While stars might cluster in the disk and the normal matter might be restricted to a nearby region around the stars, dark matter extends in a halo more than 10 times the extent of the luminous portion. Image credit: ESO / L. Calçada.

Dark matter theory triumphs in sweeping new study

When a phenomenon moves from “empirical correlation” to “theoretically explained,” that’s one of the biggest deals in science!

Ethan Siegel
Starts With A Bang!
6 min readJul 6, 2017

--

“Space and time may have a structure as intricate as the fauna of a rich ecosystem, but on a scale far larger than the horizon of our observations.”
-
Martin Rees

When you look out at the Universe, all you see is matter and light. The stars, galaxies, plasmas, and unusual astrophysical objects all emit radiation from across the electromagnetic spectrum; the dust, gas, and neutral atoms absorb it. Yet what we infer from viewing them, particularly on the largest scales, tells us that there’s much more than what we presently perceive. In addition to matter and light, there’s got to be dark energy, a form of energy inherent to the fabric of space itself that causes the expanding Universe to accelerate, and a significant amount of dark matter: massive, clustering particles that are invisible to light. Dark matter can do many things, but one prediction it’s always struggled with is exactly reproducing how galaxies are observed to rotate. It’s been a problem for decades, from the 1970s until 2017. But as of June 23rd, a new paper claims to have finally solved the problem of galactic rotation at long last.

--

--

Ethan Siegel
Starts With A Bang!

The Universe is: Expanding, cooling, and dark. It starts with a bang! #Cosmology Science writer, astrophysicist, science communicator & NASA columnist.