Underground experiments will look for proton decay

Although we know of no symmetry in nature that requires the conservation of baryon number, the stability of ordinary matter would appear to attest to the absolute stability of the proton. But we're soon to have a closer look. Two groups of high‐energy physicists are preparing to descend into mines in Ohio and Utah, to look for proton decays with detectors several orders of magnitude more sensitive than any employed for such a search in the past.