55. Leszek M. Sokołowski Metric gravity theories and cosmology: II. Stability of a ground state in f(R) theories. Class. Quantum Grav., vol. 24, pp. 37133734 (2007). [abstract] [preprint] 
Abstract: A fundamental criterion of viability of any gravity theory is existence of a stable groundstate solution being either Minkowski, dS or AdS space. Stability of the ground state is independent of which frame is physical. In general, a given theory has multiple ground states and splits into independent physical sectors. All metric gravity theories with the Lagrangian being a function of Ricci tensor are dynamically equivalent to Einstein gravity with a source and this allows us to study the stability problem using methods developed in GR. We apply these methods to f(R) theories. As is shown in 13 cases of Lagrangians the stability criterion works simply and effectively whenever the curvature of the ground state is determined. An infinite number of gravity theories have a stable ground state and further viability criteria are necessary. 
56. Leszek M. Sokołowski General relativity, gravitational energy and spintwo field Int. J. Geom. Meth. Mod. Phys. , vol. 4, pp. 123 (2007). [abstract] [preprint] 
Abstract: (Lectures given at the 42 Karpacz Winter School of Theoretical Physics, Lądek Zdrój, Poland, 611 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 fieldtheory approach to gravity? and iii) can a consistent theory of a gravitationally interacting spintwo field be developed at all? The connecting link to them is the concept of a fundamental spin2 field. A linear spin2 field encounters insurmountable inconsistencies when coupled to gravity. After discussing the inconsistencies of any coupling of the linear spin2 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 spin2 field arises in a natural way from vacuum higher derivative gravity theories. This specific spin2 field consistently interacts gravitationally.

57. Andrzej Woszczyna Mechanika zaburzeń skalarnych w radiacyjnym wszechświecie Prace Komisji Astrofizyki PAU, vol. 11, p. 117 (2007). [pdf.pl] 
Abstract: Abstract 
58. 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. 
59. 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. 
60. 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. 