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Physics on film

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January 2011 Archives

Schrödinger’s quantum kittens

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Erwin Schrödinger has proved a lasting inspiration to scientists and writers alike

By James Dacey

BBC Radio 4 is famed in the UK for broadcasting thought-provoking documentaries spanning the arts, sciences and just about anything that might be of interest to the “well-rounded intellectual”.

Yesterday was the turn of quantum mechanics via this 30-minute programme that explores the influence of Schrödinger’s cat paradox on science and popular culture.

It is an interesting show presented by UK broadcaster and comedian, Robin Ince, who talks with a handful of eminent physicists including Roger Penrose from the University of Oxford and Tara Shears from the University of Liverpool.

We are reminded that Schrödinger invented the paradox in an article of 1935 entitled The Present Situation in Quantum Mechanics as a response to the Copenhagen Interpretation of quantum mechanics that had emerged in the early 1930s. Schrödinger was bemused by the idea that all particles behaved as “fuzzy” entities until measured, and he was trying to stir a debate.

The cast discuss the appeal of the paradox and why it still fascinates scientists today. “It’s sort of a by-word for how the universe can be so amazingly complex and yet so perverse at the same time,” says Shears.

The programme also looks at how the paradox has inspired writers over the years, including Douglas Adams and more recently Philip Pullman. Writer Alan Moore explains how the multiple realities aspect of the paradox inspired a new wave of science fiction based on the idea of alternate histories.

And if you are left craving a more detailed discussion of the “Many Worlds” interpretation of quantum mechanics, you may also like to check out this webinar, part of the Physics World lecture series. It looks at the life and ideas of Hugh Everett III, who developed the idea in the 1970s.

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Heading north

By Michael Banks

Do cows align their bodies along the Earth’s magnetic field lines when grazing? What at first seems like a simple enough question is in fact becoming a hotly contested area of research.

In 2008 the answer was “yes” as zoologist Sabine Begall from the University of Duisburg-Essen in Germany and colleagues used images from Google Earth to study the patterns of 8500 cattle from 208 pastures around the world.

They found that regardless of where the cows came from, they aligned their bodies along the North–South of the Earth’s magnetic field. The effect was most obvious at high latitudes, they concluded, where the difference between magnetic North and geographical North are greatest (PNAS 105 13451).

There was a small snag, however, as the resolution of the images meant it was not clear whether it was the heads or tails of the animals that were pointing north – no doubt giving Begall and colleagues a case for further studies.

However, magnetoreception in cows has now been disputed by Jiri Hert from Charles University in the Czech Republic and colleagues who say there is no evidence for such alignment in their Europe-wide study of some 3412 individual cows in 322 herds (arXiv:1101.5263).

They claim that Begall and colleagues selected the herds and individual animals in an “inadequate way” and that “possible subconscious bias” could lead to the discrepancy between the studies as well as the use of poor-quality Google satellite images.

However, zoologist Hynek Burda from the University of Duisburg-Essen in Germany who was involved in the Begall study says it would be “useful” to see the images that Hert and colleagues have evaluated. “The images we have assessed were not of poor quality and there was no problem in determining the body axis [of the cows],” says Burda, who adds that their analysis has been supported at a forum held at the Royal Institute of Navigation.

“The case cannot be closed if only two studies come to different results,” Hert told physicsworld.com. “We hope that our study will provoke other scientists to repeat the analysis of the magnetic behaviour of cows and other mammals.”

Hert adds that he will not be studying the topic any further, however, but that his work will be “oriented in other directions” from now on.

By Hamish Johnston

The bacterium in the video above has an image problem that’s forcing it to go round in circles.

I’m not speaking in metaphors; physicists in Italy are the first to notice that certain bacteria move in anti-clockwise loops when they swim close to the surface of a liquid.

Roberto Di Leonardo and colleagues also watched as E. coli swam in a clockwise direction when they were very close to the bottom of a water-filled dish – something that others had already seen.

This behaviour is puzzling because the little creatures manage to swim in straight lines when they are a good distance away from either the top or bottom of a dish.

Now, Di Leonardo and colleagues at the University of Rome Sapienza think they know why, and have published a paper in Physical Review Letters outlining their theory.

