• Tulsi Dass

      Articles written in Pramana – Journal of Physics

    • Gauge fields, space-time geometry and gravity

      Tulsi Dass

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      A general framework for the gauge theory of the affine group and its various subgroups in terms of connections on the bundle of affine frames and its subbundles is given, with emphasis on the correct gauging of groups including space-time translations. For consistency of interpretation, the appropriate objects to be identified with gravitational vierbeins in such theories are not the translational gauge fields themselves, but their pull backs,via appropriate bundle homomorphisms, to the bundle of frames. This automatically solves the problems usually encountered in constructing a gauge theory of the conventional sort for groups containing translations. We give a consistent formulation of the Poincare gauge theory and also of the theory based on translational gauge invariance which, in the absence of matter fields with intrinsic spin, gives a local Lorentz invariant theory equivalent to Einstein gravity.

    • A stepwise planned approach to the solution of Hilbert’s sixth problem. III: Measurements and von Neumann projection/collapse rule

      Tulsi Dass

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      Supmech, the universal mechanics developed in the previous two papers (Dass, arXiv: 0909.4606[math-ph]; 1002:2061[math-ph]), accommodates both quantum and classical mechanics as subdisciplines (a brief outline is included for completeness); this feature facilitates, in a supmechbased treatment of quantum measurements, an unambiguous treatment of the apparatus as a quantum system approximated well by a classical one. Taking explicitly into consideration the fact that observations on the apparatus are made when it has ‘settled down after the measurement interaction’ and are restricted to macroscopically distinguishable pointer readings, the unwanted superpositions of (system + apparatus) states are shown to be suppressed; this provides a genuinely physics-based justification for the (traditionally postulated) von Neumann projection/collapse rule. The decoherence mechanism brought into play by the stated observational constraints is free from the objections against the traditional decoherence program.

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