Final Report Summary - FORCE (Fine Observations of the Rate of Cosmic Expansion: Combining the powers of Weak Gravitational Lensing and Baryon Acoustic Oscillations as Probes of Dark Energy) More than 95% of our universe comes in the mysterious form of dark matter and dark energy that we can neither explain nor directly detect. Dr Catherine Heymans lead a team of ERC-funded researchers who were the first to “map” dark matter on the largest of scales and place the tightest cosmological constraints yet on Einstein’s theory of general relativity in an attempt to explain the nature of dark energy.Early in the twentieth century, Einstein revolutionised our understanding of fundamental physics by concluding that mass can warp the very fabric of space and time. Using a powerful new astronomical technique called gravitational lensing, astronomers can observe the way in which the light from very distant galaxies is bent as it passes large structures of matter in the universe.With her FORCE project, Dr Heymans and her collaborators used this light-bending effect to map the invisible dark matter in the universe. They collected the most comprehensive data from one of the world-leading surveys of the universe: the Canada-France-Hawaii Telescope Lensing Survey (CFHTLenS). When analysing the deep astronomical imaging, Dr Heymans and her team looked at the light from over ten million galaxies, some six billion light years away. Their images provided a very first glimpse of the intricate cosmic web of dark matter and galaxies, spanning more than one billion light years across.By combining observations of the motion of galaxies and light in different gravitational fields, Dr Heymans’ team found their measurements to be in full agreement with Einstein’s theory of general relativity. This test provided the tightest large-scale cosmological constraint on the theory of gravity. Progress in probing and mapping the dark universe is likely to have far-ranging implications. It widely believed that, in order to understand the nature of the dark side of our Universe, we will need to invoke new physics that will forever change our cosmic view.
