By Margaret Harris

Physics and medieval history don't overlap that often. I should know: I got an undergraduate minor in medieval and renaissance studies in part because I wanted a break from doing physics. So the fact that this arXiv paper and this documentary have both come out in the past 10 days is about as unusual as – well, finding a medieval king buried in a car park.

Fascinating as the discovery of Richard III's skeleton is, though, I'm going to write instead about the arXiv paper, which proposes something even more remarkable: a possible link between space weather and episodes of famine in late medieval Europe.

The paper focuses on the years 1590–1702, a period during which Europe's population suffered repeatedly from famine. Over the same period, the Sun was experiencing a decades-long lull in activity, known as the Maunder minimum. Might there be a connection?

To answer this question, the paper's authors – physicist Lev Pustilnik and economist Gregory Yom Din – begin by summarizing the evidence for a connection between space weather and local weather. Overall, this appears fairly convincing, if a bit circumstantial. For example, a 1997 study found a link between cosmic rays and cloud cover, while a 2004 paper demonstrated a similar correlation between global atmospheric circulation and level of activity in the Earth's magnetosphere.

With the principle of a connection thus established, Pustilnik and Yom Din go on to suggest three conditions under which space weather could lead to famine:

• Local weather has to be in a "threshold state" such that it is sensitive to space weather. For example, if there is no water vapour present, clouds won't form even if space weather is "seeding" the Earth's atmosphere with lots of extra ions.

• Harvests must be sensitive to weather anomalies. This is more likely in areas of so-called "risk farming", where conditions are marginal enough that a few days of bad weather can completely wipe out a crop.

• The area has to be economically isolated, such that local shortages cannot be ameliorated by buying grain from elsewhere.

To test these hypotheses, Pustilnik and Yom Din begin by comparing levels of solar activity with grain prices in 17th century England. Between 1590 and 1700, the price of grain in England and the abundance of ¹⁰Be isotopes (a proxy for solar activity) in Greenland ice cores exhibit an almost exactly inverse relationship. High prices correspond to periods of low solar activity and vice versa. Several other European markets that the authors studied also showed strong correlations between grain prices and solar activity, but in southern Europe, where crops are more likely to suffer from drought than from excess rain, prices tended to spike during solar maxima rather than minima.

Things get a bit shakier when the authors turn their attention to 19th century Iceland. In this case, famines seem to correlate with both minima and maxima in solar activity. Pustilnik and Yom Din claim this is what they expected to see, but don't really say why; in particular, they don't explain why the Icelandic pattern should differ so markedly from the English one.

Still, it's an interesting study, and reading it stirred up some memories from my brief foray into medieval studies. In particular, I thought of a book called Lost Worlds whose author, a Swiss historian called Arthur Imhof, makes unusually good use of hard data in analysing what life was like for an ordinary person in early modern Europe. Might his book have something to add to the famine/space weather debate?

I skimmed my copy of Lost Worlds a couple of times before I located the bit where Imhof writes about famine. Tree-ring data and written sources from the 16th and 17th centuries, he notes, indicate a long series of harsh winters and summers with too much rain, resulting in exceptionally bad growing conditions. As a result, he adds, "our ancestors had more reason to beg for their daily bread between 1550 and 1700" than they did at almost any point before or since.

This is, of course, almost exactly the same period that Pustilnik and Yom Din studied, and it's nice to see that Imhof's sources corroborate their grain-price data. But Imhof wasn't interested in climate for climate's sake. Instead, he was trying to demonstrate that populations in areas prone to famine, plague and war became traumatized by their repeated misfortunes. You'd have to read the book to appreciate Imhof's argument in full, but among other things, he suggests that people in these "unlucky" areas developed fatalistic attitudes to life, death and birth. These attitudes show up not only in religious beliefs, but also in data on infant and maternal mortality. For example, even in peaceful, plague-free years, more than one-third of babies born in the plague-prone and war-torn German village of Gabelbach died in infancy. In "luckier" villages, the comparable figure was one in eight.

