A new theory puts dark matter on the chopping block

Nicole Karlis in Salon:

What if dark matter didn’t exist? Sure, scientists have never observed it, but they believe it exists because of apparent gravitational effects. But what if our current understanding of gravity was just plain wrong?

The question has been raised over the last several decades, but typically when a proposed modified Newtonian dynamics (MOND) theory is put forth it has too big a blindspot to be taken seriously in the scientific community. In this case, the theory arguing against the existence of dark matter can’t account for observations of the cosmic microwave background (CMB), which is the leftover glow of the Big Bang or explain what happens at a larger scale with galaxies. Certainly such a discovery would be a significant change in the world of physics and have a remarkable impact on science.

This month however, researchers Constantinos Skordis and Tom Zlosnik from the Czech Academy of Sciences published a paper in the journal Physical Review Letters suggesting that a new modification to the parameters of Newton’s theory of gravity could provide an answer as to why dark matter has yet to be detected. And unlike previously proposed MOND theories, this one just might stick because the new proposal can match observations of the cosmic microwave background (CMB), which is a key detail that has lacked in the previous MOND-like theories.

…Dark matter is estimated to make up 27% of the universe’s total mass and energy, which is nearly five times more than the “normal” matter that comprises planets and stars. True to its name, dark matter is hard to directly observe. So far, none of the efforts to figure out the nature of the dark matter have gone very far. Yet astronomers are quite convinced it exists because of the huge gravitational effect it has on galaxies and the stars that live within them. As far as anyone can tell, dark matter is extremely non-interacting: just as humans walk through a still room barely noticing the atmosphere that surrounds us, dark matter seems to barely ever touch, even faintly, the normal matter that it hovers around. It is bound to our world by gravity only, and only tugs on other things that also possess gravity.

More here.