The bacterium propels itself by spinning a whip-like flagellum that acts much like a ship’s screw. The presence of a solid interface below – or an air interface above – the bacterium disrupts the movement of fluid around the bacterium. It turns out that the effect of this disruption can be modelled by removing the interface and replacing it with a mirror image of the swimming bacterium.

The effect of a mirror image is a torque on the real bacterium causing it to swim in a clockwise manner if it is close to the bottom. The image has the opposite effect when the bacterium swims close to the surface.

The analysis also suggests that long rod-like bacteria swim in larger circles than stubby bacteria.

Understanding this effect could prove very important in creating bacteria ratchets, which prevent some or all motile bacteria from passing through a barrier. Such ratchets could prove useful in preventing the spread of disease.

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The oldest galaxy ever seen? (Courtesy: NASA)

By Hamish Johnston

What will astronomers see when NASA launches the James Webb Space Telescope (JWST) in 2014? That question kept cropping up a few weeks ago at the 217th meeting of the American Astronomical Society in Seattle.

With it’s huge mirror – 2.5 times bigger than Hubble’s – the JWST should be able to spot faint and distant galaxies that formed just a few hundred million years after the Big Bang.

But thanks to a recent upgrade, Hubble has also managed to spy some of these ancient galaxies, providing a preview of things to come from the JWST.

The results are published today in Nature and include the discovery of what just might be the most distant, and therefore oldest, galaxy ever seen. Astronomers believe it is13.2 billion light-years away, which means that light from the galaxy began its journey to Earth just 480 million years after the Big Bang.

Garth Illingworth of the University of California, Santa Cruz, said of the galaxy: “We’re getting back very close to the first galaxies, which we think formed around 200 to 300 million years after the Big Bang”.

Using Hubble’s Wide Field Planetary Camera 3 (WFC3), the researchers studied galaxies over a period from about 480 to 650 million years after the Big Bang. They were amazed to find that the number of stars being created in the universe increased by a factor of 10 during this relatively short time period.

“This is an astonishing increase in such a short period, just 1% of the current age of the universe,” said Illingworth.

Hubble found a similar rapid increase in the number of galaxies over the same time period.

The findings provide astrophysicists with tantalizing clues about how stars and galaxies formed in the early universe – but researchers will likely have to wait until the launch of the JWST before this trickle of information becomes a flood.

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No, it’s not Tim Henman. (Courtesy: Wikimedia Commons)

By James Dacey

With the Swiss superstar Roger Federer looking like he may well scoop his 17th grand slam title this week at the Australian Open, it is a debate that will fill the stands in Melbourne.

In fact it’s a conversation sports lovers have all time and it usually results in heated exchanges ended by a friendship-saving “let’s agree to disagree”. And it gets even more farcical when you start comparing players from different generations: on the one hand professionalism and standards of equipment tend to increase as the years go by; on the other hand, a sportsperson is necessarily of their time and can only ever be asked to beat the opponent put in front of them.

Well, a researcher in the US has attempted to take a more scientific approach to this question for the case of tennis. Fillippo Radicchi a chemical engineering researcher at Northwestern University, Illinois, has scrutinized the results of all tennis matches played by professional male tennis players during the period 1968–2010. He has then represented these matches as basic “contacts” between “actors” in a complex network where multiple matches between the same players add weight to those specific connections in the network.

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By plugging in all the results, Radicchi has managed to rank players based on an algorithm similar to that used by Google’s PageRank in web searches. The algorithm places players in order based on their “centrality” in the complex network. And so the result is…

The number one greatest player in the history of tennis, according to this ranking, is Jimmy Connors, the American player who won 8 grandslam titles during a career that spanned from the early 1970s to the mid 1990s. Ivan Lendl and John McEnroe come in at number two and three respectively, making it an all-American top three. Meanwhile, Federer, who holds double the number of grand slams as Connors, comes in at a modest seventh place. You can see the full list here:

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The reason Connors topped the list is probably explained by his extremely long and successful career. “Among all top players in the history of tennis, Jimmy Connors has been undoubtedly the one with the longest and most regular trend, being in the top 10 of the ATP year-end ranking for 16 consecutive years (1973–1988),” explains Radicchi in his research paper, which has been posted on the arXiv preprint server.

