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A Winston cone is a non-imaging light collector in the shape of an off-axis parabola of revolution [1] [2] with a reflective inner surface. It concentrates the light passing through a relatively large entrance aperture through a smaller exit aperture. [ 3 ]
The earliest practical electric fence unit was developed in 1936/1937 by New Zealand inventor William "Bill" Gallagher Snr. Built from a car's ignition coil and a meccano set, Gallagher used the device to keep his horse from scratching itself against his car. Gallagher later started a company to improve and market his invention.
Alfred William Gallagher MBE (17 May 1911 – 8 August 1990) was a New Zealand inventor, manufacturing engineer and businessman. He is notable for popularising the electric fence . Early life
Light cone coordinates can also be generalized to curved spacetime in general relativity. Sometimes calculations simplify using light cone coordinates. See Newman–Penrose formalism. Light cone coordinates are sometimes used to describe relativistic collisions, especially if the relative velocity is very close to the speed of light.
Before Dawn may refer to: Before Dawn (horse) (1979–2006), American racehorse Before Dawn: The Music of Yusef Lateef , a 1957 American jazz album featuring Yusef Lateef
Taking as event p a flash of light (light pulse) at time t 0, all events that can be reached by this pulse from p form the future light cone of p, while those events that can send a light pulse to p form the past light cone of p. Given an event E, the light cone classifies all events in spacetime into 5 distinct categories:
In geometry, a hypercone (or spherical cone) is the figure in the 4-dimensional Euclidean space represented by the equation x 2 + y 2 + z 2 − w 2 = 0. {\displaystyle x^{2}+y^{2}+z^{2}-w^{2}=0.} It is a quadric surface, and is one of the possible 3- manifolds which are 4-dimensional equivalents of the conical surface in 3 dimensions.