I will describe our current state of knowledge on some key aspects of the physics of GRBs, by following the history of the field, in particular the revolution in the 90's and the 2000's made possible by the CGRO, Beppo-SAX and Swift satellites.
I will then focus on some key open questions in the field, which are relevant to many fields in physics and astronomy and are the subject of ongoing extensive studies. Among them are: What is the nature of GRB progenitors ? How is energy being extracted ? What are the radiative mechanisms, and could GRBs be related to cosmic rays ? How can shock waves accelerate particles and produce strong magnetic fields ?

Newton’s elementary geometrical derivation of:

(a): Kepler’s 2nd law of planetary motion,
(b): inverse square law of gravitational force from conical orbits,
(c): the inverse of procedure (b),

will be briefly reviewed. Since just a small number of physicists and/or physics students appears to have actually been exposed even to a small portion of Principia, this might be a useful thing to do. In particular, the procedure (c) above of Newton provoked a lot of discussions for over 300 years. An alternative elementary geometrical method by Feynman will be presented. If time allows, of several important subjects an important study on dual forces, initiated by Newton but overlooked for far more than 200 years before its resurrection, which has an important bearing also in QM, will be touched upon.

*The talk will be an abbreviated version of the semi-public lecture at the Faculty of Physics, Univ. of Barcelona, July 2008.

Mass outflows in Active Galactic Nuclei (AGN) are revealed through high-ionization absorption lines in the UV that are blueshifted with respect to their host galaxies. The mass outflow rates are comparable to the accretion rates needed to power the active supermassive black holes, indicating the importance of outflows in determining the overall structure and energetics of AGN. Using high-resolution UV spectroscopy from FUSE and HST, including multiple-epoch observations of the variable absorption lines, we have derived detailed constraints on the physical conditions, transverse velocities, and locations of the outflowing absorbers. We have also recently isolated a component of the emission lines that likely arises in the outflowing absorbers, which allows us to place tight constraints on the locations, geometry, and dynamics of the outflows. In the best-studied Seyfert galaxy to date, NGC 4151, the available evidence favors magnetocentrifugal winds over radiation driving or thermal expansion as the dominant acceleration mechanism for the outflows.

As argued many years ago by Hawking, black holes appear to violate quantum mechanics by destroying the reversibility of physical processes. Recent results in string theory however suggest a radically different picture of the black hole interior; instead of being just ‘empty space with a central singularity’, it is now filled with a tangle of stringy matter. This picture would resolve the `information paradox' raised by Hawking, and show that quantum gravity effects are not confined to the planck length but instead stretch over distances that increase with the mass of the object being studied.

Our understanding of the physical properties of materials has proven to be essential in developing new systems and modern devices. It is essential to think ahead and probe new avenues in ‘Electronics’ and 'Photonics' to increase and improve the functionality of the existing systems. This talk will introduce the properties of several less explored narrow gap semiconductor (NGS) structures which can play essential roles in developing next generation of devices. Our goal is to develop a better understanding of the quantum states and dynamics of interacting, confined, or strongly driven carriers or spins in NGS based materials.

What do the laws of thermodynamics look like, when applied to microscopic systems such as optically trapped colloids, single molecules manipulated with laser tweezers, and biomolecular machines? Over the past decade or so there has been considerable interest and progress in addressing this question. I will give an overview of some of these developments, with a focus on results pertaining to fluctuations far from thermal equilibrium, and I will argue that these developments have refined our understanding of the second law of thermodynamics.

This colloquium will describe how the GEM*STAR approach divorces nuclear energy from some of the perennial problems associated with reactors: weapons proliferation, waste, and safety. The key elements include: Provide neutrons to induce fission using today's improved accelerators. Use molten salt reactor to provide uniform fuel use at constant reactivity. Operate with graphite moderated thermal-neutron spectrum at reduced energy density. Run as a sub-critical system for safety and neutron efficiency. The result is no need for uranium enrichment, no reprocessing (and thus Pu economy), can burn current light-water reactor waste, and removes the need for a civil nuclear waste repository thus providing safe energy for all nations without contributing to global warming.

