Robert Gentry, M.S.
Reprinted by Permission of the Creation Science Fellowship, Inc., Pittsburgh, Pennsylvania, U.S.A., from the Proceedings of the 1986 First International Conference on Creationism. (See Credits)
[Note: The main text in this report is identical with the first part of my AAAS report given on pages 269-283 of this Appendix, and is not repeated here. Instead we go directly to the Discussion and Closure sections.]
[The Discussion section features objections and criticisms offered by three scientists. The Closure section consists of our responses to these objections and criticisms.]
Attempts to find radiohalos in meteorites and moon rocks have been unsuccessful, although both galactic cosmic ray and solar cosmic ray tracks have been found in appropriate crystals from each of these sources. The limitation of radiohalos to earth minerals of hydrothermal classification suggests that water may be essential to the process(es) by which radiohalos are formed. The location of radiohalo centers in mica along conduit paths and cleavage planes supports this inference.
The existence of mature uranium halos in association with unsupported polonium halos presents a problem for a view that limits the real time ages of all minerals to less than 10,000 years. A 5 micron radius sphere of pure uraninite as a radiohalo center would require in the order of 3 million years to produce sufficient alpha particles to develop the minimum crystal disordering for a detectable 33 micron radius radiohalo (Polonium-214). A 3 micron radius sphere of monagite with one uranium impurity atom per unit monagite lattice element would require about 190 million years to develop a minimally detectable 3 micron radius radiohalo in mica. Thus the in situ creation of polonium impurity centers for unsupported polonium radiohalos and uranium impurity centers for mature uranium radiohalos at any time within the last million years also requires the uranium centers and are in every way indistinguishable from halos that would be produced by the uranium decay series as presently observed. For many individuals such a scenario requires the Creator to produce unnecessary "evidence" for events that did not occur in reality.
In presenting to the public at large, or any segment thereof such as the scientific community, the Biblical creationist interpretations set forth in this paper, it is desirable to recognize that Polonium halos are definitive evidence of instantaneous, in situ creation only if one has perfect and complete knowledge concerning all other possibilities. Such knowledge may be possessed only by deity. The present limits to human knowledge do not justify asserting that there are no possible circumstances under which the regular processes maintained by the Creator could have progressively deposited Polonium within some samples of granite, comparable to the much more readily understandable accumulation at Polonium centers in "coalified" wood.
If the polonium for unsupported polonium radiohalos in granite was an in situ primordial creation at halo center sites, it would be the only known primordial appearance of an element with other than a complete spectrum of isotopes. Polonium has 26 isotopes, all of which are radioactive. The 5 longest half-life members of this family, together with their half-lives and stable end products are:
According to the well-established empirical relationships between isotope abundance, half-life, and binding energy per nucleon, primordial polonium would be composed largely of its longer-lived isotopes, and its residue would be principally thallium 205 and lead 204. However thallium has never been reported as a polonium radiohalo center constituent, and lead 204 may be absent also [Robert V. Gentry, Nature 252 (Dec. 13, 1974), pp. 564-566; Annual Review of Nuclear Science 23 (Dec. 1973), pp. 347-362, specifically page 360]. Why is only lead 206 featured, the end product of uranium daughter products polonium 218, 214 and 210? The presence in uranium and polonium radiohalo centers of selenium, which would be precipitated also under conditions favoring the precipitation of uranium and polonium, favors explanation of radiohalos with processes involving solution transport of uranium and its daughter products, even though the details of such processes cannot be elaborated at the present lack of knowledge concerning hydrothermal environments and crystal formation [Norman Feather, Communications to the Royal Society of Edinburgh, No. 11, 1978, pp. 147-158].
Synthesis of a hand-sized piece of granite would prove that at least one laboratory procedure may be successful; it would be only suggestive, not definite, with respect to the actual processes that have determined the characteristics of a specific sample of natural granite.
It is unsound to assert (p2, ¶3), without firm theoretical or observational support, that large variations in alpha decay rate were associated with alpha particles of unvarying penetration range. An explanatory model that contains such a requirement suffers a severe loss in credibility.
The suggestion attributed to Gentry, et al., in the quotation from Norman Feather (p5, ¶1, reference 24) accounts for unsupported Polonium halos by radiation from daughters of hypothetical, extremely long-lived, extinct isomers of Polonium parents, not in terms of the fiat, in situ creation explanation given in this paper.
A critical reader of the paper may wonder why Pb atoms are expected to be less tightly fitted into a Zr2SiO4 lattice than U and Th atoms.
Since the He content of He-producing gas wells increases with well depth, it would be desirable to clarify the relationship between temperature, ambient He pressure, and expected He retention in zircons with U and Th impurity.
In conclusion, this reviewer wishes to express appreciation for the discussion of Polonium halos in "coalified" wood that is given in this paper.
Robert H. Brown, Ph.D.
Earth Science Associates