Dark Energy
The mysterious force that makes the universe expand at ever increasing speed. At the start of the twentieth century, scientists believed that the universe was of a constant size and held in place by gravity. When Albert Einstein formulated the general theory of relativity he acknowledged it as " The cosmological constant" because his other findings contradicted the convention of a static universe. In the 1920s U.S astronomer Edwin Hubble discovered through observation of the red shift of light from distant galaxies that, far from being static, the universe is expanding. This prompted Einstein to declare the cosmological constant his "greatest blunder". It was then assured that the rate of expansion would be slowing as gravity pulls galaxies towards each other. However, in 1998 three astrophysicists - Americans Adam, Reiss, and Saul Perlmutter and Australian Brian Schmidt - discovered that the expansion was accelerating. This necessitated the reintroduction of the ...