To: All Subject: Evidence #11 for a Young World In article CLFMut.EBp@watserv2.uwaterloo.c

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From: glenn r morton To: All Subject: Evidence #11 for a Young World From: (glenn r morton) Organization: Oryx Energy In article Alan Scott wrote: >#11. Not enough helium in Earth's atmosphere > > All naturally occurring families of radioactive elements generate >helium as they decay. If such decay took place for billions of years, as >alleged by evolutionists [there they go messing with nuclear physics], much >helium should have found its way into the earth's atmosphere. Taking into >account the slow rate of escape of helium from the atmosphere into space, >and assuming no helium was in the atmosphere to begin with, it would take less >than (bold) two million years (end bold) to accumulate the small amount of >helium in the air today.[23] > This means the atmosphere is much younger than the evolutionary >(italics) five billion years (end italics) - again consistent with a recent >creation (6,000-10,000 years) of functional atmosphere. > >[23] Vardiman, L., 'The age of the earth's atmosphere estimated by its > helium content', PROCEEDINGS OF THE FIRST INTERNATIONAL CONFERENCE > ON CREATIONISM, Vol.2, Creation Science Fellowship, Pittsburgh, > 1987, pp.187-195 I have briefly looked at the above article and it has some major problems. Vardiman uses an equation which I think was taken from J.H.Jeans _The Dynamical Theory of Gases_ Cambridge 1916 or E. Leonard Jones, Trans., Cambridge Phil. Coc., Vol 22, 1923. The equation is F= n(g He/2pi)^1/2 (1+(R+z)/He)exp(-(r+z)/He) where n is the particle density z is the height, g is the acceleration due to gravity and He is the scale height at the base of the exosphere. The equation reference is quite old so I don't know if it is still considered correct. He admits that there is a great difficulty with estimating the influx of helium to the atmosphere out of the crust. As near as I can tell at this point, he uses a 4.5 billion year earth and an amount of helium of 6 x 10^38 atoms entering the atmosphere yields a rate of 2 x 10^6 atoms/cm^2-sec. 6 x 10^38 atoms is the number of atoms of helium in the atmosphere according to him. The guts of his argument is found in the following quote. "To evaluate equation 2 we assume the reference density is 3.4 x 10^13 atoms/ cm^3 at a height of about 100 km. The temperature at the homopause is approximately 185 degrees K and the exospheric temperature is 1500 degrees K. The concentration is further adjusted by the helium mixing ratio shown in Table 1. With these assumptions, the value of the helium flux is calculated to be 5 x 10^4 atom/cm^2-sec. This escape rate is about 40 times less than the average source rate estimated to be coming into the atmosphere from the crust of the earth. By dividing this escape flux into the column density of helium in the atmosphere (1.1 x 10^20 atoms/cm^2), the characteristic escape time for atmospheric helium is found to be about 70 million years. By divid- ing the source flux of 2 x 10^6 particles / cm^2-sec into the column density, the residence time is found to be about 2 million years. The characteristic residence time for helium is much smaller than the character- istic escape time. In other words, it takes a much longer time for a given quantity of helium to escape from the atmosphere to space than it does to enter the atmoshere through the crust." p. 191 of above article e First, the data he is referring to in table 1 is the atmospheric composition. My gut feeling is that there should be more helium in the upper atmosphere than there is in the average atmosphere. Helium is much lighter than the other atmospheric constituents and so should preferentially be on the top. Secondly, the output flux is what he calculated would be required to account for the helium in the atmosphere in 4.5 billion years. He allowed for no primordial helium and considering that there should have been some helium in the pre-solar nebula, his rate of escape from the crust would be too high. He then discusses very briefly three other escape mechanisms. Polar wind escape which is the escape of He+ through the open field lines at the poles. He then says "Axford(22) has applied the polar wind model specifically to the escape of helium and calculated an escape flux of about 1 x 10^5 atoms /cm^2-sec. much lower than even Jean's escape." Last time I checked 1 x 10^5 is greater than 1 x 10^4 unless the laws of math have changed since I left college many years ago. Axford's article is cited as Journal of Geophysical Research Space Physics 73, 1968, p. 6317-6323 He claimed that the solar wind mechanism escape flux would be quite low but gives no numbers. The last mechanism of escape he talks about is hot ion exchange but once again gives no numbers. One must wonder whether the work he refers one to Fahr and Shizgal Rev. of Geophys. and Space Physics, 21, 1983 , pp 75-124 has numbers which are embarrassing for his position. He also pooh-poohs a suggested mechanism of escape proposed by Spitzer and Hunten (Spitzer, "The Terrestrial Atmosphere above 300 km", in _The Atmospheres of the Earth and Planets_ Univ. Chicago Press, 1949 p. 211-247 and Hunten "The Escape of light gases from planetary atmospheres" J. of the Atmos. Sci. 30, 1973, p. 1481-1494). Their mechanism is that the earth's outer atmosphere is periodically heated by large solar storms to 2000 deg. K which then allows the helium to escape. He of course provides no numbers. He ends the article with the silliest idea of the distribution of radioactive elements I have heard in a while. He says. "The recent discoveries of helium coming through the crust from the mantle where no radioactive decay process is known to produce helium, has led to the statement that primoridal helium exists in the mantle. Why then, is it so hard to believe that primordial helium still exists in the atmosphere? The lack of an escape mechanisms and the likelihood that, the helium we observe in the atmosphere is primordial provides evidence that the earth's atmosphere is quite young." p. 193 It is believed that there is not as much radioactivity in the mantle as there is in the crust but to make the claim that there is none is quite a stretch. I have not looked at the articles he cited I will order them now and take a look when they come in.


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