Where does this leave us regarding space weather? Well, if we add Imhof's conclusions to Pustilnik and Yom Din's, it seems that the behaviour of heavenly bodies could have influenced not only the viability of medieval grain crops, but also the habits and attitudes of the people who tended them – perhaps even to the extent of determining whether their children were likely to live or die. That might not be very surprising to the peasants of 17th century Gabelbach, who lived in a more religious age (and, according to Imhof, believed fervently in astrology). But to me, it's absolutely mind-blowing – and a whole lot more interesting than England's "Tricky Dick" turning up in a car park.

By James Dacey

Will the universe go on expanding forever? Why should we care about climate change? Can we make objects invisible?

These are Big questions with a capital B, which individually could occupy the mind of a scientist for an entire academic career. In fact I am sure they have.

But yesterday at Imperial College in London we asked a bunch of physicists to tackle questions of this size and stature and to answer them in 100 seconds or less – using nothing more than a white board and a few marker pens. It was a seriously tough challenge in the overlapping arts of brevity and clear communication.

The presentations were filmed as part of our 100 Second Science video series and they will be joining the existing batch of these "mini lectures". The picture above shows the PhD student and radio DJ Martin Archer preparing for his moment in the spotlight during which he tackled several questions on the fundamentals of quantum mechanics.

One of the questions Martin addressed related to one of the seemingly paradoxical implications of quantum mechanics: "Is Schrödinger's cat dead or alive?". I won't spoil Martin's 100 Second Science video on this famous thought experiment, but let us know your thoughts on this question by visiting our Facebook page and taking part in our poll where we ask:

Is Schrödinger's cat dead or alive?

It must be one or the other at any given time
It exists in a superposition of dead and alive
It could be dead and alive in separate universes
Another outcome is possible

We look forward to your responses. Look out for more in this series of films over the coming months.

Bubbles are wonderful things – as well as giving children hours of fun, they provide physicists with a number of fascinating phenomena to study and genuine mysteries to solve.

One curious effect that physicists have known about for some time is that tiny air bubbles in water will last much longer when they are stuck on a surface – rather than floating freely. A free bubble with a diameter of 100 nm or less will only survive a few microseconds, while a bubble of similar size on a surface can endure for days.

Why is this interesting, you might wonder? For one thing, controlling nanobubbles can be very important when designing tiny machines that shift fluids about. A coating of nanobubbles could make it easier for a fluid to flow along a tiny channel. Conversely, bubbles in the wrong place could gum up the works. Nanobubbles could someday be designed to carry drugs to specific places in the body, popping on arrival.

Such applications could be one step closer thanks to work published today in Physical Review Letters. Joost Weijs and Detlef Lohse at the MESA+ Institute for Nanotechnology at the University of Twente in the Netherlands have devised a theoretical model that tries to explain why bubbles on a surface stick around for so much longer.

The pair say that two important effects are at play. The first – and most obvious – is that bubbles stuck to a surface aren't spherical, but rather are flattened out on the surface. This means that they have radii of curvature that are much larger than spheres of similar volume. It's well known that the smaller the radius of curvature, the faster that gas leaks from a bubble.

The second reason is related to the fact that the nanobubbles are fixed on a surface and tend to be surrounded by other nanobubbles. This means that the liquid in the vicinity of the surface becomes saturated with escaping gas molecules that must diffuse away. This puts the brakes on gas that is trying to diffuse out of the bubbles. Free bubbles don't have this problem because as they rise in a liquid, they move away from gas molecules that they have released.

You can read the paper here.

This isn't the first time that a paper has appeared in Physical Review Letters about nanobubbles. In 2011 Lohse and two other colleagues at Twente published this novel proposal about how nanobubbles on surfaces could be recycling gas molecules.

It's the first of the month so – as if by clockwork – the February issue of Physics World is now ready for your enjoyment, in print, online and through our apps.

