Young-earth "proof" #6: The Moon contains considerable quantities of U-236 and Th-230, both of which are shortlived isotopes that would have expired long ago if the Moon were 4.5 billion years old.
Thorium-230 is an intermediate decay product of uranium-238 which has a half-life of about 4.468 billion years (Strahler, 1987, p.131). Thus, it will be continually generated as long as the supply of U-238 lasts. Funny, that Wysong, whose argument Hovind is using, should have overlooked the intermediate decay products of longlived isotopes!
According to the McGraw-Hill Encyclopedia of Science and Technology, 7th edition (1992), the naturally existing uranium isotopes are: U-234 (0.00054%); U-235 (0.7%); U-238 (99.275%). However, trace amounts of U-236 also exist in nature. Dalrymple (1991, p.376) informs us that "U-236 is rare but is produced by nuclear reactions in some uranium ores where sufficient slow neutrons are available."
Thus, Th-230 and U-236 are currently being generated and their existence in nature proves nothing. Creationists will find the following table of the known radioactive nuclides with half-lives greater than 1 million years far more interesting. Here is elegant proof that the earth is old!
|Nuclide||Halflife (years)||Found in nature?|
|V-50||6 x 10^15||Yes|
|Nd-144||2.4 x 10^15||Yes|
|Hf-174||2.0 X 10^15||Yes|
|Pt-192||1 x 10^15||Yes|
|In-115||6 x 10^14||Yes|
|Gd-152||1.1 x 10^14||Yes|
|Te-123||1.2 x 10^13||Yes|
|Pt-190||6.9 x 10^11||Yes|
|La-138||1.12 x 10^11||Yes|
|Sm-147||1.06 x 10^11||Yes|
|Rb-87||4.88 x 10^10||Yes|
|Re-187||4.3 x 10^10||Yes|
|Lu-176||3.5 x 10^10||Yes|
|Th-232||1.40 x 10^10||Yes|
|U-238||4.47 x 10^9||Yes|
|K-40||1.25 x 10^9||Yes|
|U-235||7.04 x 10^8||Yes|
|Pu-244||8.2 x 10^7||Yes|
|Sm-146||7 x 10^7||No|
|Pb-205||3.0 x 10^7||No|
|U-236||2.39 x 10^7||Yes-P|
|I-129||1.7 x 10^7||Yes-P|
|Cm-247||1.6 x 10^7||No|
|Hf-182||9 x 10^6||No|
|Pd-107||7 x 10^6||No|
|Mn-53||3.7 x 10^6||Yes-P|
|Cs-135||3.0 x 10^6||No|
|Tc-97||2.6 x 10^6||No|
|Np-237||2.14 x 10^6||Yes-P|
|Gd-150||2.1 x 10^6||No|
|Be-10||1.6 x 10^6||Yes-P|
|Zr-93||1.5 x 10^6||No|
|Tc-98||1.5 x 10^6||No|
|Dy-154||1 x 10^6||No|
(Dalrymple, 1991, p. 377) – Nuclides currently produced by natural processes are tagged with a "P"
Look again at the table above. Notice how every single nuclide with a half-life greater than 80 million years is found in nature; every single nuclide with a half-life less than 80 million years is not found in nature unless it is currently being produced by nature. Does that tell you something?
You’re looking at prime evidence in favor of an old Earth! Those radioactive nuclides with half-lives below a certain value have, in the turning of the ages, decayed away to nothing. The only survivors are those which can be created by nature.
Could this be a chance arrangement? Not likely. The odds against being able to draw a line anywhere which divides the nuclides in the above table so that all the nuclides above that line are found in nature while all those below are not, is 536 million to one! (To be fair, we don’t count those which nature can create.) Actually, in testing for a 10,000 year-old Earth, we should extend the table downwards to include nuclides with a half-life of 1000 years or more. They should be present if the earth is only 10,000 years old. If you do that, you will get the same pattern as before. The odds (based on an eligible list of 56 nuclides) now jump to 72 quadrillion to one! Any takers?
Those who argue that the missing nuclides were never created must hope and pray that there is some natural process which works against the creation of shortlived nuclides. However, that argument comes up empty also.
There is good evidence that nucleosynthesis occurs in stars today and did so in the past. The spectra of some old stars, for example, reveal the presence of technetium, an element that has no stable nuclide and does not occur either in the Sun or on Earth (Merrill, 1952). . . Promethium has also been found in stars (Aller, 1971), and yet the longest-lived isotope of Pm has a half-life of only 18 years.
In the Large Magellanic Cloud, which is a small companion galaxy to our own Milky Way, a spectacular supernova (SN1987A) occurred in 1987. After the main explosion died away, much of the light from this supernova was actually powered by radioactive elements! For a time cobalt-56 (with a half-life of 77.1 days) dominated. It is a decay product of nickel-56 (with a half-life of only 6.1 days) which was produced in quantity by the explosion. After the cobalt-56 decayed away over a period of about 4 years, cobalt-57 (with a longer half-life of 270 days) became the main source of the supernova’s light. The decay of cobalt-56 and cobalt-57 liberates gamma rays of very specific energies, and these diagnostic gamma rays can be detected by highaltitude balloons or satellites. Moreover, astronomers could actually watch the light fade according to the exact decay rates of these two cobalt nuclides! (Gehrels et al, 1993, p.75).
