I assume you are familiar with the recent Purdue University and Israel Geological Survey studies? Here are some links:
Decay is affected by the sun's core:http://arxiv.org/abs/1205.0205
Decay is affected by solar flares:Solar Flares, Radioactive Decay, and The Age of the Earth - eNews for March 05, 2013
Only short-life isotopes have been mentioned in those studies, the effects on the longer life isotopes, those used to measure earth's earliest rocks, are not discussed. But what can be seen is that there is a negative relationship between speed of decay and penetration of the earth's magnetic field. Slight changes to penetration (flares/seasons/suns core) cause slight changes to decay rates.
Yes, I'm familiar with Fischbach's claims. Some comments:
1) Fischbach has been involved with other crazy-sounding theories going back many years, such as a search for a "fifth force".
2) Fischbach is largely a phenomenologist. This means that he starts with the experimental data of others and tries to find patterns that they have missed. The danger is that a phenomenologist is not intimately familiar with the experiments. Often the phenomenologist is the one who is missing things, not the original experimenters. And a phenomenologist rarely has a theoretical justification for his suggestions.
3) when I looked into Fischbach's claims a few years ago, I found that others had claimed to disprove him, and that he had claimed to disprove them, and that this went back and forth. At the least, this causes extreme doubt for his claims. (sorry; I can't find these references in the limited time that I have at the moment. Maybe someone else can find and post links to them?)
4) my tentative explanation for the very small periodic signals that Fischbach saw in the BNL decay data is a changing measurement sensitivity, not a changing decay rate. I suspect that the detectors (plastic scintillators?) that they used to measure the decay had a slight sensitivity to temperature or humidity, causing a seasonal variation in the decays that they were able to detect.
Edited by kbertsche, : No reason given.
"Science without religion is lame, religion without science is blind." — Albert Einstein
I am very astonished that the scientific picture of the real world around me is very deficient. It gives us a lot of factual information, puts all of our experience in a magnificently consistent order, but it is ghastly silent about all and sundry that is really near to our heart, that really matters to us. It cannot tell us a word about red and blue, bitter and sweet, physical pain and physical delight; it knows nothing of beautiful and ugly, good or bad, God and eternity. Science sometimes pretends to answer questions in these domains, but the answers are very often so silly that we are not inclined to take them seriously. — Erwin Schroedinger