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Home » Page 1691

Director quits Canadian theory institute

The Perimeter Institute was founded by Mike Lazaridis, chief executive of Research in Motion — the company that makes Blackberry wireless handheld devices. He hired Burton, who has a PhD from the University of Waterloo, to turn the institute into a world-class centre for the study of fundamental questions in areas such as cosmology, particle physics and quantum gravity. It is now home to more than 60 resident researchers.

However, Burton refuses to explain exactly why he left, citing only certain “difficulties that had lasted awhile, many [of which] were not directly related to the goals of the institute”. But he admits to being disappointed at having to leave so suddenly. “The normal practice is to give notice and have a search for the better part of a year before moving on,” he told Physics World.

John Matlock, a spokesman for the institute, admits that Burton’s departure may have surprised some people. However, he adds that “for many of us it was pretty clear that Howard would not be remaining at the Perimeter Institute for ever. He has a lot of passions and interests and a lot of great ideas.” Institute bosses have already started asking faculty members who they think should replace Burton. The search will also involve the institute’s scientific advisory committee as well as its board of directors.

Whoever replaces Burton will find an institute in good shape. It recently received sufficient funding from the Canadian government to keep going for the next five years, while the National Sciences and Engineering Research Council reviewed its work favourably, concluding that the institute “has been a great success on a world-wide scientific scale for Canadian science”. The institute also attracts many physicists from around the world and has a strong public-outreach programme.

“Burton has developed an efficient administration that makes all this activity possible,” says Princeton University cosmologist Paul Steinhardt, who chairs Perimeter’s science advisory committee. “To some degree he’s really been scientific director, educational director, and outreach director, as well as executive director.”

There is also praise from Anthony Leggett, the Nobel-prize winning physicist from the University of Illinois, who is a member of Perimeter’s scientific advisory committee. “Burton has turned the Perimeter Institute into an institution that’s practically unique in the world, particularly in its emphasis on the more speculative aspects of theoretical physics,” he says. “It’s one of the few places where quantum foundations is a strong field.”

Burton, whose interests in literature, music, theatre, philosophy and sports make him something of a Renaissance man, now plans to take a year off in the south of France. “I’ve done a reasonable amount of writing and I hope to continue. I’m finishing a book about the institute and I have a few other projects,” he says.

Tiny spheres could control light

Plasmons are “quasiparticles” that describe the collective oscillations of electrons on the surfaces of metals. Plasmons interact with light and researchers are trying to exploit this property in “plasmonic” devices for processing and transmitting data.

Now, Maxim Sukharev and Tamar Seideman of Northwestern University have used a computer simulation to study the interaction between light and the plasmons on the surfaces of tiny metal spheres. Using the example of a T-junction composed of silver nanospheres, the simulation revealed that the path taken by the light through the spheres could be altered by changing the polarization of the light. The researchers believe that this effect – which has yet to be confirmed experimentally — could be used in an optical nanoswitch, or inverter.

The calculations also suggested that incident light can be confined within “plasmonic crystals” made from periodic arrays of nanoparticles. Moreover, depending on the geometry of the crystal, the light could be focused and guided. In addition, the computer results suggested that the effect could be harnessed in nanoscale light sources with controllable coherence and polarization properties.

The researchers believe that their modelling techniques could offer a practical way to predict the optical responses of plasmonic devices during the design process.

NMR gets seriously small

NMR spectroscopy is a popular technique for studying the physical and chemical properties of matter because it is non-invasive and can distinguish between different species of atomic nuclei. It involves placing a sample in an external magnetic field, which aligns the magnetic moments of atomic nuclei with non-zero spin. A radio-frequency pulse is then applied to the sample, which perturbs the alignment of the magnetic moments and makes them wobble. The precise nature of this wobble is detected via currents that are induced in a coil surrounding the sample. The signal from the coil is used to create a NMR spectrum that contains information about the chemical and physical environment surrounding the nuclei.

For small samples, however, these induced currents can be tiny and difficult to distinguish from thermal noise. In the case of liquids, this problem can be overcome by making the coil as small as possible and placing the sample inside it. But this approach cannot be used for solids because the nuclei have a fixed position with respect to the external magnetic field, which means that structures in the NMR spectrum are smeared out and tricky to interpret.