Radichi also applies the same ranking algorithm to each decade independently and in this case Federer does come out top for the period 2001–2010. Likewise Pete Sampras bossed the 1990s, Ivan Lendl was the man to beat in the 1980s and Connors had his heyday in the 1970s.

So that’s it, the debate is settled? Somehow I doubt it…

By Matin Durrani

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With Tunisia in political turmoil, parts of Australia under water and dozens dead in a Moscow bomb blast, a meeting on SI units in the confines of the Royal Society in London might seem absolutely right at the bottom of anyone’s news agenda. Surely the conservative world of metrology, where physicists spend years sharpening up their measurements of the seven fundamental base units, is unlikely to cause much of a stir?

But the two-day meeting, which ended yesterday, did attract a dozen or so journalists, that led to reports in the Wall Street Journal, the Guardian, New Scientist and the BBC. They were no doubt attracted in part by the presence of the world’s top metrologists, but also by the meeting’s focus: to discuss whether to revamp the SI system of units so that it is based purely on the fundamental constants of physics.

The importance of the meeting was underlined by the fact that the organizers had managed to snare the UK’s minister for universities and science David Willetts, who in his opening remarks gave a good impression of at least seeming to understand what metrology is all about; he isn’t nicknamed “two brains” for nothing.

As Willetts pointed out (thanks no doubt to his speechwriters), metrology and the measurement system are important on three counts. First, it’s vital for us as consumers to be confident about what we buy – we don’t want to be ripped off at the checkout with an underweight bag of carrots or, more seriously, be given the wrong dose during radiotherapy for cancer treatment. Second, metrology is key for advanced technology – accurate timekeeping via atomic clocks has proved essential for GPS, for example. Third, and this is what the meeting was about, the work is essential if we are to define our measurement system entirely in terms of fundamental constants.

That’s the name of the game in metrology these days – finding a way of defining mass without just resorting embarrassingly, as we do now, to a lump of metal in the basement of the International Bureau of Weights and Measures (BIPM) outside Paris and saying “that’s a kilogram”. After all, periodic inspections of the lump have shown it’s been changing its mass slowly over time. As laser physicist Bill Phillips from the National Institute of Standards and Technology (NIST) told delegates during one question-and-answer session on Monday, “It’s a scandal that we’ve got this kilogram hanging around that’s changing its mass”.

In among the audience at the meeting was Physics World columnist Robert Crease from Stony Brook University in New York, who in December wrote about visiting the BIPM last autumn for what could be one of the last ever annual inspections of the kilogram. Crease was on hand to get the latest goings-on among the world’s metrology community for a feature on the redefinition of the kilogram in the March issue of Physics World magazine – so keep an eye out for that.

But redefining the kilogram is not that easy. One option is to take a large, nearly perfect silicon sphere, count how many atoms are in it (which determines Avogadro’s constant) and then multiply that number by the mass of each atom. If you’re interested, a new paper in Physical Review Letters provides the most accurate value for the Avogadro constant to within 30 parts in a billion – the result of a collaboration between eight different national metrology institutes around the world.

The other is to use a “Watt balance”, which does not require big collaborations, but is conceptually harder to understand. It involves balancing the force through a coil with the mass of an object, and then doing another bit of jiggery pokery involving the quantum-Hall effect (to measure resistance) and the Josephson junction (to measure voltage).

The plan is for the world’s metrology community – represented by the CIPM – to put forward a proposal at its meeting next October that the SI system should be revamped. That proposal will go to the organization to which the CIPM reports – the General Conference on Weights and Measures (CGPM) – which is basically a bunch of diplomats in a smoke-filled room (without the smoke). If they give it the nod, well then it’s time to rewrite the physics textbooks.

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In the current system, the kilogram, ampere, kelvin and the mole are all linked to exact numerical values of the mass of the international prototype kilogram in Paris, the permeability of the vacuum, the triple-point temperature of water, and to the molar-mass of carbon-12 respectively. The plan is to change all that so that these four units are linked to exact numerical values of the Planck constant, the charge of the electron, the Boltzmann constant and to the Avogadro constant respectively.

