Dark matter's gravitational pull is the glue of the universe, holding together galaxies and clusters of galaxies. Dark matter warps space like a funhouse mirror, stretching images of far-flung galaxies. Dark matter is also imprinted on the acoustic waves frozen in our snapshot of the 13.7 billion year-old universe, cosmic microwave background radiation.
Therefore, dark matter is not an illusion based on some lack of understanding of gravity, as some have suggested. "If solving dark matter calls for a modified theory of gravity I'll eat my PowerPoint slides - and my laptop computer!" said astrophysicist Mike Turner, of the University of Chicago.
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In fact, "dark" is a misnomer says Harvard University theoretical physicist Lisa Randall because it does not interact with radiation. A dark object still absorbs or reflects a little light. A black cat eating licorice in a coal bin is dark matter.
So, let's call the glue of the universe invisible matter, with a tip of the hat to 19th century poet Hughes Mearns:
"Yesterday, upon the stair;
Invisible matter particles were presumably cooked up when the newborn universe was a "quark soup," 1/100,000th of a second after the Big Bang. The seething hot universe was essentially a nuclear reactor for making particles more massive than quarks.
One idea is that invisible matter was born out of a phase transition - like water vapor turning into droplets. It may have decoupled from normal matter to make such hypothetical particles as axions or WIMPs (Weakly Interacting Massive Particles). Normal matter and invisible matter may have transferred properties between each other in the primeval cauldron. Both forms of matter store the same amount of energy in the same volume, so they must have a kinship.
Today there is an ongoing do-loop between theories and experiments for invisible matter. One theory is that invisible matter particles occasionally collide with each other to make specific flavors of cosmic rays, anti-protons or gamma rays. And, all of this must be sorted out from the cacophony of high-energy radiation saturating the universe.