Covariant Formulation of Light Propagation in Cosmological Models

Covariant entropy conjecture and concordance cosmological models

Recently a covariant entropy conjecture has been proposed for dynamical horizons. We apply this conjecture to concordance cosmological models, namely, those cosmological models filled with perfect fluids, in the presence of a positive cosmological constant. As a result, we find this conjecture has a severe constraint power. Not only does this conjecture rule out those cosmological models disfav...

Light Propagation in Generally Covariant Electrodynamics and the Fresnel Equation *

Within the framework of generally covariant (pre-metric) electrodynamics, we specify a local vacuum spacetime relation between the excitation H = (D,H) and the field strength F = (E,B). We study the propagation of electromagnetic waves in such a spacetime by Hadamard’s method and arrive, with the constitutive tensor density κ ∼ ∂H/∂F , at a Fresnel equation which is algebraic of 4th order in th...

Covariant Majorana Formulation of Electrodynamics

We construct an explicit covariant Majorana formulation of Maxwell electromagnetism which does not make use of vector 4-potential. This allows to write a “Dirac” equation for the photon containing all the known properties of it. In particular, the spin and (intrinsic) boost matrices are derived and the helicity properties of the photon are studied.

Dispersive light propagation at cosmological distances: Matter effects

gradual erasure of subjectivity: a study of samuel beckett’s trilogy in the light of postmodernism

ساموئل بکت بیشتر از هر نویسنده دیگری در نیم? دوم قرن بیستم با گفتارش زمان? ما را به آستان? از هم پاشیدگی کشانده است، آستانه ای که در آن مدرنیته با سرانجام گریزان اما غیرقابل اجتناب خود مواجه می شود. در این تحقیق روی مفهوم فردیت و محو آن در دوران پسامدرن تاکید شده و در طی آن سعی شده است که فردیت مدرن و پسامدرن در رمان های سه گانه بکت بررسی گردد. تحقیق حاضر یک بررسی کتابخانه ای و کیفی بر روی سه ر...