Fundamental interactions, also known as fundamental forces, are the interactions in physical systems that do not appear to be reducible to more basic interactions. Much like the periodic table of elements are not reducible to other substances, these are basic physical forces-gravitational, electromagnetic, strong nuclear, and weak nuclear. Recently scientists in Hungary at the Hungarian Academy of Sciences published a paper in the journal Physical Review Letters that theorized about a sub atomic particle, called a protophobic X boson
This particle was first thought to be a force 30 times larger and more powerful than an electron. It's a common theory that each fundamental force has a corresponding subatomic particle, so when this boson was being investigated it naturally brought up the possibility that there could be a 5th fundamental force in the universe, at least according to a team at UC Irvine that reviewed the paper. The Irvine team also believes that this discovery could lead to more information on dark matter, so far a mystery in physics, because it's not identifiable or detectable. It took centuries to fully understand the established forces of physics, figuring this one out could take awhile as well.
