1Yup that's right. They are indeed accelerating particles at extremely high speeds. Well put it this way, it is both a test for previous theories on quantum physics as well as ground for hundreds more ground breaking discoveries. It really is change at its best.
Quantum Physics asks the stupidest and therefore deepest questions about nature. For example, what really gives matter its mass?
I read about one 'Higgs' particle which is postulated to be present at the time of big bang. The experiment would check its validity.
And think about the possibility that there wouldn't be any such thing. Imagine being told that all the impressions of the universe have been wrong, and further moving on to discover what is it the true nature then!
If you are wondering whether such technical stuff is going to be of any practical use, consider this. People thought the same when Michael Faraday first discovered induction of electricity via changing magnetic fields.