| Abstract from DBPedia | The ergosphere is a region located outside a rotating black hole's outer event horizon. Its name was proposed by Remo Ruffini and John Archibald Wheeler during the Les Houches lectures in 1971 and is derived from the Greek word ἔργον (ergon), which means "work". It received this name because it is theoretically possible to extract energy and mass from this region. The ergosphere touches the event horizon at the poles of a rotating black hole and extends to a greater radius at the equator. A black hole with modest angular momentum has an ergosphere with a shape approximated by an oblate spheroid, while faster spins produce a more pumpkin-shaped ergosphere. The equatorial (maximal) radius of an ergosphere is the Schwarzschild radius, the radius of a non-rotating black hole. The polar (minimal) radius is also the polar (minimal) radius of the event horizon which can be as little as half the Schwarzschild radius for a maximally rotating black hole.エルゴ球（エルゴきゅう、英: ergosphere）とは、回転するブラックホールの外に位置する領域である。その名前は古代ギリシア語で仕事を意味する語、ergon に由来する。この領域からエネルギーと質量を取り出すことが理論的に可能であることにちなみ、ジョン・ホイーラーらによって名付けられた。 (Source: http://dbpedia.org/resource/Ergosphere) |
