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Feasibility Of Measuring The Shapiro Time Delay Over Meter-Scale Distances, Stefan Ballmer, S. Marka, P. Shawhan
Feasibility Of Measuring The Shapiro Time Delay Over Meter-Scale Distances, Stefan Ballmer, S. Marka, P. Shawhan
Physics - All Scholarship
The time delay of light as it passes by a massive object, first calculated by Shapiro in 1964, is a hallmark of the curvature of space-time. To date, all measurements of the Shapiro time delay have been made over solar-system distance scales. We show that the new generation of kilometer-scale laser interferometers being constructed as gravitational wave detectors, in particular Advanced LIGO, will in principle be sensitive enough to measure variations in the Shapiro time delay produced by a suitably designed rotating object placed near the laser beam. We show that such an apparatus is feasible (though not easy) to …
Is The Spacetime Metric Euclidean Rather Than Lorentzian?, Rafael D. Sorkin
Is The Spacetime Metric Euclidean Rather Than Lorentzian?, Rafael D. Sorkin
Physics - All Scholarship
My answer to the question in the title is "No". In support of this point of view, we analyze some examples of saddle-point methods, especially as applied to quantum "tunneling" in nonrelativistic particle mechanics and in cosmology. Along the way we explore some of the interrelationships among different ways of thinking about path-integrals and saddle-point approximations to them.