Our lead news story this month is about how Barack Obama, who was sworn in for a second term as US president last month, deals with the US "fiscal cliff" and what impact any resolution has on funding for science.

Elsewhere, we examine the lasting impact of two famous astronomers – Fred Hoyle and Sir Bernard Lovell. The former's impact is felt most acutely in the "Hoyle state" – a short-lived excited form of carbon-12 that holds the clue to life in the universe but is still baffling today's best nuclear physicists. As for Lovell, his notorious visits to the Soviet Union in the 1960s at the height of the Cold War might have been frowned upon by authorities in the West, but they set the tone for international collaboration and helped to pave the way to today's ITER fusion experiment.

There's also a great feature on how researchers are gaining valuable information about the black hole Cygnus X-1. Plus don't miss Peter Kenny's lateral thoughts about the mysteries of mathematical subtraction and find out why friends hold the key to career success.

If you're a member of the Institute of Physics, you can access the entire new issue online through the digital version of the magazine by following this link or by downloading the Physics World app onto your iPhone or iPad or Android device, available from the App Store and Google Play, respectively.

If you're not yet a member, you can join the Institute as an IOPimember for just £15, €20 or $25 a year via this link. Being an IOPimember gives you a full year's access to Physics World both online and through the apps.

For the record, here's a rundown of highlights of the issue:

• Fiscal cliff leaves funding concerns – Impending cuts to science may temper the optimism that some physicists had over the re-election of Barack Obama, as Peter Gwynne reports

• The rocky road to reform – A power struggle at one of Serbia's largest and best known science institutes has led to its director being forced to resign after allegedly failing to restructure the lab, as Mićo Tatalović reports

• Thinking big about the future – As the US eyes a manned mission to an asteroid or Mars, Kirstin Matthews and Padraig Moloney argue that NASA needs better support for basic research – especially nanotechnology – to realize such ambitions

• Game-show physics – Robert P Crease explains why science is never an idealized process that operates following simple rules

• The secret of life – Life as we know it would not be possible were it not for a particular nuclear energy level of carbon-12 predicted 60 years ago by Fred Hoyle. But the true nature of this energy level remains one of the biggest unsolved questions in nuclear physics, say David Jenkins and Oliver Kirsebom

• A fusion of minds – Mystery still surrounds the visit of the astronomer Sir Bernard Lovell to the Soviet Union in 1963. But his collaboration – and that of other British scientists – eased geopolitical tensions at the height of the Cold War and paved the way for today's global ITER fusion project, as Richard Corfield explains

• The swan's dark heart – Astronomers discovered what they thought was the first black hole more than 40 years ago but have only recently verified its identity by establishing its distance, mass and spin. These fascinating observations are yielding new insights into Cygnus X-1's past and future, as Ken Croswell explains

• Another side of black holes – Kulvinder Singh Chadha reviews Gravity's Engines: the Other Side of Black Holes by Caleb Scharf

• Visible improvements – James Davenport reviews Visual Strategies: a Practical Guide for Scientists and Engineers by Felice Frenkel and Angela DePace

• Forget about networking – Marc Kuchner argues that if scientists really want to advance their careers, they should concentrate on making friends instead of networking

• Borrowing from nowhere – In this month's Lateral Thoughts, Peter Kenny gets all mixed up with subtraction

By Hamish Johnston

In their 2010 book The Grand Design, Stephen Hawking and Leonard Mlodinow expressed the opinion that philosophy was dead as a useful vocation – and that it was now scientists who must address the big questions such as "How was the universe created?".

Of course this is not the first time that scientists – primed by the many triumphs of their craft, particularly in the last few centuries – have put down philosophy, and the debate about its usefulness will continue.

A recent instalment pits the biologist Lewis Wolpert of University College London against Steve Fuller, who is a philosopher at the University of Warwick. It was organized by the Institute of Art and Ideas (IAI) and you can watch it on the IAI's video website. Also sticking his oar in on the side of philosophy is Jonathan Derbyshire, who is culture editor of the New Statesman. You can watch the debate here .

