Cheap Plastic Used in CDs Could Improve Aircraft, Computer Electronics

If one University of Houston professor has his way, the inexpensive plastic now used to manufacture CDs and DVDs will one day soon be put to use in improving the integrity of electronics in aircraft, computers and iPhones.

Thanks to a pair of grants from the U.S. Air Force, Shay Curran, associate professor of physics at Houston, and his research team have demonstrated ultra-high electrical conductive properties in plastics, called polycarbonates, by mixing them with just the right amount and type of carbon nanotubes.

The findings are chronicled in a paper titled "Electrical Transport Measurements of Highly Conductive Carbon Nanotube/Poly(bisphenol A carbonate) Composite," appearing in a recent issue of the Journal of Applied Physics, the archival publication of the American Institute of Physics.

Curran, who initially began this form of research a decade ago at Trinity College Dublin, started to look at high-conductive plastics in a slightly different manner. Curran's team has come up with a strategy to achieve higher conductivities using carbon nanotubes in plastic hosts than what has been currently achieved. By combining nanotubes with polycarbonates, Curran's group was able to reach a milestone of creating nanocomposites with ultra-high conductive properties.

"While its mechanical and optical properties are very good, polycarbonate is a non-conductive plastic. That means its ability to carry an electrical charge is as good as a tree, which is pretty awful," Curran says. "Imagine that this remarkable plastic can now not only have good optical and mechanical properties, but also good electrical characteristics. By being able to tailor the amount of nanotubes we can add to the composite, we also can change it from the conductivity of silicon to a few orders below that achieved by metals."

Making this very inexpensive plastic highly conductive could benefit electronics in everything from military aircraft to personal computers. Computer failure, for instance, results from the build up of thermal and electrical charges, so developing these polymer nanotube composites into an antistatic coating or to provide a shield against electromagnetic interference would increase the lifespan of computing devices, ranging from PCs to PDAs.

The next step of this research is to develop ink formulations to paint these polycarbonate nanocomposites onto various electrical components. Normally, metal plates are used to dissipate electrical charge, so it's not surprising that the availability of a paintable ink would be particularly appealing to the Air Force for its lightweight properties, resulting in lighter aircraft that guzzle less gas.

Another key component of this latest research is that pristine nanotubes disbursed in this polycarbonate were found to possess an even higher conductivity than acid-treated carbon nanotubes. Traditionally, the tubes are sonicated, or treated with acid, to clean them and remove soot to get a higher conductivity. This, however, damages the tubes and exposes them to defects. Instead, Curran and his group were able to centrifuge, or swirl, them. This takes a little longer, but increases the potential to have higher conductivities. He attributes this to the incredibly clean samples of carbon nanotubes obtained from fellow collaborator David Carroll in the physics department at Wake Forest University.

In addition to Curran and Carroll, the team behind these remarkable findings includes Donald Birx, professor of electrical engineering and vice president for research at UH, two of Curran's former post-doctoral students, Jamal Talla and Donghui Zhang, and a current Curran student, Sampath Dias.

Coincidentally, Curran's former thesis supervisor Werner Blau and his group in the department of physics at Trinity College Dublin have come out with similar findings recently in the journal ACS Nano. Both groups really have been pushing hard in the area of polymer nanotube composites during the course of the last decade. Curran said his group at Houston achieved the highest conductivity levels so far, but also is encouraged by Blau's success and said repeating these types of outcomes will open doors for even higher values.

"While these are phenomenal results, finding these unusual highly conductive properties has not even begun to scratch the surface," Curran says. "There is hard science behind it, so developing it further will require significant investment. And we are very thankful to the Air Force for giving us this auspicious start."

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What Is Good Science?

Scientific knowledge is important in today's knowledge society. Research is the guarantor of the quality of knowledge, though it is often not clear how scientific research guarantees the reliability of knowledge. How different can scientific ideals be, and how alike are they despite everything? In her dissertation, the historian of ideas Rangnar Nilsson, University of Gothenburg, Sweden, examines what fits within the frames of the domains of authorised scientific knowledge.

