Dark Energy

What is dark energy? Theorized force opposing gravity. This force would accurately explain the current accelerating expansion of the universe. Possible it might be related to the inflation period of the early universe.

Supporting Evidence Measurement of supernovae type Ia, SN1997ff, actually predicted to be brighter than it appears in space, thus providing evidence that universe is expanding.

other Defining Properties Dark Energy is said to be uniform through out space

Supporting Fact CMB anisotropy indicate the universe is flat. Thus, matter density + energy density = critical density. But, matter density only contributes 1/3 of the critical density! So, in order for energy density to have escaped detection it must be distributed uniformly.

Importance of Dark Energy Currently it is estimated that the composition of the universe is approx. 70% dark energy 25% dark matter 2-5 % matter (stars, H, He, neutrinos, heavy elements)

Importance of Dark Energy Possibly predict the future of the universe. If repulsion from dark energy becomes strong, could potentially lead to a Big Rip. Or, a variable dark energy might fade away and then flip into a future that pulls the universe together rather then pushing it apart, into a Big Crunch

References Dark Energy and the New Cosmology, http://supernova.lbl.gov/~evlinder/turner.pdf Dark Energy by Wikipedia http://en.wikipedia.org/wiki/Dark_energy