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Physics in fiction

The podcast is hosted by James Dacey and features four books in total. The first two, The Sky’s Dark Labyrinth and The Sensorium of God, are both fictionalized versions of real episodes in physics history. They are part of a trilogy (the third book is due to be published in 2013) by the science writer Stuart Clark, and in the podcast they are covered by Physics World‘s reviews editor, Margaret Harris.

Next up is a thriller by Robert Harris called The Fear Index. This book is set in the modern-day world of mathematical finance, and as Physics World‘s editor Matin Durrani explains, its main character is a rather unsavoury ex-CERN physicist who has become a hedge-fund tycoon.

The last book discussed in the podcast is Mr g. This one is a bit harder to describe but author Alan Lightman – a physicist at the Massachusetts Institute of Technology – bills it as “a novel about the creation”, which seems pretty spot-on to us.

So are any of these books destined to become classics of physics fiction? Unlike in physics itself, there are no right or wrong answers here – but there are plenty of opinions, and we would love to hear your favourite examples of physics in fiction after you’ve listened to the podcast. You can post them as comments to this article, e-mail them to us at pwld@iop.org or send them to @PhysicsWorld on Twitter.

Special Report: Japan

By Michael Banks

Japan is certainly not resting on its laurels in maintaining its world-leading position in physics.

Only last week a Japanese government committee on high-energy physics released the English-language version of its highly anticipated report looking into the country’s particle-physics research programme for the coming decade.

Physics World Special Report: Japan

The 19-member committee not only recommended that Japan should take a lead in the design for a collider to study the Higgs boson, such as the International Linear Collider, but also that it should lead on plans to build a large-scale neutrino facility to study charge–parity violations in neutrino oscillations.

It is exactly for this reason – Japan’s history as a leading nation in physics – that we decided to take a closer look at physics in the country. Not only the many successes it has enjoyed, but also what challenges it faces in staying ahead.

We’ve now put together a new Physics World special report, which you can view online here, that draws together a selection of our recent articles about physics in Japan. Several of the articles are based on a week-long road trip to Japan that I went on earlier this year that included visiting Tokyo and Osaka.

In the issue we look, for example, at a major upgrade to Japan’s famous KEKB collider, a new asteroid-sample-return mission, as well as the world’s first compact X-ray free-electron laser. But Japan also faces many challenges to its world-beating status in physics, including how to entice foreign scientists to work and study in the country as well as attracting more women into physics.

I hope you find this special report stimulating and please do let us have your comments by e-mailing pwld@iop.org.

Here’s a rundown of what’s inside.

• Recovering from the quake – I discuss how Japan’s World Premier Institutes – set up to attract international researchers – have fared following the Fukushima nuclear accident in 2011

• The only woman in town – Mio Murao of the University of Tokyo explains how to get more women interested in physics in Japan

• Japan’s X-ray vision for the future – I travel to the remote SACLA facility, which houses the world’s first compact X-ray free-electron laser

• JAXA pushes for asteroid encore – Dennis Normile looks at plans to launch a second asteroid-sample-return mission after Japan’s successful Hayabusa probe

• Getting a grip on antimatter – Yasunori Yamazaki of the RIKEN laboratory in Tokyo describes his research on antimatter

• Coping with “Galapagos syndrome” – although Japan has introduced a number of reforms to reverse a trend of increasing isolation, some fear they may not be enough, as Dennis Normile reports

• Revamping Japan’s atom smasher – with the KEKB facility in Tsukuba undergoing a major upgrade, I describe how it could one day help to explain why there is more matter than antimatter in the universe

Scientists see saccharin star

Rho Ophiuchi star-forming region in the infrared


(Courtesy: ALMA (ESO/NAOJ/NRAO)/L Calçada (ESO) and NASA/JPL-Caltech/WISE Team)



By Tushna Commissariat


A team of astronomers in Denmark has spotted sugar molecules in the gas surrounding a young Sun-like star. And why is finding sugar in the gas surrounding a star important, you ask? It’s important because it tells us that complex organic molecules, like the sugars, that form the building blocks of life can be found around young stars at the time when planets could be begin to form around them.

