Nature Podcast

This is a transcript of the 25th April 2013 edition of the weekly Nature Podcast. Audio files for the current show and archive episodes can be accessed from the Nature Podcast index page (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 mailto:podcast@nature.com.

Thea Cunningham: This week, the researcher who's risked his safety for his work on firearms control.

Garen Wintemute: It turned out that people we were collecting data were probably professional firearm traffickers. I think the consideration from their point of view was how do we take care of this threat to our business.

Kerri Smith: And physicists open the black box of quantum mechanics.

Ben Reichardt: Using these tests of quantumness we are able to characterize exactly what is going on inside these devices

Thea Cunningham: This is the Nature Podcast. I'm Thea Cunningham.

Kerri Smith: And I'm Kerri Smith.

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Kerri Smith: Quantum computers with their exponentially faster speeds than classical computers sound really useful, but the thing about quantum systems is they're really unpredictable. Lots of what goes on inside them can't be known about because we who are not quantum don't have the right measuring tools and anyway if you try and measure them you change them. So, if you're trying to probe a quantum system, you'll get an answer out but you won't know how you got it or what it means which might be part of the reason you can't buy a quantum laptop yet. This conundrum has been bothering physicists for decades. One such scientist is Ben Reichardt from the University of Southern California, in Los Angeles. Nature 496, 436–437 (25 April 2013); Nature 496, 456–460 (25 April 2013)

Ben Reichardt: We ourselves are not quantum or we simply don't experience quantum mechanics ourselves. So if have an experimental system that's quantum mechanical that we think is quantum mechanical, we can't interact with it in sort of on equal terms, it is only get classical information in or out. In this case, since you're interacting with it classically, it's not clearly that you should be able to tell the difference.

Kerri Smith: I mean of course, you guys as theoretical physicists, the idea of whether you can tell the difference between classical and quantum system is just an interesting challenge.

Ben Reichardt: Sure it has a long history in physics. I mean it started back in the '30s with Einstein, Podolsky and Rosen, they asked if there might be a theory in physics that lies underneath quantum mechanics, a classical theory that lies underneath it. That's where Bell started to come up with a test for quantumness, sort of a way of distinguishing quantum systems from a classical system and we really extend that sort of much further.

Kerri Smith: This is the idea that physicists, Bell had this idea in the '60s I believe, he called it nonlocality. I mean, can you just pick this apart for us, tell us about John Bell's discovery?

Ben Reichardt: Right. I mean if you're given a single system, just in a single piece, there's no way of knowing what's going on inside, you can't tell if it's classical or physical or what the inner workings are, but if you're given two systems and they're separated from each other, then you can actually distinguish classical from quantum because the set of allowable quantum correlation is strictly larger than what can be achieved classically. It's sort of like quantum physics is a generalization and probability theory and it involves more kind of correlation than are allowed by classical probability distributions, that's what Bell showed and since then a lot of people have actually experimentally tested what are known as Bell inequalities to verify that actual systems are behaving quantumly.

Kerri Smith: How exactly do you use that to measure the sort of quantumness of a system or something else about its properties?

Ben Reichardt: Well, originally what Bell and later people did is they just came up with a test, that said, sort of the yes no test, that said is this system quantum or is it classical? But we do it differently is that, we show that if you pass the test with high probability and actually we extend the test to say if you pass many of the tests in a row, then in fact, you must have one particular quantum state. So, it tells you more than just whether the system is quantum or classical, it actually tells you what is going on inside the system.

Kerri Smith: What shift was there in your thinking that allowed you to do this because this is essentially the same type of theory, I suppose as the previous people had it back in their '60s?