It’s likely that the CIPM proposal will seek to redefine the kilogram in terms of Planck’s constant when and if the experiments – the Watt balance and the Avogadro approach – come into reasonable agreement. Which they aren’t now. The metrologists clearly don’t want to play favourites regarding the technology, if only because they don’t want to get burned if one or the other doesn’t live up to promises.

As you can see, and as I soon discovered at the meeting, there’s more – much more – to SI units than meets the eye. And without wanting to steal Crease’s thunder – he’s busily putting the finishing touches to his Physics World feature on a plane back to the US as I write – I think I had better stop.

Just to say that on display in the foyer at the Royal Society are copies of what used to be known as the “standard yard” and the “standard pound” (see above), which made the venue a suitably appropriate place for this week’s meeting. I can’t help feeling, though, that despite the flaws of artefacts like the standard pound, there’s more of an emotional connection with a real object like it than a seemingly esoteric definition based on the Planck constant.

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Climate researcher Phil Jones (left) discussing Climategate with Sir Paul Nurse

By James Dacey

At the end of November last year, the presidency of the UK’s Royal Society passed from cosmologist Martin Rees into the hands of the Nobel-prize-winning geneticist Sir Paul Nurse. Heading the world’s oldest scientific academy brings a responsibility to uphold the organization’s grand aim “to expand the frontiers of knowledge by championing the development and use of science, mathematics, engineering and medicine for the benefit of humanity and the good of the planet.”

And Nurse, it seems, is wasting no time in grabbing his presidency by the reigns. Last night he appeared on UK television presenting an episode of the long-standing documentary series Horizon, entitled “Science under attack”. The hour-long show explored the public’s relationship with science, as influenced by the media, and it focused primarily on climate science and the rise of public scepticism.

Towards the beginning of the show, Nurse cited a recent poll that found nearly half of people in the US, and more than a third of Britons, believe that manmade climate change is being exaggerated. “It’s this gap between scientists and the public that I want to understand,” proclaimed Nurse, teeing up the show.

For the next 50 minutes or so, Nurse then visited a selection of players on either side of the debate. It was framed within the narrative of a personal journey: an eminently reasonable scientist who knows lots about the process of science but not the specifics of climate science. And to his credit, Nurse played his part exceptionally well, showing that science involves personalities and conflicts just like any other human activity.

Naturally, the show came to focus on “Climategate”, the controversy that erupted in November when internal e-mails between members of the Climate Research Unit at the University of East Anglia, UK were leaked to the public. The main controversy blew up around an e-mail sent by the then CRU director Phil Jones to a colleague in which he referred to “Mike’s Nature trick”, describing the splicing of temperature data from direct and indirect sources.

“The [World Meteorological Organization] wanted a relatively simple diagram for their particular audience,” Jones explained to Nurse. When asked why he thought there had been such a huge reaction to the leaks, Jones is obviously still perplexed. “A number of the climate change sceptics or doubters or deniers, whatever you want to call them, just wanted to use these e-mails for their own purposes, to cast doubt on the basic science.”

Following his visit to UEA, Jones then paid a visit to a person firmly on the other side of the debate, James Delingpole, the online journalist who broke the “Climategate” story on his Telegraph blog. This led to the most captivating scene of the documentary when Nurse puts it to Delingpole that denying climate change is like ignoring the consensus medical view when choosing how to treat cancer.

Asking Nurse to change the topic, Delingpole retorts, “I think it’s very easy to caricature the position of climate change sceptics as the sort of people who don’t look left and right when crossing the road.” Adding that he “slightly resented” the way the analogy had been brought in.

UK viewers can watch the documentary at this link.

Integrating electronics with the human body

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By Louise Mayor

We’ve come a long way in the fields of both electronics and medicine. But the possibility of intimately combining these – integrating electronics with the human body – has so far remained in the minds of creators of cyborg characters such as the Terminator and Star Trek’s Seven of Nine.

