8 citations · 8 across the 1 of their papers we have counts for
21 papers
Isotropic universe with almost scale-invariant fourth-order gravity
H. -J. Schmidt, D. Singleton
We study a broad class of isotropic vacuum cosmologies in fourth-order gravity under the condition that the gravitational Lagrangian be scale-invariant or almost scale-invariant. T…
Gravitoelectromagnetism and other decompositions of the Riemann tensor
H. -J. Schmidt
We present gravitoelectromagnetism and other decompositions of the Riemann tensor from the differential-geometrical point of view.
Vacuum solutions which cannot be written in diagonal form
F. Canfora, H. -J. Schmidt
A vacuum solution of the Einstein gravitational field equation is given that follows from a general ansatz but fails to follow from it if a certain symmetric matrix is assumed to b…
The square of the Weyl tensor can be negative
H. -J. Schmidt
We show that the square of the Weyl tensor can be negative by giving an example.
Comment on 'Stability of the semiclassical Einstein equation'
H. -J. Schmidt
Some mathematical errors of the paper commented upon [W.-M. Suen, Phys. Rev. D 40, (1989) 315] are corrected.
The Newtonian limit of fourth and higher order gravity
Ines Quandt, H. -J. Schmidt
We consider the Newtonian limit of the theory based on the Lagrangian L = R + \sum a_k R \Box^k R. The gravitational potential of a point mass turns out to be a combination of Newt…