It's a long-running joke in the physicsworld.com newsroom that physicists see power laws everywhere. Indeed, a quick scan of the arXiv preprint server reveals physics papers that apply power-law analysis to a wide range of topics from cosmology to geography.

But how many of these studies actually produce useful results? Not many, argue two applied mathematicians in the UK.

A power-law description of nature says that a physical quantity or probability distribution is proportional to an exponential power of another quantity. A simple example is the inverse-square law that describes the gravitational attraction between two masses. A more statistical formulation is the Gutenberg–Richter law, which describes the number of earthquakes experienced in a location as a function of earthquake magnitude.

But what does power-law analysis actually tell us about the physical properties of a system? Its proponents argue that if different things – say earthquake frequency and measles outbreaks – share the same power law, then there must be something similar about the fundamental dynamics that drives both systems. This train of thought has already proved very useful in the study of thermodynamic phase transitions, for example, where seemingly unrelated systems change phase in exactly the same manner.

But should physicists expect the same success when power laws are applied to other systems? Writing in today's issue of Science, Michael Stumpf of Imperial College London and Mason Porter of the University of Oxford argue that, so far, the track record is not very promising.

They argue that many power-law studies have poor statistical underpinnings and don't shed much light on the underlying mechanisms of the systems of interest. Indeed, they write that "even the most statistically successful calculations of power laws offer little more than anecdotal value". That is fighting talk, so expect a robust response from the power-law community in the letters pages of Science.

Hmm, I wonder if the time gaps between letters will follow a power law? You can read all about that particular effect in this Physics World article by Albert-László Barabási, who is one of the discipline's leading exponents.

You can read Stumpf and Porter's article here, but it may require a subscription.

By James Dacey

Some have dubbed it the "Brian Cox effect", others cite a whole raft of reasons, but all concerned agree that physics in the UK has undergone something of a popularity transformation in recent years.

Indeed, applications to study undergraduate physics (including astronomy) increased by 34% between 2004 and 2009, rising year on year. And the trend appears to be continuing unabated.

According to the nuclear physicist Jim Al-Khalili of the University of Surrey – himself something of a media darling these days – there have been 320 applicants for 60 physics places this year at his institution alone, a 40% increase from last year. And this increase has occurred despite a 10% overall decline in applications at the university – blamed on the nationwide rises in tuition fees introduced this year.

To me, it is impossible to attribute the recent resurgence in physics to one specific reason. But I believe it is clear that the likes of Brian Cox and Jim Al-Khalili have helped to rebrand physics, thanks to their passionate communication of science in the popular media and their knack for explaining difficult ideas using simple, everyday concepts.

In this week's Facebook poll question, please give us your opinion on the following.

Who is the most inspiring of the current physics communicators?

Brian Cox
Brian Greene
Michio Kaku
Lisa Randall
Neil deGrasse Tyson
Stephen Hawking

And, of course, feel free to explain your choice or suggest an alternative communicator by posting a comment on the poll.

In last week's poll we asked you a question related to particle physics. We wanted to know where you think the International Linear Collider (ILC) – a proposed successor to the Large Hadron Collider (LHC) – should be built.

Some 52% of respondents opted for CERN, the home of the LHC on the Franco-Swiss border. 30% went for Fermilab in the US, which hosted the LHC's former rival accelerator, the Tevatron, which shut down towards the end of last year. 11% believe it is time for Japan to have its turn, following recent speculation in the Japanese press that the ILC could be built on the island of Kyushu. The remaining 6% believe that the ILC should never be built.

Thank you everyone for your responses and we look forward to your responses in this week's poll.

By Hamish Johnston

One thing you can say about most houses in the UK is that they are solid. All walls, including internal ones, tend to be made from masonry – bricks in Victorian and Edwardian homes, and cement blocks in more modern buildings. It's rare to see the flimsy-looking wooden frames that miraculously become houses in North America, for example.

But there is a downside to this solid construction. Masonry – and older bricks in particular – tend to suck-up moisture from the ground. Indeed, this is such a common problem in the UK that they named a sitcom after it – Rising Damp.

One symptom of rising damp is efflorescence, which means "flowering out". This refers to crystals of salts that grow out from the surface of masonry as the damp evaporates into the air. Efflorescence can be a real pain on interior walls because it can stain paintwork and push-off wallpaper. I should know, because we used to have it in the dining room!