Ben Reichardt: Yeah, it's interesting. Actually it turns out that we do essentially the same tests as what had been proposed before we just repeat it many times. I mean, it sounds like that should be very simple repeating the same test but the issue is when you try to characterize how the systems can play this test, how the devices can play this test in order to win it and when you play many tests in a row, it's very complicated all the different ways that the device could play. They have an infinite dimensional system, each of the devices, they share an arbitrary quantum state in the system and every time you play as a game, one after the next after the next after the next, every time you give them these tests, they could behave completely arbitrarily

Kerri Smith: Quantum physicists like to talk about Schrödinger's cat, this is like herding, Schrödinger's cats, you basically trying to look here what's going on within the systems to make that happen.

Ben Reichardt: Right exactly. So you're just pressing a button say to get zero or one, you're pressing a sequence of buttons and you're getting a sequence of output and the claim is that the only way that you can get output satisfying certain tests is if the system is quantum mechanical and if it's behaving according to one particular unique quantum mechanical strategy.

Kerri Smith: Now what's the results of all of this, I mean how might it be useful for what kinds of applications might it one day be useful to be able to know what's going on inside your quantum black boxes.

Ben Reichardt: So, for example in cryptography, in quantum cryptography, this is something that's actually being done today and has been done for a number of years now, you can buy these things commercially, there's an application trying to communicate securely between two parties. So, say you're trying to distribute a random key for communications using quantum devices, and you are not a hundred percent sure of how the devices work because after all they are quantum mechanical, using these tests of quantumness, we're able to characterize exactly what's going on inside these devices without making any assumptions about how they're working. And so therefore you can test you can verify they're behaving exactly as you like and that you really are getting a secret key.

Kerri Smith: So in the future, when quantum computers, quantum super computers, we can trust them, thanks to your quantum security device here.

Ben Reichardt: May be, if that ever happens, yes. Second application is to delegate its quantum computations so that idea of your classical computer in the server that you're outsourcing your computation to the quantum computer, so it's substantially more powerful and you can run securely quantum computations on it without making any trust assumptions.

Kerri Smith: Ben Reichardt there and you can read the paper and the associated news and views articles at http://www.nature.com/nature. Still to come, a medical bandaid inspired by a parasite. That's in the research highlights, but first, the challenge of doing gun control research in a country where everyone has the right to bear arms.

Thea Cunningham: The mass shooting of students and staff at Sandy Hook Elementary School in December last year has renewed a furious debate as to how to reduce the toll of gun violence in America. Guns claimed the lives of more than 30,000 people there last year. Garen Wintemute, an epidemiologist at the University of California, Davis says that science needs to be part of the discussion. An emergency room doctor by training, Wintemute has spent the last three decades researching which gun laws work and which don't. He is profiled in this week's Nature and he's gone further than most researchers to gather data, he has gone undercover at gun shows to study how the presence of law enforcement could stop illegal gun buying. He's even been threatened by those doing the selling. Ewen Callaway called Wintemute and started by asking him how he got involved in gun control research. Nature 496, 412–415 (25 April 2013)

Garen Wintemute: I was working as an emergency physician, but was also specifically interested in working on the prevention of the sorts of things that injured people and brought them to my emergency department.

Ewen Callaway: So, you decided to do research on the effects of gun laws, what sorts of questions were you asking.

Garen Wintemute: Our research has really been focused on questions that we think will help develop a body of evidence on which sound policy can be made. So we have done everything from mining databases to field work involving data collection in a systematic fashion at gun shows and from visits to gun dealers.

Ewen Callaway: On occasions, you've been threatened at these shows as an undercover researcher.

Garen Wintemute: Yes. There was a point in the project when I realized I have to find a way to take pictures of these. Nobody is going to believe what I tell them if I can't provide documentary evidence other than just my say so. So, came up with a procedure for using a hidden camera. It turned out that the procedure was not fool proof, an occasion or two in particular when it turned out that the people we were collecting data on whether pictures were not, were probably professional firearm traffickers and we were interfering with their business operations and I think the consideration from their point of view was how do we take care of this threat our business.

Ewen Callaway: What did you learn from this project, from going to these gun shows?

