The concept of Dark Energy goes back to Issac Newton, although he did not use the term "Dark Energy", he stated that energy has to exist to provide the gravitational force that keeps the fastest stars and galaxies confined within their orbits. Dark Energy is a hypothetical form of energy and describes the energy that must fill empty space to be able to accelerate the expansion of the Universe. Comparable to an electric or magnetic field, Dark Energy is a change in the physical laws of gravity.
Newton considered a force of attraction, or energy that varies with distance between set points. This consideration, linked with Albert Einsteins' Cosmological Constant equation in his General Relativity Theory, leads to a possible relation between the constant in the equation and the total mass of the Universe. According to Einsteins' Theory of General Relativity, all forms of energy contribute to gravitation and demonstrate the time, matter, and space continuum which is influenced by whatever energy is present. Einstein was the first to realize that empty space is not really empty at all but can have its own energy which makes it possible for more space to come into existence. He introduced the Cosmological Constant into his equation to allow for a static Universe, neither expanding nor contracting but later dismissed the constant which would prove to be a mistake in judgement in the context of understanding his equation.
In 1998, Los Alamos mounted the largest sky survey in history. In this survey they found that 70% of the Universe is made up of this galactic phenomena and Tim Schrabback, of the Leiden Observatory in the Netherlands, led a group of astronomers in an intense study conducted with Hubble of over 446,000 galaxies, which allowed independent confirmation that the expansion of the Universe is accelerated by the component of Dark Energy. The groups findings confirmed Einsteins' Theory of Relativity and the expansion of the Universe.
According to recent theories, Dark Energy has always existed and exerted the same force that it does now but in the early times of the Universe all matter was closer together with gravity slowing the expansion. Scientists believe that the density of matter became low enough to allow Dark Energy to accelerate the expansion of the cosmos. The study into dark energy has prompted the scientific community to re-employ Einsteins' theory to account for the effects of this unseen energy. The study has proved many of Newtons' theories on the laws of motion and attraction as well as Einsteins' Cosmological Constant and General Relativity Theory by strongly suggesting that the effects of Dark Energy is constant over time and space and is driving distant galaxies further away.