Torsion balance
Researchers at the University of Washington have used a spin-polarized torsion pendulum to carry out highly sensitive tests of Lorentz symmetry. The actual device (left) measures about 3 cm in diameter and is shielded by a metal cylinder. The pendulum consists of a stack of flat-faced toroids, which are formed by segments made from different magnetic materials (blue and green in the schematic). This results in a large total spin - due to some 1022 aligned electron spins - but a negligible magnetic field. The pendulum is suspended by a wire, and the whole device is rotated on a turntable. If Lorentz symmetry is broken, then anomalous spin-dependent interactions can cause small variations in the torque that can be measured with very high precision.