The nature of cosmic dark matter, the exotic matter that makes up about 5/6 of all matter in the universe, ranks as one of the two biggest unsolved components1 of the biblically predicted big bang creation model.2 (The other big unsolved component is the nature of dark energy.3) The exotic property of cosmic dark matter is that, unlike ordinary matter (matter comprised of protons, neutrons, and electrons), it does not interact or very weakly interacts with light. Now, a recent paper published in Nature by two Harvard University astrophysicists4 brings us one step closer to comprehending the nature of cosmic dark matter and thereby giving us yet more reasons to believe in the biblical description of the origin, history, and nature of the universe.
All the evidence that astronomers possess for the existence of cosmic dark matter relies on its gravitational pull on ordinary (or baryonic) matter. I offer an extensive review of this evidence in chapter 5 of the recently released book, The Creator and the Cosmos, 4th edition,5 and in a blog posted on January 22, 2018.6 The breadth of this evidence leaves no doubt that cosmic dark matter exists and that much more of it exists than baryonic matter.
However, astronomers are not satisfied. They want to know the origin and nature of cosmic dark matter. They also want to know in much more detail how cosmic dark matter influences the cosmic creation model and the design of the universe that is needed to explain the existence of life and of human beings in particular.
Nongravitational Evidence for Cosmic Dark Matter
More than two decades ago, theoretical physicist David Kaplan noted that a small degree of nongravitational coupling between cosmic dark matter and baryonic matter could explain the much greater abundance of cosmic dark matter compared to baryonic matter.7 Two years ago, a team of five astrophysicists showed that even a tiny degree of nongravitational coupling between cosmic dark matter and baryonic matter could resolve the small-scale discrepancies (properties of the innermost regions of cosmic dark matter halos and the population of dwarf galaxy satellites accompanying the Andromeda and Milky Way galaxies) in the currently most successful cosmic creation model, the lambda cold dark matter cosmic creation model.8
In a previous blog post,9 I explained how the EDGES (Experiment to Detect the Global EoR Signature) Collaboration used a sky-averaged radio spectrum to determine10 that 180 million years after the big bang creation event, the temperature of baryonic matter was less than half of its expected value. In that same blog I described how astrophysicist Rennan Barkana offered an explanation11 for how the universe’s baryonic matter cooled at that time. He showed that the cooling could be explained by scattering between baryonic particles (protons and neutrons) and cosmic dark matter particles.
Now, Harvard astrophysicists Julian Muñoz and Abraham Loeb provide an alternate explanation for the observed cooling of baryonic matter 180 million years after the cosmic creation event.12 Muñoz and Loeb show that (1) if a little less than one percent of cosmic dark matter particles possess a charge about a million times smaller than the charge of an electron; and (2) if the mass of most of the cosmic dark matter particles lies between 1–100 times the electron mass, “then the data from the EDGES experiment can be explained while remaining consistent with all the other observations.”13 They also demonstrated that serious inconsistencies arise if the entirety of cosmic dark matter particles possesses a mini-charge.
Muñoz and Loeb end their paper with suggestions on how observers and theoreticians can further probe (with existing technology) the nature of the nongravitational coupling between baryonic and cosmic dark matter. Their efforts and the ones they suggest are bound to yield more knowledge and understanding of the nature of 25.5 percent of the total composition of the universe. That progress promises to yield even more confirmation and understanding of the biblically predicted cosmic creation model.14