Beginning around November [of 1987], spectra from the Kuiper [NASA’s airborne infrared telescope] and from Australia together revealed an entire zoo of elements in the supernova core not just iron, nickel and cobalt but also argon, carbon, oxygen, neon, sodium, magnesium, silicon, sulfur, chlorine, potassium, calcium and possibly aluminum. Their intense infrared lines signaled larger quantities than could have been present in the star at its birth. The elementsthe components, perhaps, of some future solar systemwere made in the core of the star or in the explosion itself.
Such direct evidence, as well as laboratory findings and theoretical study, make it clear that when Mother Nature gets around to cooking up elements she makes plenty of those "missing" nuclides. They are missing from our old neck of the woods because they decayed away a long time ago. Dalrymple (1991, pp.280-384) supplies additional evidence showing that there is no barrier to the production of the missing nuclides. After probing the details for iodine-129, Dalrymple concludes with:
Similar arguments can be made for the other missing nuclides listed in Table 8.3. Most occupy advantageous positions in the chart of the nuclides so that ready synthesis by the r- and s- processes is expected. A few are less exposed and are produced in lesser but not negligible amounts by other nucleosynthetic processes.
Finally, to add insult to injury, we find compelling evidence that some of the shortlived nuclides really did exist in our solar system once upon a time! Take aluminum-26, for example, which has a half-life of 716,000 years.
The fact that our solar system lacks aluminum-26 suggests that it is at least 15 million years old. That’s about how long it would take for all the aluminum-26 to decay away. Mother Nature certainly knows how to make it; there’s no problem in that department. With the help of the Compton Gamma Ray Observatory, which was placed into orbit in 1991 by the space shuttle Atlantis, we now know that our galaxy is full of aluminum-26 (Gehrels et al, 1993). Most of it lies along the galactic plane as would be expected if it were produced by supernovae from time to time.
Supernovae not only produce new elements but are implicated in the birth of stars. The gas shells of ancient supernovae have been identified, and some of these coincide with swarms of young stars. This is not too surprising since the shock wave of a supernova would compress any gas clouds which happened to be in the vicinity, thus setting the stage for the formation of new stars.
Indeed, our own solar system appears to have formed in that very manner! John Wood (1982) gives an excellent account of that discovery from which the following has been abstracted. It all began with the Allende meteorite which broke up over Mexico on February 8, 1969, showering the area near the village of Pueblito de Allende with thousands of stones. Scientifically speaking, it was one of the most important meteors ever to fall. Radiometric dating showed that the material was about 4.5 billion years old which is the accepted age of our solar system. More importantly, Allende samples contain little inclusions of material which once floated freely in space before being packed together with the surrounding space dust. These inclusions are rich in calcium, aluminum, and titanium, and are called CAI minerals. CAI minerals appear to be survivors of a primeval heating of the material from which our solar system was formed.
In addition to the irregular-shaped inclusions, Allende also contains ovalshaped inclusions called chondrules which are mostly made of olivine and pyroxene. A study of the chondrules and inclusions of Allende led to a remarkable discovery in the 1970’s by Robert Clayton and coworkers of the University of Chicago. They found that the ratios of oxygen-17 to oxygen-18 in Allende (and similar meteorites) could best be explained by assuming that two fundamentally different sources supplied the oxygen in our solar system. One source might have been the original nebula from which our solar system formed, and the other might have been material injected into that nebula from a supernova explosion. The Allende discovery opened up a whole new area of scientific research with respect to meteorites.
One of the major advances on this front was made by G. J. Wasserburg and coworkers of the California Institute of Technology in 1976, when they found unequivocal evidence of the former presence of Al-26 in Allende CAI’s. This isotope has a very short half-life, only 720,000 years, toward its decay into Mg-26. For any detectable amount of it to have been "alive" in Allende inclusions requires that it was created immediately before or during the formation of the solar system, and promptly mingled with the solar system’s raw materials. It seems inescapable that a supernova (which is capable of creating Al-26, among other things) occurred near enough to the nascent solar system in space and time to contribute important amounts of freshly synthesized nuclides to it.
That ancient supernova probably triggered the collapse of a nearby nebula which, in turn, produced our sun and, most likely, a slew of other stars which have long since left the general vicinity. Such a supernova, like SN1987A, would have contributed a whole zoofull of shortlived radioactive nuclides in addition to aluminum-26. Vast quantities of oxygen, carbon, sulfur, iron, silicon and other basic elements would likely have been produced as well.
Consequently, we not only have Wasserburg’s discovery that aluminum-26 was present in the early solar system but also the supernova process responsible for it which guarantees that shortlived nuclides were a natural part of the landscape. Had the earth literally been created in seven days, Adam and Eve would have fried amongst the radioactive aluminum, cobalt, and whathaveyou!