In this week's Facebook poll we are asking which side of the fence you sit on – Hawking's or the philosophers'.

Has today's science rendered philosophy obsolete?

Yes
No

Let us know by visiting our Facebook page, and as always please feel free to post a comment to explain your answer.

In last week's poll we asked what many would consider a philosophical question: In your interpretation of quantum physics, do objects have their properties well defined prior to and independent of measurement?

64% of you answered no – and when the same question was put in 2011 to professional physicists who study quantum theory, the result was 48%. The most popular response then was "yes in some cases", which garnered 52% of the vote. In our poll, by contrast, only 18% went for that option.

Aaron Swartz at a Creative Commons
event. (CC BY Fred Benenson)

It's surprising the little nuggets of information that come our way here in the Physics World office.

A couple of weeks back, for example, we received an e-mail from Paul Ginsparg, the Cornell University physicist who set up the now-ubiquitous arXiv pre-print server more than 20 years ago.

Ginsparg had written a great article for us back in 2008, when Physics World celebrated its 20th anniversary, in which he reflected on the early days of the Web and examined how it has changed scientific communication.

At one point in that article, Ginsparg discussed the growing influence of blogs, describing how he watched someone at a scientific seminar blogging with seemingly expert ease.

"Glancing over my shoulder", Ginsparg wrote, "I was struck by how a native laptop-user can navigate text and search windows faster than the eye can follow, and assemble references, photos and graphics from multiple sources, simultaneously replying to comments, and in the end spending far less time to assemble a set of useful pedagogic pages, accessible to the entire world, than I spend writing problem-set solutions for a small class."

Ginsparg did not realize at the time who the person in question was, but he has now discovered that the mystery blogger was in fact the Internet activist and open-access advocate Aaron Swartz. Swartz had been arrested by US federal authorities in 2011 in connection with systematic downloading of journal papers form the JSTOR database and was tragically found hanged in his Brooklyn apartment on 11 January this year.

Ginsparg had been reading reports about Swartz's death and realized, from photos of the SciFoo 2007 meeting, that Swartz was the person who had been "sitting next to me...blogging with unforgettable skill".

"I didn't know who he was," Ginsparg wrote in an e-mail to me, "having missed introductions because I was going back and forth between sessions, and never did get to talk to him at all. [It was a] missed opportunity and only now I learn he was not the typical generic 20-something blogger as assumed. Oddly enough, 5.5 years later I see the precise text I'd presumably described him writing preserved here."

You can read more about the meeting in this blog entry by the science writer George Dyson.

By James Dacey

This ink-on-paper sketch of Einstein (courtesy: Sigrid Freundorfer Fine Art LLC; click to view large) will go on public display for the first time tomorrow as part of an art show in New York City. It is the handiwork of Josef Scharl, a German artist who produced the work in 1950 while visiting his close friend Albert Einstein at Princeton University in the US.

Born in Munich in 1896, Scharl gained recognition in his time after being part of the "New Munich Secession" artists in the 1920s. He won various awards including the Albrecht Dürer Award from the city of Nuremberg, and the Prix-de-Rome. But Scharl was a vocal critic of the Nazi Party and by 1935 he was considered a "degenerate artist" and banned from painting.

Einstein, who by this time was already working at the Institute for Advanced Study at Princeton, had met Scharl in 1927 in Berlin at the house of photographer Lotte Jacobi. Upon learning of the fate of his friend, Einstein offered to sponsor Scharl's immigration to the US, which the artist accepted. Once in the States, Scharl used to visit Einstein regularly and when the artist passed away in 1954 Einstein wrote the eulogy that was read at the funeral.

"Scharl was an outspoken man, not shy with his opinions, often rather witty. Einstein appreciated Scharl's candor and views on this or that, and their conversations were lively and informative for both," says Sigrid Freundorfer, the fine-art dealer based in New York who owns the drawing. "It must have been refreshing for Einstein to have had somebody like Scharl to talk to once in a while, in German at that."

