Dr. Nachum Ulanovsky and postdoctoral fellow Dr. Yossi Yovel of the Institute’s Department of Neurobiology knew that bat sonar (or echolocation) obeys the same physical laws as the sonar on a submarine: the bats (or ships) emit a sound and listen for the echo, accurately judging the type and location of objects around them by the changes in the sound waves as they are reflected back. But there’s a tradeoff between detection and localization. The beam is most intense in the center, returning more information, which is good for detection; but localization is better done on the slope, where the intensity drops off as the signal spreads out, making it easier to follow movement across the beam.

Are bats able to choose the best echolocation strategy? Drs. Ulanovsky and Yovel, in collaboration with Dr. Cynthia Moss and research student Ben Falk from the University of Maryland, trained bats to locate and land – using echolocation alone – on a black sphere placed randomly in a completely dark room. A string of special microphones arrayed around the room’s walls traced the bats’ sound waves, while two infrared video cameras tracked their flight patterns.

The Egyptian fruit bats in Dr. Ulanovsky’s lab produce their signals in pairs of clicks. The researchers identified a pattern: the first set of double clicks was aimed left, and then right, and the next set was aimed right, and then left. As the bats closed in for a landing, they continued to throw their sound beams to alternate sides of the sphere, just where a mathematical formula for sonar sensing predicted they would be most effective. As the sphere was easily detectable, the bats' optimal strategy was one of localization. To test a situation in which detection was needed as well as localization, the scientists installed a large panel behind the sphere that echoed the sound waves back to the bats’ ears. Now they had to find the sphere’s echo amidst conflicting signals. This time, as the bats approached their target, they began to narrow their sweep and aim the beams more or less directly toward the sphere.

Many types of sensation, from echolocation in dolphins to sniffing in dogs to movements in the human eye, are based on some sort of active sensing. Drs. Ulanovsky and Yovel believe that what works for bats may well work for other animals: “sensing on the slope” could play a role in all of these and others.

In her studies in Kenya, Shahack-Gross used the geo-ethno-archaeological approach to identify ancient livestock enclosures. Accompanied by a Maasai tribe elder, she collected soil samples from his village and from a series of abandoned villages in which he had lived in the past. In this manner, she managed to create a “time axis” describing the breakdown of organic matter over 40 years. Under the guidance of Prof. Stephen Weiner of the Weizmann Institute’s Helen and Martin Kimmel Center for Archaeological Science, she developed a method for identifying livestock premises using a variety of soil analyses and microscopic tests, including an analysis of phytoliths – tiny silica particles present in many grasses, including animal feed, that end up in cattle dung. An analysis of phytoliths and additional minerals allows her to identify livestock enclosures long after organic matter – a more direct but less stable evidence of their presence – has disintegrated.

Shahack-Gross then joined a Kimmel Center team at the excavations in Tel Dor, where she got an opportunity to apply her method. Together with collaborators from Israel and Spain, she showed that the white-powdered surfaces in the excavated town were collections of phytoliths originating in the dung of livestock kept in enclosures within the city (and not from man-made plaster floors, as had been believed earlier). She also found evidence that animal dung had been used as fuel. These findings suggest that today’s clear-cut divide between agricultural and urban settlements came into being later than previously thought, providing new insights into the nature of the so-called “urban revolution” thought to have occurred in antiquity in the Mediterranean region.

Shahack-Gross, a senior lecturer in the Department of Land of Israel Studies and Archaeology at Bar-Ilan University, joined the Kimmel Center as a visiting scientist as part of a joint program initiated by Weiner. She uses a variety of analytical methods – infrared spectroscopy and oxygen and carbon isotope geochemistry, as well as microscopy – to identify the phytoliths and other materials in soil and ash samples. These methods allow her to gain new information about ancient societies, including the types of food consumed by their cattle. “Today hardly any archaeological excavations are conducted without backing from the natural sciences,” she says.

