[institut] [Fwd: Odeljenje za matematiku] (fwd)

[Odeljenje za mehaniku]

Postovane koleginice i kolege,
prosledjujemo obavestenje o predavanju na Odeljenju za matematiku.

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Postovane koleginice i kolege,

Predavanje Odeljenja za matematiku ce se odrzati u petak, 28.10.2016., u
Svecanoj Sali SANU, sa pocetkom u 14h.

Srdacan pozdrav,
Marija


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Petak, 28.10.2016. u 14:15, Svecana sala SANU, Kneza Mihaila 35

James Vickers, University of Southampton

GENERALISED FUNCTIONS AND SINGULARITIES OF EINSTEIN'S EQUATIONS

This talk will describe how singularities of Einstein's equations are treated
within the theory of General Relativity. In other field theories,
such as electromagnetism, an important role is played by point charges, line
sources and surface charges. Mathematically such concentrated sources
are described using the classical theory of distributions. However Einstein's
equations are a system of non-linear PDEs so that one cannot use
classical distribution theory. This talk will explain how a non-linear theory
of generalised functions (Colombeau algebras) may be used to describe
important
physical solutions of Einstein's equations such as Cosmic Strings, shells of
matter and impulsive gravitational waves. It will also give a recent new
description of gravitational
singularities in terms of the evolution of test fields rather than the
traditional definition using world lines of test particles. It will end by
relating this work to new developments in the theory of PDEs.

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  						  Zoran Petric