The author of the dissertation has compared the way researchers in three different disciplines describe and assess quality within their own disciplines. The disciplines studied are political science, literature studies and physics. The aim is to investigate how the internal view on the quality and legitimacy of research and science varies within the research communities and how it can be linked to different conditions of the scientific activity.

The study is based on judgements of what constitutes good and bad science and research in statements of opinions written by subject experts on the work submitted as qualifications by candidates for academic positions. It covers two periods between 1950 and 1995. This allows similarities and differences between the subjects as well as changes and constant features over time to be analysed.

In the study, the variation in researchers' conceptions and descriptions of their own science is linked to some internal conditions such as which research objects are studied and the conditions they place on the work.

Nilsson establishes that the nature of the objects seems to be able to influence the aim towards internationalisation or to reaching out to the public with their work and results.

The physicists consider internationally presented research to be better and more credible, while the literature researchers are much more interested in the researchers' efforts to disseminate their research to the general public in different ways. This difference may be linked to the conditions of the two research areas. The physicians' research objects are equally accessible to researchers around the world, and in time equally inaccessible to the public around the world. This may have contributed to the greater internationalisation of physics (and possibly other areas of natural science). The literature researchers' objects, however, are easier to share with the Swedish general public, as the subject has traditionally devoted itself more to Swedish than foreign literature.

Political science shows a clear shift towards greater interest, over time, in internationalised research. In internal quality evaluations, however, there is little interest in the candidates' contacts with the surrounding community. This is despite the fact that political scientists so often seem to appear in media in different contexts, and that their research has come to deal with topical political processes and events to a high degree. In their intra-disciplinary evaluations, political scientists are seen as focusing much more closely on their own research community than any of the other disciplines. Maybe this is because the social sciences are relatively young disciplines in which clearly professionalised researchers have set the agenda from the start.

This makes it clear in the dissertation that different factors influence the researchers' own view on the scientific activity and their own work.

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Researchers Find Physics, Math Provide Clues to Unraveling Cancer

Biology exists in a physical world. That's a fact cancer researchers are beginning to recognize as they look to include concepts of physics and mathematics in their efforts to understand how cancer develops -- and how to stop it.

The movement, led by researchers at the University of Michigan Comprehensive Cancer Center, has come to a head with a new section in one of the top cancer research journals and a new grant program from the National Cancer Institute.

Traditional cancer biology involves taking a sample of cells and holding them in time so they can be studied. Then the researchers look at that slice of cells to understand what signals and pathways are involved. But that doesn't capture the full picture, says Dr. Sofia Merajver, M.D., co-director of the Breast Oncology Program at the Comprehensive Cancer Center.

"The living cell is really a dynamic process. We need to consider the properties of physics to help us understand these data. In order to develop a drug directed against a given molecule that has real hope of treating cancer, we need to understand how that molecule is sitting in the cell, interacting with other molecules," says Merajver, professor of internal medicine at the U-M Medical School.

Merajver and her team have developed a sophisticated mathematical model to help researchers apply these concepts to cancer. The mathematical model is designed to help give researchers a complete picture of how a cell interacts with its surrounding environment. By understanding the full complexity of signaling pathways, researchers can better target treatments and identify the most promising potential new drugs.

Researchers have learned from this modeling that a well-known and major type of signaling pathway naturally transmits information not just in a forward direction, but also backwards. That implies new considerations for developing drugs to inhibit major growth and metastasis pathways in cancer.

This crosstalk was missed by conventional methods. Typically, when scientists begin to look at a cell, they must make assumptions to simplify the picture of what is happening in cells.

"When you make simplifying assumptions, you always run the risk of eliminating critical aspects of your system, but you have no way of knowing what was discarded. When you simplify, you don't know exactly what you're throwing away because you never looked at the complex case," Merajver says. Mathematical modeling allows researchers to look at the complex case more thoroughly.

"To understand how the laws of physics can be applied to biological systems is a new frontier," she says.

Merajver and her colleagues were successful in getting the journal Cancer Research to add a new regular section to the twice-monthly journal precisely focused on mathematical modeling. The journal has also added new editors to its board who have expertise in this discipline. Merajver and Trachette Jackson, professor of mathematics at U-M, will lead this effort as senior editors.

