For its 2019 New Year Public Lecture, Astronomy Ireland has chosen the biggest problem in science today - what is the Dark Matter and Dark Energy that makes up 95% of the Universe and determines how everything has unfolded to where we are today? Dr. Ben Elder from Nottingham University will summarise how we know both these huge sections of the universe exist, and what astronomers are doing to try to solve the biggest conundrum in science. He'll even present a radical new theory that many are working on that may solve the puzzle albeit at the sacrifice of the work of historical giants of science like Newton and Einstein.