TY  - JOUR
A1  - Schmidt, Hans-Jürgen
T1  - Fourth order gravity : equations, history, and application to cosmology
N2  - The field equations following from a Lagrangian L(R) will be deduced and solved for special cases. If L is a non-linear function of the curvature scalar, then these equations are of fourth order in the metric. In the introduction we present the history of these equations beginning with the paper of H. Weyl from 1918, who first discussed them as alternative to Einstein's theory. In the third part, we give details about the cosmic no hair theorem, i.e., the details how within fourth order gravity with L= R + R^2 the inflationary phase of cosmic evolution turns out to be a transient attractor. Finally, the Bicknell theorem, i.e. the conformal relation from fourth order gravity to scalar- tensor theory, will be shortly presented.
Y1  - 2007
UR  - http://arxiv.org/abs/gr-qc/0602017
ER  - 
TY  - JOUR
A1  - Schmidt, Hans-Jürgen
T1  - Einsteins Arbeiten in Bezug auf die moderne Kosmologie : de Sitters Lösung der Einsteinschen Feldgleichung mit positivem kosmologischen Glied als Geometrie des inflationaeren Weltmodells
N2  - Die Arbeit von Albert Einstein von 1918 zu Willem De Sitters Loesung der Einsteinschen Feldgleichung wird unter heutigem Gesichtspunkt kommentiert. Dazu wird zunaechst die Geometrie der De Sitterschen Raum-Zeit beschrieben, sowie ihre Bedeutung fuer das inflationaere Weltmodell erlaeutert.
Y1  - 2005
UR  - http://arXiv.org/abs/gr-qc/0506121
ER  - 
TY  - JOUR
A1  - Schmidt, Hans-Jürgen
T1  - Schwarzschild and Synge once again
N2  - We complete the historical overview about the geometry of a Schwarzschild black hole at its horizon by emphasizing the contribution made by Synge in [6] to its clarification
Y1  - 2005
UR  - http://arXiv.org/abs/gr-qc/0408017
SN  - 0001-7701
ER  - 
TY  - JOUR
A1  - Schmidt, Hans-Jürgen
T1  - Untitled
Y1  - 2005
ER  - 
TY  - JOUR
A1  - Schmidt, Hans-Jürgen
T1  - The square of the Weyl tensor can be negative
N2  - We show that the square of the Weyl tensor can be negative by giving an example
Y1  - 2003
UR  - http://arXiv.org/abs/gr-qc/0302078
ER  - 
TY  - JOUR
A1  - Canfora, Fabrizio
A1  - Schmidt, Hans-Jürgen
T1  - Vacuum solutions which cannot be written in diagonal form
N2  - A vacuum solution of the Einstein gravitational field equation is shown to follow from a general ansatz but fails to follow from it if the symmetric matrix in it is assumed to be in diagonal form.
Y1  - 2003
UR  - http://arXiv.org/abs/gr-qc/0305107
ER  - 
TY  - JOUR
A1  - Kleinert, Hagen
A1  - Schmidt, Hans-Jürgen
T1  - Cosmology with curvature-saturated gravitational lagrangian
N2  - We argue that the Lagrangian L(R) for gravity should remain bounded at large curvature, and interpolate between the weak-field tested Einstein-Hilbert Lagrangian and a pure cosmological constant for large R with the curvature- saturated ansatz. The curvature-dependent effective gravitational constant tends to infinity for large R, in contrast to most other approaches where it tends to 0. The theory possesses neither ghosts nor tachyons, but it fails to be linearization stable. On the technical side we show that two different conformal transformations make L asymptotically equivalent to the Gurovich-ansatz on the one hand, and to Einstein's theory with a minimally coupled scalar field with self-interaction on the other.
Y1  - 2002
UR  - http://arXiv.org/abs/gr-qc/0006074
ER  - 
TY  - JOUR
A1  - Dzhunushaliev, Vladimir
A1  - Rurenko, O.
A1  - Schmidt, Hans-Jürgen
T1  - Spherically symmetric solutions in multidimensional gravity with the SU(2) gauge group as the extra dimensions
Y1  - 2002
ER  - 
TY  - JOUR
A1  - Gorbatenko, M. V.
A1  - Pushkin, A. V.
A1  - Schmidt, Hans-Jürgen
T1  - On a relation between the Bach equation and the equation of geometrodynamics
N2  - The Bach equation and the equation of geometrodynamics are based on two quite different physical motivations, but in both approaches, the conformal properties of gravitation plays the key role. In this paper we present an analysis of the relation between these two equations and show that the solutions of the equation of geometrodynamics are of a more general nature. We show the following non-trivial result: there exists a conformally invariant Lagrangian, whose field equation generalizes the Bach equation and has as solutions those Ricci tensors which are solutions to the equation of geometrodynamics.
Y1  - 2002
ER  - 
TY  - JOUR
A1  - Schmidt, Hans-Jürgen
T1  - A new duality transformation for fouth-order gravity
Y1  - 1997
ER  -