Source: National Post

The universe is controlled, held together and pushed apart by four fundamental forces: gravity, electromagnetism, as well as strong and weak nuclear forces.

Now, physicists in Hungary believe they found more evidence to open the discussion of whether there is, in fact, a fifth force of nature, which would force us to rethink our understanding of the universe and how it works. 

The fifth force could also potentially help researchers explain and spot black matter, which is theorized to account for 85 per cent of the universe. 

In 2015, evidence of a fifth force was first spotted by Hungarian physicists, in the radioactive decay of beryllium. Now, the same group has spotted a second example of this fifth force in an experiment involving helium, to go along with the particle they believe is carrying it. They’ve called the particle X17. 

In 2015, Attila Krasznahorkay and his colleagues at the Institute for Nuclear Research (Atomki) in Hungary started by firing protons at the isotope lithium-7, creating beryllium-8, an unstable isotope, in an effort to analyze how it would emit light as it decays. 

The decay of its particles didn’t go as expected. The beryllium-8 is supposed to transform into a positron and an electron, and as the energy of the light increases, the angle between the two particles should decrease and eventually separate completely.

The Hungarian physicists observed the electron and positron separate at an angle of 140 degrees. It’s believed that at the moment the atom decays, the excess energy created a newly discovered unknown particle. Once that particle decayed, almost immediately, it then turned into a recognizable positron and electron.

The experiment was later repeated with the same results by a group of researchers in America. It’s believed a whole new particle could, in fact, be responsible for the anomaly as its characteristics imply that it’d have to be a completely new kind of fundamental boson, a particle which can carry forces. 

It’s described as a “protophobic X boson”. At the moment we only know of four fundamental forces, while three of them have bosons that carry their messages of repulsion and attraction. The force of gravity, is carried by a hypothetical particle known as a graviton, which scientists have yet to detect. 

But this new boson could not be one of the particles known for carrying the four already established forces, because of its distinctive mass. The new boson is 17 megaelectronvolts, which is about 33 times the size of an election. It also has a tiny lifespan of about 10 to the minus 14 seconds.

To continue their research, Krasznahorkay’s team changed their focus from looking at the decay of beryllium-8 to the state of an excited helium atom. Instead of separating at a 140 angle, the positrons and electrons separated at an angle closer to 115 degrees.

The team calculated the helium’s nucleus, which could have produced a boson with a mass just under 17 megaelectronvolts, which is why they’re calling the particle X17. But it’s still a long way from being known as an official participle that can be added to models of matter. 

“According to the mass, it is likely the same X17 particle, which we recently suggested for describing the anomaly observed in 8Be,” writes the research team. 

The team’s initial experiment was accepted into the journal, Physical Review Letters. Their latest finding and study has yet to be peer reviewed, but the findings were released in late October to be scrutinized by other members in the field.

Source: National Post