Efflorescence has also fascinated physicists because, rather than emerging as a uniform coating of salt, the crystals tend to appear in clumps – but exactly why was a mystery.

But now, Marc Prat and colleagues at the University of Toulouse, France, have done experiments and computer simulations that suggest that several factors are involved in determining the locations of salt flowers.

One is that the rate of evaporation is often not uniform across a wall. Not surprisingly, moisture is drawn to regions of the surface where air currents or other factors boost evaporation, and this causes more efflorescence in these areas. The irony, of course, is that reducing humidity and increasing ventilation could actually encourage efflorescence!

Turning their attention to the network of tiny pores that exist in masonry, the team worked out that certain pathways are extremely efficient at transporting water to the surface, while others are not. The researchers concluded that the salt flowers form where these efficient pathways emerge at the surface. Once a crystal is established on the surface, its presence increases the flow of water through that particular pathway, further depriving surrounding less-efficient pathways of liquid. The result is regions with large crystals, and other regions with no salt.

Finally, they tried to explain why the salt crystals grow outwards from the surface, rather than spreading out. The reason, it seems, is that the moisture would rather travel through a salt crystal than along a masonry surface. Putting all of this together, the team believes that it has made a good first effort at understanding efflorescence.

The research is described in Phys. Rev. Lett. 108 054502 and you can read the paper here.

By Margaret Harris

Last autumn I visited Fermilab to learn more about the US particle-physics lab's plans for the future now that its flagship particle accelerator, the Tevatron, has closed for good.

You can read more about those plans in this article, but if you'd like a slightly more visual guide to how the lab is changing, I've put some photographs from my trip on Physics World's Flickr page.

I'm hardly a professional photographer, but it's easy to take good photos in a place as beautiful as Fermilab, with its spacious Midwestern skies, iconic structures, and famous herd of American bison. But even if pretty pictures aren't your thing, the photos also illustrate some of the changes going on at the lab, with the empty, slightly forlorn-looking CDF control room contrasting sharply with the buzz of activity in Fermilab's neutrino-research areas.

In other Fermilab news, the Chicago-based composer Mason Bates apparently found the lab's soundscape as inspiring as its landscape. Bates is the composer-in-residence at the Chicago Symphony Orchestra, and last year he visited Fermilab to record material for a new composition called Alternative Energy. According to the website for the symphony, the piece blends ambient noises from the lab with percussion and orchestra, and it had its première on Thursday 2 February. You can watch a video of Bates making his recordings here.

By Tushna Commissariat

This year the European Southern Observatory (ESO) is celebrating its 50th birthday. In honour, ESO plans to release a monthly "then and now" comparison image that shows how much things have changed over the past half of a century at ESO's two main observatory sites (La Silla and Paranal), at ESO offices in Santiago de Chile and at its headquarters in Garching, Germany.

February's photos of choice (images above courtesy of ESO/J Dommaget) depict the La Silla Observatory in the late 1960s and the present day. Only one telescope is visible in the historical image – the ESO 1 m Schmidt telescope, which saw first light in 1971. The present-day image has two new telescopes visible – the MPG/ESO 2.2 m telescope (left) and the New Technology Telescope on the peak to the right. According to ESO, the MPG/ESO 2.2 m telescope has been in operation since 1984 and its construction is apparently the reason why the modern-day photograph could not be taken from exactly the same spot as the one from the 1960s. It also points out that back in the day, astronomers would sleep in the huts running along the right-hand side of the road. Luckily, researchers now have the luxury of using a more comfortable hotel on the edge of the site.

It is also interesting to note the cars in both images. ESO informs me that the car in the historical image is a Volkswagen 1600 Variant, while now all ESO vehicles on site at La Silla – such as the Suzuki 4WD in the new image – are white, to improve visibility at night.

Keep an eye out for more "then and now" images from ESO in the months to come.

By Matin Durrani
My eye was caught this morning by a new report from the Institute of Physics, which publishes physicsworld.com, about the number of physicists at UK universities.

Entitled Academic Physics Staff in UK Higher Education Institutions, you can read the full report here, but what I found particularly interesting were the data on women in physics.

The report reveals that the proportion of staff in UK physics departments who are women has risen steadily from 13% in 2003/04 to 16% in 2009/10. (See figure above: data in it are from the UK's Higher Education Statistics Agency.)

