Dark Matter May Not Be Invisible After All. This Discovery Could Prove It.
Ultrafine dark matter, millions of times lighter than electrons, could flow through the cosmos in waves.
We might just have an easy way to check for tiny interactions between this dark matter and the ionosphere.
If this idea is validated, it’s an inexpensive and low-lift way to confirm or rule out one theory.
In the ongoing science quest to observe dark matter, there’s a new method in town. Researchers from Cornell University said in a new preprint paper (not yet peer reviewed or published) that dark matter could be striking Earth’s ionosphere—the magnetized plasma portion of Earth’s outermost atmosphere that is constantly struck by solar radiation—burning out, and fading away into low-frequency radio waves that could be isolated and measured.
Paul Sutter explained the dark matter landscape while reporting on the paper for Live Science. “Dark matter may be made of massive particles, but searches for those kinds of particles have largely turned up empty,” he said. “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.”
Sutter explained that these maybe-particles of dark matter are “millions of times lighter” than anything we observe or theorize about in the visible universe. Think of these forms of matter like granulated sugar and powdered sugar—the differences, including how they behave in recipes and must be handled, make it easy to imagine how ‘fine and fluffy’ exotic dark matter would create a new paradigm.
Part of that paradigm could be completely revolutionary—the dark matter may not be completely ‘dark’ at all. Dark matter is called ‘dark’ because it’s invisible to us and does not measurably interact with anything other than gravity. It could be interspersed between the atoms that make up the Earth and everything on it, all the time, and we’d never know for sure. But for certain very specific types of dark matter, there may be some ‘cross-lightness’ mingling.
The authors said that if a particular set of parameters is true, we should be able to observe a certain kind of dark matter within Earth’s ionosphere. That dark matter is not completely dark, as Sutter puts it, and has some rare and weak interaction with visible particles.
The team describes two types of ultrafine dark matter: one that sometimes interacts with photons, and one that sometimes interacts with two photons. The former interaction requires a plasma—the state of matter where a cloud of atoms act together—to be present. The latter requires a background magnetic field. When the wave of ultrafine dark matter flows over the Earth, our ionosphere meets both conditions.
The ionosphere is an ideal place to look for the telltale signs of this particular form of dark matter, the scientists explain, because we already spend a lot of time and resources doing studies of it. We have good tools and working models in place, and scientists wouldn’t have to venture far outside of those paradigms to look for ultrafine dark matter. Additionally, the ionosphere has natural CAPTCHA-style protection from false positives, like a daily solar fluctuation that would show in a true signal and not show in a “spurious” one.
What this calls for, the researchers conclude, is a new kind of antenna tuned to the particular details of this dark matter scenario. But it would be straightforward to make there, and cheap enough to build and install them that the team suggests an entire array of them be put in place. In a place with the least amount of human-made noise, and the right kind of tools in place, we might finally observe dark matter after all.
You Might Also Like
