Clara Nellist answered on 16 Mar 2014:
We know that everything around us is made from particles. Some of these particles we’ve known about for a long time, such as electrons and protons, and others we have only recently confirmed the existence of, such as the Higgs boson. To study these particles, first we need to create them and to do that, we need a lot of energy! Particle accelerators, like the Large Hadron Collider at CERN, take small particles (in this case, protons), make them travel at almost the speed of light and then smash them together to create this energy. From the energy, our new particles are created and now we can study them!
Being able to study these new particles in a controlled way is really important to expand our understanding of the universe. We still have a lot about the universe that we don’t understand yet.
One example is antimatter. Normal matter is made from particles like electrons and protons. Antimatter is made from antiparticles which are apparently identical to particles, but they have the opposite charge. So the antiparticle of the negatively charged electron is the positively charged positron. We think that the same amount of matter and antimatter was created at the beginning of the universe. If this was the case, then matter and antimatter should have all met up and when it does this there is a massive ANNIHILATION and only light is left. So why are we still here? This is what the LHCb experiment on the LHC at CERN is trying to work out. They’re trying to find a difference between matter and antimatter that could explain why slightly more matter survived and this would tell us a lot about how the universe works.
Another question is what is dark matter? We’ve seen from studying space that there is more mass in galaxies than we think there should be. We call this dark matter because we haven’t seen it yet. From our measurements there’s about 4 times more dark matter than normal matter – so that’s a lot of stuff to not understand! We don’t know what this dark matter is, but some scientists think that it comes from a whole new set of particles we haven’t seen yet. To test this, we’re trying to find evidence of them in the new particles we create at the LHC at CERN!
Thomas Elias Cocolios answered on 16 Mar 2014:
The LHC has been designed to recreate the sort of energies that were present in the universe in its very early stage.
By colliding protons, we are able to destroy their matter and turn that into energy from which new particles may emerge. This has allowed us, amongst other things, to produce Higgs bosons: that particle was the last piece to complete the Standard Model of particle physics, a model that unifies our understanding of the constituents of matter.
But much more can be achieved at the LHC, such as the search for anti-matter that Clara has described below. Another is the search for the state of the universe even before particles, such as protons & neutrons. That primordial ‘soup’ is called a quark-gluon plasma. The quarks and gluons are particles that cannot be found on their own anymore: they must be bound, either by 3 (like in the protons & neutrons) or by 2 (making particles called ‘mesons’). However, by colliding lead nuclei against each other at the LHC, a sufficient amount of energy is released to allow the quarks and gluons to temporarily be released from their shackles, a phenomenon we call ‘deconfinement’. In particular, the ALICE detectors at the LHC has been especially designed to study this process.