As one might expect, the biggest rises are at more junior levels, with the proportion of female lecturers going up from 11.3% to 19.8% over that period. Senior-lecturer numbers have increased from 9.0% to 11.2% and although the proportion of female professors has risen form 3.9% to 5.5%, women in these top positions are still very much in the minority.

Given that women make up about 22% of UK physics undergraduates, is it too much to hope that in 15 or 20 years' time women will also make up a fifth or so of physics professors?

Another intriguing statistic concerns the highly international level of UK physics, particularly among women. According to the report, the proportion of female staff at UK universities who are not from the UK has risen from 46% in 2003/04 to 51% in 2009/10. This is much higher than the fraction of male non-UK nationals at UK universities, which has gone up from 31% to 40% in the same period.

Overall, across both men and women, the biggest proportion of non-UK staff working in UK physics departments come from Germany, followed by Italy, the US, China, Russia, France, India, Greece and the Netherlands. Make of that what you will.

You can read the full report here.

By Hamish Johnston

Japan has announced that it will bid to host the International Linear Collider (ILC), which is expected to be the next big experiment in particle physics after the Large Hadron Collider at CERN. The Japanese press is saying that the particle smasher – which is expected to cost about $8bn and stretch for 40 km underground – could be built on the island of Kyushu.

The word on the street is that either Japan, CERN located on the Swiss-French border, or Fermilab in the US will play host to the massive project. Physics World's Margaret Harris was at Fermilab recently to find out what will become of the facility now that its premier collider – the Tevatron – has shut down. Margaret didn't focus on the lab's chances of bagging the ILC, but rather on the plethora of experiments that are ongoing or planned for the near future. Her article about the visit also includes a series of audio clips of Fermilab physicists describing their work.

So, do you think Fermilab is the place for the ILC? This week's poll question is:

Where should the International Linear Collider be built?

At CERN (Europe)
At Fermilab (US)
In Japan
It should never be built

Have your say by visiting our Facebook page. And feel free to explain your vote, or suggest another location, by posting a comment on the poll.

In last week's poll, we asked, "Do you believe that researchers will always view the scientific paper as the gold standard for sharing new results?". 56% of you think that the scientific paper will endure, while the remaining 44% believe the paper will be replaced by other forms of communication. That's hardly a ringing endorsement of something that has served science well for several centuries.

One thing that commenters could agree on is the importance of peer review in science communication. One voter, Robert Minchin, said "Peer review is far too useful, not just as a 'gatekeeper' for what gets into the literature, but also in preventing us from embarrassing ourselves: like most (if not all) scientists, I've had referees spot errors that I had been completely blind to." He goes on to say that while the concept of a paper will endure, they "may not be anything like we have had in the past". He added, "I would expect it to become standard for journal publishers to provide the ability to manipulate and search data tables, view them graphically, etc. as part of their value-added service."

Another pollster, Jose Riera, agrees about the importance of peer review, writing: "The real question is peer-reviewed papers or not peer-reviewed. My answer is that only peer-reviewed papers could have some minimum standards or scientific value."

Thank you for all your responses and we look forward to hearing from you again in this week's poll.

The February issue of Physics World magazine is now out, featuring some great articles that I think I ought to tell you about.

Physics comes to life – Mark Haw from the University of Strathclyde and Otti Croze from the University of Glasgow explore the strange world of swimming micro-organisms – and how it is having an impact on biology, biotechnology and fundamental physics.

Gallery of whispers – Oliver Wright from Hokkaido University in Japan looks at a little-known effect dubbed "whispering-gallery waves". Dating back to the work of Lord Rayleigh at St Paul's Cathedral in London, it appears throughout science in fields as diverse as astronomy, optics and acoustics.

Securing the future – John Womersley, chief executive of the UK's Science and Technology Facilities Council, explains why the country's research community needs to safeguard its own future.

Careers, interrupted – Jan West describes the work of the Daphne Jackson Trust, which has helped more than 200 people to return to working in science after a career break.

Don't miss either Rick Trebino's Lateral Thoughts article "Fire in a crowded theatre", while over in news and analysis, we have an interview with Italian theorist Giorgio Parisi entitled "The Italian activist" and an update on the work of the SESAME synchrotron being built in the Middle East. Plus enjoy Margaret Harris's feature "Fermilab's next frontier" in all its glory.

Members of the Institute of Physics (IOP) can read the new issue free online through the digital version of the magazine by following this link or by downloading the Physics World app to your iPhone or iPad or Android device, available from the App Store and Android Marketplace, respectively.

