Physics Colloquia Archives

Fall 2007

September 6, 2007
BARRY BARISH
Caltech

"The Next Great Particle Accelerator:  The International Linear Collider"

There is a consensus among the worldwide high energy physics community that a TeV scale linear electron positron collider should be the highest priority long term goal for the field.  This next great particle accelerator, together with the Large Hadron Collider (LHC) at CERN, will enable a comprehensive exploration of the TeV energy scale where many of the new phenomena we seek, like supersymmetry or possibly even extra dimensions could reveal themselves.  The international community has chosen the superconducting RF technology to be the basis of the international linear collider final design, in anticipation of a construction project to begin in about 2012.  A global design effort has been created to guide the R&D and technical design toward construction of the ILC.   In this presentation, I will discuss the science motivation, the technology, and will review recent progress and plans toward this exciting future international facility.

September 13, 2007
GABRIELLA SCIOLLA
MIT

"Beauty in the Mirror: Looking for New Physics in CP Violation"

When CP violation was first discovered in 1964, it came completely unexpected, and its theoretical interpretation was unclear. Could this phenomenon be explained by the Standard Model of Particle Physics, or was it the first sign of New Physics? The experimental investigation of CP violation has taken a major turn since the B factories started taking data in 1999. The abundant dataset accumulated at these machines allowed the first quantitative test of CP violation in the Standard Model. Recently, the B factories entered a new phase of precision CP measurements, in which they have the potential to uncover effects of New Physics beyond the Standard Model. After an introduction to the CP symmetry and its consequences, how measurements of CP violation in B decays are sensitive to New Physics will be discussed, the latest results reviewed, and implications discussed.

September 20, 2007
SHAMIT KACHRU
Stanford University

"Naturalness" in Field Theory, String Theory and Nature

Several of the greatest mysteries in fundamental physics center on large hierarchies of scales.  These include central problems in particle physics (like the electroweak hierarchy problem) and in cosmology (like the cosmological constant problem, and the puzzle of why the geometry of our universe is so homogeneous, isotropic, and flat). I describe some models in quantum field theory and string theory which may explain these puzzles, and which will be tested in the near future with the LHC and Planck satellite.  These models are motivated by clashing notions of “naturalness” in theoretical physics, and near term experiments may confirm or overthrow some of these notions.

September 27, 2007
DAN KLEPPNER
MIT

"Michelson and the development of modern physics"

The astonishing predictive power of physics rests largely on physicists'
ability to verify theory to high precision. We owe the modern concept of high precision measurements to Albert A. Michelson (1852-1931). Although Michelson is best known for the Michelson-Morley experiment, which he regarded ever as a failure, he deserves recognition for revolutionizing metrology and spectroscopy, creating the first atomic physical standard, providing the first confirmation of Maxwell's kinetic theory, discovering the fine structure of hydrogen, and making seminal contributions to astronomy and astrophysics. As a young man with only cursory undergraduate training and no research experience, he measured the speed of light ten times more accurately than the best value from Europe. He was working on a new speed of light measurement on the day he died.

October 4, 2007
STEVE CHU
Lawrence Berkeley National Lab

"The Energy Problem and What We Can Do About It"

Among America's and the World’s most serious concerns are national security, which is tied to energy security, economic prosperity, and the risk of dire climate change. At the core of these problems is need for sustainable creation and consumption of energy. Incentives that accelerate the simultaneous invention, development and deployment of innovative solutions can transform the entire landscape of energy demand and supply. This transformation will make it possible, both technically and economically, to elevate the living conditions of most of humanity to the level now enjoyed by a large middle class in developed countries. After briefly describing aspects of the energy problem, the remainder of the talk will describe some areas of research that may lead to transformative technologies in the next 10 years.

October 11, 2007
DIMITRIOS PSALTIS
University of Arizona

“Testing Strong-Field Gravity with Neutron Stars and Black Holes”

October 18, 2007
ERIK KATSAVOUNIDIS
MIT

"Searches for gravitational waves with LIGO"

October 25, 2007
YOUNG LEE
MIT

"The Physics of Frustration in Low-dimensional Spin Systems"

November 1, 2007
Distinguished Pappalardo Lecture
JOHN MATHER

NASA

“From the Big Bang to the Nobel Prize and on to James Webb Space Telescope”

