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GPFSeminars 2024

Seminars for the year:     2024     2023     2022     2021     2020     2019     2018     2017     2016     2015     2014     2013     2012     2011     2010     2009     2008     2007
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Time:   15. March 2024, 11:00h
Place:   Institute of Physics, room 360
Speaker:   Petar Petrasinovic
Title:   Moore-Penrose inverse of matrix and its application to solving general linear systems
Abstract:
In linear algebra, the Moore-Penrose inverse stands as a generalization of the conventional matrix inverse, having been independently introduced by E.H. Moore in 1920 and later by Roger Penrose in 1955. The Moore-Penrose inverse is uniquely defined for all matrices whose entries are either real or complex numbers and extends its applicability to rectangular and even singular matrices. The versatility and uniqueness of the Moore-Penrose inverse are the major reasons for its significance (and discovery), which is reflected in solving general linear systems of equations, or tensor systems which can be reshaped into matrix form. In this seminar, I will discuss the properties of the Moore-Penrose inverse, display some of the calculation methods, and demonstrate its practical applications.

Time:   23. February 2024, 11:00h
Place:   Institute of Physics, room 360
Speaker:   Mihailo Cubrovic
Title:   Chaos and factorization beyond classical horizons
Abstract:
Chaotic dynamics of black holes has proven to be of vital importance for the understanding of the black hole information problem. Within the replica formalism, a related issue is that of nonfactorization of partition functions of wormhole geometries. We consider these questions deep in the stringy regime, described by the BFSS and IKKT matrix models, where the notions of geometry and horizon do not apply anymore. Generic solutions factorize when averaged over the quantum fluctuations, whereas the chaotic properties are non-universal. We argue that the correct notion that characterizes the black hole scrambling is instead that of quantum magic (stabilizer Renyi entropy), which guarantees that the dynamics is complex enough to accommodate the total information on infalling matter.

Time:   2. February 2024, 11:00h
Place:   Institute of Physics, room 360
Speaker:   Dusan Djordjevic
Title:   Massless minimally coupled scalar field in dS spacetime
Abstract:
In this talk, we will review the quantisation of scalar fields in de-Sitter spacetime. We will discuss the differences between the case of minimally coupled massive and minimally coupled massless scalar fields, as well as the possibility of obtaining, in the massless case, a vacuum state that is invariant under the full SO(4,1) group. The talk will be based on the following papers:

Klaus Kirsten, Jaume Garriga, arXiv:gr-qc/9305013
Andrew Tolley, Neil Turok, arXiv:hep-th/0108119

Seminars for the year:     2024     2023     2022     2021     2020     2019     2018     2017     2016     2015     2014     2013     2012     2011     2010     2009     2008     2007
Follow our seminars online via:    GPF BigBlueButton server