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

By James Dacey

A new report released earlier this week concluded that physical scientists use and access information in very different ways depending on the precise field they work in. Based on interviews and focus groups with a range of physical scientists, Collaborative Yet Independent reports that researchers have started to use online tools such as social networking sites in relation to their work. It found, however, that when it comes to disseminating new scientific results, publication in a traditional scientific journal remains the “gold standard” for researchers.

We want to know whether you think this will remain the case looking to the future of science. In this week’s Facebook poll we are asking the question:

Do you believe that researchers will always view the scientific paper as the gold standard for sharing new results?

Yes
No, it will be replaced by other forms of communication

To cast your vote, please visit our Facebook page. And, as always, please feel free to explain your response by posting a comment on the poll.

In last week’s poll you may have clocked that we addressed the timely issue of timekeeping. It was the topic of the hour because last Thursday delegates were debating whether or not we should scrap the “leap second”, at a meeting of the International Telecommunication Union in Geneva. This is a second that is added to or taken away from Co-ordinated Universal Time (UTC) every few years to take account of the slight speeding up or slowing down in the rotation of the Earth.

Since the first leap second was inserted in 1972, people have deliberated whether this is the most effective way of dealing with time. Some have suggested swapping the leap second in favour of the addition of a larger chunk of time after a longer period – such as a leap hour roughly every millennium. Others have suggested abandoning astronomical time altogether, replacing it with an Earth-based reference such as an atomic clock. To do so would decouple time from the Earth’s rotation, allowing traditional night hours to gradually become day hours, and over millions of years the seasons would shift from their traditional months.

We asked for your opinion on this issue and 72% of respondents believe that we should define time using an atomic clock. The remaining 28% would prefer to maintain our connection with the heavens by keeping astronomical time.

One commenter, Robert Minchin, believes that we should keep the leap second to save a stitch in time. “Getting rid of them would simply be storing up problems for the future, when a larger leap-something will need to be introduced before the night becomes the day,” he wrote. Another respondent, who goes by the name of Strum Cat, feels strongly that we should ditch astronomical time. He wrote: “Are you kidding? Defining time by the rotation of Earth is fine for getting to work on time, but useless for precise science.”

It appears, however, that the debate is set to continue for some time yet. Last Thursday – after our poll went live – officials at the ITU announced that they have sent the issue back to a panel of experts for further assessment. They say a revised proposal will be introduced no earlier than 2015.

Thank you for all of your votes and comments, and we look forward to hearing from you again in this week’s poll.

By Hamish Johnston

Anyone who has trained as a scientist has learned about the "scientific method" – but the concept remains ill-defined and its origins are a topic of debate among philosophers and historians.

In this week's instalment of In Our Time on BBC Radio 4, Melvyn Bragg and his cabal of intellectuals discuss the role of the English polymath Francis Bacon (1561–1626) in the development of the method. Through writings such as Novum Organum Scientiarum, Bacon (right) championed the use of inductive reasoning in science. Indeed, Bacon had a very important influence on a future generation of scientists who founded the Royal Society in 1660.

Another character associated with the development of the scientific method is Isaac Newton. According to historian Simon Shaffer of Cambridge University, Newton first developed his rules of scientific enquiry to study a very non-scientific subject: the Bible's Book of Revelation. Newton then further developed his ideas by applying them to what we would think of as science.

Rounding off Bragg's panel are the philosophers John Worrall of the London School of Economics and Michela Massimi of University College London. The quartet go on to discuss how Charles Darwin's 1859 On the Origin of Species was first received by Victorian scientists. Not very well it seems – Darwin's arguments seemed to fly in the face of the scientific method because the processes of evolution could not be observed in laboratory experiments.

The team also looks at how the overthrow of Newtonian physics in the early 20th century by relativity and quantum mechanics led to a rethinking of the scientific method. Leading the way was philosopher Karl Popper with his idea of falsifiability and Thomas Kuhn with his theory of paradigm shifts.

You can listen to the programme here.

By Matin Durrani

I travelled up to London last night to attend the official opening of a new exhibition at the Science Museum celebrating the Cambridge University cosmologist Stephen Hawking, who turned 70 earlier this month.

Sadly, Hawking was too ill to attend in person, but he did deliver a "speech" via his trademark voice synthesizer, in which he said that "it has been a glorious time to be alive and doing research in theoretical physics".