The team found molecules of one of the simplest form of sugar – glycolaldehyde – in the gas surrounding a young binary star known as IRAS 16293-2422, which has a mass similar to that of the Sun. While the sugar has been found in space before – within our galaxy itself – this is the first time it has been found in close proximity to a star; in fact, it’s as close to IRAS 16293-2422 as Uranus is to the Sun. This discovery shows that some of the chemical compounds needed for life existed in this system at the time of planet formation. IRAS 16293-2422 is also located only about 400 light-years away from us – a mere hop, skip and jump in astronomical terms, making it an excellent target for astronomers studying the molecules and chemistry around young stars.

“In the disc of gas and dust surrounding this newly formed star, we found glycolaldehyde, which is a simple form of sugar, not much different to the sugar we put in coffee,” explains Jes Jorgensen from the Niels Bohr Institute in Denmark, who was the lead researcher of the team that used the Atacama Large Millimeter/submillimeter Array (ALMA) to observe the star. “This molecule is one of the ingredients in the formation of RNA, which – like DNA, to which it is related – is one of the building blocks of life.”

The image above shows the Rho Ophiuchi star-forming region in the infrared, as seen by NASA’s Wide-field Infrared Explorer (WISE). IRAS 16293-2422 is the red object in the centre of the small square. The inset image is an artist’s impression of glycolaldehyde molecules, showing glycolaldehyde’s molecular structure (C2H4O2).

“What it is really exciting about our findings is that the ALMA observations reveal that the sugar molecules are falling in towards one of the stars of the system,” says team member Cécile Favre of Aarhus University in Denmark. “The sugar molecules are not only in the right place to find their way onto a planet, but they are also going in the right direction.”

Jorgensen further explains that the gas and dust in clouds surrounding newly formed stars is initially extremely cold (only around 10 degrees above absolute zero at –273 °C) and simple gases such as carbon monoxide and methane settle on particles of dust and solidify as ice, and only after this occurs are more complex molecules formed. The newly formed star then heats its neighbourhood, evaporating the complex molecules from the dust and gas, and these molecules are then detected as radio emissions at low frequencies by telescopes such as ALMA.

“A big question is how complex can these molecules become before they are incorporated into new planets? This could tell us something about how life might arise elsewhere, and the ALMA observations are going to be vital to unravel this mystery,” concludes Jorgensen.

Stephen Hawking to narrate Paralympics opening

By Hamish Johnston

While the opening ceremony of the 2012 Olympics did a wonderful job of highlighting what was great about Britain (and Northern Ireland), I couldn’t help thinking that the nation’s scientists were short-changed. While the ceremony celebrated the industrial revolution, there was no reference to the great British scientists who developed the scientific groundwork that made it possible.

Now it looks as if Britain’s scientists will bask in the glory of this evening’s opening ceremony of the 2012 Paralympics – with Stephen Hawking playing a prominent role. Co-directed by Bradley Hemmings and Jenny Sealey, the ceremony begin at 20:30 BST and is called “Enlightenment” – and yes, it refers to the Enlightenment!

The British press is reporting that it will include references to British scientific giants of that era – with the Daily Telegraph quoting London Olympics and Paralympics head Sebastian Coe as saying “It focuses on that extraordinary period in European history and the great intellectual revolution that took place…Everything from Newton making sense of gravity and motion to Napier with logarithms and Harvey with blood circulation.”

Logarithms – I can’t wait, and if that isn’t enough excitement, the BBC reports that Stephen Hawking will provide some of the narration for the ceremony. “We worked very closely with Professor Hawking to develop a series of messages that are very much integrated into the storytelling of the ceremony,” the BBC quoted Hemmings as saying.

Living tissue is laced with electronic sensors

Embedding electronic circuitry inside human tissue has long been a mainstay of science fiction. Now, scientists in the US have devised a way to grow a culture of live tissue over a matrix containing tiny electronic sensors. As well as leading to better tissue cultures for drug testing, the work could also contribute to the development of synthetic replacement organs.

The growth of living tissue with embedded electronic sensors could have a range of biological and medical applications. However, the only option up to now had been to culture the tissue and then to insert electrodes into it. This is undesirable for two reasons. First, a series of electrodes pushed in like needles do not access the tissue in a precise and sensitive manner. Second, inserting electrodes into tissue will inevitably cause damage.

Now, Charles Lieber’s team of chemists at Harvard University has teamed up with tissue engineers at the Massachusetts Institute of Technology and Boston Children’s Hospital to develop a better way of integrating tissue and electronics. Instead of using traditional electrode-based detectors – which deliver weaker signals as they are made smaller – Lieber and colleagues opted for silicon field-effect transistors (FETs) as detectors. FET sensors can be extremely small – in this case made from 30 nm-diameter nanowires – and still give accurate readings.

