Rocky Foundations
There may be a fifth fundamental force of the universe that we haven’t documented yet — and, according to new research, our best bet of uncovering it may not lie in deep space, but in objects relatively close to home.
As detailed in a study published in the journal Communications Physics, astronomers propose that close observations of asteroids in our Solar System could be used to interrogate the existence of a new particle that forms dark matter, the invisible substance that is believed to account for 85 percent of all mass in the universe.
They point to the wealth of data gathered by the NASA OSIRIS-REx mission on the near-Earth asteroid Bennu as evidence of this potential testing ground. Since Bennu and other near-Earth asteroids are already extensively tracked, any deviations in their data could represent significant gaps in the Standard Model of physics, according to study lead author Yu-Dai Tsai.
This is, after all, how the existence of planet Neptune was predicted before it was even observed: through irregularities in the orbit of neighboring Uranus, the researchers note.
“The trajectories of objects often feature anomalies that can be useful in discovering new physics,” Tsai, a researcher at Los Alamos National Laboratory in New Mexico, said in a statement.
Straw Boson
The Standard Model of physics currently accounts for three of the four known fundamental forces of the universe, and all three have their own particles to explain them. The one outlier is gravity, which isn’t incorporated because it’s technically not a force but a warping of spacetime, according to Einstein’s theory of general relativity (that is, unless gravity is quantum).
And beyond the realm of forces, gravity isn’t the only odd one out. A lot of our understanding of the universe doesn’t yet fit the neat picture painted by the Standard Model. Dark matter is a prime example, even though it is essential to our understanding of how the universe organizes on a cosmic scale.
Scientists don’t know what dark matter is, and its existence is mainly inferred through its enormous gravitational influence that governs the structures of galaxies. One leading hypothesis proposes that a possible form of dark matter may be particles called ultralight bosons, so-named because their masses would be less than one-billionth of an electron.
Previous research has tried to tease out the existence of ultralight bosons by studying interactions around black holes. Using just data from Bennu, however, the researchers say they’ve established constraints on this possible fifth force.
“The tight constraints we’ve achieved translate readily to some of the tightest-ever limits on Yukawa-type fifth forces,” said coauthor Sunny Vagnozzi, a physicist at the University of Trento in Italy, in the statement.
To advance their theory, the researchers plan to turn their eyes to Apophis, another near-Earth asteroid that’s expected to swing by our planet in a close approach in 2029.