About seven years ago, physics departments faced large service course loads with declining numbers of majors. The situation was complicated by tight funding for research, a rapidly changing disciplinary landscape, a changing university environment, and entering students with skills and attitudes that diverge from those of their predecessors (and their professors.) The physics community united to understand these changes, to develop strategies to meet them and to implement these strategies. At the present time, physics is seeing increasing numbers of undergraduate majors. Other departments are facing similar challenges, and the strategies tested in physics can work for them.

Astronomy, arguably the oldest of all physical sciences, has been the source of much our current understanding of the fundamentals processes that shape the physical world. Thus, it was through astronomical observations that atoms were recognized and true nature was understood. Since then, astronomy and atomic physics have progressed jointly and interdependently.

In this talk I review such progress in astronomy and atomic physics up to the present. I show that atomic physics for astrophysics is today as vibrant and important as ever. Then, I describe some of the work we carry out at Virginia Tech. Finally, I discuss some pressing questions for the future, whose answers will require major theoretical advances and fundamental physics research.

How do you keep a classroom of 100 undergraduates actively learning? Can students practice communication and teamwork skills in a large class? How do you boost the performance of underrepresented groups? The Student-Centered Active Learning Environment for Undergraduate Programs (SCALE-UP) Project has addressed these concerns. Materials developed by the project are now in use by more than 1/3 of all science, math, and engineering majors nationwide. Physics, chemistry, math, biology, engineering, business, nursing, and even literature classes are being taught this way, at more than 50 institutions nationwide

Educational research indicates that students should collaborate on interesting tasks and be deeply involved with the material they are studying. We promote active learning in a redesigned classroom for 100 students or more. (Of course, smaller classes can also benefit.) Class time is spent primarily on “tangibles” and “ponderables”—hands-on activities, simulations, and interesting questions. There are also hypothesis-driven labs. Nine students sit in three teams at round tables. Instructors circulate and engage in Socratic dialogues. The setting looks like a banquet hall, with lively interactions nearly all the time.

Hundreds of hours of classroom video and audio recordings, transcripts of numerous interviews and focus groups, data from conceptual learning assessments (using widely-recognized instruments in a pretest/posttest protocol), and collected portfolios of student work are part of our rigorous assessment effort. We have data comparing 16,000+ students. Our findings can be summarized as the following:

• Ability to solve problems is improved
• Conceptual understanding is increased
• Attitudes are improved
• Failure rates are drastically reduced, especially for women and minorities
• Performance in later courses is enhanced

In this talk I will discuss the classroom environment, describe some of the activities, and review the findings of studies of learning in various SCALE-UP settings.

Galactic winds are the primary mechanism by which energy and metals are recycled in galaxies and are deposited into the intergalactic medium. New observations are revealing the ubiquity of this process, particularly at high redshift. I will describe the physics behind these winds, discuss the observational evidence for them in nearby star-forming and active galaxies and in the high-redshift universe, and consider the implications of energetic winds for the formation and evolution of galaxies and the intergalactic medium. To inspire future research, I will conclude with a set of observational and theoretical challenges.

The phenomenon of neutrino flavor oscillations is now well-established. Mixing among the three flavors is characterized by three mixing angles, with θ₁₃ being the only presently unknown angle. A precise measurement of θ₁₃ can be made by utilizing a powerful nuclear reactor as the anti-neutrino source, going deep underground to reduce the background, and building "identical" near and far detectors to minimize the systematics. We have proposed such an experiment at the Daya Bay nuclear reactor in south China. This project is well on track - the civil construction is underway, the detector installation will commerce in 2009, and we expect exciting results in a few years. In this talk, I will stress the physics motivation of such a measurement, introduce you to the world of making precise oscillation measurement with reactor neutrinos, and look into the near future of the Daya Bay experiment.

Nanowires are one-dimensional nanostructures with electrical carriers confined in the other two (perpendicular) directions. They exhibit interesting physical properties that are noticeably different from those of quantum dots and the bulk. In order to understand the quantum confinement effect, we have performed first-principles calculations of the electronic, vibrational, and optical properties of silicon nanowires. Of particular interest is the enhanced electron-hole Coulomb interaction in this confined geometry that results in an unusually large binding energy (1-1.5 eV) for the excitons, which dominate the optical absorption spectrum. In the Si/Ge core-shell nanowires the near-gap electronic states are found to be spatially separated within the core or the shell region, making it possible to generate a one-dimensional electron or hole gas confined in different regions.

