Radiometric dating assumes that radioisotope decay rates are constant, but
this assumption is not supported. All processes in nature vary according
to different factors, and we should not expect radioactivity to be
Morris, Henry M. 1985. Scientific Creationism. Green Forest, AR: Master
Books, p. 139.
- The constancy of radioactive decay is not an assumption, but is
supported by evidence:
- The radioactive decay rates of nuclides used in radiometric
dating have not been observed to vary since their rates were
directly measurable, at least within limits of accuracy. This is
despite experiments that attempt to change decay rates (Emery 1972).
Extreme pressure can cause electron-capture decay rates to increase
slightly (less than 0.2 percent), but the change is small enough
that it has no detectable effect on dates.
- Supernovae are known to produce a large quantity of radioactive
isotopes (Nomoto et al. 1997a, 1997b; Thielemann et al. 1998).
These isotopes produce gamma rays with frequencies and fading rates
that are predictable according to present decay rates. These
predictions hold for supernova SN1987A, which is 169,000 light-years
away (Knödlseder 2000). Therefore, radioactive decay rates were
significantly different 169,000 years ago. Present decay rates are
likewise consistent with observations of the gamma rays and fading
rates of supernova SN1991T, which is sixty million light-years away
(Prantzos 1999), and with fading rate observations of supernovae
billions of light-years away (Perlmutter et al. 1998).
- The Oklo reactor was the site of a natural nuclear reaction 1,800
million years ago. The fine structure constant affects neutron
capture rates, which can be measured from the reactor's products.
These measurements show no detectable change in the fine structure
constant and neutron capture for almost two billion years
(Fujii et al. 2000; Shlyakhter 1976).
- Radioactive decay at a rate fast enough to permit a young earth would
have produced enough heat to melt the earth (Meert 2002).
- Different radioisotopes decay in different ways. It is unlikely that a
variable rate would affect all the different mechanisms in the same way
and to the same extent. Yet different radiometric dating techniques
give consistent dates. Furthermore, radiometric dating techniques are
consistent with other dating techniques, such as dendrochronology, ice
core dating, and historical records (e.g., Renne et al. 1997).
- The half-lives of radioisotopes can be predicted from first principles
through quantum mechanics. Any variation would have to come from
changes to fundamental constants. According to the calculations that
accurately predict half-lives, any change in fundamental constants
would affect decay rates of different elements disproportionally, even
when the elements decay by the same mechanism (Greenlees 2000; Krane
Matson, Dave E., 1994. How good are those young-earth arguments?
- Emery, G. T., 1972. Perturbation of nuclear decay rates. Annual
Review Nuclear Science 22: 165-202.
- Fujii, Yasunori et al., 2000. The nuclear interaction at Oklo 2
billion years ago. Nuclear Physics B 573: 377-401.
- Greenlees, Paul, 2000. Theory of alpha decay.
- Knödlseder, J., 2000. Constraints on stellar yields and Sne from
gamma-ray line observations. New Astronony Reviews 44: 315-320.
- Krane, Kenneth S., 1987. Introductory Nuclear Physics. New York:
- Meert, Joe, 2002. Were Adam and Eve toast?
- Nomoto, K. et al., 1997a. Nucleosynthesis in type 1A supernovae.
- Nomoto, K. et al., 1997b. Nucleosynthesis in type II supernovae.
- Perlmutter, S. et al., 1998. Discovery of a supernova explosion at
half the age of the universe and its cosmological implications.
Nature 391: 51-54. http://xxx.lanl.gov/abs/astro-ph/9712212
- Prantzos, N., 1999. Gamma-ray line astrophysics and stellar
nucleosynthesis: perspectives for INTEGRAL.
- Renne, P. R., W. D. Sharp, A. L. Deino, G. Orsi and L. Civetta,
1997. 40Ar/39Ar dating into the historical realm: Calibration against
Pliny the Younger. Science 277: 1279-1280.
- Shlyakhter, A. I., 1976. Direct test of the constancy of fundamental
nuclear constants. Nature 264: 340.
- Thielemann, F.-K. et al., 1998. Nucleosynthesis basics and
applications to supernovae. In: Nuclear and Particle Astrophysics,
J. Hirsch and D. Page, eds., Cambridge University Press, p. 27.
Johnson, Bill, 1993. How to change nuclear decay rates.
created 2001-2-18, modified 2003-6-4