And there’s a reason for this, which I found out while recording this video interview with John Rogers from the University of Illinois at Urbana-Champaign. As Rogers explains, all known forms of biology are soft, elastic and curvilinear, whereas all known forms of electronic technologies are rigid, planar and brittle. “As a result,” he continues, “if you want to integrate electronics with biology – with human skin or tissue – you have severe challenges in a mechanics mismatch and a geometrical form mismatch.”

But this limitation is now being broken by Rogers and his team, who are developing electronics in formats that are much more tissue-like in their geometry and mechanical properties.

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LED array stretched over the tip of a pencil for scale. (Courtesy: John Rogers)

One specific type of device they’re developing is bio-integrated light-emitting diodes (LEDs), and as proof of principle they have already implanted an LED array under a mouse’s skin.

But does glowing skin bring anything to the table other than futuristic-looking tattoos? In the video, Rogers explains that they can be a diagnostic tool when used for spectroscopy – combining an LED array with sensors allows tissue to be diagnosed based on how it reflects and absorbs light.

But there are therapeutic uses too: Rogers is also interested in putting LEDs in the body along with certain classes of drugs that can be photoactivated. “So you introduce them into the body in an inactive form, and then you can activate them locally by exposing them to light,” he says, adding that there is also evidence emerging that phototherapy – simply irradiating tissue with light – can actually accelerate the wound-healing process.

The above video forms one of a four-part series filmed at the MRS Fall Meeting in Boston. In the video below, Amy Moll – MRS’s head of public outreach – explains why spreading the word about research like this is so important.

We also accosted conference delegates to hear their take on materials science, and had a more in-depth chat with incoming director of the National Science Foundation’s Division of Materials Research, Ian Robertson, about how the agency might allocate their 2011 budget of $320m.

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Thin blue line: BBC Radio explores our atmosphere (Courtesy: NASA)

By Hamish Johnston

Last night I listened to the second instalment of BBC Radio’s Thin Air, a three part series that looks at the wondrous properties of the Earth’s atmosphere.

In part two science journalist Gabrielle Walker looks at the various gases that make up air. What I found particularly fascinating is the account of how the atmosphere has evolved over billions of years to become what it is today.

Oxygen, for example, was initially a toxic waste-product of life rather than a life giver. For a long time it was absorbed by rocks, allowing early life to flourish, but then the rocks could take no more. The subsequent build-up of oxygen in the atmosphere is described as the worst pollution incident in the history of the planet by James Lovelock, who is one of the scientists interviewed on the programme.

The first episode looks at the atmosphere as a whole, weighing the air in the Albert Hall and discovering that blood boils above a certain altitude.

You can listen to the first instalment here.

The second episode can be found here, but only for six more days.

After that, the second (and eventually third) programme should be found here.

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By Hamish Johnston

It’s what chic geeks are wearing this year, a T-shirt emblazoned with Garrett Lisi’s E8 theory of everything.

On the front of the shirt is a 2D projection of the E8 lattice, which itself occupies eight dimensions. The vertices of the lattice are decorated with colourful shapes, each representing a fundamental particle.

On the back of the shirt you’ll find a series of equations and Lisi’s signature. Indeed, Lisi was involved in the design, according to Tess Smidt who runs the California-based fashion house BlondeGeek.

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Tess is an undergraduate physics student at MIT and seems to run BlondeGeek in her spare time – or maybe it’s the other way round.

The firm’s other T-shirts include one sporting two bonded glucose molecules and the caption “How Sweet!”. Yikes, that’s a bit too sickly for me but I do like their “Evil geniuses prefer blondegeeks!” take on “Gentlemen prefer blondes”.

Garrett Lisi, by the way, is an independent researcher who burst onto the scene in 2007 when he published “An exceptionally simple theory of everything” on the arXiv preprint server.

Lisi’s theory has received a mixed response, with some leading physicists including the Perimeter Institute’s Lee Smolin praising it while others like Jacques Distler of the University of Texas find fault with it.

Lisi’s 2007 paper has not been published in a peer-reviewed journal, apparently because it has never been submitted.

He posted a related paper to arXiv last year, and this paper was also submitted for publication in the proceedings of the Conference on Representation Theory and Mathematical Physics, which was held in 2009 at Yale University.