In another ethno-archaeological study, conducted with Prof. Israel Finkelstein of Tel Aviv University, she used analysis of materials, including phytoliths, to help solve a controversy over settlements created in the Negev Highlands during the Iron Age, corresponding to the Biblical period of Kings (circa 1,200 – 600 BCE). One opinion, based on the Bible, states that certain buildings are remains of fortresses built by King Solomon to protect his kingdom from Egypt and that they were destroyed by Pharaoh Sheshonq I during his northern campaign in the late tenth century BCE. Finkelstein, however, claimed that these buildings had been erected by cattle herders, but he relied on “circumstantial” evidence: The so-called “fortresses” were not located at strategic positions and did not have the uniform appearance of military structures.

Shahack-Gross collected numerous ash and soil samples from two sites near Sde Boker. Her analysis revealed traces of goat dung in the central courtyards of these fortresses. The sediments at the Negev Highlands sites were very low in phytoliths, reflecting a diet of wild plants and lichen. In addition, no phytoliths originating in domestic cereals – in other words, in agricultural crops – were found. These results, backed by analyses of sediments in contemporary Bedouin settlements in the Negev, suggest that the residents of the fortresses were indeed shepherds. And the hypothesis that the Iron Age settlements in the Negev Highlands were built as part of the Kingdom of Judea must be reconsidered.

The dating of plant remains using radioactive carbon, conducted in collaboration with Dr. Elisabetta Boaretto of Bar-Ilan University and the Weizmann Institute’s Kimmel Center, showed that these sites were set up in the late tenth century BCE and operated for about 100 years, until the end of the ninth century BCE. “Sheshonq’s campaign might have led to the creation rather than destruction of these settlements,” Shahack-Gross says. “Moreover, evidence suggests that these were seasonal settlements typical of nomadic herders.” In additional analyses, the scientists will try to determine whether these settlements were indeed seasonal and what they were like during the Iron Age.

Is it a qubit?

At the level of atomic and subatomic particles, things work very differently from the macro world of everyday objects. For instance, there's wave-particle duality: The basic bits of matter and light behave sometimes as discrete particles and sometimes as waves, which can be in many locations at once. And there's quantum superposition – particles existing simultaneously in more than one state at a time – which could, theoretically, provide a dramatic increase in computing power. An electronic computer bit can be in only one of two states (0 or 1), whereas a quantum bit (called a qubit) can exist simultaneously in both 0 and 1, in an infinite number of different superpositions. The challenge for scientists is to connect these fragile quantum states to the larger world without destroying them.

Several years ago, Prof. Ady Stern of the Condensed Matter Physics Department came up with a way to test a system to see whether it could be used as a special kind of qubit – a topological quantum bit. The system in question involves, on the one hand, electrons moving in a very cold two-dimensional plane, with a strong magnetic field applied at right angles to the plane and, on the other, quasiparticles. These "imaginary" particles – which have electrical charges of one-third, one-quarter or one-fifth of an electron – don't exist in nature, but they have been created and measured in the lab of Prof. Moty Heiblum of the Condensed Matter Physics Department.

Such a system must meet several criteria before it can be considered a possible qubit. The particles must be able to exchange places, and this exchange must leave a sort of trail that can be traced – that is, it must preserve information. In Stern's theoretical experiment, two parallel lines of current run through such a system with a separation "wall" containing quasiparticles between them. An odd number of quasiparticles should cause the electrons in the current to behave as particles, flowing in line through the material. But if they are separated by an even number, the electrons in the system should act as waves, producing interference patterns at the end of the current pathways.

In addition to the number of fractionally charged particles in a system, the fraction itself is relevant. The quasiparticles Heiblum measured in the 1990s had odd denominators, and these don't leave traces when they exchange places in the plane, making them unfit for storing information. Even-denominator fractions might be better for the purpose, but they're harder to produce. This past year, Heiblum and Stern, together with research student Merav Dolev and Drs. Vladimir Umansky and Diana Mahalu, all of the Condensed Matter Physics Department, succeeded in creating a nanoscopic device in which quasiparticles with one-quarter the charge of an electron were measured for the first time. They are now continuing their experiments to find out if quarter-charge quasiparticles are truly suitable candidates for quantum bits.

