Marvin Edwards
Veteran Member
We have been looking for a cause for radioactive decay for over a century. All our best efforts, and all our best theories, say that it's uncaused - it just happens with a probability that depends only on the isotope under consideration, giving each radioactive isotope a specific and unalterable half life.
We can say with certainty what will happen to a large accumulation of a radioisotope, but can say nothing with certainty about the fate of a single nucleus. A given 238U nucleus has a 50:50 chance of decaying sometime in the next ~4,500,000,000 years. It could be today, or it could be eight eons or more from now. And as far as we know, there's no cause; no event that leads to this decay now rather than then. Lots of effort has been expended on trying to influence decay rates of radionuclides, but short of direct interventions such as neutron bombardment to transmute the nucleus to an isotope with a different half-life, none has been successful.
Assuming that there must be a hidden cause is purely a personal preference; It has no basis in any current physics. Indeed, given our abject failure, it's seeming increasingly likely that radioactive decay is (for individual nuclei) uncaused and random. The randomness aggregates to a predictable probability for very large numbers of events, and as macroscopic quantities of anything contain vast numbers of atoms, this indeterminate system translates to a fairly predictable macroscopic world. But not a fully determined one.
Okay, so it sounds like we do know something about the causes of radioactive decay. You mentioned that neutron bombardment of the nucleus can speed up the decay by converting it to a different isotope with a different half-life. If I may ask, doesn't radioactive decay do the same? I mean, doesn't decay convert the specimen to a new isotope?
I just visited the Wikipedia article on radioactive decay, and it suggested that the weak force interactions are responsible for beta-decay. So, I'm a little confused as to why we would consider these events uncaused. It sounds more like the issue is the unpredictability as to when these events take place. After all, they are happening in the nucleus, and I don't think anyone is observing and taking notes on these events. So, we cannot assume they are not reliably caused, we can only assume that when and where it will happen is unpredictable.