Creation Moment 4/6/2018 - Dark Matter Versus MOND

Dark Matter Versus MOND

"Astronomers largely ignored this “missing mass” problem for a half-century. However, a series of papers in the 1970s studying orbital motion within many galaxies showed the same result—the dynamic mass was always far greater than the lighted mass, typically by a factor of 10. By the 1980s, astronomers stopped ignoring this problem as they came to grips with the fact that most of the

universe’s mass was invisible. What was this dark matter, as it was soon called? It was very clear that it wasn’t “normal matter,” like the stuff that we are made of. Different theories soon arose about what exotic particles might account for dark matter. Tests of various theories were devised, and the results eliminated the theories. Conclusion: most of the universe’s mass is probably in a form of matter that we haven’t yet contemplated.

Some physicists found this prospect unsettling, so they opted for an alternate solution: modifying the basic physics of gravity. MOND (for MOdified Newtonian Dynamics) makes a small change in the way that gravity works. Over small distances (less than thousands of light years), the difference between MOND and traditional Newtonian gravity is not noticeable. But on a galaxy-sized scale, the difference shows up. Physicists fit the orbital data from within galaxies to develop their model of MOND. However, the majority opinion, particularly among astronomers, is that dark matter is the correct resolution to this question.

What Was Recently Discovered?

A recent discovery revealed that a nearby galaxy, NGC 1052-DF2, has little or no dark matter. NGC 1052-DF2 is a little more than 60 million light years away and is about the same size of the Milky

Way. However, NGC 1052-DF2 is much fainter than the Milky Way or other galaxies of similar size. Application of the M/L ratio reveals a lighted mass of about 200 million times that of the sun. The orbital motion of 10 objects, presumed to be globular clusters, produced a dynamic mass only slightly larger than the lighted mass. Considering the likely errors involved, this result is consistent with little or no dark matter in this galaxy. However, this galaxy certainly is large enough for MOND to operate, if MOND is correct. The fact that the dynamic mass of this galaxy is consistent with its lighted mass would seem to eliminate MOND as a viable theory. Paradoxically, the discovery that there is no dark matter in this particular galaxy amounts to evidence that dark matter exists in other galaxies.

 Isn’t it humbling that God created the universe so complex that we don’t even know what most of it is made of?" AIG
 I, even my hands, have stretched out the heavens, and all their host have I commanded.
Isaiah 45:12