World's Largest Particle Accelerator Starts off Successfully

This isn't directly related to nuclear power but I'm sure many of the readers here could appreciate the significance and relevance of this event. 

From the European Organization for Nuclear Research (CERN):

The first beam in the Large Hadron Collider at CERN was successfully steered around the full 27 kilometres [17 miles] of the world’s most powerful particle accelerator at 10h28 this morning. This historic event marks a key moment in the transition from over two decades of preparation to a new era of scientific discovery.

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Starting up a major new particle accelerator takes much more than flipping a switch. Thousands of individual elements have to work in harmony, timings have to be synchronized to under a billionth of a second, and beams finer than a human hair have to be brought into head-on collision. Today’s success puts a tick next to the first of those steps, and over the next few weeks, as the LHC’s operators gain experience and confidence with the new machine, the machine’s acceleration systems will be brought into play, and the beams will be brought into collision to allow the research programme to begin.

What is the purpose of the LHC?

The Large Hadron Collider (LHC) is a gigantic scientific instrument near Geneva, where it spans the border between Switzerland and France about 100 m underground. It is a particle accelerator used by physicists to study the smallest known particles – the fundamental building blocks of all things. It will revolutionise our understanding, from the minuscule world deep within atoms to the vastness of the Universe.

Two beams of subatomic particles called 'hadrons' – either protons or lead ions – will travel in opposite directions inside the circular accelerator, gaining energy with every lap. Physicists will use the LHC to recreate the conditions just after the Big Bang, by colliding the two beams head-on at very high energy. Teams of physicists from around the world will analyse the particles created in the collisions using special detectors in a number of experiments dedicated to the LHC.

There are many theories as to what will result from these collisions, but what's for sure is that a brave new world of physics will emerge from the new accelerator, as knowledge in particle physics goes on to describe the workings of the Universe.

Pretty sweet stuff! For more information, check out the page on Wikipedia.

Update:

Luke Weston at Physical Insights has more to add.