Two mysterious ingredients – dark matter and dark energy – make up 95% of the Universe, yet we still do not understand what they actually are. Join three leading cosmologists as they discuss the quest to uncover their true nature. From the largest scales imaginable, mapping the cosmic microwave background and the three-dimensional distribution and shapes of galaxies across the sky, down to the smallest, studying dwarf galaxies and the delicate streams of stars torn from them by gravity, researchers are gathering clues from every corner of the cosmos. Along the way, intriguing cracks have appeared in our standard model of the universe – including the puzzling mismatch between different ways of measuring how fast the Universe is expanding today. A new generation of cutting-edge surveys is coming online to sharpen these measurements. Could they resolve the puzzle, or reveal that our understanding of the Universe is really in crisis? Find out from three of the field's biggest names: Prof. George Efstathiou (Kavli Institute for Cosmology, Cambridge) Prof. Wendy Freedman (University of Chicago) Prof. Risa Wechsler (Stanford / KIPAC)