The Large Hadron Collider has spent the past two years being upgraded . It's a huge machine, and it takes up an entire city block in Geneva ( Switzerland ).
The Large Hadron Collider has spent the past two years being upgraded . It started operation again today and will soon have nearly twice as much energy as it used to . The restart was delayed for nearly two weeks by a short circuit . Scientists hope to unravel the mysteries of dark matter , which makes up 84 % of the universe but has never been detected before .