Science in Christian Perspective

 

 

METHODS OF DATING THE EARTH 
AND THE UNIVERSE
Delbert Eggenberger
Research Chemist, Amour and Company

From: JASA 3 (March 1951): 1-3.


 The problem of the age of the earth has been a difficult one to solve. ~tow an almost constant friction between the estimates of the scientific world loom of the theological world. Most of these differences were needless inasmuch estimates in both camps were quite tenuous. Before proceeding further with the resolution of these differences we shall examine the methods of In Betting the age of the earth and of the universe.

Suspicion that the earth was immensely aged was raised by Halley in the early eighteenth century from a study of salt deposited in the sea. Later in the same century., Hutton, basing his conclusion upon the study of geological formations stated that he could find "no vestige of a beginning!" During the nineteenth century., estimates of the earth's age were rampant, with virtually no upper limit. Kelvin,, however., basing his results on studies of temperature gradients in the earth., assuming it to have started from a molten ejection from the sun, concluded that the earth must not have been present for more than 400 million years. He later reduced this figure considerably. However., the discovery of radioactivity with its continuous generation of heat in the earth's crust vitiated Kelvins work.

More recent work in several directions has indicated an age of several billion years. It appears that the ages of the earth and of the universe are of the same order - at present, no difference can be detected by direct measurement. In this paper,, methods will be considered under three general headings, namely  terrestrial, solar (referring to extraterrestrial bodies within the system), and cosmic.

Terrestrial

Radioactivity measurements comprise the most important method of dating the earth. Details of the method and its limitations may be found in the American Scientific Affiliation publication entitled "The Ageof the Earth! (1948).

The ages of the oldest undisturbed rocks are given as about 1.8 x 109 years for Siberian uraninite and 2.0 x 109 years for uraninite from Manitoba. The latter is particularly interesting in that the rock affords three checks, one with uraninite containing uranium., another with monazite containing thorium and a third -with mica containing rubidium. The ages range from 2.0 to 1.6 billion years. (1),(2). Undisturbed rock ages provide the lower limit to the earth's age.

It was suggested by H. N. Russell that the age of the earth's crust could be determined by taking representative values for the quantities of uranium and the corresponding lead isotope. The assumption is., of course., that lead isotope 206 all came from uranium parentage. This Investigation has been carried out by several workers. Holmes (3) in studying collected results found a concentration of values around 3.35 x 109years. This figures or one only slightly lowers has been verified by others. (4). (5). Therefore it appears that the age of the earth's crust can be placed somewhere around 3.5 billion years.

One further support of the age of several billion years has been suggested by Gamow, (6). Nuclear transformation theory  requires that the original abundance of u235 be about the same as that of u238. 11ith a knowledge Of the half-lives of each of these Isotopes and the present abundance ratio or 1 to 139, it is Possible to calculate the approximate time of their equal abundance. This figure is of the order of several billion years.

Solar System

The present state of the moon's motion is that of a spiral of increasing radius. Calculations by Sir George Darwin Indicated that the time required for the present state to develop, assuming the moon had its origin near the earth, would be several billion years. Darwin evolved a tidal theory of the formation of the moon, which theory has been quite generally discarded since the work of Jeffries. The latter showed that frictional energy within the combined body would be so great as to preclude such destructive resonance as Darwin postulated. However, the possibility that the lunar satellite originated at or near the earth is at present considered reasonable.

The ratio of helium to uranium or thorium in meteorites, studied by Paneth and others (8) gives ages ranging from six million to seven billion years. However since the smaller ones have the higher helium content it appears they have been affected by alpha particle bombardment. The upper limit is concluded to be about three billion years for the Age of meteorites.

Cosmic

Star clusters are plentious throughout our galaxy. Chandrasekhar (9) has shown that the probability of a starts escape from the gravitational field of the cluster in time t -- such escape velocity having been attained statistically by an "evaporation" pr3cess resulting from the buffeting action of the other stars in the cluster -- to 1 -e -t/to where to depends on parameters of the cluster. This buffeting results from gravitational forces acting through a distance, If t = to.. this probability is 0.63 which may be considered the order of lifetime for the cluster. to for the Pleiadps is 3 x 109 years. Since clusters such as Pledades are quite common yet in our galaxy., that figure is taken as a reasonable average age for the clusters.