You can see the slides from Lisi’s talk at the conference here.

Relativity’s flaws revealed on Twitter

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Stephen Fry, wit, actor, Twitter giant (Courtesy: Wikimedia Commons)

By James Dacey

I visualize the social-networking site Twitter as a giant cocktail party where multiple conversations, all taking place at once, result in a cacophony of chitchat. Strolling around this gathering you come across crowded pockets where fans huddle round their favourite celebrities, looking for some juicy gossip or dazzling insight into their everyday lives. At the heart of all this you might spot a particularly attentive crowd gathered around the English actor and comedian, Stephen Fry, as he dishes out his devilishly sharp one-liners, always within the limit of 140 characters.

In reality, most of what Fry writes on Twitter is, as the man would say himself, Quite Interesting. But he does sometimes come out with some obscure gems, like yesterday when he drew the attention of his 2 million+ fans to this hilarious entry on Conservapedia about the supposed flaws in Einstein’s theory of relativity. For those not familiar with Conservapedia, it is promoted as “the trustworthy encyclopedia”, and directly contrasts itself with Wikipedia, which it criticizes on a number of points.

The Conservapedia entry comprises a list of 33 “counter-examples to relativity”, and I thought I would just pull out a couple.

Number 9: “The action-at-a-distance by Jesus, described in John 4:46-54”.

Number 21: “The lack of useful devices developed based on any insights provided by the theory; no lives have been saved or helped, and the theory has not led to other useful theories and may have interfered with scientific progress. This stands in stark contrast with every verified theory of science.”

I hope this blog entry doesn’t sound too sneering of people who might hold religious beliefs. And it is certainly not a bad thing to hope that science can lead to useful technologies that can help improve everyday lives. But these “counter-examples” on this ridiculous website give a completely false representation of the process of science. Besides, to say that relativity has no practical use is just plain wrong , as the accuracy of GPS systems depends on relativistic corrections, and these systems help to save plenty of lives. But there is no point in arguing with some people.

My sense of unease intensified when I read that Conservapedia boasts over 200 million views and more than 810,000 edits. Among the website’s guidelines it states that “we are neutral to the facts” and “everything you post must be true and verifiable”.

Just to give you a flavour of the site, here is Conservapedia’s entry for “a liberal”: “someone who rejects logical and biblical standards, often for self-centered reasons. There are no coherent liberal standards; often a liberal is merely someone who craves attention, and who uses many words to say nothing”. Yep, that sounds both neutral and verifiable.

As for why Fry felt the need to tweet about this entry now…well it’s probably no coincidence that his picture appears on the Conservapedia homepage alongside an article on “atheism and obesity”. And why I wrote this blog entry giving Conservapedia more oxygen? Well, I’m not quite sure. Guess I was just quite angry.

Hubble rap

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By Hamish Johnston

If you’ve ever wondered what Edwin Hubble would be like if he was reincarnated as an English rapper, you are in luck.

The “science rapper” Zach Powers has made a video of his interpretation of how the great astronomer would rap about his discovery of the expanding universe.

Hubble was an American mid-westerner born and bred, but Zach portrays him with an English accent. Hubble had spent a few years at Oxford and was apparently a bit of an Anglophile – although I doubt he ever affected a south London drawl.

Zach, by the way, describes himself as “a native New Yorker and professional scientist”. Zach is working towards a PhD at the Mount Sinai School of Medicine where he studies the structure of chromatin proteins.

The rap and video are pretty good, and the physics is spot on. One of my favourite lines is:

“I’m stark raving mad for what do I see? The farther the star, the greater the velocity.”

If you enjoy the science rapper, you might want to check out “The PCR Rap” – that’s polymerase chain replication – which celebrates the work and lifestyle of Nobel laureate Kary Mullis. In this rap Powers sounds a bit like Lou Reed, just what you would expect from a native New Yorker.

By Hamish Johnston at the AAS meeting in Seattle

The jetlag and non-stop astronomy must be getting to me because I can’t stop thinking about various aspects of astrophysics in terms of my favourite sitcoms.