Freundorfer bought the painting last year from someone in the field of manuscripts and rare books "Being an art dealer, I bought it first as a magnificent drawing by Josef Scharl, depicting this great man Einstein, signed by both men," she said. The image will go on sale at the Master Drawings New York exhibition, which runs 26 January – 2 February and has a preview show on 25 January.

By James Dacey

Last week my colleague Hamish Johnston wrote about a fascinating survey carried out recently in the quantum research community. Physicists, philosophers and mathematicians were asked to give their responses to a series of questions about the foundations of quantum mechanics. Topics covered aspects of the subject from Einstein's views on the topic to the prospects of a practical quantum computer. The survey is described and analysed in this accompanying paper posted on the arXiv preprint server.

Perhaps the most fascinating outcome of the survey was the extent of variation in responses to the questions about interpretations of quantum mechanics. This is perhaps surprising given the fact that the modern theory of quantum mechanics has been knocking around now for the best part of a century. Perhaps it just goes to show how many of the key concepts at the heart of this strange theory are still strong sources of debate for physicists. In this week's Facebook poll we thought it would be interesting to ask you one of the questions from this recent poll:

In your interpretation of quantum physics, do objects have their properties well defined prior to and independent of measurement?

Yes, in all cases
Yes, in some cases
No
I'm undecided

Let us know by visiting our Facebook page, and as always please feel free to post a comment to explain your answer.

In last week's poll we asked you a question about the mechanism by which fundamental physics research is transformed into commercial products. We asked you whether you think patents are hampering the commercialization of graphene. The question was motivated by the publication of a new report from the intellectual-property consultancy CambridgeIP, which suggests that the UK might be losing out in the quest to commercialize this material. 78% of respondents said "yes" it is being hampered, while the remaining 22% said no.

Thank you to everyone for taking part and we hope to hear from you again this week.

By Matin Durrani

How do you tackle the world's biggest problems such as making sure everyone has enough food, clean water, a secure energy supply and access to proper medicine and healthcare?

According to Shirley Ann Jackson, president of Rensselaer Polytechnic Institute in the US, the answer lies in a novel kind of research endeavour, which she dubs "the new polytechnic".

Speaking at the 2013 ERA Foundation international lecture at the Royal Academy of Engineering in London last night, Jackson spelled out the principles of such an endeavour, which would essentially involve bringing researchers from different subjects, countries, cultures and sectors together to work on important multidisciplinary problems. Exploiting computer technology, the Web and big data sets would be the key to tackling such challenges, she reckons.

Jackson, who trained as a particle theorist and is also a member of Barack Obama's science advisory council discussed three interesting fields that, she thinks, could – indeed, already do – benefit from such an approach. They are using tissue-regeneration techniques to heal injured patients, incorporating solar panels and other forms of energy-saving devices into buildings, and exploiting the "data trails" we leave when we use social media.

I found Jackson a polished speaker, no doubt honed by her years in top positions in the US. Apart from being one of Obama's science-policy wonks, she was boss of the US Nuclear Regulatory Commission between 1995 and 1999 and is a former president of the American Association for the Advancement of Science. Before that Jackson was part of the faculty at Rutgers University, spent 16 years at Bell Labs and had spells as a postdoc at Fermilab and CERN. Her impressive CV also includes a string of directorships at the likes of IBM and FedEx.

Jackson was less detailed on the nitty-gritty of setting up her "new polytechnic" or explaining who would fund such an enterprise. Last night was perhaps not the forum for those questions. But to me the elephant in the room was the whole concept of multidisciplinarity itself, which surely can only work if you have strong, vigorous disciplines in the first place. Jackson pointed to the likes of Cardinal Newman as advocates of the need for a broad education as long ago as the mid-19th century, but there are probably very valid reasons why so many of us prefer to hone our talents in a particular discipline and why the goal of multidisciplinarity can be so hard to put into practice.

