In classical mechanics, the Laplace–Runge–Lenz vector (or simply the LRL vector) is a vector used chiefly to describe the shape and orientation of the orbit of one astronomical body around another, such as a planet revolving around a star. For two bodies interacting by Newtonian gravity, the LRL vector is a constant of motion, meaning that it is the same no matter where it is calculated on the orbit; equivalently, the LRL vector is said to be conserved. More generally, the LRL vector is conserved in all problems in which two bodies interact by a central force that varies as the inverse square of...

In physics, matrix string theory is a set of equations that describe superstring theory in a non-perturbative framework. Type IIA string theory can be shown to be equivalent to a maximally supersymmetric two-dimensional gauge theory, the gauge group of which is U(N) for a large value of N. This matrix string theory was first proposed by Luboš Motl in 1997 and later independently in a more complete paper by Robbert Dijkgraaf, Erik Verlinde, and Herman Verlinde. Another matrix string theory equivalent to Type IIB string theory was constructed in 1996 by Ishibashi, Kawai, Kitazawa and Tsuchiya. This...

George's Secret Key to the Universe is a 2007 children's book written by Lucy and Stephen Hawking with Christophe Galfard. The book was followed by four sequels, George's Cosmic Treasure Hunt in 2009, George and the Big Bang in 2011, George and the Unbreakable Code in 2014 and George and the Blue Moon in 2016. It is intended for readers aged 9 and up. == Synopsis == The main characters in the book are Susan Focker, Larry Focker, George, Eric, Annie, Dr. Reeper, and Cosmos, the world's most powerful computer. Cosmos can draw windows allowing people to look into outer space, as well as doors which...