Another of the missing nuclides (very nearly so) is that of radioactive iodine-129 which has also left solid evidence of its former extensive existence in our solar system. (The small amount of iodine-129 found in tellurium ores, where it is produced from tellurium-130 by cosmicray muons [Dalrymple, 1991, p.376], and that from atomic bomb fallout do not affect our argument.) In the Richardson Meteorite, which fell in 1918, and the black stone Indarch, which fell in 1891, one finds regular iodine-127. That’s the iodine you hopefully find in iodized salt. Since iodine-129 would have been produced along with ordinary iodine-127 during nuclear fusion, and since their chemical similarity would have tended to keep them together, we have a mystery. Where did all the iodine-129 go?
Studies showed that the above two meteorites have unusually large amounts of xenon-129 trapped in them, and, you guessed it, xenon-129 is a stable decay product of iodine-129! There was far more xenon present than could be created by cosmic rays. But there is more:
In the Earth’s atmosphere, Xe-129 constitutes about onefourth of total xenon. … Yet in many meteorites Xe-129 is as much as 30 times more abundant, relative to the other xenon isotopes, than expected (Reynolds, 1967: 294, 1977: 217). As it is very probable that isotopes of the same element were thoroughly mixed when the Solar System formed, where did the excess Xe-129 come from?
Thus, we have something missing and something extra, and the two are only sensibly linked by radioactive decay! Iodine-129, which would have been created side by side with its chemical twin, iodine-127, had long ago decayed away, and xenon-129 is a daughter product of that decay.
With a half-life of 16.4 million years, 99.97% of that iodine-129 would still exist if our earth were only 7000 years old! Since it’s all gone, save that produced by atomic bombs and in tellurium ores, Earth is at least 300 million years old.
When we consider the above table of nuclides as a whole, we find that the earth is more than a few but less than about 10 billion years of age (Dalrymple, 1991, p.387). For a variety of reasons this approach can only give us a rough estimate, but it’s enough to easily put away the youngearth claims.
Out of sheer desperation, creationists often challenge the constancy of the decay rates. Maybe radioactive elements decayed much faster in the past! However, neither theory nor laboratory experience offers any hope for them (see topic R2). That fact, of course, hasn’t prevented creationists from taking flights of fantasy via their homespun theories about the universe. They simply toss Einstein’s relativity, quantum mechanics, and any other inconvenient bit of science into the trash bin!
But, hey! Special relativity (and to a lesser extend, general relativity) and quantum mechanics have earned their stripes. They are the great success stories of modern science! We’re not talking about rank speculation here! Atom smashers are built according to the specifications of special relativity; quantum mechanics is the proven core of theoretical chemistry. Both have been tested by diverse and clever experiments, and have run true in thousands of applications.
Who are these creationists who can walk in and, without even putting their case before the scientific community, make up their own theories about the universe? They are generally individuals who are driven by religious doctrines of biblical literalism rather than by an honest search for truth. On the pretense that we have no reliable theoretical knowledge, they ask who was there, in those long lost ages, to check those decay rates. That is their ultimate refuge against the reliability of the radiometric clocks.
The astounding fact, as noted in another context a page or two earlier, is that we do have a direct observation pertaining to ancient decay rates! The light of supernova SN1987A, in its trailing phases, was produced almost entirely by the radioactive decay of cobalt-56, at first, then cobalt-57 a few years later. Those two nuclides of cobalt were positively identified by their gamma rays as they decayed. In both cases the rate at which the light faded precisely matched the decay rates for cobalt-56 and cobalt-57! (Regarding the claim that the speed of light may have slowed down, see topic A6.)
All we need now is the distance to SN1987A which turns out to be around 170,000 lightyears (i.e. 52,700 parsecs). See topic A6 for more details. Surprisingly, that distance does not depend on the speed of light (in a Newtonian sense). Putting it all together, we reach the firm conclusion that we are seeing SN1987A as it was about 170,000 years ago. Thus, as it were, we have a window on the past which confirms that there has been no changes in the decay rates for cobalt56 and cobalt57. Hence, there is no reason for believing that any of the decay rates have changed as quantum mechanics describes them all and has been vindicated in the case of the two cobalt isotopes.
We also have a less direct but equally reliable window on the past in the formation of the present Atlantic Ocean. The magnetic stripes on the Atlantic sea floor, running parallel to the Mid-Atlantic Ridge, show that the sea floor has been spreading at a rate which has been roughly constant. That rate, which can now be measured directly with fair accuracy, is 1.5 inches per year. Averaging a couple of measurements of the width of the Atlantic from my trusty globe, I came up with 3500 miles as a good ball park figure. At 1.5 inches per year it would have taken 147 million years for the Atlantic to reach its present dimensions. It turns out that the oldest sediments in the Atlantic, those near the continents, are from the latter part of the Jurassic Period. The Jurassic Period, as determined by radiometric dating, covers a period of time from 135-190 million years ago. Therefore, the two methods are in excellent agreement. Obviously, there was nothing much wrong with those radiometric decay rates even 150 million years ago!
It’s "miracle time" once again for those young earth creationists. However, if your viewpoint requires a miracle to save it, then it doesn’t belong in the science classroom.
Last updated: Tuesday, 28-Dec-1999 17:57:28 MST