscher: Yes that's right. In this particular blazar that we observed, the speed of the jet is 98% the speed of light and its coming at us at an angle of only about 6 or 7 degrees, so it's coming almost at us.

Kerri Smith: Now we'll come back to what you actually did and what you actually measured in a minute, but I just wonder could you tell us, what the current theory is on how these jets are propelled from these blazars and why its been so difficult to test that theory?

Alan P. Marscher: This was one of the great cosmic mysteries for quite sometime, since we discovered the jets in the 1970s. Nature seems to do some things very easily and making jets is one of them and yet it's something that extraordinarily difficult to imagine how it happens. Finally, over the last may be 15 years, the theorists have come up with an idea that as gas falls into the black hole, if there is a magnetic field in that material and there usually isn't in the cosmos, then the magnetic field gets twisted around, just like water going down a drain, it tends to spin around for a while before it falls in. And when you twist around a magnetic field that creates a force that pinches things together and that makes gas not only kind of come together but also to be expelled outward. So the magnetic field both propels the plasma out and it focuses it into a very narrow jet.

Kerri Smith: And so in this paper then you report how you went about testing whether that is actually the case. How did you do that, I gather there is quite a lot of telescopes involved.

Alan P. Marscher: Yes, the big challenge has always been to be able to peer close enough to the black hole to see the magnetic field in action. The problem has been that even instruments like the Hubble space telescope have resolution which is far to poor to see down in those central regions. The closest that we can come is with a radio interferometers. Sets of radio telescopes in this case scattered around the world that look at the same blazar at the same time, what we want to see is where the magnetic field is coiled up if that in fact is the case and the jets are both accelerated outward and focussed into narrow object. So we combine that with some NASA satellite data from the Rossi X-ray Timing Explorer, which observes an x-rays and also invisible light and also a feature of the light called polarization that tells what direction the magnetic field is in. We are able to match the polarization that we saw in a bright spot moving down the jet in a sequence of images that we took with Very Long Baseline Array. We are able to match that with a polarization direction that we saw with our visible light telescopes. So we are able to associate this event with the bright spot that we saw moving down the jet in the radio images.

Kerri Smith: So that's the punch line then, your observations fit almost directly with the theory?

Alan P. Marscher: Yes, that's right.

Kerri Smith: Given your findings studying this particular blazar, how generalizable do you think that is to other blazers like this in the other galactic nuclei in the universe?

Alan P. Marscher: That's a very good question. According to theorists, it should be exactly generalizable to different objects. But blazars have always been surprising to us, in fact they are sort of like children, each one of them has their own personality even though they may have a lot of similarities. So we are very interested in applying the same techniques to other blazars especially after the expected launch next month of NASA's Gamma-ray Large-Area Space Telescope Glass which will be able to measure how the Gamma-ray brightness changes with time with very high precision. And so by combining all these techniques, we hope to apply this to probably about 10 or 20 blazars to see if this is a general phenomenon.

Kerri Smith: Well they sound like fascinating creatures.

Alan P. Marscher: They certainly are to me.

Adam Rutherford: Alan Marscher there and by a happy coincidence Marscher has also provided our Sound of Science this week. He has written a song about blazars called 'Superluminal Lover'. Yes! Really! I'm Adam Rutherford.

Kerri Smith: And I'm Kerri Smith. Thanks for listening. [Sound of Science]

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