We give a closed expression for the Minkowski -dimensional metric in the radar coordinates of an arbitrary non-inertial observer in terms of ’s proper acceleration. Knowledge of the metric allows the non-inertial observer to perform experiments in spacetime without making reference to inertial frames. To clarify the relation between inertial and non-inertial observers the coordinate transformation between radar and inertial coordinates also is given. We show that every conformally flat coordinate system can be regarded as the radar coordinate system of a suitable observer for a suitable parametrization of the observer worldline. Therefore, the coordinate transformation between arbitrarily moving observers is a conformal transformation and conformally invariant -dimensional theories lead to the same physics for all observers, independently of their relative motion.
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2005
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