Dark energy
Dark energy is the name given to the force that is believed to accelerate the expansion of the universe. Distant galaxies appear to be moving away from us at high speed: the idea is that the universe is getting bigger and has been since the Big Bang. Measurements are now accurate enough to allow astronomers to tell that these galaxies seem to be accelerating away from us. The universe is expanding at an increasing rate.
Understanding
This faster and faster expansion is not understood by scientists. There are many ideas for what might be causing the rapid expansion. However, at the moment, cosmologists who study it do not have an answer. It is as if there was something there in empty space providing a repulsive force (Anti-gravity) that makes the universe expand. This has been named dark energy.
A 2011 research article sets out the problem for theoretical physics.[1]
Dark Energy Media
Diagram representing the accelerated expansion of the universe due to dark energy.
A Type Ia supernova (bright spot on the bottom-left) near a galaxy
Estimated division of total energy in the universe into matter, dark matter and dark energy based on five years of WMAP data.
The equation of state of Dark Energy for 4 common models by Redshift. *A: CPL Model, *B: Jassal Model, *C: Barboza & Alcaniz Model,*D: Wetterich Model
