In recent years, physicist Robert Gentry has called our attention to an unusual phenomenon which he interprets as pointing to the instantaneous creation of certain granites. His conclusions have been published in scientific journals and in his book Creation's Tiny Mystery.
Scientists have long known that when each particular radioactive atom decays, it gives off energy at a characteristic level. This energy burst damages the mineral matrix in which the atom rests, and the size of the damaged zone reflects the level of energy released. Because uranium atoms (for purposes of this discussion) are usually found within certain minerals as inclusions of billions of atoms (which together still occupy a very tiny point of space), the decay of these unstable atoms over time produces a sphere of damage around the radio-centers.
As mentioned before, uranium decays to lead through a series of intermediate steps, each of which has its own characteristic energy level upon decay. If the inclusion resides in a well-formed crystalline structure, as is common in the mineral biotite (a form of mica frequently found in granitic rocks), the damage will form a series of concentric spheres around the inclusion or a series of concentric circles when one views a slice of the sphere through a microscope. These circles have come to be known as “pleochroic halos,” or radio halos. Each element has its own characteristic halo. By observing the particular array of halos, one can deduce the make-up of the original inclusion (or the type of parent element present when the mineral formed).
Several of these intermediate decay steps have extremely short half-lives. For instance, when radon-222 (half-life of 3.82 days) changes into polonium-218 (half-life of 3.05 minutes), it rapidly changes once again into lead-214. Likewise, when bismuth-214 (half-life of 29.7 minutes) changes into polonium-214 (half-life of 1.6 X 10-4 seconds), it rapidly changes once again into lead-210. Obviously, the atom does not linger very long in either polonium state before it decays into the next isotope in the decay chain.
Amazingly, the set of halos characteristic of polonium isotopes is sometimes found without the more slowly forming uranium halos, showing no evidence of a parent cluster of uranium - just polonium. Apparently, there never was a uranium cluster present at this location, and the original cluster must have been only polonium.
Granite is thought to require many years to cool from an original melted crystals to form, although the individual minerals, especially when concentrated, can rather quickly solidify once the temperature drops to the crucial point. Even pegmatite, a coarser-grained version of a granite, frequently occurring as veins within granite, requires an appreciable length of time to harden. Since polonium isotopes have such a very short half-life, it would be incredibly unlikely for the polonium halo to occur by itself with no evidence of its parent material. This has led Gentry to speculate that the granites were instantaneously created in a hardened condition with polonium inclusions present, which subsequently decayed.
It is contended by Gentry that polonium occlusions by themselves could not occur in a slowly cooling granite, nor could they migrate to a central location all the while decaying rapidly. The granite would have to be in a rather fluid state so that polonium could concentrate in one location in the first place, then must be solid when the polonium decayed, in order for the zone of damage to be preserved. But the granite cools too slowly, and the polonium decays too rapidly to accomplish this in any scenario other than instantaneous creation, or so it apparently seems. Evolutionists have come to call this a “tiny mystery.”
Gentry feels that the evidence only fits the idea that God created polonium, with its short half-life, and allowed it to decay instantly during creation week as His signature of creation. An alternative view is that after Adam sinned, and God declared “cursed is the earth for [Adam's] sake” (Genesis 3:17), certain elements became unstable and began to decay. Obviously, we can't know for sure. God hasn't given us all the details. But the polonium halos do exist, and must be explained. The only hope for a true interpretation necessitates going back to Genesis for our basic model.
Gentry's proposal is not without critics, even among creationists. Sticky points include the fact that all of these “orphan” halos are of elements included in the decay chain of naturally occurring uranium and thorium atoms. Why have no halos of other possible elements, which are truly independent, ever been discovered? Another problem is that some of Gentry's halos, which while discovered in association with granites, were found in “pegmatite dikes,” and pegmatites are suspected to form much more rapidly that the host granite, although not instantaneously. Furthermore, granites are sometimes found within Flood deposits, demonstrating conclusively that granites are not all Creation rocks. Also, how could fully formed uranium halos be found in the same rocks as the polonium halos? The uranium halos, which consist of numerous rings reflecting the longer decay chain, would seem to take a much longer time to form. Gentry proposes a short but intense burst of radioactivity, with altered decay rates for most radioactive isotopes, to account for these halos.
Gentry's proposal of more rapid decay rates at times in the past has some merit. In fact, several creationist theorists, for a number of reasons and with good observational data and Biblical hints to focus their research, have speculated on such changing of decay rates, most likely associated with the “stretching out of the heavens,” mentioned often in Scripture, as occurring during Creation week, and possibly during the Flood. These projects are as yet incomplete, but are leading in some interesting directions.
Several critiques of Gentry's concept have been advanced, and as yet, some questions remain. I present this evidence here because I feel it is quite compelling, and I suspect that out of this exercise will come a strong and persuasive argument for the Biblical model of earth history.
As encouraging as these finding are, let me not leave the impression that radioisotope dating has been disproved. It has been called into question, flaws in its foundation exposed, and its results shown to be inconsistent. In short, it is in trouble, but it is still a very formidable concept in the minds of many. Much research needs to be done, and is being done at ICR and elsewhere.
Excerpt from The Young Earth by John D. Morris, Ph.D., Master Books, 1994—with permission from the Institute for Creation Research
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