Professor John Barrow
The Origin of the Universe
We will describe the development of ideas about the origin of the universe in modern cosmology and the range of observations that provide information about the very early stages of the Universe. In particular, we will see how the influx of ideas from elementary particle physics has complemented the astronomical information to create a range of surprising possibilities for the past and future of the universe.
Professor Mike Kelley
Exciting New Discoveries in Ionospheric Science
New experimental tools, particularly optical ones, have been added to radiowave and in situ observations of the Earth's upper atmosphere. CCD cameras, lidars, and remote optical sensing from space have all developed dramatically and have improved our understanding of the near space regions of the Earth. New phenomena have also been discovered and old mysteries have been reopened using these new observational tools. A few will be discussed here. Above heights of 80 km the atmosphere is so tenuous that chemical reactions leading to excited states are not quenched by collisions before emitting light. This means photographs can be taken from space or the ground, leading to new insights about atmospheric phenomena. In particular, waves propagating upward from the lower atmosphere can be observed as they interact with each other and with the background medium. This interaction leads to major changes in the atmosphere, leading, for example, to the extremely cold temperatures (less than 100 K) in the polar mesosphere. The highest clouds form there as well, near 85 km, and seem to be a sensitive marker of global change. This same height range is where most meteors end their fiery entry, leaving behind trails of atoms and dust that form a layer around the Earth. Sometimes these trails linger on for tens of minutes, remaining visible to the naked eye. A series of laser-based experiments have revealed just how much we do not know about this phenomenon. Of somewhat more practical interest is the ionization blanket surrounding the Earth, through which satellite-based communications and navigation systems must propagate. These signals are slowed down and sometimes distorted by turbulence in the ionosphere, one component of space weather that affects mankind. Ground and space-based optical methods have revealed quite a bit about these ionospheric storms. Much remains as yet unexplained, particularly at midlatitudes.
Professor Michael Hough
Physics education in a globalising economy where knowledge and information are competitive advantages
This paper reviews the rapid developments of new forms of knowledge in a globalising economy where, increasingly, certain forms of knowledge and knowledge systems are becoming both a competitive advantage for business and valuable commodity. The emerging forms of new technologies will be reviewed and this review will include an insight into the emerging features of e-commerce based economies and the perceived forms of new assets. The review of new technologies will be accompanied by a particular emphasis on explaining the disruptive impacts as well as the sustaining impacts of new technologies on current practices.
From this review the implications for physics as a discipline and for physics education in particular will be covered. Particular aspects will include: the move to a bio-chemical based emphasis in Science, the demise of answers based and certainty based scientific paradigms, and the need for values based science.
Professor Dean Zollman
Quantum Mechanics for Everyone: Can it be done with Technology?
Research on teaching and learning has indicated clearly that learning proceeds very well when students begin with concrete ideas and examples, then move to abstract concepts, models and theories. In many pedagogical strategies hands-on activities with real apparatus precede any introduction of new concepts. After the students have first learned a new idea, they reinforce it with additional activities. These teaching-learning strategies are well suited to a classroom environment and to introductory level material. However, distance learning via the Web and/or abstract topics present additional challenges in keeping the pedagogy consistent with knowledge about how people learn. Our group is attempting to meet these challenges by creating materials to teach quantum mechanics to a wide range of students, including many who do not have the background normally thought to be necessary to learn this topic.
The Visual Quantum Mechanics project has created a series of teaching/learning units to introduce quantum physics to a variety of audiences ranging from high school students who normally would not study these topics to undergraduate physics majors. Interactive computer visualizations are coupled with hands-on experiences to create a series of activities which help students learn about some aspects of quantum mechanics. Our goal is to enable students to obtain a qualitative and, where appropriate, a quantitative understanding of contemporary ideas in physics. Included in the instructional materials are student-centered activities that address a variety of concepts in quantum physics and applications to devices such as the light emitting diode, the electron microscope, an inexpensive infrared detection card, and the Star Trek Transporter. Whenever possible the students begin the study of a new concept with an experiment using inexpensive equipment. They, then, build models of the physical phenomenon using interactive computer visualization and conclude by applying those models to new situations. For physics students these visualizations are usually followed by a mathematical approach. For others the visualizations provide a framework for understanding the concepts. Thus, Visual Quantum Mechanics allows a wide range of students to begin to understand the basic concepts, implications and interpretations of quantum physics.
