[Triumf-seminars] TRIUMF Seminar today at 14:00

[postmaster@admin.triumf.ca]

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Date/Time: Mon 2004-10-04 at 14:00

Location:  Auditorium          

Speaker:   Gregory Volovik (Landau Institute for Theoretical Physics, Russia)

Title:     Emergent physics: a condensed-matter primer

Abstract: Why is the cosmological constant  so small? Do the properties of vacuum at transplanckian scales influence the quantum radiation of black holes predicted by Hawking? In my talk I shall try to demonstrate that studying special condensed-matter systems may help to solve these fundamental problems. The phenomenon of emergent physical laws, which is manifested in most of the
condensed-matter systems, is becoming the paradigm of the modern physics. We hope that this phenomenon can be also applicable to the high energy physics and gravity. The encouraging fact comes from universal properties of the ground states of quantum liquids, which play the role of the quantum vacua in particle physics. The role of matter in the these systems is played by the fermion zero modes and by the bosonic collective modes of the liquid. There are only two basic universality classes of quantum vacua. The more common class contains the vacua whose fermionic excitations are characterized by the Fermi surface. Fermionic excitations in the vacua belonging to the other class are characterized by Fermi points -- points in momentum space where the energy of excitation is zero. Near the Fermi points, excitations behave as relativistic massless Weyl fermions, while the bosonic collective modes interacting with them simulate the gauge and gravitational fields. In this universality class the gauge fields, chiral fermions, Lorentz invariance, gravity, relativistic spin, and other features of the Standard Model gradually emerge at low energy. The condensed-matter experience provides us with some criteria for selection of the particle physics theories and theories of gravity, allows us to test the theories experimentally and even to suggest specific solutions to different fundamental problems. In particular, one can explicitly demonstrate how the main cosmological problem is solved in the quantum liquids: one finds that the huge contribution of the zero point energy of quantum fields to the vacuum energy density is cancelled without any fine tuning by the microscopic degrees of freedom above the  Planck cut-off . Among the other quantum field phenomena, the analog of the chiral anomaly was experimentally confirmed, and we also found unexpected influence of the event horizon on the quantum vacuum. Detailed discussion of these issues can be found in my book "The Universe in a Helium Droplet", Clarendon Press, Oxford (2003).

Stimulants available 15 minutes before the talk.

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