Dark Energy – From Extensions of Gravity to Supernovae

Over the past 20 years, overwhelming evidence has accumulated that the expansion of the Universe is accelerating. This is a big puzzle for cosmologists, since according to our current understanding of gravity (given by Einstein's theory of General Relativity), a Universe filled with just matter and radiation (light) should be decelerating. This could be due to a cosmological constant or some other exotic form of anti-gravitating energy, dubbed Dark Energy, which effectively drives the Universe apart. Or, General Relativity could not be the final word on gravity.  
The connector Dark Energy aims to shed light on the cause of the acceleration by studying, both theoretically and using advanced simulations, how the universe and the structure within it evolve in these different scenarios. The result will then be compared with a broad range of observations, from the recession velocities of nearby galaxies measured using Supernovae to the cosmic microwave background.