Garen Wintemute: From a policy perspective, it tells me that while it's good to have laws on the books, there needs to be an active enforcement presence, putting an undercover in particular, law enforcement presence at gun shows and making it known that there is an undercover law enforcement presence whether by advertising it or making some busts and making sure that those were widely known is essential. Enforcement matters. It is not enough just to have law on paper.

Ewen Callaway: What are some of the other major conclusions and policy implications that have come out of your research program over the years?

Garen Wintemute: We have focused a lot on the utility of background checks, an issue that has been much discussed in the United States obviously of late. It's known that background checks to identify prohibited persons work in the sense that they do identify such people and those purchases are prevented. But obviously the question that matters the most is does all of that efforts in fact affect risk for committing subsequent crimes, and we've done a couple of studies showing that it does.

Ewen Callaway: You worry that some of these groups such as the NRA perceive you as an advocate for gun control rather than a data driven scientist.

Garen Wintemute: I am aware of that perception. The perception is wrong. To me it is not enough for a researcher whether a scientist or researcher or some other sort to simply collect information, interpret it and then stop, if the results of the research suggest an intervention in order to prevent a problem that leaves people dead and disabled, I think it's the obligation of the researcher not just others to make those implications clear, and to the extent that they are comfortable seek to help directly in translating their research evidence in to public policy.

Ewen Callaway: On April 17th the US Senate voted against legislation that would increase background checks on potential gun buyers, what are your views on this news?

Garen Wintemute: The amendments that are passed are entirely worthwhile but unfortunately they are amendments to a bill that will itself not move forward. So, the people most involved are surveying the wreckage because we are left essentially with nothing and are in the process of deciding where to go from here.

Ewen Callaway: Is this political climate, does it prevent policy implications of your research from getting enacted in a lot of places?

Garen Wintemute: In the short term, yes. I had been working for and had been for some time working for comprehensive background checks, which I think are the policy that the evidence suggests is appropriate. I have been doing this for 30 years and I have actually a written plan for the next 20 years of work. This is not just a career investment for me. It's a long term subject of debate for the country. So yes, this week as you and I sit and talk about this, there have been a bunch of no votes. To that, I say, fine. Let's keep working.

Kerri Smith: That was Garen Wintemute. Research highlights now with Charlotte Stoddart.

Charlotte Stoddart: Dirt roads may be helpful in the spread of seeds in natural habitats. Researchers at Doñana biological station in Spain collected hundreds of samples of animal poop along dirt tracks and adjacent scrubland in a national park. Rabbits and carnivores tended to defecate mainly on the tracks leaving behind lot more seeds than in scrubby areas, so dirt roads could be helping out animals spread seeds between isolated plant populations. There's a downside though, they might also provide invasion routes for non-native species say the researchers. Learn more at the Journal of Applied Ecology. Nature 496, 401 (25 April 2013)A sticky intestinal parasite has inspired a sophisticated medical adhesive. Researchers in Boston made an adhesive with tiny spikes which can attach to both skin and intestine, much like the proboscis of a spiny headed worm. The micro spikes punch into tissues, and swell to stay in place. The experimental bandage is easily removed but it also sticks more tightly than surgical staples and medical glues. You can read more in Nature Communications. Nature 496, 400 (25 April 2013)

Kerri Smith: The news chat is coming up. Richard van Noorden is ready and waiting to join us in just a few minutes. Before that studying the atmosphere by looking inside the earth. Nature (2013)

Thea Cunningham: Oxygen in the atmosphere coincides with the evolution of complex life on our planet. Somewhere around 2.4 billion years ago, oxygen levels drastically increased in what is being called the Great Oxidation Event. To find out more about what happened, scientists measured ancient oxygen levels using chemical evidence from rocks. They looked at sulphur which is preserved in different versions or isotopes depending on whether there was oxygen in the air at the time. All well and good, but things don't quite line up. Evidence from other sources gives quite a different answer. Noah Baker spoke to Chris Reinhard from the California University Institute of Technology to find out more.

