Observations show that almost everything in the universe is moving away from us and that the further away something is the faster it is moving away. Hubble demonstrated that the redshift of light from galaxies was linearly correlated with their distance with a constant of proportionality now known as Hubble's constant. However, during the late 1990s, observations of type Ia supernovae suggested that the expansion of the universe is accelerating.
So not only is dark matter invoked to explain the dynamics of galaxies but now dark energy is invoked to explain the accelerating expansion of the Universe by opposing the force of gravity! These dark materials overwhelm the directly observable substance of the cosmos:
