41 research outputs found
Unitary representations of U/2,2/ and massless fields
Unitary representations of U-2,2 and massless field
Landau damping in a relativistic plasma
Landau damping in relativistic plasm
Sufficient conditions for curvature invariants to avoid divergencies in Hyperextended Scalar Tensor theory for Bianchi models
We look for sufficient conditions such that the scalar curvature, Ricci and
Kretchmann scalars be bounded in Hyperextended Scalar Tensor theory for Bianchi
models. We find classes of gravitation functions and Brans-Dicke coupling
functions such that the theories thus defined avoid the singularity. We compare
our results with these found by Rama in the framework of the Generalised Scalar
Tensor theory for the FLRW models.Comment: 13 page
Mathematical surprises and Dirac's formalism in quantum mechanics
By a series of simple examples, we illustrate how the lack of mathematical
concern can readily lead to surprising mathematical contradictions in wave
mechanics. The basic mathematical notions allowing for a precise formulation of
the theory are then summarized and it is shown how they lead to an elucidation
and deeper understanding of the aforementioned problems. After stressing the
equivalence between wave mechanics and the other formulations of quantum
mechanics, i.e. matrix mechanics and Dirac's abstract Hilbert space
formulation, we devote the second part of our paper to the latter approach: we
discuss the problems and shortcomings of this formalism as well as those of the
bra and ket notation introduced by Dirac in this context. In conclusion, we
indicate how all of these problems can be solved or at least avoided.Comment: Largely extended and reorganized version, with new title and abstract
and with 2 figures added (published version), 54 page