Radioactive Decay Rates May not be Constant After All

This is a direct copy of a SciPop or news article preserved here because things on the internet have a bad habit of disappearing when you try to find them again. Full credit is given to the original authors and the source.

– Matty

One of the first things that Physics students learn when they study radioactivity is the idea of the half-life. 

A half-life is the period of time in which it takes one-half of a given amount of a radioactive substance to decay. Radioactive decay happens when a radioactive substance emits a particle. It’s impossible to predict exactly when a given atom of a substance will emit a particular particle, but the decay rate itself over a long period of time is constant.

Or, at least, that’s what we thought.  But if physicists at Stanford and Purdue are correct in their findings, the whole theory of constant radioactive decay rates could be thrown out the door.

The story begins, as scientific discoveries often do, randomly.  Literally, in this case.  The team of physicists was investigating the possibility of using radioactive decay rates to generate random numbers, since the rate is constant but the emission of individual atoms is unpredictable, it seemed like a perfect fit.

Then came the problem:

As the researchers pored through published data on specific isotopes, they found disagreement in the measured decay rates – odd for supposed physical constants.

Checking data collected at Brookhaven National Laboratory on Long Island and the Federal Physical and Technical Institute in Germany, they came across something even more surprising: long-term observation of the decay rate of silicon-32 and radium-226 seemed to show a small seasonal variation. The decay rate was ever so slightly faster in winter than in summer.

Was this fluctuation real, or was it merely a glitch in the equipment used to measure the decay, induced by the change of seasons, with the accompanying changes in temperature and humidity?

As it turns out, they probably aren’t.

After poring over the data, engineers and physicists noted a recurring pattern 33 days long that affected the decay rates of the various radioactive substances. That’s a pattern that corresponds to the rotation of the Sun’s core. Which got the physicists to thinking that maybe the sun was involved. But the only explanation that makes sense would be solar neutrinos — which leads to a result that means, as one of the researchers observed, “What we’re suggesting is that something that doesn’t really interact with anything is changing something that can’t be changed.”

If it’s not neutrinos, then it may be that the sun is emitting some other mystery particle heretofore unknown and unpredicted.

In the meantime, it remains to be seen how these findings will affect the use of radioactive decay in technological applications. For example, if radioactive decay isn’t constant, then adjustments will have to be made for its use in dating materials, especially in the case of Carbon-14 dating. And doctors may need to look into adjusting radiation doses for cancer therapies, as they are, in part, based on radioactive decay rates.

This finding is just one more reason why I love reading about physics.  Just when you think you’re starting to get a handle on the universe, the universe lets you know that reality is stranger than you thought.

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