Neutrons normally exist inside the nucleus of an atom. If the nucleus is stable, the lifetime of the neutron is theoretically forever. Outside of a nucleus, however, things are very different. Due to interactions with other bits of matter, neutrons decay to other particles after about 15 minutes. Physicists and other scientists would like to nail down that decay to a very precise number—doing so would help in developing theories about what occurred just after the Big Bang, for example. The problem is, scientists currently have just two different ways to measure the decay and the answers the two return differ by so much that either the measuring techniques have to be improved, or the theories changed to reflect a different reality. Current research is leaning, quite naturally, towards the first approach.
Read more at: Phys.org