Oftentimes, when we are not looking for something specific, that is when a new idea arises or a discovery is made. This is more or less how scientists almost discovered a fifth force in the universe. Even though Einstein did not speak of a fifth force specifically, he believed in a unified theory that explained all the forces of nature. That is what modern physicists continue to seek: the exploration of phenomena that challenge known theories.
Before discussing the fifth force, we need to remember the 4 already-proven ones
Before we talk about this possible fifth force in the universe, it’s important to recall the four known ones:
- Gravity
- Electromagnetic
- Strong nuclear
- Weak nuclear.
While three are well-explained by the standard model, gravity remains the outlier, and that’s where Einstein’s theory comes in
In the theory of General Relativity, Einstein shows that gravity is not a traditional force, as explained in the Newtonian model, but rather a curvature of space-time caused by mass and energy. He also believed in a unified theory that would explain all known forces. His dream was to be able to describe the entire universe through just one mathematical structure.
The research that opened the door to a 5th force
In 2023, scientists working on Muon g-2 at the Fermilab in Chicago announced that they were close to proving the existence of a fifth force of nature. This was truly news that shook the world of physics.
Scientists reached this conclusion after measuring the magnetic moment of the muon, which is a particle similar to the electron, but 200 times heavier. The experiment showed an oscillation in the behavior of the muon in a magnetic field. This oscillation, in turn, diverged from the predictions of the standard model of the four forces, and it was then that an expectation of discovering new phenomena – and, in this case, the fifth force – arose.
From euphoric discovery to error
What initially appeared to be the discovery of the century in physics, after undergoing intense revision, turned out to be a flaw in the original theoretical approach.
By applying advanced lattice QCD techniques, Fermilab researchers discovered that theory and experiment were in fact aligned, indicating that the mystery of the fifth force has been solved; until now, it has not been proven.
Could asteroids hold the key to the 5th force in the universe?
Also in 2023, NASA’s OSIRIS-REx mission managed to collect samples from the near-Earth asteroid Bennu. These samples not only provided insights into the universe, but also data to investigate the possible existence of the fifth fundamental force in the universe.
According to Yu-Dai Tsai, an astrophysicist at LANL:
“Interpreting the data we see from tracking Bennu has the potential to add to our understanding of the theoretical underpinnings of the universe, potentially revamping our understanding of the Standard Model of physics, gravity and dark matter”.
When the trajectory of an asteroid is established, scientists can pay attention to every change that occurs with it, and, in this case, some changes analyzed could not be explained only by the forces already known.
Now, even without being able to confirm the discovery of a new force, the OSIRIS-REx team has already set limits on where it could be hidden. Already thinking about the future, they plan to study the asteroid Apophis in 2029 to continue investigating.
Research like this shows how science is constantly evolving; it is no wonder that Einstein himself died before being able to unravel countless mysteries surrounding our Universe. One of them, for example, was confirmed after 40 years: an object hidden in the Solar System was detected by NASA.
