2010 Winter Physics Colloquia

Multimessenger astronomy, including gravitational waves, shall continue to be a fruitful path towards deciphering otherwise hidden aspects of the high-energy transient universe. Gamma-ray, X-ray, optical, radio and neutrino observations of cataclysmic cosmic events are often associated with plausible gravitational wave emission. Beyond strengthening our ability to discover gravitational waves, multimessenger observations can enhance the value of our results. They can enable us to draw conclusions that we would not be able to do with gravitational waves alone. I will review results of past multimessenger searches, interpret their astrophysical consequences, and present an outlook on the future of gravitational wave astrophysics.

The public (as well as students) are generally fascinated by magic. Like others, I have exploited this by incorporating stage magic, illusions and other effects into my physics lectures, a summer H.S. science camp, as well as public lectures. However, unlike others who often use magic unrelated to any physics per se, I have incorporated (or developed) magic that has a direct relevance to a specific physics topic and the the "magic" of Nature revealed in physics research: Penetration effects: quantum-mechanical tunneling and radioactive decay,the age of the Earth and evolution. Mentalism and predictions: the relevancy of time (relativity) and the possibility of time travel (or not). Vanishing effects: matter-anti-matter and the Big Bang. Math-based magic: the quark model, etc. Several of the above will be demonstrated.

This talk has two related themes reflecting the interests of the speaker. In the first part we will explain why the top quark -- the heaviest of all known elementary particles -- will play a crucial role at the LHC experiments, providing both a commissioning of the detectors and a natural bridge between Standard Model physics and what may lie Beyond it. We will survey ATLAS' strategy for measuring the rate of production of top quarks with the early 2010 LHC collision data, with particular emphasis on the measurement of backgrounds from data, as opposed to Monte Carlo simulations. In the second part we describe some of the substantial progress made in recent years at the interface between M theory, particle physics and cosmology. These developments derive from the consideration of M theory ground states in which the seven extra dimensions form a manifold whose local symmetry is the exceptional Lie group G2. The ubiquitous top quarks play an important role in the experimental signatures for such models at the LHC. The level of exposition throughout will be non-technical, emphasising ideas and results.

Professor Assanis will give an overview of ongoing research at the Michigan Memorial Phoenix Energy Institute and discuss in detail his own recent research. He will describe his research activities aimed at significantly improving efficiency of future powertrains while satisfying ever more stringent toxic and greenhouse gas emission standards. Among the concepts presented, Homogeneous Charge Compression Ignition (HCCI) is a highly promising, low temperature combustion process that constitutes a paradigm shift from the traditional, high temperature, pollutant forming engine combustion. HCCI offers the potential for virtually eliminating engine-out NOx and particulate emissions, while achieving 15%-20% higher thermal efficiency. His group.s efforts have shed light into the complex thermo-kinetic factors that control the auto-ignition process and govern its high load limits, due to knock and NOx constraints, and its low load limits resulting from ignition failure and excessive unburned HC and CO emissions. Current efforts focus on novel approaches to control and extend the operating range of HCCI, its operability with a diverse range of fuels including biofuels, and its synergy with hybrids.

Soon, the Large Hadron Collider at CERN will advance the experimental frontier of particle physics to the heart of the Fermi scale, reaching energies around one trillion electron volts for collisions among the basic constituents of matter. We do not know what the new wave of exploration will find, but the discoveries we make and the new puzzles we encounter are certain to change the face of particle physics and echo through neighboring sciences.

In this new world, we confidently expect to learn what sets electromagnetism apart from the weak interactions, with profound implications for our conception of the everyday world. We will gain a new understanding of simple and profound questions: Why are there atoms? Why chemistry? What makes stable structures possible? A pivotal step will be finding the Higgs boson and exploring its properties. But there may be much more: we have hints of other new phenomena, including some that may clarify why gravity is so much weaker than the other fundamental forces. We also have reason to believe that candidates for the dark matter of the Universe could be lurking on the Fermi scale.

Beyond the Fermi scale lies the prospect of other new insights: into the different forms of matter, the unity of quarks and leptons, and the nature of space-time. The questions in play all seem linked to one another-and to the relationship of the weak and electromagnetic interactions. Where will the revolutions end?

The Cosmic Microwave Background Radiation is our most important source of information about the early universe. Many of its features are in good agreement with the predictions of the so-called standard model of cosmology -- the Lambda Cold Dark Matter Inflationary Big Bang. However, the large-angle correlations in the microwave background exhibit several statistically significant anomalies compared to the predictions of the standard model. On the one hand, the lowest multipoles seem to be correlated not just with each other but with the geometry of the solar system. On the other hand, when we look at the part of the sky that we most trust - the part outside the galactic plane, there is a dramatic lack of large angle correlations. So much so that no choice of angular powerspectrum can explain it if the alms are Gaussian random statistically isotropic variables of zero mean.

