Paradox of radiation of charged particles in a gravitational field Coulomb field of the supported charge, but too small to be observable. So although the Coulomb law was discovered in a supporting frame, general relativity tells us that the field of such a charge is not precisely formula_2. The radiation from the supported charge viewed in the freefalling frame (or vice versa) is something of a curiosity: where does it go? Boulware (1980) finds that the radiation goes into a region of spacetime inaccessible to the co-accelerating, supported observer. In effect, a uniformly accelerated observer has an event horizon, and there are regions of spacetime inaccessible to this observer. C.
Speed of sound km) can produce refraction equal to a typical temperature lapse rate of . Higher values of wind gradient will refract sound downward toward the surface in the downwind direction, eliminating the acoustic shadow on the downwind side. This will increase the audibility of sounds downwind. This downwind refraction effect occurs because there is a wind gradient; the sound is not being carried along by the wind. For sound propagation, the exponential variation of wind speed with height can be defined as follows: where In the 1862 American Civil War Battle of Iuka, an acoustic shadow, believed to have been enhanced