Graham P Smith on the challenge of redefining 'big' in a dark universe.
Humankind faces an intriguing and exciting truth at the beginning of the 21st century. Data from our most powerful and innovative telescopes is consistent with the overwhelming majority of the matter and energy in our Universe being invisible – the so-called dark matter and dark energy. Indeed, the only direct evidence for these fundamental constituents of the Universe comes from astronomical observations. The evidence comes literally from pointing ever more powerful telescopes at the night sky, and peering deeper and deeper into outer space.