Willard F. Libby won the Nobel Prize for Chemistry in 1960 for his part in the development of radiocarbon dating. The impact of this dating method on archaeology was tremendous. Colin Renfrew (1979) goes so far as to call the introduction of radiocarbon dating into archaeological research the “Radiocarbon Revolution”. For such an important event you would think everyone would know exactly when that event occurred. In researching the prior blog post on the calculation of radiocarbon dates, I noticed that there is no consistent date given for the discovery of the radiocarbon dating method. The dates people use for the development of radiocarbon dating range from the 1940s into the 1950s. This imprecision of the dating of the origin of this most important method seems bizarre and a bit ironic. I decide to settle the matter in my own mind, mainly to satisfy my own curiosity, but also as an examination of the origin of ideas, in which I happen to be very interested.
To get at the date for the origin of radiocarbon dating, we need to know exactly what people mean when they say “origin”. Few writers offer a specific idea of what they are dating. Do they mean the first time the idea came into someone’s mind? Do they mean the first time the basic concepts were demonstrated in the laboratory? Do they mean the first time the method was successfully tried in the laboratory? Or do they mean the first time the method and results were published in a professional publication? The answers to all of these questions are different dates for the origin of radiocarbon dating. I derived the following chart from R. E. Taylor’s excellent book Radiocarbon Dating, an Archaeological Perspective published in 1987. Taylor has the best synopsis of the history of radiocarbon dating in chapter 6 of that book.
|1911||Discovery of cosmic radiation by V. F. Hess||Libby 1952|
|1932||Libby builds the first Geiger-Muller type radiation detector assembled in the United States, and publishes his first official publication.||Libby 1932|
|1933||Development of a Screen-Wall Counter by Libby||Libby 1933, 1934|
|1934||Radiocarbon produced in the laboratory by Kurie
Forecast of the existence of natural “cosmic radio-elements” in the atmosphere by Grosse
|1936||Attempt to produce 14C with cyclotron at Berkeley. This attempt failed because of a mistaken assumption concerning the half-life of 14C.|
|1939||First published prediction that 13C and 14C formed in nature by cosmic radiation.
Libby and Korff were working separately but along similar lines of research to develop neutron counters.
Libby stated that as soon as he had read Korff’s 1939 paper he thought “that’s carbon dating”.
|Korff and Danforth 1939, Korff 1940, and others
|1940||Recognition that 14C half-life was much longer than previously thought.||Kamen 1963|
|1946||More accurate half-life of 14C by Libby
Libby’s first open acknowledgement of his intention to develop a dating method based on 14C
Libby’s first statement of the basic principles on which 14C dating depend.
|1947||Libby, Grosse and Anderson conduct initial experiment with biomethane and petromethane to demonstrate the difference in 14C activity and correctness of Libby’s fundamental assumptions.
First published statement that 14C might be used to determine the “ages of various carbonaceous materials”.
Anderson et. al. 1947a and b.
|1948||Improvements of a screen-wall counter specifically for carbon dating by Anderson
First reported 14C age determination on a piece of cypress wood from the tomb of Djoser.
|1949||Anderson demonstrates that 14C is relatively constant in the biosphere
Publication of the curve of knowns in “Age determinations by radiocarbon content: checks with samples of known age”
AAA/GSA committee formed to collaborate with Libby
Arnold and Libby 1949
|1950||First list of provisional 14C dates sent to collaborators.|
|1951||First list of 14C dates published in Science||Arnold and Libby 1951|
|1952||Libby publishes the first edition of his book, Radiocarbon Dating||Libby 1952|
|1960||Libby wins the Nobel Prize for Chemistry for his work developing the Radiocarbon dating methods|
Looking at this table it is apparent that to assign a single year as the “origin” of radiocarbon dating ignores the obvious process of the development of the method. In fact there was considerable prior art, as they say at the patent office, to even the actual idea of the method, that is not even reflected in this table. The amount of research into radioactivity before the advent of radiocarbon dating is huge and I will not presume to venture into that material. More to the point, the discovery in 1911 by V. F. Hess, of cosmic radiation was the key piece of information for future radiocarbon dating researchers. The knowledge of cosmic radiation lead to speculation of what that radiation did when it encountered earth’s atmosphere and what it produced. Willard Libby’s own PhD work also laid the foundation for radiocarbon dating through the development of a screen-wall counter in 1933. It was just such a counter that he later used to derive the first radiocarbon dates.
The year 1939 stands out as the year Libby thought of radiocarbon dating as a possibility. W. F. Libby and S. A. Korff worked separately but along similar lines to build counters that would be sensitive to neutron radiation. Korff succeeded in constructing such a counter and was able to demonstrate that thermal neutrons were produced in the upper atmosphere by cosmic radiation. The neutrons collided with atmospheric nitrogen to form 14C. This is the basic concept on which radiocarbon dating is based and as soon as Libby read Korff’s 1939 paper stating what he had found, Libby though of the using this for dating.