Non-invasive process

The FETs, together with the interconnecting circuitry, were embedded within a special porous, biocompatible 3D matrix. The researchers then cultured the tissue over the top of this matrix, which created a fine network of FET sensors embedded inside the tissue. “The big difference between our method and the older method is that our method is a non-invasive process,” says Jia Liu, a student in Lieber’s lab and one of three lead authors of a paper on the work. “When we record or stimulate the tissue, we don’t need to use electrodes that puncture through the tissue.”

The researchers tested to see whether the presence of these sensors would have any impact on cell viability over several weeks and found that any effect was minimal. They admit, however, that longer-term studies would be necessary before the technology could be used to create medical implants.

To demonstrate the usefulness of their technology for drug testing, the researchers produced a tissue of cardiac cells integrated with FET sensors. They used the sensors to monitor the effect on the cardiac tissue of noradrenaline, a drug that speeds up the heart rate. They measured a twofold increase in the tissue’s contraction frequency following the application of the noradrenaline.

Synthetic muscles

“This is an excellent paper and the very first example of combining flexible electronics with tissue engineering. Nanowire-based flexible electronics technology could be one of the best approaches to such 3D tissue scaffolds that can be electrically probed,” says Zhenqiang Ma, an expert on epidermal electronics at the University of Wisconsin-Madison. Ma suggests that the technology could be particularly valuable for producing synthetic versions of tissues such as muscles and neurons that involve electrical signals in their functions.

In the near future, the researchers believe that the work’s applicability is likely to be confined to improving tissue cultures for drug testing. Nevertheless, Liu agrees that, in the long term, the contribution to the quest to produce synthetic versions of body parts could be significant. He explains that researchers in this field already use extracellular matrices of the type used here to culture synthetic tissue. “In the past, however, this tissue scaffold has been a passive material that just supports the cells as they grow,” says Liu. “But right now, we have made a nanoelectronic tissue scaffold that not only supports the growth of the cells, but can also monitor their functionality.”

The research is published in Nature Materials.

Nanocrystalline alloys can take the heat

Using a combination of experiments and analytical thermodynamic modelling, researchers in the US have produced a new tungsten-based nanocrystalline alloy that is stable at temperatures above 1000 °C. Nanocrystalline alloys rarely survive such high temperatures and this breakthrough could lead to the development of new materials that combine great strength with high-impact resistance.

Metals comprising nanocrystalline grains – tiny crystallites measuring just tens of nanometres across – are much stronger than those containing larger micron-sized structures. Unfortunately, these nanocrystalline materials are also more unstable. One problem is that the tiny grains can grow and merge together at high temperatures – something that softens the metal. This is not a welcome phenomenon, given the elevated temperatures routinely employed in metals’ processing. Although researchers have tried to devise methods to prevent such unwanted grain growth, no satisfactory solution has yet been found.

Now a team at the Massachusetts Institute of Technology (MIT) led by Christopher Schuh may have come up with a way. The researchers have designed and fabricated alloys containing nanocrystals that do not coalesce at high temperatures. “Our design method is based on calculating the energies of all the atoms/bonds in a given alloy, including those in crystal environments and those that are located at the grain boundaries, between crystals,” Schuh explains. “We specifically calculate the effects that different alloying elements have on the structure’s energy, and seek to identify which elements can stabilize the grain boundaries and so lead to and maintain the nanocrystalline state.”

Industry has been trying to create alloys with ever-smaller crystalline grains for years now, Schuh says, but nature favours low-energy states, which inevitably means larger crystals.

New blends

Following on from the calculations, the MIT team then successfully synthesized the alloys that it had designed using suitable combinations of different metals in predefined proportions. The researchers also looked at metal blends that are not usually found together and that have never been produced before, even in the lab. For example, in this preliminary work on tungsten alloys they considered combinations of 12 different elements, including titanium, chromium, copper, silver and eight others. “Conventional approaches to designing alloys do not generally take grain boundaries into account but instead focus on how compatible the different metals are,” explains Schuh. “However, grain boundaries are crucial for creating stable nanocrystals, so we decided to include these in our calculations.”

