A post at physics forums has just pointed out to me a fascinating new article on arXiv that one shows that the radioactive decay rate of certain isotopes depends on what time of year one makes the measurement.
A new article, Evidence for Correlations Between Nuclear Decay Rates and Earth-Sun Distance by Jere H. Jenkins, Ephraim Fischbach, John B. Buncher, John T. Gruenwald, Dennis E. Krause, and Joshua J. Mattes, August 25, 2008, suggests that the different decay rates, which have been observed by laboratories in the US and Germany, on Si-32 and Ra-226, are correlated with the distance to the sun, and therefore, to the flux of neutrinos. However, in both sets of data there is a lag which suggests an effect due to the gravitational potential of the sun (which would be modified by the gravitational potential of the local galaxy stars), or perhaps local motion relative to a preferred reference frame. Either way, this is not good news for Einstein.
Relativity as an Anthropic Theory
As creatures of incredibly complicated biochemistry, which involves very large numbers of very carefully constructed molecules, our lives depend on the laws of physics as much as they depend on the earth not getting too close or too far away from the sun.
For these reasons, it’s not surprising that early estimates of the distance from the earth to the sun concluded that it was constant. If we lived on a planet with a very eccentric orbit, well, life would have been that much harder to evolve. As creatures we need very stable environments. So it’s a natural consequence that our planet has an approximately circular orbit. And since our minds appreciate symmetry, our early astronomers naturally assumed that our orbits were perfect circles. It was only when more careful measurement came along that the corrections to ellipses could be made.
And, if our universe did not have at least an approximation of Lorentz invariance, our biochemistry would be at the mercy of our absolute speed as measured by the “preferred reference frame”. So the early measurements showing that the speed of light does not apparently depend on direction were not so surprising. Life needs stability to evolve.
Similarly, if life was very sensitive to gravitational potentials, then we’d have difficulty as we increased or decreased in altitude. Thus the special and general theories of relativity can be thought of as anthropic theories. They are not surprising because these symmetry principles need to be at least approximately obeyed in order to provide a stable environment for life.
On the other hand, we should not be too surprised when these symmetries that we thought were exact turn out to be, like the circular orbits of long ago, only approximations.
Violations of Relativity
Given that there is small violations of relativity, which forces would be expect them to be first seen in?
The electromagnetic force is decisively important for life and it should be difficult to measure relativity violations in it. But the weak and strong forces don’t need to be so stable so it’s not too surprising that our first measurements of violations of relativity would occur with nuclear decay.