In 2016, Attila Krasznahorkay made news around the world when his team published its discovery of evidence of a fifth force of nature. Now, the scientists are making news again with a second observation of the same force, which may be the beginning of a unified fifth force theory. The researchers have made their original LaTeX paper available prior to acceptance by a peer-reviewed journal.

Study of the hypothesized fifth force, a subfield all by itself, is centered on trying to explain missing pieces in our understanding of physics, like dark matter, which could be expanded or validated by an important new discovery or piece of evidence. Scientists and specifically cosmologists are baffled by the amount of our universe made of dark matter and energy we can’t observe except in indirect ways and still don’t understand.

The scientists’ first observation in 2016 was of an isotope of beryllium, and their second is of an isotope of helium. Both observations involved circumstantial evidence of a force exerted by a new form of particle the researchers are calling X17 because of its energy potential of 17 megaelectronvolts. In 2016, the researchers wrote, “The deviation between the experimental and theoretical angular correlations is significant and can be described by assuming the creation and subsequent decay of a boson.” This new boson is the proposed X17 particle.

Read more: Popular Mechanics