Louis Witten

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Mutations in the Leucine Rich Repeat Kinase 2 (LRRK2) gene, first described in 2004 have now emerged as the most important genetic finding in both autosomal dominant and sporadic Parkinson's disease (PD). While a formidable research effort has ensued since the initial gene discovery, little is known of either the normal or the pathological role of LRRK2. We(More)
Due to the singularity theorems of Penrose, Geroch, and Hawking [1] and the many examples that have been found in various models of gravitational collapse [2], it has now come to be generally accepted that the gravitational collapse of a sufficiently massive star will lead eventually to the formation of a black hole. In one particular class of models, the(More)
We derive an equation for the acceleration of a fluid element in the spherical gravitational collapse of a bounded compact object made up of an imperfect fluid. We show that non-singular as well as singular solutions arise in the collapse of a fluid initially at rest and having only a tangential pressure. We obtain an exact solution of Einstein equations,(More)
We study the spherical gravitational collapse of a compact object under the approximation that the radial pressure is identically zero, and the tangential pressure pθ is related to the density ρ by a linear equation of state pθ = kρ. It turns out that the Einstein equations can be reduced to the solution of an integral for the evolution of the area radius.(More)
We calculate the quantum stress tensor for a massless scalar field in the 2-d selfsimilar spherical dust collapse model which admits a naked singularity. We find that the outgoing radiation flux diverges on the Cauchy horizon. This may have two consequences. The resultant back reaction may prevent the naked singularity from forming, thus preserving cosmic(More)
We describe a simple method of determining whether the singularity that forms in the spherically symmetric collapse of inhomogeneous dust is naked or covered. This derivation considerably simplifies the analysis given in the earlier literature, while giving the same results as have been obtained before. e-mail address: sukkoo@relativity.tifr.res.in 2 e-mail(More)
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