Before Present (BP) years is a time scale used mainly in geology and other scientific disciplines to specify when events in the past occurred.his usage differs with the recommendation by van der Plicht & Hogg, followed by the Quaternary Science Reviews, both of which requested that publications should use the unit  a  [for year] and reserve the term BP for radiocarbon estimations.
The standard model of cosmology indicates that the total massâenergy of the universe contains 4.9% ordinary matter, 26.8% dark matter and 68.3% dark energy. Thus, dark matter constitutes 84.5% of total mass, while dark energy plus dark matter constitute 95.1% of total massâenergy content.
Another explanation for dark energy is that it is a new kind of dynamical energy fluid or field, something that fills all of space but something whose effect on the expansion of the universe is the opposite of that of matter and normal energy.