- In physics, spacetime is a mathematical model that combines the three dimensions of space and one dimension of time into a single four-dimensional manifold. Spacetime diagrams can be used to visualize relativistic effects, such as why different observers perceive differently where and when events occur.
- General relativity (Wikipedia)
General relativity, also known as the general theory of relativity and Einstein’s theory of gravity, is the geometric theory of gravitation published by Albert Einstein in 1915 and is the current description of gravitation in modern physics. General relativity generalizes special relativity and refines Newton’s law of universal gravitation, providing a unified description of gravity as a geometric property of space and time or four-dimensional spacetime. In particular, the curvature of spacetime is directly related to the energy and momentum of whatever matter and radiation are present. The relation is specified by the Einstein field equations, a system of second order partial differential equations.
- George H. W. Bush (allthetropes.org)
George Herbert Walker Bush (June 12, 1924 - November 30, 2018) was the 41st President of the United States. In his earlier life, he had been a World War II naval aviator (and for a time was the youngest one), completing one mission with an aircraft on fire. He also spent a year as Director of the CIA. He is the father of the other President Bush, George W. Bush.