Scientists can get around this problem by rotating solid samples rapidly at an angle of 54.7° to the magnetic field. This technique, known as “magic-angle” spinning (MAS), averages away much of the smearing and leaves a high-resolution spectrum similar to that seen for liquids. Unfortunately, no one has been able to build a device that could spin a tiny solid sample at 50 kHz or more, while the sample is inside a stationary coil any smaller than about 1 mm diameter.

Now, however, Dimitrios Sakellariou and colleagues at CEA Saclay have found a clever way around this problem. The researchers wrapped a small coil of 750 µm diameter directly around a 200-nanolitre solid sample and spun the coil along with the sample at up to 70 kHz. A second static coil was placed around the spinning ensemble and this static coil detected the NMR signals from the sample via inductive coupling to the spinning coil. The new method achieved a signal to noise ratio that was eight times better than a conventional MAS employing a coil of 2.5 mm diameter.

The researchers have dubbed their technique magic-angle coil spinning (or MACS) and, according to Art Edison at the University of Florida, the technique is essentially a simple modification to conventional MAS, so existing hardware can be used. As a result, the technique could be used in automated high-throughput NMR studies for looking at many samples in a short period of time.

The technique could also be used to study tiny biological samples such as cell cultures and forensic evidence and Sakellariou believes that the technique could someday be used to observe the chemical processes inside single biological cells.

Wireless power a reality

Power without wires isn’t a new concept – in the early 1900s before electricity grids were established, the Serbian inventor Nikola Tesla envisioned a world of wireless power using a network of high-voltage “Tesla coils”. Although his scheme didn’t catch on because of the dangerously large electric fields involved, recent proposals of wireless power employing radiation from a transmitter have begun to rekindle interest. Unfortunately, those that have relied on transmitters emitting in all directions have been too inefficient, and those that have opted for unidirectional transmitters have been impractical for most applications because they need a clear line of sight between transmitter and receiver.

Last year, physicists at the Massachusetts Institute of Technology (MIT) proposed a way to avoid these problems by employing non-radiative “evanescent” electromagnetic waves. These waves are usually generated in addition to the familiar radiative waves used in wireless communications, but decay very quickly as they extend from an antenna. Marin Soljacic and colleagues thought that if the receiver could resonate with the transmitter, the evanescent field would instigate a current between the two. In this way, non-resonant objects placed in the field would neither interrupt the signal nor absorb much of the field’s energy (see related story: “Gadget recharging goes wireless”).

Now, Soljacic’s team have put their idea into practice. Using their theory, they have created a pair of ring-shaped copper antennas. One of these they connected to an electricity supply, while the other they connected to a 60-W light bulb placed two metres away. When they ran an oscillating current through the first, it produced a magnetic field that “resonantly coupled” to the second, thus inducing a current. This current, the MIT team claim, fully lit the bulb with a transmission efficiency of 40%, just as their theory predicted.

Although the antennas demonstrated were over half a metre in diameter, Soljacic and co-workers say that scaled-down versions of the system could be made for portable devices without sacrificing efficiency. This might also enable the design of electronic medical implants that do not need cumbersome wiring.

Once a physicist: Walter Ray Williams Jr


What is your background in physics?

I was always good at maths and interested in science and when I took physics at high school it just seemed to make sense. I then got an associate degree in mathematics and physics at Chaffey Community College, near Los Angeles, followed by a BS in physics with a minor in maths at California Polytechnic University at Pomona.

How did your talent for bowling develop?

As a youngster, I won the boys’ world horseshoe-pitching championships three times and went on to win the men’s championship six times. For those who are not familiar with the sport, it involves taking a U-shaped metal object weighing about 2.5 lb and “pitching” it 37 ft at a 15 inch high stake. The aim is to make a “ringer” where the horseshoe encircles the stake – world champions can usually do this around 85% of the time. Since horseshoe pitching is an underarm motion similar to ten-pin bowling, I thought that I might be good at that too. During college I bowled in local events when I could and joined the Professional Bowlers Association (PBA), which ultimately helped me pay my way through college.

