Condensed matter physics studies how huge numbers of interacting particles give rise to collective behaviour that no single particle shows on its own — superconductivity is the textbook example. This simulator renders a small crystal lattice as a grid of ions and lets you cool it through its critical temperature in real time. Above Tc, free electrons scatter randomly off the vibrating lattice, exactly like current through an ordinary resistive wire. Cross below Tc and the electrons condense into Cooper pairs that flow around the sample as a single persistent current with zero measured resistance. Push the applied magnetic field past the material's critical field while it is cold and watch the condensate quench back to a normal conductor — the same competition between temperature and field that limits every real superconducting magnet, from MRI scanners to fusion-reactor coils.