Wednesday, 11 January 2012
Einstein on Emptiness
In Einstein's theory of the universe, the 12 field equations include a cosmological constant (Λ) that corresponds to an energy density of empty space. Depending on its sign, the cosmological constant can either slow (negative Λ) or accelerate (positive Λ) the expansion of the universe. Recent research on supernovae has detected a large amount of "dark energy" that is accelerating the universe's expansion. It is unlikely that this dark energy corresponds to a positive Λ, although alternative theories cannot be ruled out as yet. Russian physicist Zel'dovich suggested that Λ is a measure of the zero-point energy associated with virtual particles of quantum field theory, a pervasive vacuum energy that exists everywhere, even in empty space.