It's a socking great physics experiment.
They're speeding up teeny bit of stuff in a huge underground tunnel to really really fast, smacking them into one another and seeing what happens.
CERN
It's a bit like how toddlers find out about the expensive stuff.
DDs getting on well - was a bit concerned when she came home in borrowed trousers today but it turned out she'd just been a bit enthusiastic with the water play ...
DD2's really jealous though. She gets really upset cos I take her into a hall full of toys then bring her straight home. And repeat 2 1/2 hours later!