I was reading a blog where someone stated that the decay of a free neutron is characterized by a 'mean lifetime' but not by a half-life. They went on to indicate that the decay time is not random (in the sense that leads to a true half life) but rather most decay at the mean lifetime (said to be about 15 minutes), and very very few decay at times shorter or longer than this. So if you had a collection of neutrons, they would all be gone (decayed) shortly after the 15 minutes went by (as opposed to the half, then quarter, then 1/8... sequence seen in a half life situation). Is this right? How could that be true, unless the individual neutron "knows" how old it is??