# Has the half-life of an isotope ever been accurately predicted before it could be measured?

The half lives of many radioactive isotopes have been measured directly. But are their half-lives known to be a function of their composition?

In other words, can someone say "given an atom with this many protons, neutrons and electrons, and given the known strengths and ranges of the various forces at play inside an atom, we can quantify how unstable such an atom would be by saying that a collection of them would have a half-life of X"?

Has such a prediction ever been made about an isotope before people had encountered it, then later borne out by experiment?

• I think the answer is probably technically no: it was not until fairly recently that we knew bismuth is actually radioactive, albeit with a ludicrously long lifetime. But this is an excellent question, particularly if lifetimes are restricted to a billion years or so. – Ed V May 26 at 2:49
• Actaully $^{209}\ce{Bi}$ would seem to be an example. Theorists had evidently long suspect that the isotope was radioactive. See for example: "A SEARCH FOR α-PARTICLES FROM THE DECAY OF Bi209" E. P. Hincks and , C. H. Millar, Canadian Journal of Physics, 1958, 36(2): 231-251, doi.org/10.1139/p58-027 – MaxW May 26 at 5:17
• @Mithoron My apologies if my question doesn't meet your standards. I'm very much a beginner. My motivation: decay rates are used in radiometric dating, and young earth creationists sometimes allege that decay rates may have changed. I'd like to know if there exists a function that can accurately tell us the half life of any isotope based on its structure and the basic nuclear forces, such that half lives can't have changed unless nuclear forces have. An accurate prediction would be strong validation for such a function. I would leave quantifying the accuracy to the judgment of respondents. – Nathan Long May 26 at 13:52
• Other options would be the relatively recently created elements, but there good accuracy of the predicted lifetimes is getting within an order of magnitude. – Jon Custer May 26 at 14:10
• @NathanLong - Don't waste any effort trying to convince young earth creationists that their belief is wrong. They have seen "The Flintstones" on TV and know that people and dinosaurs roamed the earth together. Corollary:"Never try to teach a pig to sing. It frustrates you and annoys the pig." – MaxW May 26 at 20:03