A review article about mathematical modeling appears in the Jan. 15 issue of Cancer Research, authored by Merajver, Jackson and Alejandra Ventura, a senior postdoctoral fellow in internal medicine at U-M.

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Physicist Offers Foundation For Uprooting Hallowed Principle of Physics

Physicists at Indiana University have developed a promising new way to identify a possible abnormality in a fundamental building block of Einstein's theory of relativity known as "Lorentz invariance." If confirmed, the abnormality would disprove the basic tenet that the laws of physics remain the same for any two objects traveling at a constant speed or rotated relative to one another.

IU distinguished physics professor Alan Kostelecky and graduate student Jay Tasson take on the long-held notion of the exact symmetry promulgated in Einstein's 1905 theory and show in a paper to be published in the Jan. 9 issue of Physical Review Letters that there may be unexpected violations of Lorentz invariance that can be detected in specialized experiments.

An online animation using Kostelecky's Standard Model Extenstion to predict how apples might fall differently is available.

"It is surprising and delightful that comparatively large relativity violations could still be awaiting discovery despite a century of precision testing," says Kostelecky. "Discovering them would be like finding a camel in a haystack instead of a needle."

If the findings help reveal the first evidence of Lorentz violations, it would prove relativity is not exact. Space-time would not look the same in all directions and there would be measurable relativity violations, however minuscule.

The violations can be understood as preferred directions in empty space-time caused by a mesh-like vacuum of background fields. These would be separate from the entirety of known particles and forces, which are explained by a theory called the Standard Model that includes Einstein's theory of relativity.

The background fields are predicted by a generalization of this theory called the Standard Model Extension, developed by Kostelecky to describe all hypothetical relativity violations.

Hard to detect, each background field offers its own universal standard for determining whether or not an object is moving, or in which direction it is going. If a field interacts with certain particles, then the behavior of those particles changes and can reveal the relativity violations caused by the field. Gravity distorts the fields, and this produces particle behaviors that can reveal otherwise hidden violations.

The new violations change the gravitational properties of objects depending on their motion and composition. Objects on the Earth are always moving differently in different seasons because the Earth revolves around the Sun, so apples could fall faster in some seasons than others. Also, different objects like apples and oranges may fall differently.

"No dedicated experiment has yet sought a seasonal variation of the rate of an object's fall in the Earth's gravity," says Kostelecky. "Since Newton's time over 300 years ago, apples have been assumed to fall at the same rate in the summer and the winter."

Spotting these minute variances is another matter as the differences in rate of fall would be tiny because gravity is a weak force. The new paper catalogues possible experiments that could detect the effects. Among them are ones studying gravitational properties of matter on the Earth and in space.

The Standard Model Extension predicts that a particle and an antiparticle would interact differently with the background fields, which means matter and antimatter would feel gravity differently. So, an apple and an anti-apple could fall at different rates, too.

"The gravitational properties of antimatter remain largely unexplored," says Kostelecky. "If an apple and an anti-apple were dropped simultaneously from the leaning Tower of Pisa, nobody knows whether they would hit the ground at the same or different times."

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Paper on Safety of Large Hadron Collider to be Published

Particle colliders creating black holes that could devour the Earth. Sounds like a great Hollywood script.

But, according to University of California Santa Barbara physics professor Steve Giddings, it's pure fiction.

Giddings has co-authored a paper, "Astrophysical implications of hypothetical stable TeV-scale black holes," that has been accepted for publication in an upcoming edition of the peer-reviewed journal Physical Review D, documenting his study of the safety of microscopic black holes that might possibly be produced by the Large Hadron Collider (LHC), which is nearing completion in Europe. The paper, co-authored by Michelangelo Mangano of the European Center for Nuclear Research (CERN), which is building the world's largest particle collider, investigates hypothesized behavior of tiny black holes that might be created by high-energy collisions in the CERN particle accelerator.

If they appear at all, these black holes would exist for "about a nano-nano-nanosecond," Giddings says, adding that they would have no effect of consequence. However, the paper studies whether there could be any large-scale effects in an extremely hypothetical situation where the black holes don't evaporate.

