Nuclear Decay May Vary With Earth-Sun Distance

KentuckyFC writes "We've long thought that nuclear decay rates are constant regardless of 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 two puzzling experiments from the 1980s that found periodic variations over many years in the decay rates of silicon-32 and radium-226. Now a new analysis of the raw data says that changes in the decay rate are synchronized with each other and with Earth's distance from the sun. The physicists behind this work offer two theories to explain why this might be happening (abstract). First, some theorists think the sun produces a field that changes the value of the fine structure constant on Earth as its distance from the sun varies. That would certainly affect the rate of nuclear decay. Another idea is that the effect is caused by some kind of interaction with the neutrino flux from the sun's interior which also varies with distance. Take your pick. What makes the whole story even more intriguing is that for years physicists have disagreed over the decay rates of several isotopes such as titanium-44, silicon-32, and cesium-137. Perhaps they took their data at different times of the year?"

Comments

Re:Carbon Dating

[meringuoid]

I'd expect not. The variation would be over the course of a year, and carbon dating works on a timescale of centuries to millennia; it would even out. Besides that, we have other clocks to calibrate carbon dating against; you can carbon-date a historic artefact of known age, you can count tree rings or ice layers, stuff like that.

On a timescale of billions of years, however, the luminosity of the Sun has increased substantially, and if that accelerates radioactive decays by some neutrino interaction then the uranium-lead clock would be off and the Earth might be considerably older than we thought.

Re:Carbon Dating

[necro81]

I get your joke, but it presents an opening to state the following little known fact:

Diamonds are not, in fact, forever

Under normal temperature and pressure conditions, diamond is not the most stable form of carbon - graphite is. Using thermodynamic arguments and building a free energy curve, one can show that some fraction of a diamond must decay to graphite in order to achieve a minimum energy state. It does take a very long time for this to happen - geologic time - but even a "long time" is not forever. If you aren't that patient, heat the diamond up to, say, 1500 C to speed things up. Oh, but be sure to do that in the absence of oxygen, because diamond burns just like other forms of carbon.

Some references: [1], [2], [3]

Re:Engineering Ramifications?

[AliasMarlowe]

If I understood correctly, the variance in decay rate between Earth's aphelion and perihelion is .1%. Earth's distance from the sun doesn't change by that much in astronomical terms...

But Earth's distance from the sun does change by more than 0.1% during its orbit:
Aphelion distance = 152.1 million km
Perihelion distance = 147.3 million km
So aphelion distance from the center of the sun is 3.2% greater than perihelion distance. Alternatively, both aphelion and perihelion differ from their mean by 1.6%.