The Age of the Earth

Scientists use the rate of nuclear decay in atoms to measure the ages of very old things like archeological artifacts and even the age of the earth. Using these "radiometric dating" techniques gives an age of the earth, for example, of about 4.5 billion years. The reliability of the method depends on the assumption that the rate of nuclear decay we see today is the same as it has always been throughout earth history. If the rate has changed then the method is going to give an age that's either too high or too low.

A recent study has shown that the rate of decay can be effected by tiny particles called neutrinos produced in enormous quantities by the sun, especially in solar storms. If that's so, then it's possible that the earth is not as old as radiometric dating techniques suggest.

The article is not really about radiometric dating so much as it is about using fluctuations in decay rates to predict solar storms, but if decay rates do fluctuate then we have to wonder how reliable they are in determining very old ages.

Here's the essay's lede:

Radioactive materials decay at a predictable rate — so predictable, in fact, that scientists widely use them to date artifacts and geological objects. That, at least, is the received wisdom, which Jere Jenkins and Ephraim Fischbach, from Purdue University in Indiana, think may need revising. In 2006 Dr Jenkins noticed that the decay rate of the radioactive isotope manganese-54 dipped 39 hours before a solar flare came crashing into Earth's protective magnetic field. Now it seems that the sun might affect other types of decay, too.

As the researchers report in Astroparticle Physics, the decay rate of chlorine-36 increases as Earth approaches the sun. The difference is tiny: the rate fluctuates by less than 1% between the aphelion and perihelion, the points on Earth's orbit when it is farthest and closest to the sun, respectively. But it is discernible and persistent. As-yet-unpublished data for manganese-54 suggest that isotope follows a similar pattern. If confirmed, the insight might, among other things form the basis of a system for forecasting dangerous cosmic storms.

If - and it's a big if - the techniques that've been used to determine the age of the planet turn out to be unreliable then there are some interesting implications for science and philosophy. If the earth is considerably younger than radiometric techniques indicate then Darwinian evolution could lose its most crucial support - vast stretches of time to allow extraordinarily improbable combinations of genetic changes to become probable. If earth is of relatively recent origin then unguided, purposeless processes simply don't have enough time, even under the most optimistic scenarios, to have brought forth human beings from primordial sludge.