For example, Father Ted brings us the “Dougal effect”, whereby the actual size of an astronomical object cannot be inferred from its observed size alone. Distance must also be considered and Ted explains this to Dougal using nearby toy cows and a distant herd of real cows. “These are small… but the ones out there are far away,” is the best way to define the effect.

Then there’s that astronomical unit of temperature defined in I’m Alan Partridge. Alan uses a microwaved apple pastry as a weapon, discovering “It’s hotter than the Sun”. To calibrate your thermometer to one “Partridge” put a petrol-station pastry in the microwave for eight minutes and presto.

Well, that’s all from me in Seattle. I’m about to fly back to Blighty and I’ll be looking for astronomy references in The Inbetweeners, which is featured on the in-flight entertainment system.

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A supermassive black hole could look like this: but how did it form? (Courtesy: NASA)

By Hamish Johnston at the AAS meeting in Seattle

The universe is full of supermassive black holes (SBHs). Indeed, they make up the core of just about every galaxy. These monstrosities can be a billion times more massive than the Sun. But despite their size and ubiquity, astrophysicists don’t really understand how they are formed.

That was the topic of a fascinating talk by Mitch Begelman of the University of Colorado, who is an expert on SBH formation.

According to Begelman there are two competing theories – the small seed that takes a long time to grow, and the large seed that grows quickly.

The small seed refers to the collapse of a massive star of about 100–1000 solar masses to form a black hole that grows slowly by sucking in surrounding gas and merging with other structures until it is an SBH.

The large seed refers to the direct collapse of a huge cloud of gas to create a supermassive star that could be heavy as a billion Suns. According to Begelman, such stars would be very fragile and would only last a few million years until their cores collapsed to create a black hole.

But instead of exploding in a supernova like much smaller stars, the remaining matter would puff out to become a “quasistar” – resembling a red giant. This surrounding matter is rapidly sucked in and what remains is a black hole that Begelman believes could be as large as one million solar masses. This is around the lower limit of an SBH, and it could keep growing.

Sounds great, but is there any chance of seeing a supermassive star or quasistar?

Unlikely for supermassive stars, says Begelman, because they would be very hard to distinguish from clusters of hot stars. He is a bit more hopeful about quasistars, because they could stand out in the optical and infrared wavelengths. However, he concedes that this would be a tough job, even with the upcoming launch of the James Webb Space Telescope.

To paraphrase Begelman’s conclusion, SBH formation models are getting more sophisticated but the problem has not yet been solved.

By Hamish Johnston at the AAS meeting in Seattle

You know it has been a good day when you learn a new amazing fact.

Today I discovered that the Moon is brighter than the Sun when it comes to gamma radiation.

How can a cold lump of rock give off more gamma radiation than a seething fusion reactor?

The answer, according to NASA’s Julie McEnery, is that both bodies glow with gammas because they are illuminated by cosmic radiation. The Sun’s strong magnetic field deflects much of this radiation away from the star. The Moon, however, has an extremely weak field that is not much use at deflecting cosmic rays.

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By Hamish Johnston at the AAS meeting in Seattle

Everyone likes a good thunderstorm – the spectacular flashes, crashes and wind, and then calm, clear air. But for the past few years physicists have begun to realize that thunderstorms can generate very-high-energy gamma rays – 100 MeV being the highest seen so far.

Now, researchers have discovered that these gamma rays are creating beams of positrons (the antimatter version of electrons) and hurling them into space!

These bizarre discoveries have come about thanks to the Fermi gamma ray telescope – the primary mission of which is to scan the heavens for gamma ray bursts. However, the satellite can’t help detecting terrestrial gamma ray bursts (TGBs) and once it determined that they are a regular occurrence over the tropics it was optimized to look down as well as up.

While most TGBs last about a millisecond, Fermi has seen events that last for much longer. What’s more intriguing is that one of these events appeared to occur over southern Egypt, where there was no thunderstorm activity.

Loving a good mystery, Michael Briggs at the University of Alabama and colleagues decided to investigate. One thing that they noticed was a preponderance of gamma rays at 511 keV, which are produced when electrons and positrons annihilate.

