Primordial Helium Abundance Test of Big Bang Cosmology

Primordial Helium Abundance Test of Big Bang Cosmology

It is hard to exaggerate the theological significance of big bang cosmology.

Until the twentieth century the Bible was the only “text” explicitly describing the fundamentals of big bang cosmology—a Causal Agent beyond space and time, a beginning of space and time, a beginning of matter and energy, continuous cosmic expansion, and constant laws of physics—as well as implying other features, such as continuous cosmic cooling and the confinement of matter and energy to the cosmic surface.1

Today, the scientific evidence for big bang cosmology is overwhelming. Nevertheless, because of its enormous theological implications, strong resistance to accepting this explanation for the universe’s beginning as truth remains. Atheists, pantheists, and Hindus, among others, reject it because it so strongly supports Christian theology. Within the Christian community young-earth creationists anathematize the big bang because it establishes that the universe is about 14 billion years old. Thus, big bang cosmology illustrates the principle that the more important and more specific the theological implications of a particular theory, the greater the need for additional evidence to establish its veracity.

In this context it is welcome news that two Mexican astronomers, Manuel Peimbert and Antonio Peimbert, and a Spanish astronomer, Valentina Luridiana, have improved by more than a factor of three what many astronomers consider the most definitive test for big bang cosmology.2 That test is the primordial helium abundance for the universe.

In the hot big bang creation model a certain fraction of the universe’s hydrogen gets fused into helium during the first four minutes after creation. The WMAP data showed that if the hot big bang creation model is correct the fraction = 0.24815 ± 0.00033.3 This fraction can be compared with measurements of the helium abundance in the universe’s firstborn stars and in the gas clouds or nebulae that formed the firstborn stars. Since the spewed-out ashes of burnt stars comprise the only other possible source of helium in the universe, measuring the helium abundance in the nebulae that gave rise to the first-formed stars tells astronomers how much helium the universe started out with before stars formed.

Astronomers had previously measured the helium fraction by two different means and two different samples of nebulae to be 0.249 ± 0.0094 and in the gas clouds that formed the first stars to be 0.250 ± 0.009.5 Both of these measurements, however, failed to take into account the collisional excitation of hydrogen Balmer spectral lines as well as a few other complications in both the hydrogen and helium spectral lines.

Earlier, the Peimberts and Luridiana had shown that when all these factors are considered the primordial helium abundance measures to be 0.2391 ± 0.0020.6 Their estimate of the probable error in their measurement, though, did not include uncertainties that existed in the computations of certain atomic physics coefficients or in the collisional excitation of hydrogen Balmer spectral lines.

Thanks to new and much more precisely achieved computations of the relevant atomic constants, most of the uncertainty in the Peimberts’ and Luridiana’s original determination of the primordial helium abundance has now been removed. Their revised measure of the fraction of primordial hydrogen that is fused into helium by the big bang = 0.2477 ± 0.0029.7 This measurement is three times more accurate than the best previous determination. It is remarkably consistent with the big bang cosmic creation model, differing from its prediction by only 0.00045.

The Peimberts’ and Luridiana’s reassessment is also amazingly consistent with what the big bang creation model would predict from the primordial abundance of deuterium or heavy hydrogen.pdf). While the big bang creation model predicts that a large fraction of the universe’s hydrogen gets fused into helium during the first four minutes after creation, it also predicts that a tiny fraction of the remaining hydrogen will be fused into deuterium. In big bang cosmology the ratio of the primordial deuterium to primordial helium is highly specified. Therefore, an astronomical measure of the primordial deuterium abundance directly translates into a measure of the primordial helium abundance. That translation from the best available measurement of the primordial deuterium abundance = 0.2476 ± 0.0006.8

Such a remarkable fit between the observed abundance of primordial helium in the universe and the expected abundance predicted by the big bang cosmic creation model justifies great confidence in that model and consequently great confidence in the Bible’s story of cosmic origins and cosmic history. In my book, Creation As Science, our model predicted (on pages 185-86) that scientific evidence for the big bang cosmic creation model would grow stronger and individual evidences for the model would become more consistent.9 In contrast, atheistic and young-earth models predicted the opposite. Thanks to the Peimberts and Luridiana, the contrasting predictions have been put to the test.

As the researchers point out, we can look forward to additional tests.10 Another factor-of-three improvement in astronomers’ ability to measure the primordial helium abundance (a realistic goal for the next few years) will enable much tighter constraints on any possible variation in:

  1. the lifetime of an isolated neutron;
  2. the difference between the mass of the neutron and the mass of the proton;
  3. the fine-structure constant; and
  4. the gravitation constant.

Such a precise measurement also would decide whether or not certain decaying particles are present during the episode (between three and four minutes after the cosmic creation event) in which big bang nucleosynthesis (the manufacture of heavy elements from hydrogen) takes place. To put it another way, astronomers will soon be able to deliver an even more definitive and rigorous test for the big bang cosmic creation model. At the same time new research will provide a much more detailed model of cosmic creation, in which we can expect the details to show even more evidence for the supernatural design of the universe for the specific benefit of physical life, and human life in particular.

  1. Hugh Ross, The Creator and the Cosmos, 3rd ed. (Colorado Springs: NavPress, 2001), 23-29; Hugh Ross, Creation As Science (Colorado Springs: NavPress, 2006), 67-77, 83, 87-102.
  2. Manuel Peimbert, Valentina Luridiana, and Antonio Peimbert, “Revised Primordial Helium Abundance Based on New Atomic Data,” Astrophysical Journal 666 (September 10, 2007): 636-46.
  3. D. N. Spergel et al., “Three-Year Wilkinson Microwave Anisotropy Probe (WMAP) Observations: Implications for Cosmology,” Astrophysical Journal Supplement 170 (June 2007): 377-408.
  4. Keith A. Olive and Evan D. Skillman, “A Realistic Determination of the Error on the Primordial Helium Abundance: Steps Toward Nonparametric Nebular Helium Abundances,” Astrophysical Journal 617 (December 10, 2004): 28-49.
  5. Masataka Fukugita and Masahiro Kawasaki, “Primordial Helium Abundance: A Reanalysis of the Izotov-Thuan Spectroscopic Sample,” Astrophysical Journal 646 (August 1, 2006): 691-95.
  6. V. Luridiana et al., “The Effect of Collisional Enhancement of Balmer Lines on the Determination of the Primordial Helium Abundance,” Astrophysical Journal 592 (August 1, 2003): 846-65.
  7. Peimbert, Luridiana, and Peimbert: 642-45.
  8. Peimbert, Luridiana, and Peimbert: 645.
  9. Hugh Ross, Creation As Science (Colorado Springs: NavPress, 2006), 185-86.
  10. Peimbert, Luridiana, and Peimbert: 636.