An Accelerating Reference Frame for Electromagnetic Waves in a Rapidly Growing Plasma: Unruh Radiation and the Dynamic Casimir Effect

In 1974, Hawking showed1 that Black Holes can evaporate by the emission of low temperature thermal radiation, now named Hawking Radiation. Shortly thereafter, a closely related effect called Unruh Radiation became apparent. According to Unruh2 and Davies2, observers of the electromagnetic field in an accelerating reference frame should see thermal radiation at a temperature T: where a is the acceleration relative to an inertial frame, c is the speed of light and ħ and K are Planck's and Boltzmann's constant respectively. In a frame accelerating at g= 980 cm/sec2, equivalent to the acceleration experienced at the earth's surface3, this thermal radiation is at a temperature of only 4× 10−20 °K. Therefore, physicists hoping to observe this radiation, have sought out systems being subjected to extreme acceleration. For example, J. S. Bell has suggested4 that the spin depolarization of electrons accelerating around a synchrotron storage ring may be interpreted as being due to such radiation.