No need for dark matter?

Theoretical physicist Erik Verlinde has a new theory of gravity, which describes gravity not a force but as an illusion. The theory says gravity is an emergent phenomenon, possible to be derived from the microscopic building blocks that make up our universe’s entire existence. This week, he published the latest installment of his theory showing that – if he’s correct – there’s no need for dark matter to describe the motions of stars in galaxies.

Verlinde, who is at the University of Amsterdam, first released his new theory in 2010. According to a statement released this week (November 8, 2016):

… gravity is not a fundamental force of nature, but an emergent phenomenon. In the same way that temperature arises from the movement of microscopic particles, gravity emerges from the changes of fundamental bits of information, stored in the very structure of spacetime.

Dark Matter May Be More Complex Than Physicists Thought

Dark matter—the unseen 80 percent of the universe’s mass—doesn’t emit, absorb or reflect light. Astronomers know it exists only because it interacts with our slice of the ordinary universe through gravity. Hence the hunt for this missing mass has focused on so-called WIMPs—Weakly Interacting Massive Particles—which interact with each other as infrequently as they interact with normal matter.

Physicists have reasons to look for alternatives to WIMPs. For two decades, astronomers have found less dark matter at the centers of galaxies than what WIMP models suggest they should. The discrepancy is even worse at the cores of the universe’s tiny dwarf galaxies, which have few ordinary stars but lots of dark matter.

About four years ago, James Bullock, a professor of physics and astronomy at the University of California, Irvine, began to wonder whether the standard view of dark matter was failing important empirical tests. “This was the point where I really started thinking hard about alternatives,” he said.

Invisible Dark Matter May Show Up in GPS Signals

GPS satellites are crucial for navigation, but now researchers think this technology could be used for an unexpected purpose: finding traces of enigmatic dark matter that is thought to lurk throughout the universe.

Physicists estimate there is nearly six times as much dark matter in the universe as there is visible matter. But despite a decades-long search, scientists have yet to find direct evidence of invisible dark matter, and its existence is inferred based on its gravitational pull on galaxies and other celestial bodies. Without the extra force of gravity from dark matter, researchers say, galaxies wouldn't be able to hold themselves together.

Physicists don't know what dark matter is made of, but some think it's composed of particles that barely interact with the visible world, which is why dark matter is invisible and has been difficult to detect.

Read the entire article:
http://www.space.com/27900-dark-matter-gps-satellites.html