In Current Science, dark energy is an unknown form of energy hypothesized to exist and cause the accelerating expansion of the universe. The need is to explain the observed increase in redshift of distant Type 1a supernova.
Dark energy is claimed to permeate all space with a constant density that is maintained despite the increase in cosmic volume due to the metric expansion of the universe as presumed by the Hubble redshift of distant galaxies.
This is taken to mean that as the universe expands the proportion of dark energy relative to matter is continuously increasing. Energy from the “vacuum” is continuously being added into the universe increasing its total energy content!
At the present moment of cosmic history dark energy is hypothesized to represent 73% of the total mass/energy of the universe. This percentage was smaller in the past and will be greater in the future.« Back to Glossary Index