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The Role of Short-Lived Radioisotopes in Creating Life

Have you thanked God for short-lived radioisotopes today? You should. Because our solar system was exposed to a huge abundance of short-lived radioisotopes (SLRs) at the time of its birth, primordial Earth was transformed from being rich in volatiles (gases and liquids) and poor in refractories (heavy elements resistant to heat and wear) to being exactly the opposite. This transformation made it possible for Earth to become a home for advanced life. Praise be to God!

Some of you at this point may protest that you can’t thank God for something you do not even understand. Fair enough. SLRs refer to radioactive nuclides with half-lives less than about 10 million years. (The half-life is the period of time during which half of the radioisotope decays.) The bathing of the primordial solar system with a high abundance of SLRs—in particular aluminum-26 (with a half-life of 717,000 years) and iron-60 (with a half-life of 2,600,000 years)—drove off nearly all of Earth’s volatiles, leaving Earth extremely volatile poor and refractory rich.

How volatile poor is our Earth? Compared to the few extrasolar planets of similar size and surface temperature where the volatile abundance can be measured, Earth possesses nearly 1,200 times less carbon-based atmospheric gas and about 500 times less liquid water.1 Earth’s paucity of liquid water (less than 0.03 percent of its total mass) allows continents to form, and the combination of continents, rivers, lakes, and seas provides for multiple habitats and the efficient nutrient recycling that advanced life requires. Earth’s thin atmosphere permits the existence of creatures with lungs.

Evidence that the primordial solar system was bathed in a high concentration of SLRs comes from the presence of daughter nuclides in meteorites (that arose from the decay of SLRs). These daughter nuclides reveal that the primordial solar system was exposed to at least a dozen different SLRs, of which aluminum-26 and iron-60 predominate.

How did Earth get to be bathed with such a high concentration of aluminum-26 and iron-60? The only possible explanation is that the solar system formed in the vicinity of a few massive stars that all exploded as supernovae. The diversity and abundance of SLRs requires contributions from different kinds of supernovae.

Astronomers have produced two possible scenarios within the supernovae explanation. The first is that the supernovae directly polluted the primordial solar system with a huge abundance of SLRs. The second is that the massive stars formed first, erupted as supernovae, and then the expanding shock waves from the supernovae, super-enriched with SLRs, triggered the formation of the solar system.

Many astronomers objected to the first scenario on the grounds that it required a tremendous amount of fine-tuning design. For the scenario to work, the supernovae would need to explode nearly simultaneously. The supernovae’s distances relative to the primordial solar system must not be so close as to disrupt the solar system nor so far as to provide inadequate injection of SLRs. Also, the supernovae must not explode either too much before or too much after the birth date of the solar system. For these reasons, astronomers have favored the second scenario, which suggests that the solar system formed as a result of shock waves emanating from supernovae.

Recently, astronomers Richard Parker and James Dale in Britain and Germany, respectively, tested the likelihood of the second scenario.2 They ran a wide range of computer simulations of star formation (both smoothed and N-body particle hydrodynamics). They concluded that the second scenario required “very contrived situations”3 in order to explain the SLR bathing that the primordial solar system received. In Parker and Dale’s words, the “triggered star formation event is as improbable, if not more so, than the direct pollution of the protosolar disc.”

The apparently inescapable conclusion is that the established bathing of the primordial solar system by a great diversity and abundance of SLRs implies a huge degree of fine-tuning design. Such design, especially when combined with the scientific evidence for fine-tuning design throughout the entire history of the solar system, all for the specific benefit of the human race, points unmistakably to the handiwork of the Creator God of the Bible.

  1. David Charbonneau et al., “A Super-Earth Transiting a Nearby Low-Mass Star,” Nature 462 (December 2009): 891-94; Geoffrey Marcy, “Extrasolar Planets: Water World Larger Than Earth,” Nature 462 (December 2009): 853–54.
  2. Richard J. Parker and James E. Dale, “Did the Solar System Form in a Sequential Triggered Star Formation Event?” Monthly Notices of the Royal Astronomical Society 456 (February 2016): 1066–72.
  3. Ibid., 1066.