Can quantum errors be corrected?
Quantum "weirdness" – the strange reality that rules the world of ultra-tiny particles – presents some unique challenges. For instance, how can one perform calculations in a system in which the very act of measurement changes the basic configuration of that system?

Quantum superposition has been demonstrated in particles such as electrons, but it has never been observed in larger objects composed of many particles. The reason, scientists believe, is that in larger groups the particles interact with one another and with their environment, forcing the quantum superposition of the system into a single classical state. (Measurement is one form of interaction.) This transition is called decoherence. One could conceivably build a very simple quantum computer with only a few qubits, but how to create one that has millions?

Since joining the Weizmann Institute in 2007, Dr. Roee Ozeri and his students Nitzan Akerman, Yinnon Glickman, Shlomi Kotler, Yoni Dallal and Anna Keselman have been setting up a lab in the Physics of Complex Systems Department, and they have recently begun to conduct experiments that may one day help overcome the limitations. Ozeri is especially interested in error correction in quantum computing. Today's electronic computers compensate for possible errors by building in redundancy and using error-correction protocols. In analog quantum protocols, different kinds of error correction may help overcome decoherence and keep superpositions of many particle states "alive." Ozeri is also investigating ways of creating complex quantum logic gates – the basic operations of quantum computing – in which actions performed on one qubit can, under the right conditions, change the state of a second. Because quantum systems can't be measured directly without affecting the result, Ozeri must use roundabout methods that ascertain whether there are errors in the qubits' final state.

His experimental quantum system is based on ions – specifically, atoms of the element strontium that have undergone "laser surgery" to remove some of their electrons. Several of these ions are fired into a vacuum chamber, where they're trapped in an array of electrical fields, while another laser cools them to within a few millionths of a degree of absolute zero. Although Ozeri's experiments trap just a few ions at a time, he can examine the effects of decoherence by applying an electromagnetic field to create noise in the ions' environment. For "communicating" with the ions, he uses yet more lasers, which are precisely tuned to interact with various transitions between strontium ion states.

While the challenge of creating the basis of future computers is compelling, it is ultimately the questions of basic physics that Ozeri finds most fascinating: "We've been exploring the physics of the quantum world for around 100 years, and those of macro systems for much longer, but we still don't know much about the point at which one takes over from the other, how the transition happens or whether it's possible to push the limits and extend the quantum superposition principle into many-particle systems. This research might help provide answers to some of these very basic mysteries."

Do quantum codes communicate better?
Assuming quantum computers become a reality one day, what will they be used for? Will they be more efficient for every type of operation? For example, factoring large numbers – a process that could be used to break some encryption codes – is believed to take an impossibly long time on today's computers, but it could be done quite efficiently on a quantum computer. Prof. Ran Raz of the Computer Science and Applied Mathematics Department investigates whether communication between computers would be better with quantum methods. Quantum computers may be far in the future, but quantum communication has already been successfully demonstrated in experiments.

An example of a problem involving communication is a program for setting up a two-person meeting. The minimum number of bits needed to be communicated today to find a common free hour in each participant's network calendar equals the number of calendar slots that must be checked (n). But a quantum communication protocol could perform the same task using just the square root of (n) bits. Raz found that the difference for some other communication problems could be even greater: The improvement would be logarithmic. In other words, as the value of n rises, quantum communication protocols should quickly leave classic ones behind in the dust.

Bone and shell are composite materials in which the mineral component forms within a framework of soft macromolecules such as proteins. The framework is essentially a "mold" that directs the mineral formation. Bone grows continuously, layer by layer; but, unlike shell, it also undergoes constant remodeling. This makes it hard for scientists studying bone to distinguish new material from old, much less to trace the process by which bone is formed. Because of this difficulty, conflicting theories have arisen as to the mechanisms of bone formation. Many scientists thought that the minerals precipitate directly from a solution in the way that stalactites and stalagmites grow from elements dissolved in water. But findings published in the 1960s already hinted at the possibility that a different process was at work.

