Reasons to Believe

Proving Cosmic Expansion Using Direct Measurements Only

Opponents of the anthropic principle and of big bang cosmology (whether atheists or young-earth creationists) frequently attempt to push aside compelling physical evidence for these biblically predicted cosmological features1 by picking apart the limiting factor in determining the details of the cosmic creation story. This limitation is the inability of astronomers to determine accurate distances to galaxies, both nearby and far away, through direct measurements.

Ultimately, all cosmic distance measurements are based on the plane geometry theorems taught in high schools. As an example, if one knows the length of an isosceles triangle's base, then measurements of the angles at either end of the base will deliver the distance to the vertex of the triangle. For measuring distances to nearby stars, the diameter of Earth's orbit about the Sun (about 185,912,076 miles or 299,195,741 kilometers) has served as the traditional base of the triangle. But astronomically speaking, this base is so tiny that distances to even the nearest stars cannot be determined to be accurate to within an error bar no better than a few percent. This presents a problem.

To gain any measurement of the universe's history and insights into its creation event, astronomers must use their limited direct distance techniques to compute indirect distance methods for more remote objects, such as galaxies. The indirect methods make certain assumptions about the properties of the observed objects. Only the direct methods are assumption-free.

Clearly, astronomers need to push the direct techniques' range far beyond the stars within a few hundred light-years of Earth, so that at least a few of the indirect measuring methods can be accurately calibrated. The cosmological ideal would be to measure the cosmic expansion rate using only accurate direct distance measurements.

In the July 2, 2007 and the March 3, 2008 editions of Today's New Reason To Believe, I reported on measurements made on microwave maser sources orbiting around the supergiant black hole that resides in the center of the galaxy NGC 4258. The spectra of the maser sources yielded the orbital velocities of the sources about the black hole. Newton's laws of motion translated those velocities into measured diameters for the orbits. Radio astronomy research teams then used electronically-linked radio telescopes all over the world to create an instrument with the equivalent resolving power of a telescope several thousand miles in diameter.

With this instrument, the researchers achieved an angular resolving power a thousand times better than the biggest ground-based optical telescope and a hundred times superior to the Hubble Space Telescope. Combining accurate measurements of the angles subtended by the orbits with precise calculations of the diameters of the orbits in kilometers, the team used the same geometry theorems used to compute distances to nearby stars to calculate the distance to NGC 4258.2 This technique extended accurate direct measurements out to 25 million light-years, or about 25,000 times more distant than any such previous measurement. It confirmed that the indirect distance measuring methods were reliable.

At 25 million light-years away NGC 4258 is still too close to yield an accurate measurement of the cosmic expansion rate completely independent of the indirect methods. Consequently, for several years now astronomers have been searching for maser sources in remote galaxies. So far, almost one hundred such masers have been discovered,3 though most emit a signal strengths too weak to be useful for expansion rate determinations. A few months ago, however, two radio astronomers discovered 4 a strong water maser source orbiting about the nucleus of the Seyfert galaxy, UGC 3789.

Indirect measurements reveal that UGC 3789 is about 150 million light-years away. This galaxy is the first sufficiently distant galaxy in which astronomers have found a strong enough maser source to produce an accurate direct calculation of the cosmic expansion rate. In fact, radio astronomers are confident that measurements on the UGC 3789 maser will produce a direct measurement of the expansion rate accurate to within an error bar no greater than three percent.5

So far, the best determination of the cosmic expansion rate has an error bar equal to seven percent. Furthermore, it's based on indirect measurements. Thus, the UGC 3789 maser will deliver a value for the cosmic expansion rate more than twice as precise as the current best measurement–with the added bonus that the value will be free of all the uncertainties inherent in the assumptions and calibrations that go with the indirect measuring methods.

Forthcoming greater accuracy of the measured value for the expansion rate will give cosmologists a much more detailed history of the universe and a more exact picture of the cosmic creation event. The limiting factor cited by big bang critics may not be so limited after all. This development will allow deeper and more rigorous tests of the big bang creation model. It could provide even more evidence for the Bible's description of cosmic creation and history.

Reasons To Believe scholars predict that the big bang creation model and the anthropic principle that the Bible mentioned more than two thousand years before modern science will pass these future measurement tests with flying colors.

Endnotes:

  1. Hugh Ross, The Creator and the Cosmos, 3rd ed. (Glendora, CA: Reasons To Believe, 2001), 23-29.
  2. A. L. Argon et al., "Toward a New Geometric Distance to the Active Galaxy NGC 4258. I. VLBI Monitoring of Water Maser Emission," Astrophysical Journal 659 (April 20, 2007): 1040-62; E. M. L. Humphreys et al., "Toward a New Geometric Distance to the Active Galaxy NGC 4258. II. Centripetal Accelerations and Investigation of Spiral Structure," Astrophysical Journal 672 (January 10, 2008): 800-16.
  3. J. A. Braatz and N. E. Gugliucci, "The Discovery of Water Maser Emission from Eight Nearby Galaxies," Astrophysical Journal 678 (May 1, 2008): 96-101
  4. Ibid.
  5. M. J. Reid et al., "The Megamaser Cosmology Project. I. Very Long Baseline Interferometric Observations of ±UGC 3789," Astrophysical Journal 695 (April 10, 2009): 287-91.

 

Subjects: Big Bang, Origin of the Universe, Universe Design

Dr. Hugh Ross

Reasons to Believe emerged from my passion to research, develop, and proclaim the most powerful new reasons to believe in Christ as Creator, Lord, and Savior and to use those new reasons to reach people for Christ. Read more about Dr. Hugh Ross.