A computer simulation, a computer model, or a computational model is a computer program, or network of computers, that attempts to simulate an abstract model of a particular system. Computer simulations have become a useful part of mathematical modeling of many natural systems in physics (computational physics), astrophysics, chemistry and biology, human systems in economics, psychology, social science, and engineering. Simulation of a system is represented as the running of the system's model. It can be used to explore and gain new insights into new technology, and to estimate the performance of systems too complex for analytical solutions.

Computer simulations vary from computer programs that run a few minutes, to network-based groups of computers running for hours, to ongoing simulations that run for days. The scale of events being simulated by computer simulations has far exceeded anything possible (or perhaps even imaginable) using traditional paper-and-pencil mathematical modeling. Over 10 years ago, a desert-battle simulation, of one force invading another, involved the modeling of 66,239 tanks, trucks and other vehicles on simulated terrain around Kuwait, using multiple supercomputers in the DoD High Performance Computer Modernization Program Other examples include a 1-billion-atom model of material deformation (2002); a 2.64-million-atom model of the complex maker of protein in all organisms, a ribosome, in 2005; and the Blue Brain project at EPFL (Switzerland), begun in May 2005, to create the first computer simulation of the entire human brain, right down to the molecular level.

David Vaughan Icke (pronounced /aɪk/, or IKE, born 29 April 1952) is an English writer and public speaker, best known for his views on what he calls "who and what is really controlling the world." Describing himself as the most controversial speaker in the world, he is the author of 19 books and has attracted a global following that cuts across the political spectrum. His 533-page The Biggest Secret (1999) has been called "the Rosetta Stone for conspiracy junkies."

Icke was a well-known BBC television sports presenter and spokesman for the Green Party, when in 1990 a psychic told him he was a healer who had been placed on Earth for a purpose, and that the spirit world was going to pass messages to him so he could educate others. In March 1991 he held a press conference to announce that he was a "Son of the Godhead" – a phrase he said later the media had misunderstood – and the following month told the BBC's Terry Wogan show that the world would soon be devastated by tidal waves and earthquakes. He said the show changed his life, turning him from a respected household name into someone who was laughed at whenever he appeared in public.