Jackson hinted that leadership is the key in her new vision, highlighting Nelson Mandela as an example of the kind of bold, visionary thinker who is needed to get her blueprint off the ground. I found Mandela on odd choice given that he is not the first person you would associate with revolutions in higher education, but Jackson was right that managing, leading and encouraging multidisciplinary teams – particularly if they are spread over different continents and different time zones – is crucial.

Next stop for Jackson on her European tour is the World Economic Forum in Davos, Switzerland, this week. Whether she's got time to pop in on her old haunt – CERN – I'm not sure.

Courtesy: Jesse Karjalainen

Camera phones at the ready! 2013 marks the 25th anniversary of Physics World and we want you to be a part of the celebrations this year. To kick things off we would like you to submit photos containing the text "PW25" to our Flickr group, a selection of which we will then publish later in the year. To give you an idea of the sort of photos we are looking for, we created the scene above using copies of Physics World magazine. If you're looking for inspiration, think about your working environment. You might consider using laser writing, empty drinks cans, lines in the sand, basically use anything you can find in your vicinity. Happy snapping!

It has become almost a cliché to call graphene the "wonder material", but this super-thin 2D honeycomb array of carbon atoms boasts some enviable electronic and mechanical properties. Apart from being the strongest material ever measured, graphene is also the stiffest and has an electrical current density a million times that of copper. Hardly surprising then that companies and institutes around the world have been stumbling over themselves to carry out research into this material, which was first isolated through Nobel-prize-winning work at the University of Manchester in the UK in 2004.

But a new report from the intellectual-property consultancy CambridgeIP suggests that the UK might be losing out in the quest to commercialize this material. By the end of last year, companies and institutes in China had apparently applied for or won a total of 2204 graphene-related patents – more than any other nation – ahead of the US, with 1754, and South Korea with 1160.

The most prolific firm in the patent-filing business is the South Korean electronics giant Samsung, with 407 patents and patent applications, followed by the US tech company IBM in second, with 134. The whole of the UK, in contrast, has filed and applied for just 54 graphene patents, with only 16 of those coming from the University of Manchester. UK science minister David Willetts complained that this was "the classic problem of Britain inventing something and other countries developing it".

But do patents tell the whole story? After all, not all patents applied for actually get granted and many graphene patents may be merely speculative applications either made as a kind of insurance policy, or as shots across the bow to ward off rival businesses from entering the same territory. And even if a company or institute has a particular patent granted, the technology still has to be exploited – plus there is always the danger of having to defend one's patent, often at great cost.

In the University of Manchester's case, it is therefore focusing its patent efforts on areas that are likely to be "most useful", such as scalable manufacturing techniques, coatings and composites, and is seeking only a few patents related to applications of graphene, such as graphene-polymer composites and fluorographene. Continued research is the key, the university claims, because by the time reliable methods for making graphene have been developed, today's patents may have in any case expired.

But is the huge number of patents on graphene a positive sign that this material could soon find its way into real products that will revolutionize our lives? Or is the fact that big business is snapping up patents likely to hamper the commercialization of graphene?

Let us know what you think by taking part in this week's Facebook poll

Are patents hampering the commercialization of graphene?

Yes
No

Please feel free to explain your answer by posting a comment on the poll

In last week's poll we asked you if you felt that university professors have one of the least stressful jobs. The question was inspired by a ranking exercise on the website careerscast.com, which suggested that being an academic researcher is one of the cushiest jobs around. That conclusion had got quite a few scientists pretty steamed up, so we wanted to find out what you thought.

Physics World's Facebook followers proved to be fairly evenly split, with 47% of respondents agreeing that being a prof is an easy number and 53% saying no. One poll respondent – Leonardo Paulo Maia – felt our question was too broad-brush. For him, university professors who don't actually do any research – and presumably are more involved in teaching and admin – definitely do have a relaxing time, even if they might be busy. He felt the really stressed-out people are the active researchers.

