Lars Vegard: key communicator and pioneer crystallographer

The Norwegian physicist Lars Vegard studied with William H. Bragg in Leeds and then with Wilhelm Wien in Würzburg. There, in 1912, he heard a lecture by Max Laue describing the first X-ray diffraction experiments and took accurate notes which he promptly sent to Bragg. Although now remembered mainly for his work on the physics of the aurora borealis, Vegard also did important pioneering work in three areas of crystallography. He derived chemical insight from a series of related crystal structures that he determined, Vegard's Law relates the unit-cell dimensions of mixed crystals to those of the pure components, and he determined some of the first crystal structures of gases solidified at cryogenic temperatures.