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.
Refraction medicine, particularly optometry, ophthalmology and orthoptics, "refraction" (also known as "refractometry") is a clinical test in which a phoropter may be used by the appropriate eye care professional to determine the eye's refractive error and the best corrective lenses to be prescribed. A series of test lenses in graded optical powers or focal lengths are presented to determine which provides the sharpest, clearest vision. In underwater acoustics, refraction is the bending or curving of a sound ray that results when the ray passes through a sound speed gradient from a region of one sound speed to a region of a