But another respondent – Lois Hoffer – was quite clear on her views. In a magnificent 250-word diatribe on the reality of a typical academic's lot, Hoffer painted a picture of a life with far too much teaching, not enough money to hire a postdoc or student for research, no departmental administrators, complicated European grant applications, no office, plus poor students who jabber away during lectures, don't know how to take exams and yet still have to be taught, marked and graded.

"Yes the money is good, and the job is for life," Hoffer concluded. "But lack of stress?? You gotta be kidding."

Thank you to everyone for taking part and we hope to hear from you again this week.

Modern quantum mechanics has been around for a century or so and has proven to be an incredibly useful tool for both understanding nature and creating practical technologies. Therefore, it might come as a surprise that different "attitudes" to quantum mechanics still exist among experts in the field.

These are highlighted in a paper recently uploaded to the arXiv preprint server. It describes a poll of 33 leading physicists, philosophers and mathematicians that asks their opinions on quantum theory. The survey was done at a conference in 2011 in Austria that was called "Quantum Physics and the Nature of Reality".

Delegates were asked which is their preferred interpretation of quantum mechanics. Not surprisingly, "Copenhagen" was the winner with 42% of the vote, followed by an "information-based" approach" with 24%.

On the subject of quantum information – that is, the ongoing development of quantum computing, cryptography etc. – 76% of the respondents agreed that "it's a breath of fresh air for quantum foundations", whereas only 12% thought it was not relevant to the study of the foundations of quantum mechanics.

And what about that question that physicists are hearing a lot of these days: "When will we have a working and useful quantum computer?" While only 9% said within 10 years, 42% chose within 10–25 years.

The paper is by Maximilian Schlosshauer of the University of Portland, Johannes Kofler of the Austrian Academy of Sciences and Anton Zeilinger of the University of Vienna. As well as presenting the results, the trio look at correlations between different responses to try to build a picture of participant's overall view of quantum theory. They also compare the responses to a similar poll done in 1997. You can read the paper here .

If you are looking for a nice, relaxing job that is reasonably well paid with excellent job security, then university professor is the career for you. At least that is according to a new ranking exercise on the website careercast.com, which names "university professor" as the least stressful job of 2013 – followed by seamstress/tailor, then medical-records technician. The survey is based on criteria such as "physical demand" and "deadlines", and is part of a more extensive categorization of the best and worst jobs that will be released in April.

Since the list was published last week there has been a mighty backlash from some members of the academic community, who feel their working life has been falsely characterized. A large dose of this anger was directed at this article in the magazine Forbes, which gleefully endorsed the results. Forbes journalist Susan Adams described the life of an academic with several gems, including "Working conditions tend to be cozy and civilized and there are minimal travel demands, except perhaps a non-mandatory conference or two." However, after the article appeared, it received so many comments from disgruntled academics that Adams felt moved to write an addendum to reflect these sentiments and to clarify her position.

Let us know what you think about the debate by taking part in this week's Facebook poll.

Do university professors have one of the least stressful jobs?

Yes
No

Please feel free to explain your answer by posting a comment on the poll.

In last week's poll we asked you a question that involved a scientist whose fame now extends far beyond his academic research. We asked whether Stephen Hawking's appearance in a recent advert for a price-comparison website was good for the communication of science. In the advert, Hawking is seen to create a black hole on a UK high street to destroy the comedy character known as Gio Compario. The poll was tightly contested, with 46% of respondents saying yes the advert is good for science communication, and the remaining 54% saying no it is not.

Of course, it was a very open question, so the poll attracted many comments. "It helps raise the profile of scientists in a jokey way. More and more people are now familiar with Hawking, Jim Al-Khalili and Brian Cox as TV personalities, and are enjoying and benefiting from their appearances on TV," wrote Paul Londale. Another commenter, Raul Raúl, also has no qualms with Hawking taking part in the advert. "Isaac Asimov, a PhD in biochemistry and icon science-fiction writer and science popularizer, used to advertise IBM PC machines in late 1980s. So, let them do it," he wrote.