Ten years ago, research in a group headed by Profs. Lia Addadi and Stephen Weiner of the Institute's Structural Biology Department confirmed these earlier observations for shells. They showed that organisms first produce packets of amorphous material (unorganized material, as opposed to the ordered organization of crystal). These packets are transferred from the inside of cells to the building site – the spot where the mineralized tissue eventually forms. There, the packets undergo structural changes that turn them into a hard crystal. This observation triggered widespread interest in amorphous precursor mineral phases, and many different invertebrate mineralization processes were investigated.

Addadi and Weiner revealed this process in sea urchin spines, and their findings have been joined by a body of global research confirming that this method of construction is common to many different invertebrates that have shells, spines or other hard body structures. Addadi: "The original idea of precipitation from solution would require huge quantities of liquid to flow from inside the mollusk to the outside of its body. Transferring the materials in solid form – 'bricks and cement' – is a much more energy-efficient way of doing things."

While the issue has been more or less settled for the shells of invertebrates, the question of how vertebrate bones are formed remained unresolved. This is partly because of the difficulty inherent in attempting to observe a substance with no fixed location that exists for only a fleeting stage of growth. Recently, however, research student Julia Mahamid, together with Addadi and Weiner, found a biological system that enabled them to follow bone formation step by step and identify the processes taking place at each stage. This system is the fin of a small aquarium denizen called a zebrafish. The zebrafish fin bones, which continue to grow throughout the fish's lifetime, form a sort of fan. Each bony rib of the fan is composed of segments, and the segments nearest the fin's edge are always the newest. Thus the segments can be studied as a sort of timeline of bone formation. In addition, zebrafish, which live in relatively cold water, grow slowly, and the leisurely pace of their bone development enabled the scientists to get a good look at each stage.

Using both light microscopy and scanning electron microscopy, the scientists succeeded in observing abundant spherical parcels of amorphous mineral material in the newly formed fin bone. Their findings, which appeared in the Proceedings of the National Academy of Sciences (PNAS), USA, showed that about half the mineral makeup of the newer bone segments is amorphous – a fraction that dwindles in the segments farther away from the fin edge. Their observations suggest that the amorphous material does, indeed, turn to crystal over time.

These findings are shedding light on a number of scientific mysteries, giving scientists a unique perspective on how the hard substances in our body – bones and teeth – are formed. The scientists hope that a deeper understanding of these biological processes may, in the future, help researchers find cures for diseases involving faulty bone development or repair.

What is the difference between the experimental and theoretical fields? To understand, it helps to know that astrophysics examines how the universe – and the stars, galaxies, and other astronomical objects within it – works. Theoretical astrophysicists rely on the basic laws of nature to develop a physical understanding of the diverse phenomena that exist in the universe. Experimental astrophysicists collect information about the precise nature of these phenomena, providing their theoretical colleagues with the data to construct and test their models, as well as motivation for additional theoretical investigations to explain new and surprising observational results.

As an experimental astrophysicist, Dr. Gal-Yam has dedicated himself to the phenomena of supernovae. A supernova can be very basically defined as “a star that explodes,” says Dr. Gal-Yam; such an explosion, or supernova event, is observed as a tiny source of light that appears where none was visible before. Given the size of the universe, it is extremely difficult to find a new light source that represents an exploding star.

The key to finding supernovae is change. Most objects in the sky appear unchanged over a human lifetime. Take as an example Earth’s nearest star – its own sun. With a life expectancy of 10 billion years, it is highly unlikely that any changes in it will be observed. The same is true of most stars, and for this reason, much of astronomy is the study of things that do not change. However, this also means that if a scientist comes across a new source of light, chances are they have found something exciting.

