Posted: May 12, 2016 6:55 pm
It's a piece of apologetics from creation.com. First of all, the assertion that radiometric dating relies upon "unprovable assumptions" gives the game away. Except that, oh wait, the constancy of decay rates over geological time isn't an "assumption", it's been tested, with respect to such data as the observations from SN1987A, in which the decay rates observed for isotopes in the supernova remnant were observed to be the same as those today, despite the fact that the spectroscopic data indicating this took 169,000 years to reach us.
As for the assertion that Huh's paper cast doubt upon radiometric dating, this is another piece of dishonest creationist fabrication that bears no relation to the content of his actual paper. First of all, scientists proposed that electron capture could be affected by altering the electron density around the nucleus of certain isotopes over 50 years ago, but didn't have the means to verify this when the proposal was first presented. Second, the decay mode of the principal isotopes used for dating of ancient material (such as 238U, 235U, 147Sm) decay by alpha decay, which is not postulated to be affected by changes in electron density. Other isotopes such as 87Rb, decay via beta decay, again not affected by electron density. Third, a change in the decay constant for a long-lived nuclide, even if reliably detected, of the order of just 1.5%, would not be enough to force-fit a 4.6 billion year half-life into 6,000 years - a 1.5% decrease of such a half-life would reduce it from 4.6 billion years to 4.531 billion years, so such an effect would be completely useless as a device to try and force-fit the actual data to conform to fatuous mythological assertions, unless of course one was relying upon the stupidity of the audience, as is frequently the case with creationists.
Furthermore, let's take a look at what Huh actually said in his paper, shall we? The paper in question is this one:
Dependence Of The Decay Rate Of 7Be On Chemical Forms by Chin-An Huh, Earth and Planetary Science Letters, 171: 325-328 (1999) [Full paper downloadable from here]
First, in the introduction, Huh reports as follows:
References [1] and [2] cited above are the following papers:
Possibility Of Altering The Decay Rate Of A Radioactive Substance by E. Segré, Physical Review, 71: 274-275 (1947)
Alteration Of Radioactive Periods Of The Elements With The Aid Of Chemical Methods by R. Daudel, Reviews of Science, 85: 162 (1947)
Now it turns out that R. Daudel was pretty prolific on the subject, and also has the following paper associated with him:
The Decay Probability Of Be7 As A Function Of The Ionization Of The Atom by P. Benoist, R. Bouchez, P. Daudel, R. Daudel & A. Rogozinski, Physical Review, 76(7): 1000-1001 (October 1949)
So the idea that constancy of decay rates was an "assumption", is another of those dishonest creationist fabrications, given that scientists set out to test this as far back as 1947. But of course, you won't see any of this mentioned in duplicitous creationist apologetics.
Moving on, let's see what Huh says in the discussion section of his paper, shall we?
So already, Huh's paper builds on the previous work of Daudel and others in 1947, by applying modern, high-precision methods unavailable to those earlier authors, to the proposition advanced back then. Furthermore, a reason for Beryllium being most affected by this phenomenon amongst the elements thus far studied, is because it only has four electrons, and the electrostatic forces on K shell electrons are subject to virtually no shielding. Heavier elements, on the other hand, will exhibit this effect to a reduced extent precisely because of that shielding of K shell electrons. So even if we assume that the variation in decay constant for a heavier element is the same 1.5% for heavier elements, as opposed to the lesser value Huh clearly states will be the case above, then the variation in half-life for 40K, an isotope used in dating that does decay by electron capture (but, note not solely via this route), will modify the half-life thereof from 1.251 billion years to 1.232 billion years. A lesser modification of the decay constant will result in a lower reduction. Once again, the idea that this validates fatuous assertions about the universe only being 6,000 years old, is as fatuous as those assertions.
As for the assertion that Huh's paper cast doubt upon radiometric dating, this is another piece of dishonest creationist fabrication that bears no relation to the content of his actual paper. First of all, scientists proposed that electron capture could be affected by altering the electron density around the nucleus of certain isotopes over 50 years ago, but didn't have the means to verify this when the proposal was first presented. Second, the decay mode of the principal isotopes used for dating of ancient material (such as 238U, 235U, 147Sm) decay by alpha decay, which is not postulated to be affected by changes in electron density. Other isotopes such as 87Rb, decay via beta decay, again not affected by electron density. Third, a change in the decay constant for a long-lived nuclide, even if reliably detected, of the order of just 1.5%, would not be enough to force-fit a 4.6 billion year half-life into 6,000 years - a 1.5% decrease of such a half-life would reduce it from 4.6 billion years to 4.531 billion years, so such an effect would be completely useless as a device to try and force-fit the actual data to conform to fatuous mythological assertions, unless of course one was relying upon the stupidity of the audience, as is frequently the case with creationists.
