exciting!
Large Hadron Collider restarts after two-year rebuildBy Jonathan Webb Science reporter, BBC News
The Large Hadron Collider has restarted, with protons circling the machine's 27km tunnel for the first time since 2013.
Particle beams have now travelled in both directions, inside parallel pipes, at a whisker below the speed of light.
Actual collisions will not begin for at least another month, but they will take place with nearly double the energy the LHC reached during its first run.
Scientists hope to glimpse a "new physics" beyond the Standard Model.
Rolf Heuer, the director-general of Cern, which operates the LHC, told engineers and scientists at the lab: "Congratulations. Thank you very much everyone… now the hard work starts".
Cern's director for accelerators and technology, Frédérick Bordry, said: "After two years of effort, the LHC is in great shape.
"But the most important step is still to come when we increase the energy of the beams to new record levels."
The beams have arrived a week or so later than originally scheduled, due to a now-resolved electrical fault.
http://www.bbc.com/news/science-environment-32160755