The study of binary stars affords another statistical method of estimating the age of the universe. The influence of an outside star near a binary pair is felt more by the nearer of the pair. The result of these approaches is an in~ creased radius of rotation and ellipticity of the orbit. A sufficient accumulation of such approaches results in a dissolved partnership between the binary stars. Chandrasekhar (10) has calculated this disruption time for our galaxy as t = 2.2 x l015 a-3/2, where a is the semi-major axis in astronomical units (1.5 x 108 km.). Studies of the distribution of separations between stars of binaries result in the conclusion that a time of the order of several billion years is correct, Bok (11) has studied both binaries and clusters and concluded that an age of 3 to 4 billion years is quite probable.

Paradoxically, while the time-scale calculated by use of the expanding universe model would be the simplest and most direct, the value found has been somewhat difficult to reconcile with the others. The figure of 1.64 billion years obtained by using a simple classical model is considerably lower than the some three billions demanded by most other methods. Russell suggests that expansion may have been slower at first because of the smallness of space I then. Tolman (2) Applied relativistic corrections to the simple model and found that it produced an even smaller time, 1.24 billion years. He has claimed some success in expanding the time-scale by assuming the non-homogeneity of matter in space.

The evidence of the Age of stars while lending some rough support to the general picture is rather inconclusive.

Another general evtden9e is afforded In the temperature drop of the universe with time. Jeans demonstrated that the temperature would drop inversely as the square root of time. Assuming a beginning temperature of 15 x 109 OA -- necesary for nuclear transformation to occur -- and a present temperature of 50 OA, the time elapsed comes out about three billion years.

Conclusion

It appears, then from our examination of several independent lines of evidence that the beginning of our present universe was some three billion years ago. Bishop Ussher, in the seventeenth century, concluded that the Biblical creation was 4004 B.C. The inclusion of that date in a large portion of Bibles published since that time has led many to feel that Biblical and scientific cosmogonies were irreconcilable. The result has been an unfortunate breach between two groups both of which are in error. The one group holds that the very old date indicated by the methods of science is in conflict with the Scriptures and therefore the latter to not the inspired work of God. The other group., accepting the Bible as the revelation of God$ holds to a comparatively recent creation In spite of much clear evidence to the contrary.

It has been shown by Hebraists that the words translated in Authorized and other versions as "day" could as well be translated some long period of time and "morning and evening" as "beginning and ending". Also Obegat" does not necessarily imply A direct eon but may mean a descendant,

The conclusion to be drawn is, that the Scriptures themselves do not teach a short time-scale but its teachings are quite consistent, and without strained translations, with a very old date of creation and with long geological processes.

References

(1) H. N. Russell, Science 92 19 (1940)
(2) R. C. Tolman., Rev. Mod. Phys. 21. 374 U949)
(3) A. Holmes, Nature, Lond. 157, 680 (1946)
______ ,Ibid., 1959, 127 (1947).
______  ,Endeavour 6, 99 (1947)
(4) C. Feste and M. Santangelo, Amn. Geofis 2, 503 (1949)

(5) C. Morelli, Ann. Geofis, 2, 417 (1949)

(6) G. Gamow.. Lecture before physics Club of Chicago) 1949,

(8) W. J. Arrol, R. B. Jacobi, and F. A. Paneth., Nature, Lond. 2L9s 235 (1942)

(9) S. Chandrasekhar  Astrophys. J. 97, 255 (1943)
_____ ibid. 98, 54(1943)

(10) S. Chandrasekhar, Science 99, 133 (1944)

(11) B. J. Bok, Mon. Not. Royal Astro. Soc. 106, 61 (1946)

(12) P. Ropsiers Arch. des Sciences 22p 89 (1940)