Nuclear Decay Rates

From the half life of an isotope we may calculate the probability that any atom will not decay in a given time period. Do we have any idea how this probability arises? For example, Carbon 14 has a half life of approximately 6000 years which gives each atom a probability ~0.99988 of not decaying in a year. What causes this slight instability?
- Chris Oldman (age 64)
Cheltenham, Gloucestershire, England

The basic decay mechanism is quantum tunneling. The rates depend strongly on the energy of the intermediate state on the way toward decay.  The nuclear physicists understand nuclear structure well enough to approximately calculate some of those decay rates.  

It's interesting that you ask about ¹⁴C. If I remember right, some theorists in the late 1930's at first refused to believe the data on the experimental decay rate, because they had calculated a much faster rate. The calculations now are much closer, and are still being refined.

Mike W.

(published on 01/06/2014)