Today’s New Reason To Believe

Jeff Zweerink

Originally Posted on Wednesday, August 22nd, 2007

Last month’s multiverse musings delineated some philosophical objections to the existence of actual infinities. However, an extremely large but spatially finite universe could still negate the significance of the fine-tuning arguments used in Christian apologetics. Today, I want to address an email question particularly pertinent to this issue. The question is:

How do scientists measure the total density of the universe, and also the split between conventional matter, dark matter, and dark energy?

The importance of this question relates to the fact that the only hard experimental evidence currently weighing in on the size of the universe is the geometry of the universe. The WMAP image of the cosmic microwave background (CMB) radiation provides the most potent tool for measuring the geometry although the large-scale structure also contributes significantly. In a nutshell, a closed universe cannot be spatially infinite.

The total density of the universe, Ω_total, defines the universe’s geometry. For an open universe, Ω_total < 1 whereas a closed universe has Ω_total > 1. Ω_total = 1 means the universe is flat. Additionally, a measured value of Ω_total > 1 also constrains the size of the universe (not just our observable universe). The best measurements of Ω_total indicate a closed universe but are consistent with a flat or open universe within the error bars.

To get from the all-sky WMAP temperature measurements to a measurement of the cosmological parameters involves three steps:

1. Transform the CMB sky map into a set of numbers that characterize the fluctuations.
2. Run simulations to see how changing the various cosmological parameters affects the numbers characterizing the fluctuations.
3. Find the parameters that best fit the data.

The first step utilizes the common mathematical tool of spherical harmonics. Basically, you convert this into a sum of these , then you determine the amount of power at each harmonic and make a graph like this.

The next step is where all the physics enters. The CMB photons were all emitted at a common time (when the universe cooled enough for nuclei and electrons to combine and form atoms) roughly 380,000 years after the big bang. The temperature fluctuations measured by WMAP record a snapshot of the physical scale and gravitational distribution of the universe’s density. Multiple factors affect this distribution, such as the total density, the number of baryons, the relative amounts of the components making up the total density, and the spectrum of the initial density fluctuations. Using simulations, cosmologists can form pictures of the CMB fluctuations assuming different cosmological parameters. For a more detailed description of how these processes interact, see Wayne Hu’s tutorial.

The final step involves comparing the simulated CMB distribution of harmonics with the distribution calculated from the WMAP data. Max Tegmark’s CMB movies provide nice illustrations of how changing the various cosmological parameters would affect the measured distribution of harmonics. Once the best fit to the data is found, you have your measurement of Ω_total (and a number of other parameters). The current best values for some relevant parameters are:

• Ω_total = 1.02 +/- 0.02
• Normal matter = 4%, Exotic dark matter = 22%, and Dark energy = 74%.
• Spectral index n_s = 0.95 +/- 0.17 (inflation predicts a value less than one).

So now you know how to convert the WMAP data into cosmological parameters.

Kenneth Richard Samples

Originally Posted on Tuesday, October 30th, 2007

Watching Ken Burns’s new documentary on PBS about World War II led to, of all things, an apologetics epiphany on my part.

I have been a student of the Second World War since my early childhood. Because my father was an American combat soldier during the war (fighting in Europe against the German army), studying the war caused me to ask the big questions of life—especially questions about God, evil, and the unfolding of human history. It is difficult to study the bloodiest war in human history (resulting in the deaths of 50 to 60 million people) and not ask deep philosophical questions. Historian Stephen Ambrose has even called the Second World War “the greatest catastrophe in history.”

One question that I have been turning over in my mind for probably two decades is: Why was my father’s generation able to overcome so many obstacles and accomplish so much good? America’s “greatest generation” was able not only to overcome a terrible economic depression, but with the help of their allies they were able to decisively defeat two of the mightiest military powers in history. And they started out facing great military disadvantages such as a tiny military force, little military hardware (tanks, planes, etc.), and a decimated navy after the Japanese attack on Pearl Harbor. Yet within the span of four short (though terrible) years America stood triumphant.

America not only helped defeat Nazi Germany and Imperial Japan, it also singularly provided the finances and technology to rebuild these nations, as well as the rest of shattered Eastern Europe. So successful was the Marshall Plan (an economic plan to rebuild Western Europe), that just a couple of decades after the war ended both Germany and Japan boasted robust economies that challenged America in terms of gross national product. And the American World War II generation leaders created a military coalition (NATO) that protected the Western world from the powerful threat of Soviet expansionism and inevitably defeated Russian communism.

In an interview where he discussed his new film, The War, Ken Burns offered an answer to my enduring question. He said that what made the difference for the American World War II generation was that they were all in a boat with their oars in the water and they were all rowing in the same direction. Whites, blacks, Hispanics, native Americans, men and women were all united in defending America and defeating the forces of fascism. Americans, in effect, put aside their differences to a certain degree to accomplish an absolutely necessary goal.

Now the apologetic epiphany: What would happen if Christians were able to cooperate with each other to this degree? What if believers in Christ made it their goal to seriously work together to combat the great challenges of our time?

Think of the impact on our culture if conservative Christian denominations put aside their secondary doctrinal differences and cooperated with each other to accomplish mutually agreed upon goals. What would happen if even the members of local church congregations all got in a boat and decided to row “together” to accomplish important goals? How about if individual families really cooperated to make a difference?

And what would be the result if old-earthers and young-earthers who both embrace biblical inerrancy and Christian orthodoxy were able to respectfully cooperate with each other? Especially at a time when a seemingly growing number of people think that religion is a poisonous agent in the world.

I’m personally going to be giving this epiphany a great deal of thought and prayer. For I long to be part of a country, a church, an apologetics organization, and a family that cooperates in order to accomplish necessary and noble goals.

For more on a call for Evangelical Christians to effectively cooperate, see John M. Frame, Evangelical Reunion: Denominations and the One Body of Christ (Grand Rapids: Baker, 1991).

Hugh Ross, Ph.D.

Originally Posted on Monday, November 26th, 2007

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. 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 ± 0.009 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.