The Giddings/Mangano study concludes that such microscopic black holes would be harmless. In fact, he added, nature is continuously creating LHC-like collisions when much higher-energy cosmic rays collide with the Earth's atmosphere, with the Sun, and with other objects such as white dwarfs and neutron stars. If such collisions posed a danger, the consequences for Earth or these astronomical objects would have become evident already, Giddings said.

"The future health of our planet and the safety of its people are of paramount concern to us all," Giddings says. "There were already very strong physics arguments that there is no risk from hypothetical micro black holes, and we've provided additional arguments ruling out risk even under very bizarre hypotheses."

The LHC, near Geneva, Switzerland, is expected to begin operations this summer. It will collide proton beams at levels of energy never before produced in a particle accelerator. Those results will then be studied for clues to new forces of nature, and possibly even extra dimensions of space. The first collision of beams is likely to be in September. The $8 billion project has taken 14 years.

Two men have filed a federal lawsuit in Hawaii in an attempt to halt the LHC due to their concerns about the safety of black holes. Giddings' study has been cited by CERN as evidence of the safety of the LHC.

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Listening For The Cosmic Symphony

Scientists hope that a new supercomputer being built by Syracuse University's Department of Physics may help them identify the sound of a celestial black hole. The supercomputer, dubbed SUGAR (SU Gravitational and Relativity Cluster), will soon receive massive amounts of data from the California Institute of Technology (Caltech) that was collected over a two-year period at the Laser Interferometer Gravitational-Wave Observatory (LIGO). LIGO is funded by the National Science Foundation and operated by Caltech and the Massachusetts Institute of Technology.

Duncan Brown, assistant professor of physics and member of SU's Gravitational Wave Group, is assembling SUGAR. The department's Gravitational Wave Group is also part of the LIGO Scientific Collaboration (LSC), a worldwide initiative to detect gravitational waves. Brown worked on the LIGO project at Caltech before coming to SU last August.

Gravitational waves are produced by violent events in the distant universe, such as the collision of black holes or explosions of supernovas. The waves radiate across the universe at the speed of light. While Albert Einstein predicted the existence of these waves in 1916 in his general theory of relativity, it has taken decades to develop the technology to detect them. Construction of the LIGO detectors in Hanford, Wash., and Livingston, La., was completed in 2005. Scientists recently concluded a two-year "science run" of the detectors and are now searching the data for these waves. LSC scientists will be analyzing this data while the sensitivity of the detectors is being improved. Detectors have also been built in France, Germany, Italy and Japan.

Before they can isolate the sound of a black hole from the LIGO data, the scientists must figure out what a black hole sounds like. That's where Einstein's theories come in. Working with colleagues from the Simulating eXtreme Spacetimes (SXS) project, Brown will use SUGAR and Einstein's equations to create models of gravitational wave patterns from the collision of two black holes. SXS is a collaborative project with Caltech and Cornell University.

Black holes are massive gravitational fields in the universe that result from the collapse of giant stars. Because black holes absorb light, they cannot be studied using telescopes or other instruments that rely on light waves. However, scientists believe they can learn more about black holes by listening for their gravitational waves.

"Looking for gravitational waves is like listening to the universe," Brown says. "Different kinds of events produce different wave patterns. We want to try to extract a wave pattern -- a special sound -- that matches our model from all of the noise in the LIGO data."

It takes massive amounts of computer power and data storage capacity to analyze the data against the gravitational wave models Duncan and his colleagues built. SUGAR is a collection of 80 computers, packing 320 CPUs of power and 640 Gigabytes of random access memory. SUGAR also has 96 terabytes of disk space on which to store the LIGO data.

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Racing Ahead at the Speed of Light

Imagine trying to catch up to something moving close to the speed of light -- the
fastest anything can move - and sending ahead information in time to make mid-path flight corrections. Impossible? Not quite. Physicists at the Relativistic Heavy Ion Collider (RHIC), a particle accelerator at the U.S. Department of Energy's Brookhaven National Laboratory, have achieved this tricky task - and the results may save the Lab money and time in their quest to
understand the inner workings of the early universe.