For the secondary school students we have created a series of learning units which can be inserted into a traditional physics course. Each unit requires about ten hours of class time. Thus, it can be inserted into a class without a complete change in the curriculum. For physics students we have created a series of one to two hour lessons which can be correlated with many of the popular Modern Physics textbooks. The materials for medical students are now being developed as a series of units that require about 3 weeks of college instruction for each one.
Most of our efforts have concentrated on classroom activities. However, we are now developing for Web-based learning as well. Because hands-on activities are much more difficult on the Web, we have needed to modify some of our teaching-learning strategies. Some of the challenges which have been created by these modifications have been met successfully, and we are still working on others.
(This project is supported by the U.S. National Science Foundation under grants ESI-9452782 and DUE-9652888 and by the Howard Hughes Medical Institute.)
Professor Victor Ninov
Production and Structure of the Heaviest Elements
The synthesis of heavy nuclei has fundamental interest for nuclear physics. The heaviest elements provide an excellent laboratory in understanding of nuclear structure in a strong Coulomb field. For over twenty five years experimentalists sought to synthesize super heavy nuclei at or near the region of spherical shell closure at Z=114 and N=184, although some modern Hartree-Fock / Mean-Field calculations predict that the region of increased stability is located near Z=120 or Z=126.
The unambiguous synthesis of the elements 110-112 at GSI has proven difficult to proceed beyond using the so called "cold fusion" approach of bombarding lead or bismuth target atoms to produce heavy compound nuclei at low excitation energy.
Recent calculations of R. Smolanczuk indicated a dramatic increase in the production cross section of element 118 in the reaction 208Pb (86Kr,1n) 293118. We have studied this reaction at the 88-Inch Cyclotron of the Lawrence Berkeley National Laboratory using the Berkeley Gas-Filled Separator. In two experiments three ?-decay chains were observed that could be interpreted as a decay of element 118.
The surprisingly high cross section of about 2 pb for the reaction 208Pb (86Kr,1n) 293118 may be due to the lowering of the Coulomb barrier (measured with reference to the energy of the compound nucleus).
A new interpretation of existing data, the importance of shell-closures between the interacting partners as well as viability of the "cold fusion" approach will be discussed. The idea of a fusion process, where only the fission barrier properties of the compound system seem to be the determining factor of the amalgamation will be presented.
A qualitative discussion of some the simplest aspects of heavy ion collision dynamics raises interesting perspectives for the future. But it will be the experimental progress we hopefully will be able to report on that will decide the feasibility of the new ideas.
Professor Sajeev John
Photonic Band Gap Materials: Design, Synthesis, and Applications
Unlike semiconductors which facilitate the coherent propagation of electrons, photonic band gap (PBG) materials execute their novel functions through the coherent localization of photons. I review and discuss our recent synthesis of a large scale three-dimensional silicon photonic crystal with a complete photonic band gap near 1.5 microns. When a PBG material is doped with impurity atoms which have an electronic transition that lies within the gap, spontaneous emission of light from the atom is inhibited. Inside the gap, the photon forms a bound state to the atom. Outside the gap, radiative dynamics in the colored vacuum is highly non-Markovian. I discuss the influence of these memory effects on laser action. When spontaneous emission is absent, the next order radiative effect (resonance dipole-dipole interaction between atoms) must be incorporated, leading to anomalous nonlinear optical effects which occur at a much lower threshold than in ordinary vacuum. I describe the collective switching of two-level atoms near a photonic band edge, by external laser field, from a passive state to one exhibiting population inversion. This effect is forbidden in ordinary vacuum. However, in the context of a PBG material, this effect may utilized for an all-optical transistor. Finally, I discuss the prospects for a phase sensitive, single atom quantum memory device, onto which information may be written by an external laser pulse.
Professor Jeffrey Harris
Plasma physics: innovation in energy and industrial technology
Plasmas-ionised gases-are truly ubiquitous. More than 99% of the matter in the universe is in the plasma state. All of the matter that comprises the Earth, and all of the energy that powers it, has been processed through plasma fusion reactions in stars. Plasmas also play a crucial role in the Earth's atmosphere, which screens out harmful radiation, and make long distance radio propagation possible.
While the study of plasma physics was originally motivated by astrophysics, the discipline has grown to address terrestrial concerns. These include lighting, welding, the switching of large electrical currents, the processing of materials such as semiconductors, and the quest to build fusion power reactors-artificial stars-for low-emissions generation of electricity from hydrogen isotopes.