Along with hunting for supernovae, Dr. Gal-Yam is trying to identify which stars exploded, and why. He points out that this is very difficult because scientists only know there was an explosion after the fact, and since there is no longer an actual star to study, it is hard to determine what kind of star it was.

“It turns out that there are all different kinds of stars that explode, as well as different types of explosions that have different physics,” he says, likening this research to asking what the shape of something was after it has been broken. But with a well-designed experiment – and a bit of luck – progress can be made in solving this  riddle. Advanced instruments such as the Hubble space telescope and giant land-based telescopes are helping in this quest.

There are two parts to experiencing a super- nova event: seeing the light of the explosion, and detecting miniscule, invisible particles called neutrinos. Dr. Gal-Yam says that “when we observe the light, we just see the envelope – we cannot see what is inside because the explosion is not transparent.”

However, it is known that the envelope contains neutrinos – and neutrinos teach scientists a lot about the physics of a supernova. Neutrinos are ejected from the core of an exploding star and can reach Earth, but only a few laboratories have equipment capable of detecting them. Such equipment includes large tanks of ultra-pure water. When neutrinos enter the water, they collide with other molecules; these collisions emit little sparks of light that can then be measured by researchers.

For scientists to know when to look for evidence of neutrinos in the water tanks, they must know that a supernova is going to occur. But how does one find such a tiny needle in the massive haystack of the universe?

One method is to continually watch the sky. The Weizmann Institute is taking part in a project that involves a network of powerful robotic telescopes spanning the Earth. Currently, there are seven worldwide, “watching very diligently, just waiting all the time for supernovae to happen,” says Dr. Gal-Yam.

The benefit of this network is that the telescopes provide constant observation: it is always night somewhere. The telescopes also take frequent photographs, allowing researchers to identify changes in a given section of sky. This scrutiny helps astronomers see stars as they blow up, providing the time of the event, among other valuable data – and alerting them to be on the lookout for neutrinos.

Because the amount of information produced by these photographs is so massive, researchers use sophisticated software to process the mountains of data in order to find the points of light that may represent supernovae. By examining “before” and “after” photos, astronomers can tell which star exploded, and then work backward to study that star and determine its properties. 

However, telescopes that are even more powerful than Hubble and other existing equipment are needed to gather clearer and greater data. To that end, Dr. Gal-Yam is collaborating with other institutions, including the California Institute of Technology (Caltech), on a new telescope, which will basically be a super-large, high-definition camera.

“The tools of my trade, so to speak, are these telescopes,” says Dr. Gal-Yam. It can be hit-or-miss work; nonetheless, “every night we look at the sky and compare photographs. A supernova might appear as a new dot in some galaxy, and then become brighter than the whole galaxy. And some of these provide keys to physical questions that have puzzled us for decades.”

The machine is a particle accelerator. It’s nestled in a 27-km-long tunnel, dug some 100 meters beneath the border between France and Switzerland, near Geneva. This accelerator is a part of CERN, the European particle physics laboratory. CERN is a world giant in the field of physics: Its scientists came up with, among other things, the computer languages and protocols that became the basis of the World Wide Web, and it has an effect on the European economy similar to that of the American space program in the U.S. Yet for all its accomplishments, the scientists at CERN, with all their complex machinery, haven’t managed to track down this one missing particle. Their best hope yet lies with the new accelerator being built, called the Large Hadron Collider (LHC), which will be able to accelerate bundles of protons to 99.999998% of the speed of light. These bundles will be aimed straight at each other, causing collisions that will release so much energy, the protons themselves will explode. For less than the blink of an eye, conditions similar to those that existed in the universe in the first fraction of a second after the big bang will be present in the accelerator.