"Our picture of the universe has changed a great deal in the last 70 years, and I'm happy if I have made a small contribution," he added.

Hawking went on to say that he wanted to share his "inspiration and enthusiasm" for science. "There's nothing like the 'eureka' moment of discovering something that no-one knew before," he claimed.

The exhibition, which is fairly small, includes a short letter that Hawking sent to the editor of Nature in 1974 accompanying his paper showing that black holes can emit radiation – a hypothesis that he warned "might cause quite a stir".

There is also a drawing of Hawking by the artist David Hockney and some other memorabilia, including a copy of a baseball encyclopedia that was the subject of a bet with Caltech physicist John Preskill. Hawking gave Preskill the book in 2004 after conceding that information could be retrieved from a black hole, as Preskill had argued but Hawking had originally denied.

Also present last night was Hawking’s daughter Lucy, who paid tribute to her father and thanked the museum for putting on the display.

Spotted among the attendees was Graham Farmelo, author of a biography of that other great British theoretical physicist, Paul Dirac. Entitled Strangest Man, it was Physics World's Book of the Year 2010 and you can listen to an online lecture by Farmelo about Dirac here. Also present last night was Surrey University physicist Jim Al-Khalili, who recently delivered an online lecture for physicsworld.com about the scientific contributions of Muslim scholars.

More details about the exhibition can be found here.

By Hamish Johnston

For most people there are 86,400 seconds in a day – but astronomers have known for some time that days are getting longer thanks to sudden shifts in the Earth's rotation.

While most of us will live our entire lives oblivious to this tiny warping of time, it does mean that the time kept by super-accurate atomic clocks and the astronomical time calculated from Earth's motion are drifting apart by up to one second per year.

To solve this problem, the International Telecommunications Union (ITU) maintains Coordinated Universal Time (UTC). The length of the second in UTC is defined as a certain number of beats of an atomic clock, whereas the actual time of day is defined astronomically. This is done by adding or subtracting "leap seconds" to UTC when necessary.

For the past decade, however, various groups have been calling for the abolition of the leap second and the adoption of pure atomic time. The ITU will be meeting in Geneva over the next few weeks and the abolition of the leap second is on the agenda. Indeed, the first debate is scheduled for today.

If the ITU does do away with the leap second, it will end tens of thousands of years of astronomical timekeeping by humans. This bothers some scientists – including Markus Kuhn of the University of Cambridge in the UK. You can read more about the leap second, and Kuhn's arguments, here.

What do you think? You can have your say by participating in this week's Facebook poll, where the question is:

How should time be defined?

By the Earth's rotation
By an atomic clock

In last week’s poll we found ourselves in rather gloomy territory following the news that the famous Doomsday Clock had swung one minute closer to midnight. We asked you to choose from a list of scenarios the one you believe is most likely to lead to the end of civilization as we know it.

Runaway climate change emerged as voters "favourite" choice by picking up 49% of the votes. In second place was a nuclear world war, receiving 27% of votes. In third place was an asteroid impact with 12% of votes. Fourth place went to an act of bioterrorism with 10% of votes. And just 6% of voters believe that we will meet our end at the hands of an alien invasion.

Once again, the poll attracted a lot of comments from our fans on Facebook, despite its rather depressing theme. And a lot of people appeared to have given the doomsday scenario some serious thought. That includes Bill Dortch, who warned "I would say an act of bioterrorism, especially now that not one, but two researchers, with NIH funding, have demonstrated how very easy it would be."

Cathy McHale Albano also believes that our fate will ultimately lie in our own hands. "I'm guessing it's got to be something caused by humanity, so it's runaway climate change, bioterrorism or nuclear world war," she says. "The insidious nature of climate change makes it more likely, in my mind, although all it takes is one wrong move by one of the world's wackos for the other two to happen.”

However, there were plenty of others who answered the poll in jest, including Lynette Fitch Blair: "Since there is no category for zombie apocalyse, then I guess alien invasion is the next best choice." And Paul Tangney, who chipped in early to point out that we were offering "some post-festive cheer from the physics community".

Thank you for all of your votes and comments, and we look forward to hearing from you again in this week’s poll.

By Margaret Harris

Congratulations to Andrew Palfreyman of San Jose, California, for winning the Physics World Quiz of the year 2011. This annual feature tests your knowledge of great and small events that occurred in the physics community over the past 12 months, from the shutdown of Fermilab’s Tevatron to the discovery that building a nuclear reactor in your kitchen is a great way to get arrested (who knew?).

