In physics, Kaluza–Klein theory (KK theory) is a unified field theory of gravitation and electromagnetism built around the idea of a fifth dimension beyond the usual four of space and time. It is considered to be an important precursor to string theory.
Sidereal day（恒星日）：A sidereal day is the length of time it takes a planet to rotate from the perspective of a distant star. For the planet Earth a sidereal day is approximately 23 hours, 56 minutes, and 4 seconds.Astronomers use sidereal time to keep track of the direction to turn the telescopes to view a star in the night sky. By contrast, solar time is reckoned by the movement of the Earth from the perspective of the Sun. An average solar day (24 hours) is longer than a sidereal day (23…
Using the unit circle, the sine and cosine of an angle are defined by the coordinates of the point on the circle. The x-value is the cosine and the y-value is the sine.
Asteroid : Asteroids are minor planets, especially those of the inner Solar System. The larger ones have also been called planetoids. These terms have historically been applied to any astronomical object orbiting the Sun that did not show the disc of a planet and was not observed to have the characteristics of an active comet, but as minor planets in the outer Solar System were discovered, they were often distinguished from traditional asteroids.
d as such mass density. We further propose that the Cosmic Fabric deforms due to matter in space, which acts as inclusions, in a manner analogous to the deformation of a conventional thin plate (Efrati et al., 2008). By introducing a constitutive model for General Relativity, we lay the groundwork for subsequently applying Solid Mechanics concepts to Cosmology. In particular, we show that strain along the time dimension manifests as a gravitational potential and contraction along the time…
A second of arc (arcsecond, arcsec) is 1⁄60 of an arc minute, 1⁄3,600 of a degree, 1⁄1,296,000 of a circle, and π⁄648,000 (about 1⁄206,265) of a radian.
Site full of review for Algebra and Trigonometry... got to keep my head still thinking, even though I'm not in school.
The Kuiper belt /ˈkaɪpər/ or 'køypǝr (as in Dutch), sometimes called the Edgeworth–Kuiper belt, is a region of the Solar System beyond the planets, extending from the orbit of Neptune (at 30 AU) to approximately 50 AU from the Sun. It is similar to the asteroid belt, but it is far larger—20 times as wide and 20 to 200 times as massive. Like the asteroid belt, it consists mainly of small bodies, or remnants from the Solar System's formation.
Physics: Ring-shaped trap holds ions in check : Nature : Nature Publishing Group