Gravitational waves, which can be described as "ripples in the geometry of spacetime", are a key prediction of Einstein's general theory of relativity but have not been directly detected -- yet. Believed to be produced by various types of extreme astrophysical objects in the universe, the waves are incredibly weak when they reach the Earth. Nevertheless, after decades of prototyping and development, a handful of large laser-interferometer detectors around the world -- led by the LIGO Project in the U.S. -- have achieved sensitivity levels that reach into the realm of plausible gravitational-wave signals. I will describe how these remarkable detectors work and the results of some of the searches we have carried out so far. Detector upgrades and data collection runs over the next several years will take this further and begin to detect gravitational waves on a regular basis, providing a new tool for astronomy and fundamental physics that is based on listening to the gravitational echoes of highly energetic astrophysical events.

Particle physics models often contain non-particle structures that can manifest themselves in the cosmological arena. Cosmic strings are a particularly interesting variety of such structures. If heavy cosmic strings exist, they are predicted to produce a number of observable astronomical signatures such as unusual gravitational lensing of galaxies and distortions of the cosmic microwave background radiation. If cosmic strings are light but superconducting, they could still be observed via their transient radio emission or ``sparks''.

Kilometer-scale neutrino detectors such as IceCube are discovery instruments covering nuclear and particle physics, cosmology and astronomy. Examples of their multidisciplinary missions include the search for the particle nature of dark matter and for additional small dimensions of space. In the end, their conceptual design is very much anchored to the observational fact that Nature produces photons and protons with energies in excess of one hundred and one hundred million Terraelectronvolts, respectively. The cosmic ray connection sets the scale of cosmic neutrino fluxes. The problem has been to develop a robust and affordable technology to build the kilometer-scale neutrino detectors required to do the science. The AMANDA telescope transforming ultra-clear deep Antarctic ice into a Cherenkov detector of muons and showers initiated by neutrinos of all three flavors, has met this challenge. Having collected more than 6000 well-reconstructed muon neutrinos of 50 GeV ~ 500 TeV energy, AMANDA represents a proof of concept for the ultimate kilometer-scale neutrino observatory, IceCube, now almost complete and producing results exceeding in sensitivity seven years of AMANDA data.

I will review the most important scientific achievements of the Hubble Space Telescope. I will cover topics ranging from Dark Energy to Extrasolar Planets, and from the Hubble Constant to Supermassive Black Holes. I will also present spectacular images taken by the Hubble Space Telescope, and discuss the penetration of Hubble discoveries into the general culture.

Granular materials are so common that we take them for granted. Examples include your dry cereal in the morning, the road bed you drive to work on, and countless other products that you use, which spend part of their existence in granular form. Yet, at the most basic physics level, we are still striving to understand their nature. Traditional granular continuum models start from a macroscopic viewpoint that omits any microscopic information. But a zoomed-in look that starts at the particle scale, reveals fascinating behavior with parallels and deviations from what is seen for molecular matter. Granular materials are a paradigm for disordered solids near jamming, the transition from fluid-like to solid-like behavior. Low density granular systems can resemble gases, but with dissipative interations that lead to novel instabilties. Dense granular solids and fluids have their own novel features. Here, forces are often carried inhomogeously on filimentary structures known as force chains. Under shear, these chains can be very long, and when they break, they cause significant force fluctuations. This talk will start with an introduction to some of the simple properties of granular materials, and then focus on novel experiments and new statistical approaches for understanding the dense granular state, starting from a microscopic viewpoint.

A significant part of the mission of Virginia Tech is to transfer technology out of the university into the marketplace where it can be used for the improvement of society. In order to accomplish this technology transfer, it is usually necessary to create value in the inventions by protecting them through the patent and copyright process. This provides the potential for temporary monopoly needed to lower the risk associated with technology development and to attract the necessary investment. We will present how this is accomplished at Virginia Tech, beginning with creating a proper record of invention with Virginia Tech Intellectual Properties (VTIP), working with us and the attorneys to secure the patents, and finally in working with VTIP to market the inventions.