The history of the universe in a nutshell, from the Big Bang to now, and on to the future – John Mather will tell the story of how we got here, how the Universe began with a Big Bang, how it could have produced an Earth where sentient beings can live, and how those beings are discovering their history.  Mather was Project Scientist for NASA’s Cosmic Background Explorer (COBE) satellite, which measured the spectrum (the color) of the heat radiation from the Big Bang, discovered hot and cold spots in that radiation, and hunted for the first objects that formed after the great explosion.  He will explain Einstein’s biggest mistake, show how Edwin Hubble discovered the expansion of the universe, how the COBE mission was built, and how the COBE data support the Big Bang theory.  He will also show NASA’s plans for the next great telescope in space, the James Webb Space Telescope.  It will look even farther back in time than the Hubble Space Telescope, and will look inside the dusty cocoons where stars and planets are being born today. Planned for launch in 2013, it may lead to another Nobel prize for some lucky observer.

November 8, 2007
GREGOR HERTEN
Albert-Ludwigs-Universität Freiburg

"The Start of the Large Hadron Collider (LHC)"

The LHC is expected to provide proton – proton collisions at a center-of-mass energy of 14 TeV.  The construction of the accelerator and of the large particle detectors is nearly completed. Presently, the components are in the commissioning phase with the goal to start data taking in the summer of 2008. The status of the LHC and the experiments will be reviewed. Expectations are high that the LHC might be able to discover the Higgs boson, supersymmetric particles, extra space dimensions or other spectacular new physics. Estimates for achievable early physics results for 2008/2009 will be given as well as longer term perspectives.

November 15, 2007
CHARLES FALCO
University of Arizona

"The Science of Optics; The History of Art"

Recently, renowned artist David Hockney observed that certain drawings and paintings from as early as the Renaissance seemed almost "photographic" in detail.  Following an extensive visual investigation of western art of the past 1000 years, he made the revolutionary claim that artists even of the prominence of van Eyck and Bellini must have used optical aids.  However, many art historians insisted there was no supporting evidence for such a remarkable assertion.  In this talk Falco shows a wealth of optical evidence for his claim that Hockney and Falco subsequently discovered during an unusual, and remarkably productive, collaboration between an artist and a scientist.  Falco also discuss the imaging properties of the "mirror lens" (concave mirror), and some of the implications this work has for the history of science as well as the history of art (and the modern fields of machine vision and computerized image analysis).  These discoveries convincingly demonstrate optical instruments were in use -- by artists, not scientists -- nearly 200 years earlier than commonly thought possible, and account for the remarkable transformation in the reality of portraits that occurred early in the 15th century.

November 29, 2007
Distinguished David and Edith Harris Lecture
TED HAENSCH

Ludwig-Maximilians-Universität München

"What can we do with optical frequency combs?"

Optical frequency combs from mode-locked femtosecond lasers have revolutionized precise measurements of frequeny and time. They provide the clockwork for ultraprecise optical atomic clocks, and they enable new tests of fundamental physics laws. Optical high harmonic generation can extend frequency comb techniques into the extreme ultraviolet, opening a vast new spectral territory to precision laser spectroscopy. Applications of broadband optical frequency combs are expanding rapidly to new fields, from telecommunications and astronomy to sensitive molecular fingerprinting in biomedicine. Frequency comb techniques are also providing a key to attosecond science by offering control of the electric field of ultrafast laser pulses.

December 6, 2007
SERGE HAROCHE
Ecole Normale Supérieure and Collège de France

"Trapping and counting photons without destroying them: a new way to look at light"

Detecting photons is essential to many data acquisition and communication procedures. Usual photo-detectors can count them one by one, but they do it by brute force, the light being absorbed in the process. Like the marathon soldier, photons seem condemned to die upon delivering their message. This fate, though, is not imposed by quantum theory, which tells us that transparent detectors registering photons without destroying them are possible. We have demonstrated such a procedure and realized for the first time a non-demolition photo-detection at the quantum level. A microwave field is stored between two highly reflecting mirrors for time intervals reaching half a second. A stream of excited atoms behaving as microscopic clocks whose ticking rate is affected by light pass, one at a time, between the mirrors. By measuring the clocks' delay, we extract information from the field without energy absorption and the light progressively collapses into a state of well-defined photon number. Residual absorption or emission by the mirrors results in quantum jumps, recorded as sudden and random changes of the photon number. This new way to "look" at light also prepares coherent superpositions of field states with different phases or amplitudes known as “Schrödinger cats”. Their study opens new avenues for the exploration of the boundary between the quantum and classical worlds.

December 13, 2007
MICHAEL CAMPBELL

"The Role of High Temperature Gas Reactors in the Global Expansion of Nuclear Power"