At that first moment, the universe was simple, hot and very energetic. As the seconds ticked by, space expanded, and that energy began to dissipate. The universe cooled, becoming more complex as it did so, until it reached the level of complexity we know today. Inside the collider, the scientists will try to recreate those simpler, primordial conditions – a cosmos in which all particles were simply “different faces” of a small number of elementary particles, and the four fundamental forces that act between those particles were but expressions of a single force. As a first step in reconstructing that primal force, scientists have managed to join two of those forces: the electromagnetic force and the weak nuclear force. (The other two are the strong nuclear force and gravity.) But the existence of this “electro-weak” force presupposes the existence of a particle called a “Higgs” – named after the Scottish physicist Peter Higgs who, along with Robert Brout and Francois Englert, first predicted it. The only fly in the ointment is that since its prediction over 40 years ago, no Higgs particle has yet been detected.

A number of Weizmann Institute physicists have joined in the effort to find the missing Higgs particle. They’re a somewhat multigenerational scientific family – Prof. Giora Mikenberg, who heads the Israeli team, is the teacher and mentor of Prof. Ehud Duchovni, who taught Prof. Eilam Gross. Also working with these three are Dr. Vladimir Smakhtin, Dr. Daniel Lellouch and Dr. Lorne Levinson, all of the Particle Physics Department and the Nella and Leon Benoziyo Center for High Energy Physics.

High-Speed Collisions
Inside the accelerator, powerful, head-on collisions take place continuously between the protons, resulting in highly energetic particles that wink in and out of existence in a tiny fraction of a second. To obtain proof of their existence, one must identify the traces they leave behind. Thus a number of particle detectors have been created, each designed to trap a different kind of particle. The Weizmann team led by Mikenberg has developed a special detector, constructed at the Institute and other places around the world, which will contribute to detecting the elusive Higgs. “Elusive” may be an understatement: The chances of being able to find a Higgs particle in a single collision are about the same as those of coming up with a specific cell from a specific leaf on a specific plant by plucking one cell at random from all of the plants on the whole planet.

The LHC, equipped with superconducting magnets that work at temperatures of less than 2 degrees above absolute zero (absolute zero is -273° C), will produce something like a billion collisions per second. If protons were people, the collision rate would entail every person on the planet running into every other person on the planet every six seconds. Calculating and analyzing the data from all of these collisions will be akin to listening in on all of the planet’s telephone conversations at once, assuming the entire population is talking simultaneously on 20 phones apiece.

Hidden Dimensions and Black Holes
In addition to the Higgs particle, the LHC might, at some time in the future, produce millions of very tiny black holes. This surprising idea arises indirectly from string theory, which posits that the particles we know are simply manifestations of one “fundamental constituent,” called a string, and all the forces acting in nature are nothing more than different aspects of one single primeval force. Reality, as suggested by this theory, contains at least eleven dimensions, but seven of them are “curled up” and shrunk so small they can’t be observed.

Another recent model has suggested that the gravitational force can propagate in the additional dimensions, and that the size of the curvature of some of these additional dimensions might not be so small. Under these assumptions gravitational force becomes very strong at short distances, in particular for very energetic (massive) particles. Close to particle collision sites, this can lead to an enormous concentration of gravitational power in a small area. If this happens, a black hole might form. In fact, if calculations are correct, black holes could be created in the LHC at a rate of up to one per second. There’s no need to worry though: The physics of black holes dictates that the smaller the black hole, the higher its temperature. Such tiny black holes will be so hot they’ll vaporize almost as soon as they come into existence.   

An Israeli-Pakistani team at the “Atlas” experimental station

Prof. Ehud Duchovni
Ehud was born in Israel in 1953. In his youth he was an Israeli swimming and target-shooting champion. He served in an elite army unit and was later a target of a terrorist attack. He was awarded a medal for bravery by the Israeli Police, and the Verdienstkreuz am Band by the German President, for his actions in this attack. Later, while on reserve duty, he was wounded in the back. Duchovni is married to Noga and is the father of Inbal, Eynat, Gilead and Avner.

