Paul Sutter writes:

Earth may be swimming through an ocean of dark matter — and waves in that invisible ocean lapping against our planet’s upper atmosphere may generate detectable radio waves that allow us to finally find this elusive component of the universe, according to new theoretical research.

A wealth of astrophysical and cosmological evidence points to the existence of dark matter, from the inexplicable rotation curves of certain galaxies to the growth of the largest structures in the universe. Attempts to explain this wide variety of observations with alternative formulations of gravity have failed, so the vast majority of astronomers think dark matter is some unknown form of matter that only rarely interacts with light or with normal matter.

But that is a very broad idea that encompasses a lot of possibilities. Dark matter may be made of massive particles, but searches for those kinds of particles have largely turned up empty. So an intriguing alternative is that dark matter is exceptionally light, either in the form of theoretical particles known as “axions” or as an exotic form of photon that carries a bit of mass.

With that incredible lightness — millions of times lighter than the lightest known particles — dark matter could act in very strange ways. In particular, instead of appearing as individual point-like bullets, the dark matter would behave more like large waves that slosh around the cosmos.

In a recent study published to the preprint server arXiv, physicists explored models of ultralight dark matter that wasn’t entirely dark, allowing it to interact extremely rarely with normal matter. Most of the time, these interactions barely registered, producing nothing detectable. But in rare cases, the dark matter and normal matter interacted enough to produce a sizable amount of radio waves. [Continue reading…]