‘Here’s an interesting conundrum involving nuclear decay rates.
We think that the decay rates of elements are constant regardless of the ambient conditions (except in a few special cases where beta decay can be influenced by powerful electric fields).
So that makes it hard to explain the curious periodic variations in the decay rates of silicon-32 and radium-226 observed by groups at the Brookhaven National Labs in the US and at the Physikalisch-Technische Bundesandstalt in Germany in the 1980s.
Today, the story gets even more puzzling. Jere Jenkins and pals at Purdue University in Indiana have re-analysed the raw data from these experiments and say that the modulations are synchronised with each other and with Earth’s distance from the sun. (Both groups, in acts of selfless dedication, measured the decay rates of siliocn-32 and radium-226 over a period of many years.)
In other words, there appears to be an annual variation in the decay rates of these elements.’