When did you realize you could make a living as a professional bowler?

I started competing on the PBA bowling tour in January 1983, before I got my degree. I finished my thesis, which was on the physics of a bowling ball rolling down a lane, on the road. In my first full year on the tour I made more money than I spent, so I figured that I could do this for at least a few years.

What are some of the highlights of your career?

I won my first national PBA title in 1986 and after winning two more events that year was voted PBA player of the year. I have since won a total of 42 titles, which ranks me number one of all time. I have been PBA player of the year six times, and I am currently the highest ever money winner in bowling with over $3.6m in official earnings.

Are there any ways that your background in physics helps you in your career as a bowler?

I am not sure exactly what I learned from my thesis. I think I made mistakes in some of the calculations that I keep meaning to go back over and fix – but I haven’t and it has been 24 years now! However, I do think that physics is a huge part of bowling and that gives me a different insight to other players into what is going on. Unfortunately some of the variables change or are very difficult to know exactly, so it comes down to more of a statistical game – a perfect shot doesn’t always get a strike.

Striking it lucky in the oil industry

I have been working for Schlumberger for less than a year but in that time I have travelled to places I had never imagined visiting, worked offshore on a platform in the Caspian Sea, flown in a helicopter and practised putting out fires during survival training. Working in the oil industry may not be for everyone, but it definitely offers a wealth of new and exciting experiences for those who are willing to take the plunge.

I graduated from Nottingham University with a Masters degree in physics in July 2006. Unsure of what to do next, I applied to, and had interviews with, companies from both the defence and financial industries, but all they could offer me was a typical office job that would have involved staring at a computer screen all day. My father suggested Schlumberger and, not knowing much about the company, I uploaded my CV to their website and thought no more about it until I was asked to attend a two-day assessment event. This involved a couple of academic tests, although what Schlumberger really values is the ability to work well in a team and handle working abroad in potentially tough environments. I was offered a job, and began working for the firm in October last year.

Culture shock

Schlumberger is the world’s largest oilfield services company, employing 70,000 people in 80 countries to provide the technology that helps oil firms such as BP, Shell and Exxon find and exploit hydrocarbon reserves. I work as a field engineer in the reservoir monitoring and control division, which tries to maximize production from existing wells. My job involves preparing, testing and installing sensors in oil wells. This can sometimes be mundane – days can be spent checking new equipment to make sure it is up to specifications. But the exciting part of the job for me is going offshore and seeing all that work in action.

After joining Schlumberger I spent 10 days in Paris where I was introduced to the company’s culture and especially to safety issues. Safety is taken very seriously in the oil and gas industry; any employee can stop an activity taking place if they feel it is unsafe. Another common feature of the industry is the long hours: you may be expected to work 12 hours a day for six or even seven days a week. But this hard work comes with many rewards – from free plane tickets and company nights out to the chance to experience different cultures. You will have the opportunity to travel the world and spend time in every continent – there is oil everywhere and talented people are needed to exploit it.

After my training in Paris, I was allocated to work in Baku, the capital city of the former Soviet republic of Azerbaijan, which is one of the many oil-rich countries that encircle the Caspian Sea. The major operations in Baku are run by BP, which manages a number of newly constructed permanent platforms that are in the process of drilling wells and starting to produce oil. Baku has serious problems with corruption, pollution and poverty, which do not always make it the nicest place to live. The city centre has many bars and restaurants that cater almost exclusively to expatriates but, other than this, there is not much to do for a non-Russian speaker. However, when you first join the company you will not have much spare time, as you are kept more than busy enough with training and development.

The language barrier has certainly been challenging – in Azerbaijan almost everyone speaks Russian, although locals working for Schlumberger are required to have a certain amount of English. There will of course be times when your co-workers are speaking their native language and you will not understand what is going on – but if you ask them to explain, try to interact as best you can, and take language lessons, then you can turn the cultural differences into a positive thing.

Bridging the gap

I recently finished a nine-week training course based in Melun, France, that aimed to educate the field engineers in my department about the theory and practical use of current oilfield technology. The tools we learned about included an orbital welding machine that creates pressure-resistant seals and a “surface acquisition unit” that collects pressure and temperature data from oil wells. The facilities at Melun include an 800 m deep test well that contains only water – the idea being that it is better to learn here than on a customer’s installation.

