Nuclear magnetic resonance in condensed matter was discovered simultaneously by Edward Purcell at Harvard and Felix Bloch at Stanford in 1946 using different instrumentation and techniques. Both groups observed the response of magnetic nuclei, placed in a uniform magnetic field, to a continuous radio frequency magnetic field as the field was tuned through a resonance. This discovery opened up a new form of spectroscopy which has become one of the most important tools for physicists, chemists, geologists, and biologists.