Almost Robinson geometries

Photon rockets and the Robinson-Trautman geometries

We point out the relation between the photon rocket spacetimes and the Robinson Trautman geometries. This allows a discussion of the issues related to the distinction between the gravitational and matter energy radiation that appear in these metrics in a more geometrical way, taking full advantage of their asymptotic properties at null infinity to separate the Weyl and Ricci radiations, and to ...

Almost-Commutative Geometries Beyond the Standard Model

In [7–9] and [10] the conjecture is presented that almost-commutative geometries, with respect to sensible physical constraints, allow only the standard model of particle physics and electro-strong models as Yang-Mills-Higgs theories. In this publication a counter example will be given. The corresponding almost-commutative geometry leads to a Yang-Mills-Higgs model which consists of the standar...

Some Geometries that are Almost Buildings

Almost Hermitian Structures and Quaternionic Geometries

Gray & Hervella gave a classification of almost Hermitian structures (g, I) into 16 classes. We systematically study the interaction between these classes when one has an almost hyper-Hermitian structure (g, I, J,K). In general dimension we find at most 167 different almost hyper-Hermitian structures. In particular, we obtain a number of relations that give hyperKäher or locally conformal hyper...

Almost-Commutative Geometries Beyond the Standard Model II: New Colours

We will present an extension of the standard model of particle physics in its almostcommutative formulation. This extension is guided by the minimal approach to almostcommutative geometries employed in [13], although the model presented here is not minimal itself. The corresponding almost-commutative geometry leads to a Yang-Mills-Higgs model which consists of the standard model and two new fer...