 Russian discoveries and inventions in physics include the electric arc, electrodynamical Lenz's law, space groups of crystals, photoelectric cell, superfluidity, Cherenkov radiation, electron paramagnetic resonance, heterotransistors and 3D holography.Lasers and masers were co-invented by Nikolai Basov and Alexander Prokhorov, while the idea of tokamak for controlled nuclear fusion was introduced by Igor Tamm, Andrei Sakharov and Lev Artsimovich, leading eventually the modern international ITER project, where Russia is a party.Since the time of Nikolay Lobachevsky (the "Copernicus of Geometry" who pioneered the non-Euclidean geometry) and a prominent tutor Pafnuty Chebyshev, the Russian mathematical school became one of the most influential in the world.