The LHC recreates, on a small scale, the conditions of the Universe just after the Big Bang in order to learn why the Universe is like it is today.
ATLAS will investigate why the matter of the Universe is dominated by an unknown type of matter called dark matter.
If the constituents of dark matter are new particles, ATLAS should discover them and elucidate the mystery of dark matter.
It might be that this new particle is the lightest particle
postulated in theories of supersymmetry. You can learn
more about supersymmetry by clicking the link below.