Search Talks

The initial conditions for structure formation, and hence the dark matter distribution on sub-galactic scales, depend on the microphysics of the dark matter in the early Universe. I will focus on WIMPs and explain how collisional damping and free-streaming erase perturbations on comoving scales k> ~1/pc. Consequently the first structures to form in the Universe are mini-halos with mass of order the Earth. I will then describe the status of calculations of the subsequent dynamical evolution of these mini-halos. Finally, if time permits, I'll briefly overview the microphysics of axions.

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

Boundary conformal field theory finds applications not only to high energy physics but also to condensed matter systems containing quantum impurities, whose world lines can sometimes be modelled as boundaries of 2-dimensional space-time. This technique leads to exact predictions for the low temperature behaviour of gated semi-conductor quantum dot devices which have been recently confirmed experimentally. I will give a non-technical overview of both the theory and the experiments.

If low-scale supersymmetry exists in nature, then it it will be very likely that a number of superpartners will be discovered at the LHC. It is also very likely, however, that much of the supersymmetric spectrum will go unobserved, leaving many important holes in our understanding of the TeV scale. Direct and indirect astrophysical probes of neutralino dark matter can enable for some of these holes to be filled. By studying the interactions of the lightest neutralino, in many models, a much more complete understanding of supersymmetry can be achieved than is possible by using hadron colliders alone.

We discuss motivations, observational constraints and consequences of modifying the fundamental laws of gravity at large distances. Such modifications of gravity can be the reason for the observed late-time acceleration of the Universe, and can be differentiated from conventional dark energy via precision cosmology. The inevitable additional polarizations of graviton lead to observably large perihelion precession of the Lunar and Martian orbits. These theories also have potentially observable consequences at LHC .

I will discuss various different ways of quantifying the differences between two quantum observables (POVMs). Each of these approaches gives rise to a notion of approximately measuring one observable by means of measuring some other observable. This will be illustrated in the case of position and momentum by studying the question which POVMs on phase space can reasonably be said to represent a joint approximate determination of these observables. A new, universally valid trade-off relation for the associated inaccuracies will be rigorously formulated. I will sketch the proof which is an adaptation of some interesting techniques and properties of covariant phase space observables used recently by R Werner in a related project. Recommended reading (optional): quant-ph/0405184 (R Werner), quant-ph/0609185 (PB et al), and also for further background information quant-ph/0309091 (M Hall), quant-ph/0310070 (M Ozawa), quant-ph/9803051 (DM Appleby).