Claim CF210: Constancy of Radioactive Decay

This is a direct copy of a SciPop or news article preserved here because things on the internet have a bad habit of disappearing when you try to find them again. Full credit is given to the original authors and the source.

– Matty

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 different.


Morris, Henry M. 1985. Scientific Creationism. Green Forest, AR: Master Books, p. 139.


  1. 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 not 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).
  2. Radioactive decay at a rate fast enough to permit a young earth would have produced enough heat to melt the earth (Meert 2002).

  3. 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).

  4. 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 1987).


Matson, Dave E., 1994. How good are those young-earth arguments?


  1. Emery, G. T., 1972. Perturbation of nuclear decay rates. Annual Review Nuclear Science 22: 165-202.
  2. Fujii, Yasunori et al., 2000. The nuclear interaction at Oklo 2 billion years ago. Nuclear Physics B 573: 377-401.
  3. Greenlees, Paul, 2000. Theory of alpha decay.
  4. Knödlseder, J., 2000. Constraints on stellar yields and Sne from gamma-ray line observations. New Astronony Reviews 44: 315-320.
  5. Krane, Kenneth S., 1987. Introductory Nuclear Physics. New York: Wiley.
  6. Meert, Joe, 2002. Were Adam and Eve toast?
  7. Nomoto, K. et al., 1997a. Nucleosynthesis in type 1A supernovae.
  8. Nomoto, K. et al., 1997b. Nucleosynthesis in type II supernovae.
  9. 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.
  10. Prantzos, N., 1999. Gamma-ray line astrophysics and stellar nucleosynthesis: perspectives for INTEGRAL.
  11. 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.
  12. Shlyakhter, A. I., 1976. Direct test of the constancy of fundamental nuclear constants. Nature 264: 340.
  13. 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.

Further Reading:

Johnson, Bill, 1993. How to change nuclear decay rates.

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