One particular alloy based on tungsten and titanium that the team created has titanium grains that are just 20 nm in size. It was found to remain stable for one week at annealing temperatures of 1100 °C and retained its exceptional strength during this time. It could thus find use in applications where high-impact resistance is needed, such as in industrial machinery or in armour, say the researchers.

“The methodology we developed in our work could easily be exploited to make other new nanostructured materials with equally good or even better strength and stability, and additional desirable properties such as corrosion resistance,” says Schuh. “Finding such alloys would be almost impossible by conventional trial-and-error methods but we are able to calculate which metal combinations work and which do not,” add team members Heather Murdoch and Tongjai Chookajorn.

The team is now busy detailing how its theoretical approach can be extended to many other alloys and structures – work that will be detailed in a future publication.

The work is reported in Science.

Lessons learned by leading OPERA man

Defending scientific integrity
Defending scientific integrity

Ereditato, who is still a member of the OPERA group, defends the scientific integrity of the collaboration but admits he was “naive” in estimating the scale of the response this scientific result would generate beyond the physics community. He argues that scientists, the general public and the media all need to learn from this episode to improve the process of science communication in the future.

What is molecular gastronomy?

In less than 100 seconds, Peter Barham explains how fundamental science can help to produce delicious food.

Power cell generates and stores energy in one step

Researchers in the US have created a power cell that directly converts mechanical energy to chemical energy, which can then be stored and converted to electrical energy upon demand. This new system is unlike other similar technologies that first convert mechanical energy to electrical energy, which is then stored chemically. By skipping the intermediate conversions, the team says that the system is more efficient. If the technology could be further improved, it could be used, for example, in the sole of a shoe, where it could charge a mobile-phone battery while the wearer is walking.

We are using an increasing number of portable electronics every day and keeping all these devices charged can be a challenge. This is particularly difficult for infantry soldiers, who can operate for long periods of time away from reliable sources of electricity and therefore have to carry large numbers of batteries to keep communications, GPS and other devices running. As a result, researchers around the world are working on systems that can generate electricity from routine body motion. Footwear is an obvious place to start because soldiers do lots of walking and a small amount of energy could be extracted from each step by placing a generating device in the sole of a boot or shoe.

Hybrid approach

Several different approaches to shoe power are already in development, and now Zhong Lin Wang and colleagues at the Georgia Institute of Technology have created a new technology in which generation and storage occurs within a single unit.

Their cell comprises a cathode made of lithium cobalt oxide and an anode of titanium-dioxide nanotubes that are grown perpendicular to a titanium surface. The electrodes are separated by poly(vinylidene fluoride) (PVDF) film, which is a piezoelectric material. When the cell is compressed, the PVDF creates a piezoelectric charge, which drives lithium ions from the cathode to the anode. This converts electrical energy to chemical energy, which is stored in lithium titanium oxide. When the compressing force is removed, the cell relaxes but the chemical energy remains stored. More energy can then be stored in successive compression cycles. This energy can then be retrieved as electrical energy by connecting an electrical load between the anode and cathode, allowing the lithium ions to flow back to the cathode, and the device is ready to be charged again.

Powering a calculator

Using repeated compressions at a frequency of 2.3 Hz, the team was able to increase the voltage across the cell by about 60 mV in 4 min. The cell could then deliver a 1 mA current for about 2 min. While this represents a tiny amount of energy when compared with what is needed to charge a mobile-phone battery, the team used several cells connected in series to run an electronic calculator for about 10 min.

To show that their integrated design was more efficient than separate generation and storage, the researchers also created devices in which similar components were used to first generate electrical energy and then use that energy to move ions in a separate cell. Such a system developed less than 5 mV in 4 min when subjected to the same compressions.

While the technology is still in a very early stage, Wang believes that there are several ways that its performance can be boosted. For example, the researchers believe that most of the mechanical energy of compression is being dissipated in the cell's coin-like steel shell, rather than in the PVDF film.

"When we improve the packaging materials, we anticipate improving the overall efficiency," explains Wang. "The amount of energy actually going into the cell is relatively small at this stage because so much of it is consumed by the shell."

The research is reported in Nano Letters.

Pulsar timekeepers measure up to atomic clocks

An international team of astronomers has come up with a new way of keeping track of time by observing a collection of pulsars – rapidly rotating stars that emit radio pulses at very regular intervals. Although the ultimate goal of the research is to use pulsar timing to detect gravitational waves, the group has shown that the pulsar-based timescale can also be used to reveal inconsistencies in timescales based on atomic clocks.