Thank you for all your participation and we hope to hear from you again this week.

"What is temperature?" is the sort of question that a seven year old would ask – and a physicist would struggle to answer in a simple way. That's why a paper published today in Science about "negative temperature" seems very puzzling at first glance.

One way of looking at temperature is as a way of describing how energy is distributed among a collection of particles. Most particles will have a small amount of energy and the probability that a particle has a higher energy will drop exponentially with energy – the familiar Maxwell–Boltzmann distribution of an ideal gas. Temperature times Boltzmann's constant is the parameter that fits the distribution to experimental data. Implicit to this distribution is that there is a minimum energy (zero) and no maximum energy.

Now, a team of physicists has used ultracold atoms to create what is essentially a mirror reflection of this familiar scene – a system with a maximum energy and no minimum energy. Furthermore, the probability that a particle in this system has an energy approaching this maximum is very high and drops off exponentially as the energy decreases.

So if you interpret this in terms of the Maxwell–Boltzmann distribution, you get a negative temperature (or perhaps a negative Boltzmann's constant).

Ulrich Schneider and colleagues at the Max Planck Institute for Quantum Optics in Munich created this system by using an ultracold quantum gas in which the individual atoms repel each other. In this system the atoms want to move apart from each other but are trapped by laser light.

The researchers then adjust the laser light to "freeze" the atoms into a state called a Mott insulator, in which the atoms are stuck in a solid-like lattice. The interaction between atoms is then flipped to be an attractive one and the trap is switched to an "anti-trap" – the laser light tending to push the atoms apart.

The researchers then return the atoms to the gaseous state. The anti-trap provides the maximum energy, to which most of the atoms push against as they try to get closer to each other. And, hey presto, the system behaves as if it has a negative temperature.

So have Schneider and colleagues ventured below absolute zero? No, but they have done a nifty experiment!

You can read Schneider's paper here.

By James Dacey

For those of you outside of the UK, or those who were not quite so firmly glued to the telly over Christmas, you may not yet have had the pleasure (or pain) of viewing Stephen Hawking's latest dalliance into popular culture. Hawking is the chief protagonist in a new television advert for the price-comparison website gocompare.com, as part of the company's "Saving the Nation" campaign. Playing the boffin hero, Hawking apparently does the UK a favour by ridding it of the character Gio Compario, an impassioned but unbearable comedy maestro who spends his days singing about the "go compare" brand. Compario meets his sorry end on a UK high street when he is sucked into a black hole created by the mischievous Hawking, who is seen grinning with glee at the outcome.

I was left with the mixed feelings of mild amusement and utter horror at the cheesiness of the advert, precisely as intended by its creators. The fact that I am even writing this post proves that the advertisers have achieved their objective, though I would hasten to add that I neither approve nor disapprove of the website – in fact, I've never even used it. A more interesting debate to me is whether – after all things are considered – the use of physics and a celebrity cosmologist in this advert are good things for science. On the one hand, it shows just how firmly established Hawking is in the public consciousness. I think it is fair to say that when it comes to popular culture, physics and geeky humour in general are enjoying a day in the sun at the moment. You just need to look at the popularity of a show like The Big Bang Theory and the growing appeal of science television presenters such as Michio Kaku and Brian Cox, not to mention Hawking's cameo appearances in The Simpsons.

On the other hand, if you are not willing to suspend disbelief, you might start to nit-pick just a little about the plot of this advert. You might start to ask some terribly pedantic questions such as "How can it be that while Gio Compario is hoovered up by a black hole, the other people on the high street manage to miraculously escape it unharmed?". On a more political note, you may also ask whether a man of Hawking's talents should not be devoting his time to something a bit more meaningful. Though you could hardly accuse him of being the first celebrity to make a bit of cash thorough appearing in TV commercials.

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