At http://phys.org/print354867536.html … begins, 'we know that our universe is expanding at an accelerating rate … but what causes this growth remains a mystery' and the piece then goes on to suggest dark energy is responsible.
The 'Physics of the Accelerating Universe Camera (PAU Cam) will look for answers by mapping the universe in an innovative manner. It will reecord the positions of some 50,000 galaxies at once. Developed by a consortium of Spanish research institutions it was successfully tested out in June (2015). The idea is to find out if the expansion of the universe is speeding up – as claimed recently. However, the PAU Cam camera will work alongside and with computer models. These all assume the universe is expanding. They also assume the universe is around 13.7 billion years old.