Pulsars are neutron stars that rotate at very high speeds and appear to emit radio pulses at extremely regular intervals. The pulses are actually all we see of a radio beam that is focused by the star's magnetic field and swept around like a lighthouse beacon. Using a radio telescope, astronomers can measure the arrival times of successive pulses to a precision of 100 ns over a measurement time of about an hour. While this level of precision is significantly less than that offered by an atomic clock, pulsars could in principle be used to create timescales that are stable for decades, centuries or longer. This could be useful for identifying fluctuations in Earth-based timekeepers such as atomic or optical clocks, which normally do not operate over such long periods.

The team, which is led by George Hobbs at CSIRO Astronomy and Space Sciences in Australia, looked at data from the Parkes Pulsar Timing Array (PPTA) project. Using the Parkes radio telescope in Australia, the project aims to use a set of about 20 pulsars in different parts of the Milky Way to detect gravitational waves. The idea is that when a gravitational wave passes through our galaxy, its presence warps space/time such that the millisecond gaps between the pulses arriving from various pulsars are affected in a very specific way.

Extremely precise timescale

In developing the PPTA, Hobbs and colleagues in Australia, Germany, the US and China realized that the timing data from a number of pulsars could be combined to create an extremely precise timescale stretching back to the mid-1990s. A timescale is a sequence of marks in time, each separated by a defined time interval. The most precise timescales available today are generated by atomic or optical clocks, which operate using the frequencies of certain atomic transitions.

The team made a timescale based on 19 pulsars by first correcting the data from each pulsar for a number of different things that can affect the measurement of the gap between pulses. These include instrumental effects, the motion of the Earth within the solar system and the effects of interstellar plasma. Also, the frequency of a pulsar drops slowly with time as rotational energy is radiated away, and this must be corrected for.

The team then combined the data from the 19 pulsars to create the Terrestrial Time PPTA11 or TT(PPTA11) timescale, where 11 signifies that the most recent data used are from 2011. To show how their new timescale could be used to evaluate timescales generated by atomic clocks, the researchers compared it with Terrestrial Time (International Atomic Time) – TT(TAI). This is a timescale that is created by combining the results of several hundred atomic clocks worldwide. TT(TAI) is never revized, and therefore provides a historical record of the performance of atomic clocks. Instead, the atomic-clock timescale is gently "steered" towards better timekeeping through revision and reanalysis of the time standard.

Looking for deficiencies

If the new pulsar timescale is indeed precise, it should be able to reveal historical deficiencies in the atomic-clock timescale – and this is exactly what the team was able to do. The researchers compared the two timescales going back to about 1994 and found a distinct departure at around 1998. The team also did a similar comparison between the atomic-clock timescale and a corrected version of Terrestrial Time that is produced annually by the International Bureau of Weights and Measures – TT(BIPM11). The researchers saw the same distinct departure at around 1998, which suggested that, like TT(BIPM11), the pulsar-based timescale is capable of revealing inconsistencies in atomic-clock-based timescales.

The similarity between TT(PPTA11) and TT(BIPM11) also allowed the team to conclude that there are no large unexpected errors in TT(BIPM11). Furthermore, the results corroborate previous research, which concluded that the TT(TAI) timescale is not sufficiently precise to be used for pulsar-timing applications such as the detection of gravitational waves, and that TT(BIPM11) should always be used in such applications.

Team member David Champion at the Max Planck Institute for Radioastronomy in Bonn told physicsworld.com that the next step in developing the timescale is to incorporate pulsar data from other radio telescopes that were obtained over the same time period.

Proof of principle

Setnam Shemar of the Time and Frequency Group at the UK's National Physical Laboratory described the work as "proof of principle that PPTA data can be used to find anomalies in some present-day atomic timescales". While he thinks it is possible that a pulsar-based timescale could outperform the best present-day atomic timescale over long times, Shemar says that it is too early to tell. Indeed, he points out that if improvements in atomic and optical clock technologies outpace improvements in pulsar timing, as he expects to be the case, a pulsar-based timescale may in future be more useful in a search for gravitational waves than a means for checking atomic timescales.

The research will be published in Monthly Notices of the Royal Astronomical Society and a preprint is available on arXiv.

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