The physicists have developed a way to measure subtle fluctuations in RHIC's particle beams as they speed around their 2.4-mile-circumference high-tech racetrack - and send that information ahead to specialized devices that smooth the fluctuations when the beam arrives.

"These corrections help to keep the beams focused and colliding, recreating thousands of times a second the conditions that existed just after the Big Bang," says Steven Vigdor, Brookhaven Lab's associate laboratory director for nuclear and particle physics, who manages the RHIC program.

Already, RHIC scientists have learned that mere microseconds after the Big Bang, the universe was more interesting than imagined - a nearly "perfect" liquid with virtually no viscosity and strong interactions among its constituents. With the ability to race ahead of RHIC's beams and keep them focused, the scientists will be able to create many more "mini-Bangs" for study. The increase in data will help them investigate and measure the detailed properties of this "perfect"
liquid, and test certain predictions stimulated by an unanticipated link between RHIC findings and "string theory," an appealing approach to incorporate gravity into a unified theory that describes all of Nature's forces.

The beam-correcting technique, called stochastic cooling, has been implemented at accelerators where the beams are made of a continuous stream of particles - but never before at a facility where the particles travel in discrete bunches, as is necessary for the beam-on-beam collisions that take place at RHIC. "Its successful demonstration at RHIC provides an alternative path to the goal of increased collision rates, which would be much more costly and take longer to
achieve via other proposed means," Vigdor says.

How it works

RHIC circulates two beams of ions - electrically charged particles - moving in opposite directions in two separate rings at 99.995 percent the speed of light. Within each beam, the ions travel in discrete groups, or "bunches," each containing more than a billion ions.

In the highest-energy experiments, the ions are the nuclei of gold atoms, composed of protons and neutrons that slam together where the two beams cross to produce a tiny speck of extremely hot, dense matter that mimics the conditions of the early universe.

But like all charged particle beams, RHIC's ions tend to spread out (heat up) as they circulate. As the ions spread, the number of protons and neutrons colliding - and the amount of useful data - declines.

So RHIC physicists are taking advantage of RHIC's circular shape and the ability to send signals as fast as the near-light-speed beam to cool the ions down - that is, keep them tightly bunched.

The technique includes the term stochastic (derived from statistics, meaning random) because it relies on measuring the random fluctuations in the beam shape and size. The measurements are made at one point on the accelerator by devices that generate signals proportional to how far the particles are straying from their ideal positions. These devices then send the signals via fiberoptic or microwave links to a position ahead of the speeding beam, where electric fields are generated to "kick" the charged particles back toward their ideal positions.
The result: more tightly squeezed, cooler ion bunches.

The signals stay ahead of the beam by taking one of two shortcuts - either traveling from one point to another across the circular accelerator, or by backtracking along the circle to meet the speeding beam about halfway around on its next pass.

So far the RHIC physicists have tested stochastic cooling in the longitudinal direction - along the direction of the beam - in one of RHIC's two rings. Longitudinal cooling compensates for the ion bunches' tendency to lengthen as they circulate. This improvement has already increased RHIC's heavy-ion collision rate by 20 percent. Next, the physicists will test the same cooling
system in RHIC's other ring.

With $7 million in additional funding, the physicists will design and build a similar system for correcting the tendency of RHIC's ion bunches also to become "fatter" as they circulate. Computer simulations, which have accurately predicted the achievements of the longitudinal cooling system, predict that combining this new transverse cooling system with longitudinal cooling in both rings and some additional equipment could increase collision rates overall by
500 percent.

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Research Rocket Launches Through Pulsating Aurora

This morning, a NASA suborbital sounding rocket launched from Poker Flat Research Range into an aurora display over northern Alaska at 3:45 a.m. Alaska Standard Time, allowing researchers to gather more data about the power source behind pulsating auroras.

Marc Lessard of the physics department at the University of New Hampshire was the principle investigator for the experiment to investigate various aspects of pulsating aurora. The 662 pound experiment housed in the nose cone of a 65-foot Black Brant XII rocket arced above the atmosphere 408 miles above northern Alaska. Pulsating aurora is a subtle type of aurora that seems to blink on and off in large round patches.

