similar differences between their dynamic and lighted masses. Interestingly, Kahn and Woltjer (1959) found that the mass required to account for the mutual orbital motion of the Milky Way Galaxy and the Andromeda Galaxy (M31) required six times the combined mass of the two galaxies. In his first paper (in German), Zwicky referred to dunkle materie, which translates into English as dark matter. However, that term was not used by astronomers for decades. Instead, astronomers used the term missing mass. It was only since the 1980s that astronomers changed back to Zwicky’s original term. Slusher (1974) was the first to mention in the creation literature the discrepancy between the dynamic and lighted masses of galaxy clusters as a possible argument for recent origin (see p. 343 of Faulkner [2019] for other references of this in the creation literature). Slusher saw this as evidence for recent origin. His reasoning was that since the velocities of galaxies in clusters exceed the orbital velocities implied by the lighted masses of the clusters, the galaxies were not orbiting. Rather, the motions of galaxy in clusters indicated that clusters are not gravitationally bound and thus are expanding. This expansion could continue indefinitely, but it could not have been going on very long, much less than the supposed billions of year age of the universe. Bouw (1977a, 1977b) offered an early discussion in the creation literature of the velocities of galaxies in the Virgo cluster and recommended caution in using this argument based upon observations that suggest that the observed motions of its members is orbital. This amounts to a conclusion that dark matter may be real. I have agreed with this assessment (Faulkner 1998, 2017a). The opposition to dark matter that some recent creationists have may stem from a desire to maintain this argument for recent origin that Slusher pioneered. The second line of evidence for dark matter, the rotation curves of spiral galaxies, goes back nearly as far as Zwicky’s work with the Coma Cluster. A century ago, astronomers began to measure the orbital motion of objects within galaxies to determine the masses of those galaxies. The nuclei of spiral galaxies account for much of the light of those galaxies, and presumably much of their masses (more mass translates into more stars, which translates into more light). Spiral galaxies appear to be radially symmetric, suggesting the mass distribution in spiral galaxies is also radially symmetric. When mass is distributed with radial symmetry, the only mass that affects an object’s orbital velocity is that mass orbiting more closely to the center than the object. Therefore, measuring the Doppler motion across the long axis of a spiral galaxy acts as a probe of the mass distribution as a function of distance from the galaxy’s center. The summation of the mass distribution yields the total mass. A correction must be applied for how out of the line of sight the orbital motion is. For any spiral galaxy, this angle is easily determined by measuring the galaxy’s major and minor axes in a photograph. Radial velocity studies of the nuclei of spiral galaxies showed a linear relationship between orbital velocity and distance from the centers of those galaxies. If the amount of light is directly proportional to mass, then this linear relationship in the nuclei of galaxies is expected. Therefore, these studies confirm the relationship between light and mass, what astronomers call the mass to light ratio, at least in the nuclei of spiral galaxies. Since spectroscopy disperses light, it is a very inefficient use of light. A century ago, these studies required the largest telescopes that then existed, with photography that was at best 1-2 percent efficient. This severely limited how faint these studies could be conducted. Therefore, only the closest galaxies were sampled, and then only their nuclear regions. This resulted in finding only the masses of the nuclei of galaxies. But since the nuclei of spiral galaxies accounted for much of the light of the galaxies, masses measured this way were expected to be well within an order of magnitude of the entire masses of the galaxies, probably within a factor of 2-3. It was these studies, along with kinematic studies within our Milky Way Galaxy, that established the light to mass ratio that Zwicky used to establish the lighted mass of clusters of galaxies. What was the expected behavior of orbital motion outside of the nuclei of spiral galaxies? Since the light outside the nuclei of galaxies abruptly decreases just outside the nuclei and then continues to gradually decreases with increasing distance, the mass distribution was expected to similarly decline with increasing distance as well. When objects orbit a large, centrally located mass, orbital motion is inversely proportional to orbital distance. For instance, the sun contains more than 99.8% of the solar system’s mass. Consequently, the orbital speeds of planets are inversely proportional to their orbital distances. Since this condition fits planetary motion well, and Kepler’s laws describe planetary motion, then orbital velocity that is inversely proportional to orbital distance is called Keplerian. Since there is light emanating beyond the nuclear regions of spiral galaxies, the mass distribution beyond the nuclei is not zero, but it would be expected to be much smaller than the mass in the nuclei. Hence, the expected velocity function would be to begin to abruptly decrease beyond the nuclei and approach Keplerian behavior (See Fig. 1). A century ago, the size of telescopes and the observational techniques then in use did not make it feasible to extend radial velocity studies beyond the nuclei of spiral galaxies. At the edge of the nuclei, the radial velocity curves appeared to turn over, suggesting that beyond that point the radial velocities curves approached Keplerian behavior, so there was no reason to pursue the radial velocity curves farther out. Pushing the limits of what was technologically possible at the time, Babcock (1939) showed that the orbital velocities of a few objects some distance from the nucleus of the Andromeda Galaxy (M 31) were not Keplerian. Indeed, those objects had velocities that were about as high as the turnover point. The following year, Oort (1940) found similar anomalous results for the lenticular galaxy NGC 3115. He wrote that “the distribution of mass in the system appears to bear almost no relation to that of light.” Astronomers tended to ignore these anomalies for three decades. Perhaps it was because they didn’t know what to make of them. During these three decades, the masses of additional galaxies were determined by stopping at the turnover points on their radial velocity curves, again assuming that those curves were Keplerian beyond the turnover points. For instance, as I have documented (Faulkner 2021), between 1959 and 1965 Geoffrey and Margaret Burbidge and their collaborators published more than two dozen papers applying this technique to various galaxies. The non-Keplerian nature beyond the turnover point was obvious in many of those radial velocity curves. However, the Burbidges ignored this and calculated galaxy masses from the portion of the radial velocity curves in the galaxy’s nuclei. Since the Burbidges were so respected by other astronomers, they FAULKNER Dark matter and dark energy 2023 ICC 2
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