We received quite a few entries this year, and about a dozen of them came from alert readers like Palfreyman who got every question right. If you didn’t win this year, better luck next time; in the meantime, though, here are the answers.

A. Fermilab’s Tevatron accelerator
B. Wrinklon
C. The Allen Telescope Array
D. Jane Fonda
1. Studying how the Sun and aerosols affect the Earth’s climate
2. Mercury
3. Lake Baikal, Russia
4. Subaru 8 m telescope
5. “Heavenly Palace”
6. B (Mobile phones)
7. C (A degree and a PhD)
8. A (Writing research papers)
9. B (String theory)
10. A (They are part of a microgravity experiment)
11. B (David Cameron)
12. A (Jocelyn Bell Burnell)
13. E (Michael Gove)
14. D (John Ellis)
15. C (Athene Donald)
16. B (25)
17. C (The bars contained elevated levels of lead)
18. A (Building a nuclear reactor in his kitchen)
19. C (Jupiter)
20. D (Galileo Galilei)

By James Dacey

On Tuesday, the famous Doomsday Clock swung a minute closer to midnight, suggesting that humanity has recently edged slightly nearer to self-destruction. The time on the Doomsday clock now reads five minutes to midnight, having being wound back to six minutes before midnight back in January 2010.

The Bulletin of the Atomic Scientists (BAS), who created and control the clock, attributed the change to inadequate progress on nuclear weapons reduction and proliferation, and continuing inaction on climate change.

We have addressed this rather gloomy topic of Doomsday scenarios in this week’s Facebook poll in which we are asking the following question:

Which scenario is the most likely to lead to the end of civilization as we know it?

A nuclear world war
Runaway climate change
An asteroid impact
An act of bioterrorism
An alien invasion

To cast your vote, please visit our Facebook page. And, of course, if you believe that some other ghastly scenario is more likely to wipe bring us to an unsavoury end, please feel free to post a comment.

In last week’s poll we asked you to select the person you believe to be the greatest living physicist from a shortlist of five. It quickly became a two-horse race between the two Steves: Steven Weinberg and Stephen Hawking that is. But in the end Weinberg narrowly won out, gathering 36% of the vote, compared with Hawking’s 34%. In third place was Ed Witten, accruing 15% of the vote. In 4th place was Philip Anderson with 14%, and in last place was Franck Wilczek with just 2% of the vote.

The poll also attracted a lot of comments and various other scientists were proposed for this mantle of greatest living physicist. The suggestions included: Murray Gell-Mann, Leonard Susskind, Gerard 't Hooft, Sean Carroll and Peter Higgs.

Thank you for all of your votes and comments and we look forward to hearing from you again in this week’s poll. And we promise to ask a slightly more cheerful question next week!

This week's episode of the radio programme Great Lives focused on Joseph Rotblat, the Polish-British physicist and peace campaigner who died in 2005. The format of the programme involves a discussion of the person's life with a celebrity admirer – in this case the UK's Astronomer Royal Martin Rees – and an expert on the subject. The latter was Rotblat's friend and colleague Kit Hill, who is also a physicist.

Rotblat (pictured right, courtesy Nobel Foundation) was born to Jewish parents in Warsaw in 1908. He narrowly escaped the Nazi occupation in 1939 when he travelled to Liverpool to work at the university. From there, he went to the US, where he worked on the Manhattan Project to develop the first nuclear weapons.

He was the only scientist to quit the project for conscientious reasons – after seeing first hand how difficult it was proving to make a bomb, he concluded that the Nazis had no chance of succeeding and therefore the Manhattan Project was no longer purely a defensive act. Upon returning to the UK, he devoted his scientific career to studying the effects of radiation on living organisms.

In 1955 he joined forces with Albert Einstein, Bertrand Russell and other leading intellectuals to issue the Russell–Einstein Manifesto that alerted world leaders to the dangers of nuclear weapons and warfare. This led to the founding of the Pugwash Conferences on Science and World Affairs, which shared the 1995 Nobel Peace Prize with Rotblat himself.

The most intriguing question that the programme's host Matthew Parris put to Rees and Hill is why Rotblat appeared happy to work on nuclear weapons when he knew that they could be used to kill Germans, but then recoiled from the idea when he realized that they looked destined to be used against other peoples?

You can listen to Great Lives here.