It's An Intriguing Theory.
Researchers suggest our planet is being battered by waves of
dark matter, the elusive stuff that's believed to make up 27 percent of the
universe, though scientists have yet to observe it directly.
As science communicator extraordinaire Paul Sutter explores
in a piece for Live Science, the European authors of a yet-to-be-published paper posit that radio waves detected in the Earth's ionosphere — the part of
the upper atmosphere where UV and X-ray radiation from the Sun ionizes atoms to
create plasma — could be the result of particles interacting with dark matter,
and therefore a great place to hunt for the evasive substance.
It's an intriguing albeit speculative theory that could take
decades of research to prove. Nonetheless, the prize is certainly worth playing
for, potentially putting to rest one of the biggest unanswered questions about
the universe that persists today.
Over the years, scientists have proposed several candidates
for dark matter, including extremely massive particles called "Weakly
Interacting Massive Particles" (WIMPs) or extremely light ones called
"axions."
Thanks to axions' highly unusual lightness, these
hypothetical particles may act more like "large waves that slosh around
the cosmos," as Sutter explained.
That would also make them exceedingly difficult to observe.
Instead of hunting for the particles themselves, scientists have long suggested
looking for any interactions they have with other matter around them, including
plasma, which is made of highly charged particles.
Now, a team of researchers from the University of Geneva and
the European Organization for Nuclear Research (CERN) — which is at the
forefront of our hunt for exotic particles — are suggesting a new place we
could look: the Earth's ionosphere.
By studying how "waves of hypothetical dark
matter" interact with ionized particles, per Sutter, we could come one
small step closer to answering one of the biggest puzzles facing
astrophysicists today.
While it's what Sutter calls a "long shot," with
the right instruments, we may just have a chance to finally uncover dark
matter's hidden identity.
"An electrically-small dipole antenna targeting the
generated radio waves can be orders of magnitude more sensitive to dark photon
and axion-like particle dark matter in the relevant mass range," the
researchers write.
Better yet, the ionosphere is extremely close to us, making
it a tantalizing place to hunt for dark matter.
"This form of dark matter is highly theoretical, and it
would take years, if not decades, to perfect the observation technique to
search for these radio waves," Sutter concluded. "But if it works, it
would be a gold mine, allowing us to study one of the most mysterious elements
in the universe right on our cosmic doorstep."