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26
old dates by radiocarbon would really
be much more recent.
Was equilibrium a fact? Here is what
Dr. Libby found.
W ould the Equilibrium
Assumption Hold T rue ?
D r. Libby and h is associates calcu–
lated that there were 18.8 atoros of
radiocarbon being produced every min–
ute, per gram of carbon.
Jf
there were an equilibrium between
the cate of production and disinte–
gration, living samples should show
a disintegration cate of 18.8 radiocarbon
atoms per minute per gram of carbon.
However, the average of 18 samples
taken from various latitudes did not
show an equilibrium! The disintegration
rate of the samples only averaged 15.3
disintegrations per minute per gram.
The rate of production was aJmost
19%
greater than the rate of disintegration.
Libby preferred a value of
16.1
(value of inorganic samples) for the
disintegration rate - even though the
average for organic specimens was 15.3.
However, there was still a discrepancy
of almost
15%
between production cate
and disintegration rate.
How did Libby resolve this problem
in his mind? He answered this very
question
m
h is
book
Rttdiocarbon
Dating:
"The agreement seems to be suffi–
ciently within the
experimental errors
involved, so that we have reason for
confidcnce in the theoretical picture set
forth above" (p.
7).
This, of course, was conjecture.
It
was
possible that the discrepancy was
experimental error. However, science
simply
did
1101
know!
Why
So Crucial ?
Why was it so important to have this
equilibrium and agreement? Again,
Libby puts his finger on the crucial
point :
"If
one were to imagine that the
cos–
mic radiatio11 had been turned off tmtil
a short while ago,
tbe enormous :unount
of radiocarbon necessary to the equilib–
rium state
WOULD NOT
have been
manufactured and the specific radio–
activity of hving matter would be much
less than the rate of production calcu–
lated from the neutron intensity"
(Willard
F.
Libby,
Rtzdiocarbon Dat-
Ambauodor College
Photo
BRISTLECONE PINE
tree located in the White Mountains of California . Bristle–
cone pine are co nsidered the oldest living trees.
ing,
Chicago: University of Chicago
Press, 1955, p. 8).
Y
et,
the first sketch
y
bits of evidence
indicated that ec¡uilibrium has not yet
been reached.
If
so, the cosmic system
may have been turned on just a short
time ago.
There simply may not have been
enough elapscd time to produce the
quantity of radiocarbon to bring the sys–
tem to a steady-statc equilibrium.
If
lack of ec¡uilibrium is a fact, what
implications would it have for radio–
carbon dates? lt could mean something
like the following. Of two samples, one
registers, say,
26,000
radiocarbon years;
another registers
18,000
radiocarbon
years. Yet, both samples might be only
about 5,500 years old, or lcss, and
aJmost contemporaneous.
N ew Evidence Found
In 1963, geophysicist Richard E.
Língenfclter published a disturbing
report in the journal,
Reviews of
Geophysics.
His calculations and con–
clusions seemed to spell death to the
possibility that the lack of equilibrium
was only "experimental error."
Lingenfelter's conclusion was that
"there is strong indication, despite the
large errors, that the present natural
production rate exceeds the natural
decay rate by as much as 25 per–
cent ... it appears that equilibrium in
the production and decay of carbon-14