My future with Schlumberger offers many opportunities. It is part of the company culture for employees to change location and role every couple of years. To aid this movement, all employees attend short courses on everything from management training to finance. In my case, after 18 months in the field I will travel back to Southampton in the UK to work in research and development for Schlumberger Sensa – a fibre-optics company acquired by Schlumberger in 2001 to develop and install temperature sensors for oil wells. After a couple of years with Sensa I will be expected, but not forced, to change role again – perhaps back to field work; or I could try project management, recruiting or something else that appeals to me.

A physics degree may not at first seem the ideal qualification for work in the oil industry. During my degree I did not really “get my hands dirty” and one of the main reasons I chose to work in the oil industry was to learn to use my hands, as well as my brain, to help solve problems. However, physics graduates are ideally suited to developing the new breed of “intelligent” wells that use advanced technology to reach oil as diminishing supplies make it harder to extract.

Out in the field, physics graduates are easily outnumbered by engineers; but in the research and development side of the company, physics graduates are everywhere. I was employed partly to bridge the gap between these strands. Currently a lot of the tools being created by our researchers are not suitable for the field because they are designed to work in a lab, not deep underground covered in oil, water and mud. The oil industry therefore needs people who can interpret what is going on in the field and feed that knowledge back to researchers in the lab. But whether you choose to start work in research or as a field engineer, the beginning of your career is a great time to take a risk and try something new.

Casimir force learns to swim

First predicted by Hendrik Casimir in 1948, the Casmir force arises when two facing mirrors are brought towards each other in a vacuum. According to quantum mechanics, any electromagnetic fields bouncing back and forth between the mirrors should constantly fluctuate in strength. At very small mirror separations these fields exert a radiation pressure on the surfaces that is, on average, stronger on the outer than the inner surfaces. This causes an overall Casimir force that draws the surfaces together.

Now, Jeremy Munday and Federico Capasso of Harvard University in the US have shown that the Casmir force can still exist when the vacuum is replaced by a fluid. They attached a 40-µm-diameter polystyrene ball covered in a thin layer of gold to a cantilever, which they then suspended inside a bath of ethanol with a flat gold surface at the bottom. By reflecting a laser off the cantilever onto a position-sensitive photodetector, they could then determine the strength of the Casimir force attracting the ball from the size of its displacement.

They found that the force became detectable when the ball was brought within 200 nm of the flat surface, and when the separation was just 50 nm the force rose to 120 pN – about two times weaker than the force that would be found in a vacuum. This shows, according to Munday, that the ethanol screens the Casimir force by altering the allowed modes of the electromagnetic fluctuations between the surfaces.

Recently physicists have realized that the Casimir force must be taken into account when designing micromachined devices, and theorists have even considered exploiting it to test the validity of Newton’s laws of gravity on sub-millimetre distances. Munday told Physics Web that he is now proposing a form of “quantum levitation”, which would use a different fluid medium that causes the mirrors to repel rather than attract. “In that case, one could levitate one object above another while in a fluid,” he explained. “Because the objects are not in physical contact, static friction is virtually eliminated, and the levitated object would respond to even the slightest force, allowing for very sensitive sensors and accelerometers.”

LHC to skip low-energy test runs

When it finally switches on, the €6.3bn Large Hadron Collider (LHC) at CERN – the biggest experiment in particle physics – will accelerate protons in opposite directions around a ring 27 km in circumference and smash them together at energies close to 14 TeV. Researchers hope this will either allow them to glimpse the hotly-predicted Higgs boson or provide a window to “new” physics beyond our current Standard Model of particle physics.

Last year CERN, which is in Geneva, Switzerland, announced that the construction and testing of the LHC would be completed this November to allow for a two-week engineering run before the accelerator complex shuts down for winter maintenance. During this engineering run, the machine’s operators would collide the protons at their injection energy of 450 GeV without using any of the ring’s accelerating systems. This would have enabled them to gain experience steering the protons and detecting collisions before high-energy collisions take place in 2008.

