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.
Whatâs the Difference Between Dark Matter and Dark Energy? Dark matter and dark energy are the yin and yang of the cosmos. Dark matter produces an attractive force (gravity), while dark energy produces a repulsive force (antigravity). Together, they make up 96 percent of the universeâand we canât see either. Astronomers know dark matter exists because visible matter doesnât have enough gravitational muster to hold galaxies together.