Christopher Reinhard: The general paradigm or gestalt I guess is, is that somewhere around 2.4 or 2.3 billion years ago, oxygen rose very sharply, the actual quantities of oxygen in the more precise timing of this have largely now been constrained by these sulphur isotope anomalies.

Noah Baker: What's confusing about the record of the sulphur isotopes that we can see in rocks in the earth at the moment?

Christopher Reinhard: The basic understanding is that these will only be generated and preserved in marine sediments if atmospheric oxygen is extremely low, something on the order of one one-hundred thousandth or less of the modern atmospheric oxygen level. But there has been some recent work that has shown that there are some sedimentary rock units that show other geochemical evidence for the presence of oxygen and yet they at the same time preserve these sulphur isotopes and so reconciling these two things is kind of a frontier right now trying to figure out exactly how both of these things can sort of coexist in the same sedimentary rock record.

Noah Baker: Okay, so in these rocks of known age, you've got one thing saying that there was some oxygen in the atmosphere and the other thing saying there was no oxygen in the atmosphere. How do those things go together? What are they found that explains this?

Christopher Reinhard: These atmospheric sulphur isotope anomalies or signals, once they are generated and buried in marine sediments, eventually those sediments are going to become uplifted on land and they'll be weathered and much of the chemical constituents of those sediments will be delivered to the ocean and the sulphur will become mobilized again and it still contains the isotope signal that it had when it was buried but now this is much later than it's been mobilized and delivered to the ocean with the signal and so then it sort of starts the cycle all over again if you like. And then the sulphur will be delivered to the ocean and then it can be incorporated again and so they can be deposited within later sediments that are simultaneously recording evidence for oxygen in the atmosphere.

Noah Baker: You're using sulphur isotopes to investigate oxygen levels, but scientists use other kinds of isotopes, radiogenic isotopes to assess other things like the age of rocks, is that right.

Christopher Reinhard: There are a number of different isotopes systems, in which a parent isotope will decay to a daughter isotope and so you can measure the amount of parent-daughter isotope in a particular rock and if you know the speed at which the parent isotope decays the daughter, then you can measure the ratio of these two and estimate what age the rock is.

Noah Baker: If sulphur isotopes can be recycled into younger rocks, then could this problem apply to dating using radiogenic isotopes as well?

Christopher Reinhard: Well the simple answer is no, provided that you're looking at the right radiogenic system. The sulphur isotopes signal once you lock it in, it sticks around and the only way to get rid of it is to sort of dilute it through many cycles, whereas the radiogenic isotopes, their parent-daughter ratios are being set by natural processes that are coincident with the deposition of the rock, in a way that's rather different from sulphur isotopes.

Thea Cunningham: Chris Reinhard there, talking to Noah.

Kerri Smith: News time now and welcome to Richard van Noorden. Hello Richard.

Richard van Noorden: Hello Kerri.

Kerri Smith: Now first off this week, we're off to the depths of the sea near Japan, where methane is stored.

Richard van Noorden: Yes, we have known for a long time that methane natural gas is trapped plentifully in ice underneath the seabed and under arctic permafrost. The structure of ice, these H2O molecules, and the sort of hexagonal array is open enough to allow methane molecules to creep into the middle. So there's a huge amount of methane there, trapped in these frozen hydrates they're called, but getting them is the problem.

Kerri Smith: And it's not just a scientific problem is it? Because methane could be used as a very potent fossil fuel.

Richard van Noorden: Exactly, Japan where this test happened is very energy poor and doesn't have much fossil fuels, got an awful lot of coast and the icy hydrates are in the seafloor off that coast, so it's the perfect place to try and extract methane. And here the Tokyo based State Oil Company, drilled through 270 meters of quite loose sediment already underwater, a kilometre deep to reach this hydrate reservoir. What they essentially do is they reduce the pressure in this deposit and that draws the methane out of the hydrates, unlocking the gas from its icy cage and bringing it back up to a platform on the ship where you can see it because it burns in a flame.

