Public Lectures

Sixty-five million years ago dinosaurs ruled the warm Cretaceous Earth. Without warning, this world was swept away forever by the impact of an asteroid about 15 km in diameter, leaving a huge scar now called the Chicxulub crater in Yucatan, Mexico. This catastrophe set the stage for the ascendance of our own biological group, the mammals. Although the fact of this impact is now established beyond doubt, the precise means by which an impact could wipe out such a large fraction of the Earth\'s inhabitants is not fully understood. Recent study of the physical consequences of a large impact on the Earth have revealed a plethora of potentially disastrous effects, ranging from an immediate firestorm that ignited global wildfires to sulfuric acid aerosols, acid rain, and ozone depletion lasting decades. The extinctions caused by these physical traumas changed the way that the Earth\'s biosphere recycles carbon, leading to climatic changes lasting nearly a million years longer. Although no other major extinction in the past 500 million years can yet be tied unambiguously to an extraterrestrial impact, there is geological evidence of even larger impacts farther back in Earth\'s history, including the one that created the Sudbury ore body in Ontario more than a billion years ago. Concerns over the future possibility of such large impacts have led to a worldwide program to identify potentially threatening asteroids and has generated discussion of what humans might do to deflect such an asteroid if it is found. death of dinosaurs, mass extinction, extinction, dinosaurs, asteroid impact, asteroid impact effects, Jay Melosh, Cretaceous period, Chicxulub crater, 65 million years ago, large impacts, dinosaur, giant impacts, Walter Alverez, thin layer of red clay, Jan Smit, KT boundary, iridium layer, spherules, microtektites, geology, Geologic history, distal ejecta, Apophis, large extraterrestrial bodies, plate tectonics, Cretaceous-Tertiary Boundary, twinning, Yucatan, Gulf of Mexico, fern, shocked quartz, soot, ozone depletion, acid rain, two-layer, thermal radiation, depletion of CO2

Sensitive information can be valuable to others - from your personal credit card numbers to state and military secrets. Throughout history, sophisticated codes have been developed in an attempt to keep important data from prying eyes. But now, new technologies are emerging based on the surprising laws of quantum physics that govern the atomic scale. These powerful techniques threaten to crack some secret codes in widespread use today and, at the same time, offer new quantum cryptographic protocols which could one day profoundly alter the way we safeguard critical information. Quantum cryptography, quantum physics, Daniel Gottesman, cryptography, one-time pad, RSA, encryption, public key, decryption, private key, quantum computer, qubit, shor\'s algorithm, quantum key distribution, QKD

Hollywood movies about aliens abound, but do they really exist? The real scientific search for evidence of life, and particularly intelligent life, elsewhere in the cosmos is just as exciting as the “reel” version, and a lot more logical. So far, there is ‘life-as-we-know-it’ to guide our speculations and observations. But a new appreciation for the tenacity of life, a growing respect for the world of microbes, and new search technologies involving observatories and spacecraft are rapidly expanding our viewpoint. Many expect surprises. SETI is at the forefront of this research and has plans to extend its range out even further into the galaxy, looking for evidence of someone else’s technology. In the next few decades, scientists will take a much closer look at places within our solar system where liquid water (even vast oceans) may exist and harbor life. They will also probe the closest stars to see if other ‘Earths’ and biospheres exist. Dr. Jill Tarter will describe research in a discipline some call “the archaeology of the future”. Jill Tarter, extraterrestrial intelligence, SETI, \'archaeology of the future\', stardust, microbes, extreme life conditions, astrobiology, Kepler probe, Corot probe

Will big questions be answered when the Large Hadron Collider (LHC) switches on in 2007? What will scientists find? Where might the research lead? Nima Arkani-Hamed, a noted particle theorist, is a Professor of Physics at Harvard University. He investigates a number of mysteries and interactions in nature – puzzles that are likely to have experimental consequences in the next few years via particle accelerators, like the LHC, as well as cosmological observations. fundamental physics, Nima Arkani-Hamed, \'Future of Fundamental Physics\', general relativity, quantum mechanics, Large Hadrom Collider, L H C, quark, quantum gravity, string theory, special relativity, standard model, Planck scale, space-time, vacuum, Higgs boson, super symmetry