Furthermore, let's take a look at what Huh actually said in his paper, shall we? The paper in question is this one:
Dependence Of The Decay Rate Of 7Be On Chemical Forms by Chin-An Huh, Earth and Planetary Science Letters, 171: 325-328 (1999) [Full paper downloadable from here]
First, in the introduction, Huh reports as follows:
Huh, 1999 wrote:1. Introduction
Beryllium-7 is the lightest radioactive nuclide that ecays by capturing an orbital electron from the innermost electron shell (1s or K-shell) at its nucleus. It was first proposed more than a half century ago that the decay rate of 7Be could be altered by changing the electron density at the nucleus [1,2]. Following this suggestion, numerous attempts were made to determine the variations of the decay rate of 7Be in various chemical forms [3–12]. However, these experiments were primarily performed 4 to 5 decades ago [3–11] and the most recent report was published in 1970 [12]. During that time period, the detection of 7Be decay was conducted using ionization chambers or NaI detectors. The reported errors for the decay rate associated with such measurement techniques were generally of the order of 0.1–1%, making it rather difficult to resolve the subtle difference of the 7Be decay rate among different combinations of Be and anions. Considering the advances in semiconductor technologies and the lack of new measurements in the past three decades, it is expedient to revisit this issue now. Using an advanced HPGe γ-spectrometry system, the decay constants of 7Be in Be2+(OH2)4, Be(OH)2 and BeO have been measured at unprecedented high precision. The experimental procedures and results are reported below.
References [1] and [2] cited above are the following papers:
Possibility Of Altering The Decay Rate Of A Radioactive Substance by E. Segré, Physical Review, 71: 274-275 (1947)
Alteration Of Radioactive Periods Of The Elements With The Aid Of Chemical Methods by R. Daudel, Reviews of Science, 85: 162 (1947)
Now it turns out that R. Daudel was pretty prolific on the subject, and also has the following paper associated with him:
The Decay Probability Of Be7 As A Function Of The Ionization Of The Atom by P. Benoist, R. Bouchez, P. Daudel, R. Daudel & A. Rogozinski, Physical Review, 76(7): 1000-1001 (October 1949)
So the idea that constancy of decay rates was an "assumption", is another of those dishonest creationist fabrications, given that scientists set out to test this as far back as 1947. But of course, you won't see any of this mentioned in duplicitous creationist apologetics.
Moving on, let's see what Huh says in the discussion section of his paper, shall we?
Huh, 1999 wrote:3. Discussion
The decay half-life of 7Be reported previously in the literature falls in the range 52.93–53.61 d ([15] and references therein), and the weighted average of 53.3 d is generally adopted in various applications using this nuclide. The uncertainties of these measurements vary from less than 0.2% (e.g., [13,16,17]) to greater than 0.5%. Therefore, error bars of these measurements do not always overlap. Because the chemical forms of Be in these measurements were often unspecified, it is not clear whether the difference is due to different chemical environments or is simply caused by experimental errors. In the present study, by measuring the decay rate of 7Be in three common forms of Be with an unprecedented high precision of ~0.01%, it was shown that the half-life of 7Be in natural environments could vary by as much as 1.5%. The variation can be explained by a change in electron density around the nucleus of Be atom due to its association with different anions, and hence different electronic polarizability and dipole moments. Besides 7Be, some other nuclides having important geochemical applications (e.g., 26Al, 36Cl, 40K, etc.) also undergo electron capture decay. Thus, decay rates of these nuclides may also depend on their chemical forms, but the effect will probably be smaller for heavier nuclides due to a better shield of K-shell electrons by more electrons and shells.
So already, Huh's paper builds on the previous work of Daudel and others in 1947, by applying modern, high-precision methods unavailable to those earlier authors, to the proposition advanced back then. Furthermore, a reason for Beryllium being most affected by this phenomenon amongst the elements thus far studied, is because it only has four electrons, and the electrostatic forces on K shell electrons are subject to virtually no shielding. Heavier elements, on the other hand, will exhibit this effect to a reduced extent precisely because of that shielding of K shell electrons. So even if we assume that the variation in decay constant for a heavier element is the same 1.5% for heavier elements, as opposed to the lesser value Huh clearly states will be the case above, then the variation in half-life for 40K, an isotope used in dating that does decay by electron capture (but, note not solely via this route), will modify the half-life thereof from 1.251 billion years to 1.232 billion years. A lesser modification of the decay constant will result in a lower reduction. Once again, the idea that this validates fatuous assertions about the universe only being 6,000 years old, is as fatuous as those assertions.