Dark energy (not to be mistaken with dark matter) makes up approximately 68% of the universe, and it is distributed evenly not only in space, but also in time (therefore it has a global effect on the universe as a whole). This is a repulsive force, that accelerates the expansion of the universe. The rate of expansion and its acceleration can be measured by observations based on the Hubble law. The existence of dark energy is proven and its role in the universe can be described thanks to Albert Einstein’s theory of general relativity.
Example Sentence(s):
"Dark energy is generally accepted as contributing to the increased acceleration of the expanding universe, so understanding this relationship will help to refine how physicists and astrophysicists understand it."
"And there are still no final answers to the questions surrounding dark energy."