Prof. Giora Mikenberg

He was born Jorge Mikenberg in Buenos Aires, Argentina, in 1947. When he was just 16, he left his family in South America, changed his name to Giora, and set out for Israel to live on a kibbutz. In Israel, with encouragement from Prof. Yehuda Shadmi, he began to study physics, eventually ending up at the Weizmann Institute of Science. In the army, he served under Sergeant Ehud Duchovni, who would become his pupil. At CERN, Giora is known as George. 

Prof. Eilam Gross
Prof. Eilam Gross was born in Tel Aviv. After completing his army service in an elite communications unit, he left for New York to study music. There he came across a cult book, The Tao of Physics, which prompted him to come back to Israel and study physics at the Hebrew University of Jerusalem. His master’s thesis at the Weizmann Institute was written on string theory, after which he “deserted” theortical work for experimental high-energy physics and the team of Prof. Mikenberg. Today, between mathematical formulas and charting particle trajectories, he continues to work on his music, and he dreams of staging a performance that will combine music with insights gained from particle physics. He is the father of two daughters, Nuphar (20) and Yaara (15).

How many people can say that their job is directly related to those long, glorious days of childhood, when the only responsibility you had was to be home in time for dinner? Dr. Einat Aharonov is one of the lucky ones. Throughout her youth, she enjoyed long hikes, and contemplating the forces that shaped the mountains, rocks, and land that she loved.

"As a child, I was fascinated by how mountains were once under the sea and that you could find seashells on mountain sides," she says. "I wanted to understand the large forces of nature that could do that."

Now, as a researcher at the Weizmann Institute of Science, she studies these forces, devising ways to compress events that take eons in geological time so that they can be studied in her lab. Her interests are in the forces that move the Earth, from the slowly shifting tectonic plates that make up the Earth's crust to the physics of granular motion that describe the motion of massive landslides. The only problem? The phenomena are difficult to capture in the controlled settings of a research lab. Studying these events within a human lifetime - using manageable pressures and temperatures - requires computer models, analog materials such as salt or silicone, and most of all, innovation.

In one of her current projects, Dr. Aharonov and one of her doctoral students are looking at how massive landslides occur using computer models and boxes filled with fine sand. "The computer can simulate collections of grains, which can flow like fluid yet behave like solids at the same time," she says. Her research has shown that large-scale landslides are a result of the way particles move, conserving their kinetic energy through a bouncing motion. When this happens in nature - a phenomenon Dr. Aharonov dubs "spontaneous subchronization" - it can amplify a relatively small triggering event and cause devastatingly large landslides to flow unexpectedly across large distances. Dr. Aharonov and her student are in the process of writing a scientific report on this research, which she has shown in two-dimensional models. Her student is working on establishing a model to test the work in three dimensions. But there are still more dimensions to her research. Dr. Aharonov is also looking into the forces that work on tectonic plates. Rather than watching the plates themselves, which drift only inches a year, Prof. Yossi Mart of Haifa University and Dr. Aharonov have partnered with a laboratory in Sweden. Together they are using centrifuges to artificially enhance gravity and speed up geological time - at least in the lab - to see how the giant interlocking pieces of the Earth's crust move in relation to each other.

"We're trying to understand the physical processes that take place at the point where oceans meet continents," she says. Dr. Aharonov does not just study how the Earth is moved, but how it is formed. Her team is also looking at how rocks are formed and how they dissolve over time, again using special techniques and materials to speed up the process in the lab.

Since joining the Weizmann Institute in 2000, Dr. Aharonov has had an opportunity to be a force of her own, aiding in the development of a relatively new department at the Institute: the Environmental Sciences and Energy Research Department, a growing group of dedicated researchers who investigate everything from atmospheric chemistry and ocean and climate dynamics to solar energy. "It is very exciting to be a part of building this new department and these new studies," she says.

Dr. Aharonov hopes that enhanced understanding of the geophysical processes she is studying may facilitate engineering measures to better prepare us for the next time the Earth suddenly fails beneath us - as it inevitably will.