Vol. 4, Issue 1, Part F (2018)

Dark Energy is one of the most challenging problem in Physics. Recent research work suggest that the whole universe is expanding in an accelerated frame. Dark energy explains the cause behind. Many cosmological observations indicated that the universe is expanding. By studying supernovae type Ia (SNe Ia), it was found that the expansion of the universe is speeding up rather than slowing down, as was expected if only matter and radiation were present. The force responsible for this 'anti-gravity' is termed as 'dark energy'. Dark energy or cosmological constant or quintessence is an unknown form of energy. This is the dominant component of the physical Universe. This is supposed that the dark energy permeates all the space which accelerate the expansion of the universe. Distant galaxies appear to be moving away from us at high speed: the idea is that the universe is getting bigger and has been since the Big Bang. It has become apparent that the Earth, the planets, the stars and everything we are familiar with, make up only a tiny 4.9% of the total matter and energy in the universe. Increasingly dependable evidence from gravitational lensing, galaxy rotation curves and studies of the cosmic microwave background radiation (CMB) indicates that non-baryonic cold dark matter (CDM) makes up about 26.8% of the rest, but the remaining 68.3%, the dark energy, has not been satisfactorily explained. And other components such as neutrinos and photons contribute a very small amount. Again on a mass–energy equivalence basis, the density of dark energy (6.91 × 10−27 kg/m3) is very low, much less than the density of ordinary matter or dark matter within galaxies. However, it comes to dominate the mass–energy of the universe because it is uniform across space. Besides discussing the origin and nature of dark energy, this paper overviews the various models of dark energy and investigates the theoretical options for conversion of dark energy into usable energy. Besides discussing the origin and nature of dark energy, this paper overviews the unified field theory and investigates the theoretical options for conversion of dark energy into usable energy by considering the dark energy as a property of gravity.