Young-earth "proof" #14: The amount of helium in the atmosphere divided by its formation rate on Earth gives only 175,000 years.
14. The age of 175,000 years is a little steep for creationist purposes, so Dr. Hovind informs us that "God must have started the earth with some." Heaven forbid that the earth should be older than about 7000 years!
Helium-4 is the product of radioactive alpha decay whereas Helium-3 is primordial. The rates of their "production" are simply the rates of their escape from within the earth to the atmosphere.
A fair amount of helium is lost from the earth's atmosphere by simply being heated up in the elevated temperature of the exosphere (Dalrymple, 1984, p.112). The exosphere is the outermost layer of our atmosphere, beginning after the ionosphere at about 300 miles above the earth. When a lightweight helium atom is heated up, especially Helium-3, which is even lighter than Helium-4, it can easily pick up enough speed to escape Earth's gravity altogether and head off into outer space. Heating gas is a little like swatting rubber balls with a paddle; the lighter balls travel a lot faster after being swatted. In this manner about half of the Helium-3 produced is lost to outer space. The amount of the heavier Helium-4 lost by this method appears to be far short of the amount produced. Hence, the point of Morris' argument which is based on calculations by Cook. However, there are other mechanisms of helium escape which Morris and Cook have overlooked. Creationist Larry Vardiman (ICR Impact series, No.143, May 1985) at least recognizes some of these other factors. However, he has not fully addressed the matter, let alone proven that the earth is young.
The most probable mechanism for helium loss is photoionization of helium by the polar wind and its escape along open lines of the Earth's magnetic field. Banks and Holzer  have shown that the polar wind can account for an escape of 2 to 4 x 10^6 ions/cm^2 sec of Helium-4, which is nearly identical to the estimated production flux of (2.5 ±1.5) x 10^6 atoms/cm^2 sec. Calculations for Helium-3 lead to similar results, i.e., a rate virtually identical to the production flux. Another possible escape mechanism is direct interaction of the solar wind with the upper atmosphere during the short periods of lower magneticfield intensity while the field is reversing. Sheldon and Kern  estimated that 20 geomagnetic-field reversals over the past 3.5 million years would have assured a balance between helium production and loss.
Dr. Dalrymple goes on to explain that even though our understanding of the helium balance in the atmosphere is incomplete, the situation being very complicated because of various hardtocalculate factors, we do know one thing. "...it is clear that helium can and does escape from the atmosphere in amounts sufficient to balance production." (1984, p.113)
Thus, the helium balance calculations provided by creationist Melvin Cook (which are used by Henry Morris) cannot provide a reliable minimum estimate of the earth's age. Their argument is a fatal oversimplification of a complex problem.
Last updated: Thursday, 10-Mar-2011 15:57:19 CST
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