Kerri Smith: Now this isn't the first trial of this kind of approach, is it to get methane out of these hydrates but it is one of the largest?

Richard van Noorden: So, engineers before have extracted methane from underneath Canadian Tundra , but the marine deposits are much richer and the flow rates in this experiment which you could see as a sort of a real first commercial test were much bigger, 10 times more than produced by a Canadian well in 2008. The methane flowed smoothly for six days but on the final day, the pump clogged up with sand which is the real problem with extracting methane. All these sediments are loose and sandy and the wells are really unstable, is a real technical difficulty and quite a feat that Japan managed to get any methane in any proportion at all.

Kerri Smith: Is the view that it is going to be worth following up this approach?

Richard van Noorden: Well Japan because it doesn't have much gas, thinks it's definitely worth it. But realistically, we are about 10 or 20 years behind where we were with shale gas, you know, which has come up with fracking, the idea of releasing gas from its entrapment in shale, which is now a big thing in the US. So, this is for the far future, but projects in China, India South Korea remain active. Canada and the United States, they've cut their methane hydrate efforts, they have got enough gas in shale. But in places like Japan, extracting of methane from hydrates could be a key contribution to energy supply in the future.

Kerri Smith: So from deep under the water near Japan then to outer space where there is a big spat about how to name planets and moons.

Richard van Noorden: Yeah, what do you think of the name Albertus Alauda for the planet around our nearest star Alpha Centauri B.

Kerri Smith: Does it look a bit like Albertus?

Richard van Noorden: Yeah, well it was the winning name in a contest of the space education Company Uwingu, based in Boulder, Colorado launched in February and it's trying to draft a sort of baby book of names for astronomers to draw onwhen naming new exoplanets, planets outside our solar system. But the International Astronomical Union which is based in Paris is not very happy about this competition and in April it launched a press release saying can one buy the right to name a planet?

Kerri Smith: Well indeed, I mean it seems it's like quite cross about this as you say this harmless baby book of planet names.

Richard van Noorden: The Union says we're the official astronomical namer and only we get to choose what names exoplanets have. Now Uwingu says well hang on a minute, lots of informal names for astronomical objects were in use, even they haven't got their approval of this union. For example, astronomers use Osiris as an informal name for HD 209458 B, it's a much a snappier name0, this is a Jupiter sized gas planet. It was discovered in 1999 and of course, The IAU has actually sanctioned informal names for asteroids. So the IAU has to make a decision in the next six months on whether to adopt popular names for exoplanets which otherwise known by these unappealing numbers and letters.

Kerri Smith: And I suppose is it a good idea to centralize this, because you know, you can't just have multiple groups just naming things willy nilly.

Richard van Noorden: Yeah. One question is whether Uwingu has kind of suggested that its contest has actually going to contribute to the names of these planets, to charge money for people to suggest names and that money is being given away for space education and exploration projects. Uwingu is cofounded by Alan Stern, a planetary scientist, who helped discover the newest moons of Pluto and he hopes people will refer to exoplanet by whichever name wins regardless of what the International Astronomical Union says. It's a bit of a power struggle over who gets to have control over what the names of these planets are. Pluto's moons are also due to be named very soon. Again there was a contest here but this one, the International Astronomical Union has sanctioned the winners in that popular contest were Vulcan and Cerberus, Star Trek actor William Shatner suggested Vulcan and that was the runaway winner. But even now these archaic rules may prevent known names winning for Pluto's moons because Vulcan is already the name for hypothetical mini planet that is much mooted to exist between Mercury and the Sun and Cerberus is already the name for the asteroid, so that the IAU might reject those lovely names as well.

Kerri Smith: Alright and as always Richards, thank you. Let's go to http://www.nature.com/news for more on all those stories. That's it for this week. Join us again next time as we examine the real impact of GM Crops. I'm Kerri Smith.

Thea Cunningham: And I'm Thea Cunningham.