to neutrino, neutron, or cosmic radiation could have greatly changed isotopic ratios or the rates at some time in the past." It is known that neutrinos interact with atomic nucleii, so a larger density of neutrinos could have sped up radioactive decay and made matter look old in a hurry. Some more quotes from the same source: a. In the lead-uranium systems both uranium and lead can migrate easily in some rocks, and lead volatilizes and escapes as a vapor at relatively low temperatures. It has been suggested that free neutrons could transform Pb-206 first to Pb-207 and then to Pb-208, thus tending to reset the clocks and throw thorium-lead and uranium-lead clocks completely off, even to the point of wiping out geological time. Furthermore, there is still disagreement of 15 percent between the two preferred values for the U-238 decay constant. b. In the potassium/argon system argon is a gas which can escape from or migrate through the rocks. Potassium volatilizes easily, is easily leached by water, and can migrate through the rocks under certain conditions. Furthermore, the value of the decay constant is still disputed, although the scientific community seems to be approaching agreement. Historically, the decay constants used for the various radiometric dating systems have been adjusted to obtain agreement between the results obtained. In the potassium/argon system another adjustable "constant" called the branching ratio is also not accurately known and is adjusted to give acceptable results. Argon-40, the daughter substance, makes up about one percent of