How accurate are radiometric dating methods
A helium balloon, for example, will deflate over time, because the helium atoms diffuse through the balloon and into the surrounding air.Well, diffusion depends on the mass of the thing that is diffusing. Hayes has brought it up, we can take it into account, right?Most likely, the effect will be dependent on the age.I would think that the older the sample, the larger the overestimate.This newly-pointed-out flaw in the isochron method is a stark reminder of that.A good isochron was supposed to be rock-solid evidence (pun intended) that the radioactive date is reliable. I suspect that this flaw is not the last one that will be uncovered.
Of course, that error estimate is complete nonsense.
Such uncertainties are usually glossed over, especially when radioactive dates are communicated to the public and, more importantly, to students.
Generally, we are told that scientists have ways to analyze the object they are dating so as to eliminate the uncertainties due to unknown processes that occurred in the past. Hayes has pointed out a problem with isochrons that has, until now, not been considered.
If some process brought Sr-87 into the rock, it probably brought different amounts of the atom into different parts of the rock, so the ratio of Sr-87 to Sr-86 won’t stay consistent from one part of the rock to another. He says that there is one process that has been overlooked in all these isochron analyses: diffusion.
If a consistent isochron is generated, however, we can be “certain” that no process interfered with the relative amounts of Rb-87 and Sr-87, so the radioactive date is a good one. Atoms and molecules naturally move around, and they do so in such as way as to even out their concentrations.