Using results from models of the atmosphere/ocean/sediment carbon cycle, the impacts of fossil-fuel CO2 release will be examined – including the effect on climate many thousands of years into the future, rather than for just a few centuries as commonly claimed. Prof. Archer will explain how aspects of the Earth system, such as the growth or melting of the great ice sheets, the thawing of permafrost, and the release of methane from the methane hydrate deposits in the deep ocean, take thousands of years to respond to a change in climate. The duration of our potential climate adventure is comparable to the pacing of climate changes in the past, which enables us to use the geologic record of past climate changes to predict the trajectory of global warming into the deep future. In particular, the record of sea level variations in the past suggests that the ultimate sea level response to fossil fuel CO2 use could be 10 to 100 times higher than the Intergovernmental Panel on Climate Change (IPCC) forecast for the year 2100. models, greenhouse gas, temperature forecast, medieval warm, little ice age, Greenland, Heinrich Events, fossil fuel, Climber Model Hysteresis, Ganopolski, Buffett, methane hydrates, Palaeocene, Eocene, Thermal Maximum Event

Newton\'s first law of motion - and the very meaning of inertia - has been described as either completely obvious (D\'Alembert) or a \'logician\'s nightmare\' (ex-editor of the American Journal of Physics). Sometimes the simplest things in physics are the most subtle. The first law will be described in historical context, explaining a connection with the ancient Greeks’ distinction between natural and violent motion and with Descartes\' natural philosophy. You will also learn why it still requires careful handling and what it tells us about time in physics. \'Time and Motion\', Harvey Brown, time, motion, relative, Copernicus, Ptolemy, Galileo, Copernicanism, Descartes, inertia, Newton, standard of time, Fitzgerald, duration, inertial frame

From Levin’s recent book comes a strange if true story of coded secrets, psychotic delusions, mathematics, and war. This story of greatness and weakness, of genius and delusion, circulates around the parallel lives of Kurt Gödel, the greatest logician of many centuries, and Alan Turing, the extraordinary code breaker during World War II. Taken together their work proved that there are limits to knowledge, that machines could be taught to compute, that one day there could be artificial intelligence. Yet Gödel believed in transmigration of the soul and Turing concluded that we were soulless biological machines. And their suicides were complementary. Gödel, delusional and paranoid, starved himself to death fearing his food was poisoned. Turing ate a poison apple, driven to suicide after being arrested and convicted of homosexual activities. These two men were devoted to truth of the highest abstract nature, yet were unable to grasp the mundane truths of their own lives. Through it all, you will explore, along with these two odd heroes, if any of us can ever really grasp the truth. Madman Dreams, Turing Machines, Turing, Truth, Godel, Mathematical Theory of Everything, Liar\'s Paradox, Turing machine, limits, mathematical truth

This is a story of how the impossible became possible. How, for centuries, scientists were absolutely sure that solids (as well as decorative patterns like tiling and quilts) could only have certain symmetries - such as square, hexagonal and triangular - and that most symmetries, including five-fold symmetry in the plane and icosahedral symmetry in three dimensions (the symmetry of a soccer ball), were strictly forbidden. Then, about twenty years ago, a new kind of pattern, known as a \'quasicrystal,\' was envisaged that shatters the symmetry restrictions and allows for an infinite number of new patterns and structures that had never been seen before, suggesting a whole new class of materials. By chance, solids with five-fold symmetry were discovered in the laboratory at about the same time. Even so, for nearly twenty years, many scientists continued to believe true quasicrystals were impossible because, they argued, such a pattern could only be formed with complex and physically unrealistic inter-atomic forces. In this talk, you will see simple, beautiful patterns and a series of geometrical toys and games that demonstrate, with subtlety and surprise, how this last conceptual barrier has been recently overcome - leading to new insights on how to grow perfect quasicrystals and inspire new technological applications. About the Speaker: Paul J. Steinhardt is the Albert Einstein Professor in Science at Princeton University and is on the faculty in the Department of Physics and in the Department of Astrophysical Sciences. He received his B.S. in Physics at Caltech in 1974; his M.A. in Physics in 1975 and Ph.D. in Physics in 1978 at Harvard University. He was a Junior Fellow in the Harvard Society of Fellows from 1978-81 and on the faculty of the Department of Physics and Astronomy at the University of Pennsylvania from 1981-98, where he was Mary Amanda Wood Professor from 1989-98. He is a Fellow in the American Physical Society and a member of the National Academy of Sciences. In 2002, he received the P.A.M. Dirac Medal from the International Centre for Theoretical Physics. Steinhardt is a theorist whose research spans problems in particle physics, astrophysics, cosmology and condensed matter physics. He is one of the architects of the .inflationary model. of the universe, an important modification of the standard big bang picture which explains the homogeneity and geometry of the universe and the origin of the fluctuations that seeded the formation of galaxies and large-scale structure. He introduced the concepts of .quintessence,. a dynamical form of dark energy that may account for the recently discovered cosmic acceleration. He has also explored novel models for dark matter. Recently, Steinhardt and Neil Turok (Cambridge U.) proposed the .cyclic model. of the early universe, a radical alternative to big bang/inflationary cosmology in which the evolution of the universe is periodic and the key events shaping the large scale structure of the universe occur before the big bang. In condensed matter physics, Steinhardt and Dov Levine (Technion) introduced the concept of quasicrystals, a new phase of solid matter with disallowed crystallographic symmetries. Steinhardt continues to make contributions to understanding their unique mathematical and physical properties. He has written over 200 papers, edited 4 books, and holds three U.S. patents. Impossible Crystals, Paul Steinhardt, symmetry, crystal, three-fold symmetry axis, five-fold symmetry axis, two-fold symmetry axis, quasicrystals, rotational symmetry, Penrose, Penrose Tiler, Gummell-Tile, quasi-unit-cell, non-local iterations, period array, platonic crystal

