More Accurate Measures of Creation: Shoring Up the Distance Ladder Method

Opponents of the big bang creation model, both atheists and young-earth creationists, often attempt to blow past it by picking apart the least understood and least well-determined components of the model. They use this same tactic to evade the mountain of evidence establishing that the structure and history of the Milky Way Galaxy (MWG) has been exquisitely designed over the past ten billion years to make possible a suitable home for humanity. Yet compelling and overwhelming physical evidence exists—and continues to grow—in favor of this biblically predicted model.¹

The difficulty of measuring accurate distances to stars, galaxies, and gas clouds has been the limiting factor in determining the details of the MWG and the cosmos’ history and structure. These distance measurements rely on the distance ladder method, which uses direct distance measurements on nearby objects to calibrate indirect distance methods for more distant objects.

Direct distance measurements depend upon plane geometry theorems. For example, if one knows the length of the base of an isosceles triangle, then measurements of the angles at either end of the base will deliver the distance to the vertex of the triangle. Traditionally, the diameter of Earth’s orbit becomes the base of the triangle for such theorems.

For all but the most distant galaxies, the most widely applicable, consistent, and internally reliable measuring method is based on determining the brightness of the “tip of the red giant branch.” The tip of the red giant branch is the maximum intrinsic brightness reached by stars of medium mass (less than 2.25 solar masses) during their first entrance into the “red giant” phase of their burning history. Theoretically, it marks the onset of helium burning in the nuclear furnaces of these stars.

The tip of the red giant branch makes an excellent standard candle. In stars, the wide range of differences in the abundance of elements heavier than helium negatively impacts the usefulness of other standard candles in the distance ladder method. But these differences exercise little effect on the brightness of the tip, which varies by only 0.1 magnitudes. The downside, however, is that the tip of the red giant branch is a tertiary distance indicator. It is calibrated by RR Lyrae variable stars, which themselves are calibrated by direct distance measurements of the nearest RR Lyrae stars. For the tip of the red giant branch method to become fully reliable, it must be accurately calibrated by direct distance measures.

A team of three Australian astronomers has now produced for the astronomical community the first ever geometric (that is, direct distance measure) calibration of the tip of the red giant branch.² Using the Two Micron All Sky Survey and the DIRBE catalog, they detected the tip of the red giant branch in the neighborhood of the Sun. Next, they used the latest revised direct distance measurements of stars in the HIPPARCOS parallax catalog to accurately determine the distance to nearby stars that are at the red giant branch tip. From all this data they calculated that the intrinsic or absolute brightness of the tip is -6.85 ± 0.03 magnitudes. That is, they measured the brightness of the tip with a probable error that was less than half of a percent!

And the Australian astronomers delivered more encouraging news for the astronomical community. Their measurement of the absolute brightness of the red giant branch tip agrees very well with previous estimates based on stars in the Large and Small Magellanic Clouds (nearby dwarf galaxies) and on stars located in the bulge of the MWG. This confirmation means that distance measurements based on the distance ladder method are actually better than what astronomers had presumed.

The accurate calibration of the tip of the red giant branch by direct distance measurements will yield greater accuracy and trustworthiness in the measured values for the cosmic expansion rates. In turn, these superior measurements will give cosmologists a much more detailed history of the universe and a more exact picture of the cosmic creation event. This superior history and picture will allow deeper and increasingly rigorous tests of the big bang creation model. It could provide additional evidence for the Bible’s description of cosmic creation and history. We at Reasons To Believe predict that the big bang creation model and the design of the universe for humanity’s benefit, which the Bible so eloquently describes, will pass these future measurement tests with flying colors.