Ultimately, all cosmic distance measures are based on the plane geometry theorems taught in high school. 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. For determining distances to nearby stars, traditionally the base of the triangle has been the diameter of Earth’s orbit about the Sun (about 185,912,076 miles or 299,195,741 kilometers). This base, however, is so tiny, astronomically speaking, that distances to even the nearest stars can be determined to an accuracy of no better than a few percent.
Herein lies the rub. To gain any measure of the history of the universe and insights into its creation event, astronomers must use their limited direct distance measures to calibrate indirect distance methods for more-distant objects. The indirect methods make certain assumptions about the properties of the observed objects. Only the direct methods are assumption-free. Clearly, there is a need in astronomy to push the direct methods out far beyond the stars within a few hundred light-years of Earth.
In the July 2, 2007 edition of Today’s New Reason To Believe I reported on recent 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. A separate radio astronomy research effort then used electronically linked radio telescopes all over the world to create an instrument with 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. With accurate measures of the angles subtended by the orbits combined with precise measures of the diameters of the orbits in kilometers, the team used geometry theorems (the same used to calculate distances to nearby stars) to calculate the distance to NGC 4258.2 This technique extended accurate direct distance measurements out to 25 million light-years, or about 25,000 times more distant than any such measure done previously. It confirmed the indirect distance measuring methods were reliable.
The team that performed the direct distance measurement on NGC 4258 achieved 10 percent accuracy (in other words, an error of 10 percent either way). This precision was equivalent to the best indirect distance measures to nearby galaxies. However, the team recognized that their method had the potential to deliver significantly greater accuracy. Such improvements in accuracy would 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 would 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.
In the January 10, 2008 issue of the Astrophysical Journal, the team reported on eleven years’ worth of measurements on the maser sources orbiting around the central black hole in NGC 4258.3 For the first time they were able to detect a trend in accelerations of low-velocity emission as a function of Doppler velocity (the Doppler velocity is the velocity of a particular maser source in the direction toward or away from Earth). Such a trend informs the team about the disk geometry and orientation of the galaxy and about the details of the galaxy’s spiral structure. Such information removes the major source of uncertainty in determining the distance to NGC 4258.
Once the team completes the remainder of their analysis they are confident they will be able to produce a distance measure for NGC 4258 that is accurate to about 3 percent (meaning the error bar would shrink to 3 percent). Such precision will represent a factor-of-three improvement in astronomers’ capacity to measure the expansion rate and expansion history of the universe. Reasons To Believe scholars predict that such measurements will bolster the case for the big bang creation model. And, given that features of the big bang were eloquently described in the Bible more than two thousand years before any scientist dreamed of the concept, the veracity of the Scriptures will be affirmed as well.