The positrons are created when high-energy gamma rays scatter off atoms in the atmosphere, converting into electron–positron pairs. Even more electrons are created by other scattering processes and, being charged particles, the electrons and positrons travel along Earth’s magnetic field lines. As they travel, they collide with gas atoms and can emit gamma rays.

So what does this have to do with the TGB over Egypt? What Briggs and colleagues think is that the initial TGB occurred thousands of miles away in southern Africa, sending a beam of electrons and positrons hurling up and over Egypt, where collisions produced gamma rays. See the above figure.

The charged particles kept going to a mirror point, where they were reflected back down over Egypt – creating a second pulse. This entire process took less than 30 ms.

Amazingly, physicists have only known about these high-energy bursts for a decade or so. The problem, according to Briggs, is that they are difficult to detect here on Earth because the gamma rays are absorbed by the dense lower atmosphere. However, they have been seen at certain high-altitude facilities and at sea level in Japan, where thunderstorms are believed to occur lower in the sky than in most places.

The big mystery, however, remains how such high-energy gamma rays are created in the first place.

By Hamish Johnston at the AAS meeting in Seattle

Times are tough, and cutting costs was on the agenda for the two speakers who opened the 217th Meeting of the American Astronomical Society here in Seattle.

On the podium first was AAS president Debra Elmegreen, who had something to say about the cost of coffee at the Seattle Convention Center – which is astronomical. Indeed, catering is the single largest expense for the meeting, and free coffee adds over one hundred dollars per delegate. Yikes, that’s a lot of money considering that more than 10% of the 2700 folks here are undergraduates.

So no more free coffee breaks between sessions – with the exception of ticketed coffee in the exhibition – and not a groan in the audience. If only the bankers would take the same attitude towards their bonuses!

The next speaker was the Nobel laureate John Mather, who spoke about progress towards launching the James Webb Space Telescope in 2015. The big news is that construction of the telescope’s 18 primary mirrors is well under way and they should all be completed by this summer. “It’s huge,” said Mather, referring to the telescope, which is 6.5 m across, compared with Hubble at 2.4 m.

The next big step, according to Mather, is to place the entire optical system into a giant chamber at the Johnson Space Center to simulate the rigours of space.

Mather took a few questions, which is when the thorny issue of money came up. A recent article in the New York Times pointed out that cost overruns on the James Webb were going to sap funds from other NASA missions. Not surprisingly, Mather was adamant that the extra funds were needed, and expensive projects such as the Johnson testing must go ahead.

I’m afraid that at this point there was some muttering in the audience – and the person next to me said under his breath that the James Webb was consuming far too much of NASA’s astrophysics budget.

Let’s hope Mather and colleagues can keep costs under control for the sake of my neighbour’s blood pressure.

seattle.jpg

By Hamish Johnston

Greetings from Seattle, where I will be for the next few days reporting from the 217th Meeting of the American Astronomical Society.

Today was mostly one of leisure as my colleagues and I recovered from our 9.5 hour flight and prepared ourselves for the coming feast of astronomy and astrophysics.

Highlights of the day included a ferry ride across Puget Sound to Bainbridge Island. I took the above photo from the ferry and you can see that the skies were particularly leaden – but what you can’t see is the biting wind and chilly temperatures. That’s the futuristic Space Needle at the far left.

But now it’s down to business…or at least a bit of schmoozing at the pre-meeting reception.

By Hamish Johnston

After too much turkey and water shortages in Ireland, December 20th seems like an eternity ago. That’s when we published our top 10 breakthroughs of 2010, with two research groups at CERN sharing the number one slot with their work on antihydrogen.

To create the top 10, I first went through the 360 or so news stories that we published in 2010 and came up with a shortlist of about 25. Then James, Michael, Matin and I locked ourselves in a meeting room until we could agree on a list of 10.

I won’t pretend that we were 100% objective – we all have our favourite topics and physicists – but I think we caught the essence of what went well in the world of physics last year.

Over on his blog Uncertain Principles, Chad Orzel has put our list to the test by asking his readers to vote on their favourite breakthough.

You can vote here, and you can also view the results.

I’m pleased to see that Chad’s readers agree with our number one and number two choices – and a few others as well. Folks seem less keen on the holograms, invisibility cloaks and phonon lasers.