# The Mathematics and Physics Friday Colloquium

The lecture series is aimed at a broad audience, including students as well as faculty, with background in mathematics or physics. All interested are welcome! To suggest a talk, contact:

Martin G. Gulbrandsen.

Spacetime coordinates: Fridays at 14:15 (usually 45-60 mins), room E541.

**Quick link to this page: http://fymat.ux.uis.no/**
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Talks from past terms
## Programme for spring term 2016

Friday April 8:

**Eivind Dahl**
Title:

**The set of ring spectrum maps from \Sigma^\infty B^3\Z_+ to K_2**
Abstract:

*We briefly introduce the relevant Morava K-theory computations of the K_2 homology of B^3\Z=K(\Z,3) following Ravenel-Wilson. We then compute the set of all ring spectrum maps from* *\Sigma^\infty B^3\Z_+ to K_2 as the set of group-like elements in K_2^0B^3\Z. This computation is a stepping-stone in a program to produce a ring spectrum map from K(ku) to Lubin-Tate theory E_2.*
Friday May 13:

** Ray Rivers (Blackett Laboratory, Imperial)**

Title:

**Analogue Gravity: Metric fluctuations in ultracold Fermi gases.**
Abstract:

*The Analogue Gravity programme of Unruh, Visser, Liberati et al. invokes the statement by Feynman that ‘the same equations have the same solutions’ to look for parallels between cosmology/gravity and condensed matter physics. A part of the programme with which I have been involved uses the observation that tuning the sound-cone of ultracold gases by the application of an external magnetic field has parallels with the evolution of the space-time metric in FRW universes, to which I shall refer [1]. However, this analysis is semi-classical, of quantum fields in a classical metric. Our recent work [2] concerns the quantum fluctuations of the sound-cone metric itself. Whereas the quantum fluctuations of the gravitational metric i.e. of space-time itself, are unimaginably small (and even then incalculable), the quantum fluctuations of the sound-cone are calculable and are close to being measurable in time of flight experiments.**[1] The role of Causality in Tunable Fermi Gas Condensates**Jen-Tsung Hsiang, Chi-Yong Lin, Da-Shin Lee, Ray J. Rivers**J. Phys.: Condens. Matter 25 (2013) 404211**[2] Quantum stochastic behaviour in cold Fermi gases: Phonon propagation**En-Tsung Hsiang, Da-Shin Lee, Chi-Yong Lin, Ray J. Rivers**Phys. Rev. A 91, 051603 (2015)*