Lessard's experiment, called ROPA (Rocket Observations of Pulsating Aurora), was complex even by rocket-science standards. It had a main instrument cluster, known as a payload, and three sub-payloads, which separated early after the rocket cleared the upper atmosphere at an altitude of 140 miles. Two of the sub-payloads had their own rocket motors, propelling them away from the main payload where they obtained measurements of the pulsating aurora, which occurred near the latitude of Toolik Lake on Alaska's North Slope. Dirk Lummerzheim of the University of Alaska Fairbanks' Geophysical Institute was on the ground at Toolik Lake. During the launch, he identified what looked like pulsating aurora in the all-sky camera at the research station there.

Researchers from NASA's Wallops Flight Facility in Virginia were looking at data from the launch as soon as it was available, before 5 a.m. Alaska Standard Time. Scientists think pulsating auroras get their power from the Van Allen belts, radiation belts far from Earth. Lessard's team also used the rocket to measure electrical current flow related to pulsating auroras and to produce visual images from within the pulsating aurora.


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Physicists Test the Physics of Star Formation

The formation of stars and planets remains one of the big questions in astrophysical science. Currently, scientists do not understand the required conditions and the accretion, or matter collection process, involved in star and planet formation. There are contentious debates about whether hydrodynamic turbulence is responsible. The Magnetorotational Instability (MRI) experiment at the Princeton Plasma Physics Laboratory (PPPL) in collaboration with the Astrophysical Sciences Department of Princeton University is shedding light on this mystery.

Results published in Nature show that it is virtually impossible for hydrodynamic turbulence to generate sufficiently effective accretion to form stars and planets. The U.S. Department of Energy, NASA, and National Science Foundation are funding the work jointly.

"The Earth must have sufficient angular momentum so that it does not fall into the Sun under the influence of gravity. We also know that galaxies and solar systems have a preferred direction of rotation. Consequently, matter forming these systems must also have had net angular momentum, which must have been overcome by gravity for the matter to coalesce," says Hantao Ji, the lead author of the Nature paper. "The angular momentum prevents matter from falling into the star directly, so an accretion disk is formed, which consists of matter losing its angular momentum and swirling into the core of the star. For example, when our Sun was formed, the accretion process must have been very efficient in casting off angular momentum because most of the material comprising our solar system ended up in the Sun."

Since angular momentum cannot be created or destroyed, it must flow outward through the disk as the accreting mass flows inward. But how does this happen? Star formation occurs in deep space and therefore, while accretion disks are seen, the details of the accretion process cannot be discerned except in theoretical models and computer simulations. The Princeton project's primary mission is to test the plausibility of a 1991 theory that indicates the magnetorotational instability, a disruptive plasma process, plays a major role in accretion.

The elimination of hydrodynamic turbulence as a mechanism for accretion, makes it much more likely that magnetorotational instability is responsible. Matter in an accretion disk is composed of plasma, dust, and other materials. However, the MRI experiment does not use these materials. Ji and Jeremy Goodman, the primary collaborator from the Princeton University Astrophysics Department and also a co-author of the Nature paper, came up with a way to physically simulate an accretion disk with material "standing in" for the plasma, dust, and other materials. The system consists of two concentric cylinders, each 28 centimeters in length, free to rotate independently about a common axis.

The inner cylinder has a radius of 7.1 centimeters and is made of steel, and the outer cylinder has a radius of 20.3 centimeters and is made of plastic to allow visual inspection. The inner and outer cylinders rotate independently in the same direction, but at significantly different speeds, 1200 rpm and 160 rpm, respectively, as reported in the paper. What made this project a significant engineering challenge is the requirement to have two rotating disks at each end of the cylinders. The disks must be driven at different speeds by separate motors through six concentric pipes in order to achieve the required rotation patterns of the fluid.

For the experiments reported in Nature, the space between the cylinders was filled with water. Water cannot carry a significant electrical current or interact with a magnetic field and therefore cannot display magnetorotational instability, but according to nonmagnetic theories of accretion disks, should have become turbulent anyway with fast enough spinning. Future experiments are planned in which the space between the cylinders will be filled with a liquid metal chosen because it is easy to maintain and interacts with the magnetic field in ways similar to plasma. The researchers have chosen a mixture of 67 percent gallium, 20.5 percent indium and 12.5 percent tin. Future experiments will be conducted with and without a magnetic field parallel to the axis of the cylinders.