The quantum confinement provided by a semiconductor quantum dot suppresses much of the many body physics associated with the coherent nonlinear optical response observed in higher dimensional systems. This makes them attractive for potential device applications where atomic like properties, such as high Q resonances, strong optical interactions, or long quantum coherence times, could be important. In this talk, we present recent results demonstrating high field effects beyond Rabi oscillations including the Mollow absorption spectrum showing gain without inversion, dark state formation in single electron doped dots, suppression of nuclear fluctuations by the hyperfine interaction leading to longer electron spin coherence times and coherent spin rotations including a geometrical phase gate.

Emission reconstruction tomography (SPECT, PET) is a scanning method that produces accurate cross sectional images of radioactive tracers after they have been targeted to detect and quantify key neurochemical and metabolic processes within living patients.

Origins of this kind of molecular imaging emerged in the early 1960s, when the time for a beginning was right. Technical advances in digital computers, detectors, radioactive tracers and increases in research funding coincided. Together, these would enable the first proofs-of-principle for emission reconstruction tomography. Further progress depended strongly upon complex multidisciplinary efforts integrating medical science, physics, chemistry and engineering in full partnership.

Molecular imaging with emission tomography is now an essential part of the care of patients with cancer, heart and brain disorders. Research emphasizes earlier diagnosis and linkage to drug development. From brain research, there is increasing appreciation that new pharmacological classifications of patient groups (e.g., spatial patterns of metabolism, neurotransmitters, enzymes, proteinaceous accumulations) may redefine long-established clinical classifications and thus lead to earlier diagnosis and new treatments. Cancer research, hand-in-hand with drug development, gives hope that the targeting of new drugs may be matched to specific features of an individual's tumor ( e.g., proliferation, receptors, angiogenesis, hypoxia) and support personalized treatment that is more effective. Real benefits to patients will continue to be driven by these kinds of long-term research.

The Intergovernmental Panel on Climate Change (IPCC), an entity of the United Nations Environmental Programme and the World Meteorological Organization, published its Fourth Assessment Report on climate change in early 2007. Later that year the IPCC shared the Nobel Peace Prize with Al Gore. But along with the accolades, the IPCC has long been the target of criticism from a relatively few but very vocal deniers of climate change. This opposition has been voiced largely (but not entirely) outside of the regular scientific venues, principally in the mass media, in state legislatures, the halls of Congress, and in parliaments around the world. This Colloquium will review and evaluate the principal scientific issues, and assess the impact that this opposition has had on the underlying climate science and the parallel development of climate mitigation policy, both within the USA and in the wider international arena.

How do we know the distances from the earth to the sun and moon, from the sun to the other planets, and from the sun to other stars and distant galaxies? Clearly we cannot measure these directly. Nevertheless there are many indirect methods of measurement, combined with basic high-school mathematics, which can allow one to get quite convincing and accurate results without the need for advanced technology (for instance, even the ancient Greeks could compute the distances from the earth to the sun and moon to moderate accuracy). These methods rely on climbing a "cosmic distance ladder", using measurements of nearby distances to then deduce estimates on distances slightly further away; we shall discuss several of the rungs in this ladder in this talk.

Abstract pending.

The last decade has seen extraordinary progress in our knowledge of the structure and evolution of the Universe. Many detailed predictions of the basic Big Bang picture have been confirmed, but big puzzles remain. What are the dark matter and the dark energy? Why is the latter so tiny, and yet not zero. And what caused the Bang? Was it the beginning, or was there a time before it? Remarkably, these questions are becoming ripe for scientific inquiry. New approaches to quantum gravity - based on string and M-theory - allow us to study theoretically regimes where Einstein's classical theory fails. And observations only now becoming feasible may be able to conclusively discriminate between the single-bang, inflationary picture and alternate, non-inflationary, cyclical scenarios. Questions previously thought to be firmly in the realm of philosophy or theology are steadily becoming a part of normal science.

The proton is a puzzling creation made of quarks and gluons. The HERMES experiment in Hamburg, Germany and others in recent years have focused on a particular quandary: ``the Spin Puzzle''. It is now well known that the spins of the quarks account for very little of the proton's total angular momentum ... so where is the rest? The most mysterious and least accessible source is L: orbital angular momentum. L is a familiar friend in the study of bound systems such as the atom and the nucleus, but not so for the proton. Are the quarks in the proton in an s-shell like the electrons of the hydrogen ground state ... or is that even a valid question in the strange world of relativistic quantum mechanics? New data from HERMES will be presented that show glimpses of quarks in orbital motion, both within the proton and in the process of hadron formation in high-energy collisions. A summary will be presented of the ongoing theoretical efforts to understand these data and to determine how best to measure -- and think about -- L in the land of quarks.

Magnetic fields of many planets and stars are generated by a dynamo process. They often display reversals: the magnetic field flips between two states of opposite polarities. This occurs roughly periodically for the solar magnetic field and randomly in the case of the geodynamo. Both types of reversals have been recently observed in a laboratory experiment (VKS dynamo). After a short review of the observational and experimental results, the dynamics of the magnetic fields generated by these strongly different flows will be understood using low dimensional models for the large scale magnetic modes. The role of broken symmetries and mode couplings in the reversal mechanism will be emphasized.