79. Jacek Guzik, Uros Seljak, Matias Zaldarriaga
Lensing effect on polarization in microwave background: extracting convergence power spectrum
Phys.Rev. D, vol. 62, p. 043517 (2000).
[preprint] [journal]

Abstract:

80. Grazyna Siemieniec-Ozieblo, Andrzej Woszczyna
Order reduction in semiclassical cosmology
Phys. Rev. D, vol. 59, p. 083504 (1999).
[abstract] [preprint] [journal]

Abstract:
We investigate the Robertson-Walker cosmology with Lagrangian $R+\alpha_1\hbar R^2+\alpha_2\hbar R^{\mu\nu}R_{\mu\nu} +L_{rad}$ where $L_{rad}$ means classical source with traceless energy-momentum tensor. We weaken the self-consistence condition (L. Parker, J. Z. Simon, Phys. Rev. {D47}(1993),{1339}). Quantum corrections are expressed as contributions to the effective equation of state. We show that the empty space-time is stable within the class of radiation-filled expanding universes with no order reduction of the field equations.

81. Guido Magnano, Leszek M. Sokołowski
Can the local stress-energy conservation laws be derived solely from field equations?
Gen. Rel. Grav., vol. 30, pp. 1281-1288 (1998).
[abstract] [preprint]

Abstract:
According to a recent suggestion [1], the energy--momentum tensor for gravitating fields can be computed through a suitable rearrangement of the matter field equations, without relying on the variational definition. We show that the property observed by Accioly et al. in [1] is the consequence of a general identity, which follows from the covariance of the matter Lagrangian in much the same way as (generalized) Bianchi identities follow from the covariance of the purely gravitational Lagrangian. However, we also show that only in particular cases can this identity be used to obtain the actual form of the stress-energy tensor, while in general the method leads to ambiguities and possibly to wrong results. Moreover, in nontrivial cases the computations turn out to be more difficult than the standard variational technique.

82. Marek Szydlowski, Andrzej J. Maciejewski, Jacek Guzik
Dynamical Trajectories of Simple Mechanical Systems as Geodesics in Space with an Extra Dimension
Int. J. of Theor. Phys., vol. 37, p. 1569 (1998).
[preprint] [journal]

Abstract:

83. Zdzislaw Pogoda, Leszek M. Sokołowski
Does Mathematics Distinguish Certain Dimensions of Spaces? Part II.
The American Mathematical Monthly, vol. 105, pp. 456-463 (1998).
[journal]

Abstract:
Abstract

84. Zdzislaw Pogoda, Leszek M. Sokołowski
Does Mathematics Distinguish Certain Dimensions of Spaces? Part I.
The American Mathematical Monthly, vol. 104, pp. 860-869 (1997).
[journal]

Abstract:
Abstract