Department of Relativistic Astrophysics and Cosmology
 
 
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43. Leszek M. Sokołowski
General relativity, gravitational energy and spin-two field
Int. J. Geom. Meth. Mod. Phys. , vol. 4, pp. 1-23 (2007).
[abstract] [preprint]

Abstract:
(Lectures given at the 42 Karpacz Winter School of Theoretical Physics, Lądek Zdrój, Poland, 6-11 February 2006, "Current Mathematical Topics in Gravitation and Cosmology"):

In my lectures I will deal with three seemingly unrelated problems: i) to what extent is general relativity exceptional among metric gravity theories? ii) is it possible to define gravitational energy density applying field-theory approach to gravity? and iii) can a consistent theory of a gravitationally interacting spin-two field be developed at all? The connecting link to them is the concept of a fundamental spin-2 field. A linear spin-2 field encounters insurmountable inconsistencies when coupled to gravity. After discussing the inconsistencies of any coupling of the linear spin-2 field to gravity, I exhibit the origin of the fact that a gauge invariant field has the variational metric stress tensor which is gauge dependent. I give a general theorem explaining under what conditions a symmetry of a field Lagrangian becomes also the symmetry of the stress tensor. It is a conclusion of the theorem that any attempt to define gravitational energy density in the framework of a field theory of gravity must fail. Finally I make a very brief introduction to basic concepts of how a certain kind of a necessarily nonlinear spin-2 field arises in a natural way from vacuum higher derivative gravity theories. This specific spin-2 field consistently interacts gravitationally.

44. Andrzej Woszczyna
Mechanika zaburzeń skalarnych w radiacyjnym wszechświecie
Prace Komisji Astrofizyki PAU, vol. 11, p. 117 (2007).
[pdf.pl]

Abstract:
Abstract

45. Agnieszka Uczyńska - wywiad z Sebastianem J. Szybka
Kosmiczne laboratorium fizyków
Nauka w Polsce - serwis PAP (2007).
[abstract] [journal]

Abstract:
Wywiad dla Polskie Agencji Prasowej - serwis Nauka w Polsce.

46. Agnieszka Uczyńska - wywiad z Sebastianem J. Szybka
Osobliwości - patologie czasu i przestrzeni
Nauka W Polsce - serwis PAP (2007).
[abstract] [journal]

Abstract:
Wywiad dla Polskiej Agencji Prasowej - serwis Nauka w Polsce.

47. Agnieszka Uczyńska - wywiad z Sebastianem J. Szybka
Tajemnice ciemnej energii
Nauka w Polsce - serwis PAP (2007).
[abstract] [journal]

Abstract:
Wywiad dla Polskiej Agencji Prasowej - serwis Nauka w Polsce.

48. Artur Janda
Spherically Symmetric Solutions of the Einstein--Bach Equations and a Consistent Spin-2 Field Theory
Acta Phys. Pol., B , vol. B37/12, pp. 3667-3678 (2006).
[abstract] [preprint] [journal] [download]

Abstract:
We briefly present a relationship between General Relativity coupled to certain spin-0 and spin-2 field theories and higher derivatives metric theories of gravity. In a special case, described by the Einstein--Bach equations, the spin-0 field drops out from the theory and we obtain a consistent spin-two field theory interacting gravitationally, which overcomes a well known inconsistency of the theory for a linear spin-two field coupled to the Einstein's gravity. Then we discuss basic properties of static spherically symmetric solutions of the Einstein--Bach equations.

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