Ashtekar's variables without spin

Ashtekar's variables are shown to arise naturally from a 3+1 split of general relativity in the Einstein-Cartan formulation. Thereby spinors are exorcised.Comment: 5 pages, unpublished paper from 198

Lensing in the Einstein-Straus solution

The analytical treatment of lensing in the Einstein-Straus solution with positive cosmological constant by Kantowski et al. is compared to the numerical treatment by the present author. The agreement is found to be excellent.Comment: 6 pages, 1 figure, 1 tabl

Cosmological constant and lensing

The effect of the cosmological constant on the curvature of light due to an isolated spherical mass is recalculated without using the lens equation and compared to a lensing cluster.Comment: 9 pages,4 figure

Krajewski diagrams and spin lifts

A classification of irreducible, dynamically non-degenerate, almost commutative spectral triples is refined. It is extended to include centrally extended spin lifts. Simultaneously it is reduced by imposing three constraints: (i) the condition of vanishing Yang-Mills and mixed gravitational anomalies, (ii) the condition that the fermion representation be complex under the little group, while (iii) massless fermions are to remain neutral under the little group. These constraints single out the standard model with one generation of leptons and quarks and with an arbitrary number of colours.Comment: 19 pages LaTeX, 1 figure, will not be submitted to journal, v2: extension of diagram 1 and suppression of electro-weak mode

Spin group and almost commutative geometry

For Connes' spectral triples, the group of automorphisms lifted to the Hilbert space is defined and used to fluctuate the metric. A few commutative examples are presented including Chamseddine and Connes' spectral unification of gravity and electromagnetism. One almost commutative example is treated: the full standard model. Here the lifted automorphisms explain O'Raifeartaigh's reduction SU(2)\times U(3)/\zz_2.Comment: 25 pages LaTeX, 1 figure, this paper will not be submitted to any journal, in particular not to Nucl.Phys.

The noncommutative standard model, post- and predictions

I try to assess the weak and strong points of the standard model of electro-magnetic, weak and strong forces, how it can be derived from general relativity by generalizing Riemannian to noncommutative geometry and what post- and predictions this unification of all four forces entails in particle physics.Comment: contribution to Moriond '10 electro-wea

25 years ago: the official farewell to the meter

On october 21st 1983 took place in S\`evres on the western outskirts of Paris the official funeral of the meter. With it the notion of distance as a physical observable was buried

Higgs-mass predictions

A compilation of Higgs-mass predictions is proposedComment: This is the last version. Only addition: today's update by Kahana & Kahan

Noncommutative geometry and the standard model

The aim of this contribution is to explain how Connes derives the standard model of electromagnetic, weak and strong forces from noncommutative geometry. The reader is supposed to be aware of two other derivations in fundamental physics: the derivation of the Balmer-Rydberg formula for the spectrum of the hydrogen atom from quantum mechanics and Einstein's derivation of gravity from Riemannian geometry.Comment: 11 pages, 4 figures, contribution to Encyclopedia of Mathematical Physics, J.-P. Francoise, G. Naber & Tsou Sheung Tsun (eds.), Elsevier Scienc