The Large Hadron Collider at CERN carries out nucleus-nucleus collisions and proton-nucleus collisions at unprecedented energies. I review some of the key observations in these experiments, and I explain why they are interesting from a theoretical point of view. I discuss in more detail the anisotropies in particle distributions: these anisotropies originate from quantum fluctuations in the projectiles, followed by expansion into the vacuum, much in the same way as the anisotropies of the cosmic microwave background of the Universe, thus drawing an interesting parallel between high-energy physics and cosmology.

IPhT Saclay