Forming visible 238U radiohalos in small zircon crystals would require approximately 900 million years to generate 500 million 238U alphas at today’s decay rates. So, the reasonable conclusion is that if 238U radiohalos require at least 500 million decays to generate a visible radiohalo, then either the granitic rocks of the Tertiary and late Paleozoic-Mesozoic eras have been substantially misdated, or there has been a significant increase in the decay rate of 238U sometime in Earth’s past.
Is this a good argument for accelerated radioactive decay in the past?
The circular zone around the radiocenter does not begin to darken until approximately 500 million decays have occurred, and the circular zones become very dark around one billion decays
There is no explanation, no support provided, and no references given for where and how those values were obtained. AFAICT Cupps seems to have made them up himself.
Part of the problem with arguments like the halos is that each one is a “one off” argument. By itself, it has the sound of plausibility to it, but when placed in context of the sum total of evidence, its explanatory power disappears. If interested in the nuances of this particular example, you can check out the first link below. I am generally much more interested in the larger repercussions of such arguments. In this case, leading YEC arguments now call for massive radioactive decay during the creation week (second link). Yes - DECAY - in the midst of a world that is argued to be free of death and decay until man sinned. FULL STOP! While there are myriad problems raised by this (like the heat generated by accelerated decay making the planet uninhabitable for WAY longer than a week), the self-contradiction of the argument should end any further consideration.
A “just so” story is a story told to explain a phenomenon without any evidential support. I did not provide an explanation of radiohalos, but rather pointed out the repercussions of a particular claim (accelerated radioactive decay) in the context of a particular worldview (six-day creation). Not trying to quibble over the nuances of words here - just clarifying what my point was.
Agreed. I was addressing the Answers in Genesis argument concerning radiohalos. They so often complain that various explanations from peer-reviewed science are merely “just so stories”—yet Ken Ham & Co. resort to just so stories on a regular basis.
You are right, Cupps seems to have made them up. I found another source (Snelling, 2014):
According to standard estimates, uranium must eject at least 500 million alpha particles to form a single dark radiohalo. At their current very slow rate of radioactive decay, parent uranium-238 atoms would need nearly 100 million years to produce that many alpha particles. So each uranium radiohalo would require 100 million years to form.
Snelling seems to have quoted Robert Gentry here, the first guy who came up with the radiohalo argument. If this is true, we shouldn’t be able to find any U238 radiohalos in rocks that formed after the Early Cretaceous period. But apparently, we do. So what’s the reason for this?
Just for fun I found an online copy of Gentry’s original 1986 book Creation’s Tiny Mysteries.
Figure 1.2 Sunburst Effect of Alpha-Damage Trails
Sunburst pattern of alpha-damage trails produces a spherically colored shell
around the halo center. Each arrow represents 5 million alpha particles emitted from
the center. Halo coloration initially develops after 100 million alpha decays, becomes
darker after 500 million, and very dark after 1 billion.
There is no evidence or no citation in Gentry’s book either to support this claim. So we have a YEC citing a YEC citing a YEC who made it up.
I think this is all a red herring. It certainly does require a large number of decays to produce a halo, in the millions.
As I understand it, if one only had static amounts of polonium this would be a problem. However, we know that uranium is constantly generating new polonium (and other daughter products) and that polonium migrates to the center of halos along fissures to continually regenerate polonium, so the total delays over a long period of time are more than you would expect from the amount of polonium observable now. That hypothesis is apparently validated by several patterns in the data.
Now, on the YEC side, they don’t actually have a way to make sense of this, even if we were to grant that it isn’t solved in secular science. A yec timeline is certainly not enough to account for this. Presuming higher rates of decay would raise temperature past the annealing point, erasing the halos altogether. So this is not a case where YEC has presented a better model of the data, just an apparent anomaly they are pointing while ignoring the resolution of the anomaly.
The YEC assessment is correct, which makes the need to explain the halos somewhat of a moot point, at least in the young/old earth context.
What is actually happening probably does involve migration of uranium (and uranium daughter products) to sites of crystal formation where polonium is both produced and decays over millions of years.
Cupps’ other problem is that he only counts alpha production from U-238. He does not account for the decays of the 28-odd other radioactive “daughters” in the decay change, many of which have very short half-lives, hence far more decays/second.
Which raises the following question for the YEC accelerated decay folk. If radioactive decay was accelerated by orders of magnitude, the energies of decay events could not have the same energies we see today, so how would the halos then match the spectrum we expect based on today’s physical constants?. Conversely, stable energies of decay infers constant rate of decay.
Different isotopes = different decay energies different halos. There is no such thing as a “pure” U-238 halo. Even if you started out with a speck of pure U-238 you would end up with a “bullseye” of concentric halos. U-238 has eight alpha-emitters, of which 5 have sufficiently different energy to produce halos that can be observed with an optical microscope.
Fission-track dating is a powerful tool in exploring the timing of erosion and/or uplift of many terranes. Annealing temperatures of many minerals are within the range of natural geotherms of the upper crust, allowing the dating of the most recent cooling of a mineral above the annealing . Apatite, commonly used in fission-track dating can also be used for uranium-thorium dating, allowing a internal correlation of the dates.
A fair and essential question. I am not a physicist, so I could be wrong, but why I expect there would be a coupling is that half-life is dependent on the basic physical forces, essentially the strong, weak, and electromagnetic, the geometric relation of these forces in a given isotope, and their quantum behavior. There is, to my knowledge, no independent half-life variable for the various decays. As the isotope geometry is kind of by definition, that leaves turning the dial on the fundamental forces. The momentum of emission of decay particles is generally what is left over from the mass-energy balance which holds the initial atom together and the products of decay, and that is what changes with accelerated decay.
Now given that I am not a physicist, I should perhaps not indulge in such an argument I have just stated. However, it would seem that the YEC credentialed physicists, who own accelerated decay, do not have the inclination to raise such obvious details on their own. They fixate on their radiohalos as if their own halos depended on them, but just blow by the implications of their own theory as if the details did not matter. It is their YEC theory, it is up to them to work out the expected decay energies from the half-lives involved.
