Louis J. Sheehan, Esquire.  It’s nuclear physics 101: Radioactivity proceeds at its own pace. Each type of radioactive isotope, be it plutonium-238 or carbon-14, changes into another isotope or element at a specific, universal, immutable rate. This much has been known for more than a century, since Ernest Rutherford defined the notion of half-life—the time it takes for half of the atoms in a radioactive sample to transmute into something else. So when researchers suggested in August