Plasma physics is fundamentally multi-disciplinary. It requires understanding not only of the complex collective behaviour of ionised gases in unusual conditions, but also knowledge of the atomic and nuclear physics that determines how plasmas are formed and maintained, and the specialised engineering and instrumentation of the mechanical and electromagnetic containers needed to confine plasmas on Earth. These characteristics make plasma physics a fertile breeding ground for imagination and innovation.
This paper draws together examples of innovation stimulated by plasma physics research in the areas of energy, materials, communications, and computation.
Professor Jeffrey Harris is the Director of the National Plasma Fusion Research Facility and the Head of the Plasma Research Laboratory in the Research School of Physical Sciences and Engineering in the Institute of Advanced Studies at the Australian National University. He was born in the US and educated at the Massachusetts Institute of Technology (MIT) and the University of Wisconsin. His research interests have centred on the physics of ionised gases--plasmas--and the development of fusion energy technology to produce electricity using the reactions that power the Sun and stars. He has also worked on technological applications in digital signal processing and wireless communications. He came to the ANU in 1997 after nearly twenty years of research at the Oak Ridge National Laboratory, during which time he worked on international research projects in Russia, Japan, and France.
Professor Roger Horn
Surfaces Cover Everything
This talk aims to address some of the interesting science associated with surfaces, and to highlight the importance of surfaces in a wide range of modern technologies. In fact it would be more correct to speak of interfaces, meaning the boundary between two media, since materials are usually in found contact with another medium.
Many technologies rely, to a greater extent than we commonly realise, on materials that are developed to have special properties or to perform special functions. Furthermore, the surface or interfacial properties of those materials often play vital roles in their processing and/or properties. Examples range from the macroscopic world through the micrometre scale to the nanometre scale at which the atomic and molecular nature of matter must be considered.
Consider some simple questions, some of which you will know the answers to and some perhaps not:
All of these questions concern interfaces, although for some of them the connection is more obvious than for others. This talk will endeavour to explain the less-obvious connections, to give answers to some of the less-obvious questions, and in particular to discuss the science of interfaces and its connection to the exciting new world of nanotechnology.
Professor Chris Greene
Photoionization of light atoms and molecules: A window into few-body and many-body dynamics
Species as simple as atoms and molecules with two or three electrons continue to provide surprises and challenges, while resisting a full quantitative description. The past few years have seen tremendous progress. Numerous long-existing roadblocks have been overcome by theorists, as well as experimentalists working on a number of different fronts. This is an exciting time, because theoretical capabilities have improved dramatically. We can now describe complicated resonant photoionization processes in helium or molecular hydrogen that seemed inconceivable in the early 1990s. While nonresonant ejection of two electrons in these species by a single energetic photon seems unlikely, from an independent particle perspective, it can be surprisingly important. My talk will give an overview of recent progress, and will address some of the regimes where we still need to achieve a better understanding.
Professor Janet Conrad
Navigating the World of Neutrino Osciallations
Janet Conrad gained her Ph.D. from Harvard University in 1993 in the area of Neutrino Physics. She then joined CCFR/NuTeV, neutrino deep inelastic scattering experiments making precision measurements of QCD parameters. More recently, she has been investigating whether neutrinos have mass by looking for neutrino decays and neutrino oscillations.
Because of the recent results on neutrino oscillations, this is an exciting area of research. She is currently Assistant Professor in the Department of Physics at Columbia University, USA, and is continuing to pursue research at Fermi National Accelerator Laboratory (Fermilab). She is co-spokesperson of the BooNE Experiment, which will be capable of observing both nu-mu -> nu-e appearance and nu-mu disappearance; to measure the oscillation parameters, Delta m2 and sin^2 (2 theta); and to search for CP violation in the lepton sector.
This talk reviews the many new results from neutrino oscillation searches. Exciting indications of neutrino oscillations have been seen in the solar neutrino deficit, atmospheric neutrino deficit and LSND excess. These indications and reported limits on oscillations are considered. Attempts to develop a theory which addresses all of the neutrino oscillation data are discussed. Some of the remaining questions and the future experiments which will help answer these questions are described.
Professor Phillip Stiles
Condensed matter Physics: Its evolution
in the last 50 years.