Between this event and the start of the laboratory development of the radiocarbon dating method, World War II and the Manhattan Project intervened. Libby participated in the war time effort to separate 235U from 238U for use in America’s atomic bombs but still found time to work on problems related to 14C on the side such as trying to establish the half-life for the isotope.
In 1945 Libby moved to the University of Chicago and started to take up the development of carbon dating. In 1946, Libby first openly talked about attempting to develop a method to date materials with 14C and published his first suggestion of the principles on which radiocarbon dating is based (That is, the balance in living organisms of 14C and the steady predicable decay of 14C in dead organisms). According to Taylor (1987:152) this paper also introduced the term “radiocarbon” for the first time. According to L. A. Currie (2004: 186)
Like many of the major advances in science, Radiocarbon Dating was born of Scientific Curiosity. As noted by Libby in his Nobel Lecture, “it had its origin in a study of the possible effects that cosmic rays might have on the earth and on the earth’s atmosphere”. Through intensive study of the cosmic ray and nuclear physics literature, Libby made an important series of deductions, leading to a quantitative prediction of the natural 14C concentration in the living biosphere.
The year 1947 was the year for experimentation to see if Libby’s basic assumptions about 14C were correct. Moving on from the successes of these experiments, Libby and his colleagues entered what Taylor called a micro-Manhattan project for all of 1948 to develop the 14C dating method. This year saw the first actual dating of material from an archaeological site and a number of improvements in the screen-wall counter to use in measuring 14C radiation.
The next year, 1949 saw the publication of the “Curve of the Knowns” which demonstrated the close correlation between archaeological materials of known ages and estimated radiocarbon dates. After this the number of estimated dates rapidly increased and the first list of these dates was sent to archaeologists who were collaborating with Libby in 1950 and these dates there subsequently first found in print in 1951. The next year Libby published his book Radiocarbon Dating, describing the method and the results to that date.
Based on this information it can be said that Libby and his associates developed the radiocarbon dating method between 1939 and 1952 with key developments, discoveries and events in 1939, 1947, 1948 and 1949. A case can be made, as people have already done, to fix the date for the practical application of the method as 1948 or 1949.
Colin Renfrew’s statement that radiocarbon dating caused a revolution in archaeology brings to mind Ralph Waldo Emerson’s statement that “Every revolution was first a thought in one man’s mind.” Using Emerson’s criteria you could just as well make a case that 1939 was the origin of that revolution in the mind of Willard Libby.
Anderson, E. C. (1949). Natural Radiocarbon. Unpublished Ph.D. dissertation, University of Chicago.
Anderson, E. C., W. F. Libby, S. Weinhouse, A. F. Reid, A. D. Kirshenbaum, and A. V. Grosse (1947a) Radiocarbon from cosmic radiation. Science 105:576.
(1947b) Natural Radiocarbon from cosmic Radiation. Physical Review 72:931-936
Arnold, J. R.; Libby, W. F.
(1949). “Age Determinations by Radiocarbon Content: Checks with Samples of Known Age”. Science 110 (2869): 678–680
(1951). Radiocarbon Dates. Science 113:11-113.
Bowman, Sheridan (1990). Interpreting the Past: Radiocarbon Dating. Berkeley: University of California Press.
Currie, L. (2004). “The Remarkable Metrological History of Radiocarbon Dating II”. J. Res. Natl. Inst. Stand. Technol. 109: 185–217.
Grosse, A. V. (1934) An Unknown Radioactivity. Journal of the American Chemical society 56:1922.
Kamen, M. D. (1962) Early History of Carbon-14. Science 140:584-590.
Korff, S. A. (1940) On the contribution to the ionization at sea-level produced by the newtrons in the cosmic radiation. Terrestrial Magnetism and atmospheric electricity 45:133-134.
Korff, S. A., and W. E. Danforth (1939) Neutron measurements with boron-trifluoride counters. Physical Review 55:980.
Kurie, F. N. D. (1934) A New Mode of Disintegration Induced by Neutrons. Physical Review 45:904-905.
Libby W. F. (1932) Simple Amplifier for Geiger-Muller counters. Physical Review 42:440-441.
(1933) Radioactivity of ordinary elements, especially Samarium and Neodymium: method of detection. Unpublished Ph.D. dissertation. University of California, Berkeley.
(1934). Reactivity of Neodynium and Samarium. Physical Review 46:196.
(1946) Atmospheric Helium three and radiocarbon from cosmic radiation. Physical Review 69:671-672.
(1952). Radiocarbon Dating. Chicago: University of Chicago Press.
(1970) Radiocarbon Dating. Philosophical Transactions of the Royal Society of London 269A:1-10.
Marlowe. G. (1980). W. F. Libby and the Archaeologists, 1946-1948. Radiocarbon 22:1005-1014
Renfrew, Colin. (1979) Before Civilization: The Radiocarbon Revolution and Prehistoric Europe. Cambridge, U.K.: Cambridge University Press.
Taylor R. E. (1987) Radiocarbon Dating An archaeological Perspective. Academic Press, New York.