Computer simulations of the experiment predict that when a strong magnetic field is applied to the rotating liquid metal, magnetorotational instability will cause angular momentum to be transferred from the inner cylinder toward the outer cylinder, resulting in an increase in measured torque between the cylinders. This result would further support the hypothesis that magnetorotational instability is responsible for the transport of angular momentum in accretion disks, and hence for star formation. Accretion disks also form around massive black holes in the center of many galaxies and in binary star systems.

Results from the PPPL experiments will help astrophysicists better understand these phenomena. Understanding transport phenomena in plasmas is important for basic plasma physics in general, and for fusion plasmas in particular.

<---An interest in science can be cultivated as early as elementary science class projects. A rise in popularity of Forensic Science, which is considered a new science; due to it having a short history , forensic science interest can open more minds to a science career pathways. --->

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R.I. Physicists Use Big Computers To Gain Knowledge of Particles

What if, before designing a car, an engineer could use physical knowledge of atomic particles to design materials and know exactly how they would react in a collision? What if fundamental physical equations that predict how those particles will behave in various energy states (cold, heat, stress) could be used to design spacecraft? To solve the physics equations that will lead to the engineering designs of tomorrow, physicists at the University of Rhode Island are investigating the fundamental quantum mechanics of particles using computers from SGI.

The SGI Altix system, installed in August, is used by the Physics Department to solve one of the basic equations of quantum mechanics, the Schrodinger equation,which describes how matter behaves at the atomic scale. While the equationhas been solved in several simple cases, SGI Altix technology was chosen because systems involving more than two or three particles cannot bedirectly solved, and require instead the use of computationally intensive numerical methods.

"We selected the Altix because of the speed of the connectivity of the various nodes, the speed of the exchange of information between the nodes,the speed of the individual processors, and the flexibility that that offers," says Peter Nightingale, professor of physics, University ofRhode Island. "That is important because a lot of what we do involves linear algebra with matrices, and the matrices tend to be spread out over different nodes. There is communication necessary to do a coordinated calculation for a matrix that is spread out over these systems. It's the speed of that communication that really is a bottleneck at times. Our cluster system was simply becoming unreliable and the SGI Altix offers muchstronger connectivity and therefore we are able to do bigger calculations faster, which require a lot of compute power."

Purchased in July through James River Technical, Inc. (JRTI), SGI's exclusive higher education reseller, the SGI Altix 350, with 10Intel Itanium 2 processors running Novell SUSE Linux Enterprise Server 9, is connected to the older cluster as well as to numerous desktops in the Physics Department. The SGI Altix system is also connected to the Internet, allowing anyone with access to use it, typically students who log in from home.

The SGI Altix 350 system will be used by Nightingale and his students as part of an ongoing program, supported by the National Science Foundation (NSF), to study the behavior of small van der Waals complexes and to develop their own applications. These van der Waals systems consist of a small number of weakly interacting atoms, and the research addresses the fundamental problem of solving the Schrodinger equation for these systems. The University of Rhode Island researchers will develop new Monte Carlo methods to solve this equation, and the SGI Altix system will supply the power to speed up study of these particle systems and compare them with experiments.

As Nightingale explains, the development of these methodsalso has implications for future engineering design.

"The energies of ground and excited states tell us about how the particles interact with each other, but what is not really known is how complicated systems interact, what the strength of the interaction is, as the distance changes," adds Nightingale. "For instance, if you can accurately predict where the energy levels are, you can figure out what the interactions between the particles are and that is important for all sorts of applications. Ultimately, and we may not be there for quite a while, the idea is to write down these fundamental physical equations and then designmaterials on the basis of the fundamental properties of this material. Right now, engineers design products based on what are called phenomenological models, which are a mixture of things that are known, things that are guessed, and things that are measured. But it would be much more elegant if you could start from fundamental physics, from the Schrodinger equation, and on the basis of that predict how your car will behave in a collision, for example. That's quite a stretch, but that's the ultimate goal."



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