Search Talks

Mathematical aspects of modern theories of elementary particles and gravitation. Replacing the notion of particles with fundamental abstract fields (magnetic monopoles, vortices and Skyrmions) in an attempt to approach a formulation for quantum gravity.

Applying the lessons learned in quantum information theory to gain a better understanding of quantum mechanics itself. Is quantum theory simply a new type of probability theory? Exploring new directions towards combining quantum theory with gravity.

Applications of quantum theory to cryptography and computation; understanding in more concrete, physical terms what quantum theory is telling us about the nature of reality. Applications of information theory to better understand the quantum “wave function”.

Cosmology and cosmological implications of quantum gravity. Observable effects in cosmology help to identify the limits of general relativity, which could potentially be surpassed by modified theories of gravity and/or quantum gravity.

Implications of high-energy elementary particle physics for physics of the early universe and its evolution (Big Bang, creation of matter, formation of galaxies, etc). And vice-versa: implications of observable cosmological data for fundamental physics.

We present a short review of the local conformal symmetry and its anomalous violation in curved $4d$ space-time. Furthermore we discuss the ambiguities of conformal anomaly and the anomaly-induced effective actions. Despite the conformal symmetry is always broken at quantum level, it is useful for constructing the best known approximations for investigating quantum corrections to the classical action of gravity. These quantum corrections represent an appropriate basis for a number of applications in cosmology and black hole physics.

Spacelike separated classical interventions make us to rethink what is quantum and what is classical. Quantum Lorentz transformations show that identification of subsystems is a tricky business, ditto entropy, entanglement and thermodynamic quantities. Resolution of information loss problem in black hole physics is tied to a construction of a theory of quantized gravity.

Abstract: Efforts to extrapolate non-relativistic (NR) quantum mechanics to a covariant framework encounter well-known problems, implying that an alternate view of quantum states might be more compatible with relativity. This talk will reverse the usual extrapolation, and examine the NR limit of a real, classical scalar field. A complex scalar \psi that obeys the Schrodinger equation naturally falls out of the analysis. One can also replace the usual operator-based measurement theory with classical measurement theory on the scalar field, and examine the NR limit of this as well. In this limit, the local energy density of the field scales as |\psi|^2, adding credibility to this approach. With the added postulate that "all measurements correspond to boundary conditions that extremize the classical action" (see arXiv:0906.5409), additional quantitative comparisons emerge between this \psi and the standard quantum wavefunction. Uncertainty can then be introduced (along with a "collapse" due to Bayesian updating) by simply giving the classical scalar field two components instead of one, leading to an intriguing \psi-epistemic model.