ALICE (A Large Ion Collider Experiment) is a dedicated heavy ion experiment at Large Hadron Collider (LHC) at the European Center for Nuclear Research (CERN). The goal of the experiment is to study strongly interacting matter at extreme energy densities (QCD thermodynamics). Statistical QCD predicts that, at sufficiently high densities, there will be a transition from hadronic matter to a strongly interacting plasma of deconfined quarks and gluons -- a transition which the early universe passed in the first instances after the Big Bang. At the LHC, two beams of heavy ions collide with the speed close to the speed of light, and for a very short instances of time the plasma of quarks and gluons is created. The complex system of ALICE detectors register those "little Big Bangs" allowing to broaden the boundaries of our contemporary knowledge. In my talk, I discuss general picture of heavy ion collisions, giving some overview and motivation for studying heavy-ion physics. Giving place to my research work, I focus on functioning and physics of one of the two ALICE electromagnetic calorimeters, EMCal. Afterwards, I discuss ALICE results on neutral meson measurements.