In March this year, however, one of the superconducting magnets built by Fermilab in the US failed a high-pressure test designed to simulate the warming up or “quenching” that can occur when proton beams career off course into the magnets. This led many to speculate that the LHC’s start up schedule would have to be delayed in order to replace the damaged magnet and redesign similar magnets, although CERN itself gave no official statement (see related story: “Large Hadron Collider faces delay”).

Now, CERN spokesperson James Gillies has told Physics Web that the lab will announce at the end of June that the engineering run will be left out, although the accelerator will still be switching on in either late March or early April 2008 with an aim to start data collection two months later. “Things have been going well but pretty slowly – slower than the [previous] schedule foresaw,” he explained.

Nevertheless, Gillies said that one of the LHC’s octants has already been cooled to 1.97 K, and a second, adjacent, octant is following closely behind. Once they are both cooled to 1.9 K they should be able to test the anticlockwise proton beam at injection energy in a quarter of the ring. “So there is something happening this year, but it won’t be colliding beams,” he said.

European X-ray laser gets the go ahead

Speaking at the launch ceremony in Hamburg today, the German federal minister of education and research Annette Schavan said: “The funding negotiations with the 12 interested countries are so far advanced that the construction of this new research facility, which is very much sought after by the scientific community, can now begin.”

Normal lasers can generate extremely intense, ultrashort pulses of light, but the wavelength of the radiation is too long to pinpoint the location of atoms. A free-electron laser can generate radiation at shorter wavelengths by accelerating bunches of electrons and passing them through a periodic magnet called an undulator. This forces the electrons to continually change direction and so emit synchrotron radiation in the “hard” X-ray portion of the electromagnetic spectrum.

XFEL, which has strong connections to the DESY research centre in Hamburg, is an international project that is three-quarters funded by Germany with the remaining money from other European countries and China. It will accelerate electron bunches using 3.4 km of superconducting magnets to energies of 20 GeV, generating laser pulses billions of times brighter than the beams in today’s synchrotron devices. In theory, these pulses will be able to reveal the atomic structures of membrane patterns and generate atomic- and femotosecond-resolution images of plasmas.

XFEL will follow two other X-ray free-electron-laser projects around the world. These are the LCLS in the US, due to start up in 2009, and the Japanese SCSS facility, which is scheduled to come online in 2011. DESY is already home to FLASH, which is a prototype free-electron laser that operates at longer “soft” X-ray wavelengths.

In a communiqué signed during the launch ceremony in Hamburg, the representatives of the partner countries declared: “We are convinced that it is appropriate to begin the construction of the XFEL as quickly as possible in view of the international competition.”

Big particles are secret to crack-free paint

Paints are usually made by dispersing tiny particles, some of which are pigment, in a solvent such as water. As paint dries, its elastic “skin” – known as the meniscus – contracts and inflicts stress on the bulk particles, which deform as a result. But beyond a certain stress the particles can deform no more, and the paint must instead alleviate stress by cracking.

Not all paints crack, however. Because a meniscus can only contract so much – and therefore can only exert a maximum stress – particles with a sufficiently high stress limit will avoid being fully deformed, and no cracks will form. With this in mind, Mahesh Tirumkudulu and Karnail Singh of the Indian Institute of Technology in Mumbai have now determined how particle properties can be tailored to increase their stress limit.

The pair realized that the stress limit is directly related to how drying paint tries to balance the potential energy of the meniscus and the potential energy of the bulk particles. Certain particle properties – such as their size, “shear modulus” or strength, and how tightly they are packed together – affect this balance, and from this calculated how thick a paint can be applied without cracks forming. They tested their theory by drying different thicknesses of silica and acrylic dispersions, and found the properties did indeed affect the maximum thickness as predicted.

Tirumkudulu told Physics Web that the research could help paint manufacturers optimize their products. For example, bigger particles that adopt more loosely-packed structures would be less likely to crack when applied thickly. “I should admit, though, that commercial paints and coatings are much more complicated systems containing a number of additives,” he added. “However, we believe that this is the first step in understanding the complex phenomenon of cracking in paints and coatings.”

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