The laws of physics are usually meant to be set in stone; variability is not usually part of physics. Yet contradicting Einstein\'s tenet of the constancy of the speed of light raises nothing less than that possibility. I will discuss some of the more dramatic implications of a varying speed of light. João Magueijo is Professor of Physics at Imperial College London. He is currently visiting Perimeter Institute and the Canadian Institute for Theoretical Astrophysics in Toronto. He received his doctorate in theoretical physics at Cambridge University, and has been a visiting scientist at the University of California at Berkeley and Princeton University. Joao Magueijo, Theory of Relativity, speed of light, VSL, varying speed of light, Dirac, cosmology, geometry, dimensional, dimensionless, Bekenstein, Brans-Dicke, varying constant, Einstein, time dilation, length contraction, horizons, Big Bang, grand-unified theory, Planck length, Planck time, gravity, space, time, quantum gravity, varying alpha, Kelvin, quasar, laws of physics

Long before the emergence of planets, stars, or galaxies, the universe consisted of an exploding quantum soup of “elementary” particles. Encoded in this formless, shapeless soup were seeds of cosmic structure, which over billions of years grew into the beautiful and complex universe we observe today. The lecture will explore the connection between the “inner space” of the quantum and the “outer space” of the cosmos. The inner space/outer space connection may hold the key to the nature of the dark matter holding together our galaxy and the mysterious dark energy pulling apart our universe. Edward W. Kolb (known to most as Rocky) is a founding head of the NASA/Fermilab Astrophysics Group at Fermi National Accelerator Laboratory and a Professor of Astronomy and Astrophysics at The University of Chicago. Presently he is the Director of the Particle Astrophysics Center at Fermilab. A native of New Orleans, he received his Ph.D. in physics from the University of Texas. Postdoctoral research was performed at the California Institute of Technology and Los Alamos National Laboratory where he was the J. Robert Oppenheimer Research Fellow. He has served on editorial boards of several international scientific journals as well as Astronomy magazine. In addition to over 200 scientific papers, he is a co-author of The Early Universe, the standard textbook on particle physics and cosmology. His book for the general event, Blind Watchers of the Sky, received the 1996 Emme Award of the American Aeronautical Society. Rocky teaches cosmology to non-science majors at the University of Chicago and is involved with pre-college education enrichment programs. He has traveled the world, if not yet the Universe, giving scientific and event lectures. He has appeared in several television productions, and can also be seen in the OMNIMAX/IMAX film The Cosmic Voyage. His distinctions include: Fellow of the American Academy of Arts and Sciences, Fellow of the American Physical Society, recipient of the 2003 Oersted Medal of the American Association of Physics Teachers, winner of the 1993 Quantrell Prize for teaching excellence at the University of Chicago, Harlow Shapley Visiting Lecturer and Centennial Lecturer with the American Astronomical Society. He has also presented event lectures at the Royal Society of London, and in Rio de Janeiro, Valencia, and Barcelona. cosmos, quantum, cosmology, universe, galaxies collide, Barnes, Hibbard, Newton, Einstein, relativity, space, time, origin of the universe, dark energy, expansion history, vacuum quantum, Vera Rubin, invisible universe, dark matter, quantum universe, Higgs potential, Big Bang Theory, Hubble, WIMPS, cosmic background radiation