The Fifth Fundamental Force

The universe is replete with mysteries we have never heard of. Ranging from our very own planet Earth to the stars in the sky, every object of creation has a question mark. This amazing fact that human beings know so less carves out a path for new discoveries which have become a part and parcel of our lives.Physics has always been a rebellious subject. It is not only vast but it has within such secrets which no one knows. Beliefs changed as time passed since new facts were revealed every other day, thereby altering pre-existing proofs created by man. As kids in school, all of us have studied about the four fundamental forces of nature but has any of you heard of the fifth one? I guess not.  It was mid-2016 when the scientists talked about the existence of this fifth fundamental force.

The Four Fundamental Forces

Force is essentially the basis on which our universe exists. Science recognizes four basic forces in nature –  gravitational, electromagnetic and the strong and weak nuclear forces. The Gravitational and Electromagnetic forces are those that we easily observe in our daily lives, while other two are the ones that are observed at the atomic level. Before proceeding to the new discovery, let us first understand these four forces.

Gravitational Force – Gravitational force depends on a body’s inertia. It isn’t spectacularly strong in terms of magnitude. In fact, it is among the weakest, but it is quite long ranged and always attractive. We experience Earth’s gravity, largely because Earth is so huge! Any two bodies with low mass experience negligible gravity. The Gravitational force produces a gravitational field which exists around all objects due to the force that they exert on other objects. It can be defined using Newton’s law of universal gravitation. Or more accurately, Einstein’s Relativty.


Electromagnetic Force – This one is the result of electric charges. Not delving deep into the concept, it is responsible for holding atoms and molecules; by attraction and repulsion of charges. The charges create a field around them called the electromagnetic field, further inducing it on the other charges. The electromagnetic field is a combination of the electric and magnetic fields. The electric field is produced by stationary charges and magnetic field by moving charges. They are considered as smooth continuous curves according to classical physics but quantum physics has something else to say.

Even though electromagnetic force has a long range, it is quite weak. It proves to be quite useful in our daily lives since there is multifarious equipment like a transformer, which is produced because of the existence of electromagnetism.


Strong Nuclear Force– Inside atoms, resides a nucleus holding together protons. The force that is responsible for holding the nucleus together preventing the protons to move away is this strong nuclear force. Strong Nuclear Force is short ranged, but extremely strong. It does not reduce in strength as distance increases. Therefore, the quarks inside the nucleus are bound together by these forces. In other words, we can say that there is a “strong interaction” between the particles. Strong interaction can be precisely defined by quantum chromodynamics.


Weak Nuclear Force– The weak nuclear force is the one that is responsible for radioactive decay. It has a very short range. The weak nuclear force produces a weak interaction between the particles experiencing this force. The weak nuclear force is accountable for the conversion of a neutron into a proton by beta decay and also for nuclear fission. It is interesting to note that this is the sole force which can change one kind of quark into another.


A Fifth Fundamnetal Force

The four forces tend to explain almost all our observations in the universe. But some anomalies remian – such as – dark matter and dark energy. Dark matter makes up 85% of the universe, and yet does not interact with almost anything, except gravitiationally. The four forces fulfill our understanding of the universe from time to time, but they too have a limit and tend to fail to help us. This is where the fifth force comes into being. It is said that the fifth fundamental force holds the power to explain the unexplained concepts, like dark matter.


Physicists from the Institute for Nuclear Research have been conducting studies on the dark photon. Their experiment consisted of a set up in which they hit thin lithium-7 with protons, thereby creating an unstable beryllium-8. They studied its decay only to encounter an anomaly which could not be explained by any of the existing theories in physics. The decay of beryllium-8 at some specific angles posed the existence of a new particle. The new particle was called the “X-boson” and was 34 times heavier than the electron. A counter study was done on this matter which suggested that the particle posed the existence of an entirely new force.

Jonathan Feng, a researcher from the University of California termed the discovery as groundbreaking and said, “If true, it’s revolutionary.”

What Then?

According to Galileo, a feather and a rock falling in a vacuum will fall together. This is called the principle of equivalence. This was further modified by Albert Einstein concerning the equivalence of gravitational and inertial mass. According to Einstein, the gravitational force experienced by a body kept on a large inertial body is equal to the pseudo-force experienced by the body kept on an accelerated medium.

According to the recent researches performed by scientists, they partially rejected this theory. It was said that a feather would fall faster than the stone in a vacuum because of this newly found fifth force which was named “hypercharge.” But the effects of hypercharge are almost negligible and so localized that it actually cannot alter Einstein’s theory.

Although hyper charge might not be involved in the regular physics, there are chances that it can uncover other mysteries of the universe.


Does it Actually Exist?

Well, the discovery was limited to a new particle which came into being while searching for a dark photon. And since there was nothing that could explain the behavior of the particle, a new kind of force was said to exist. There have been experiments in the past too which suggest such existence but the foundations remain shaky.

Perhaps the suppositions of the scientists are correct, but there is no proof to go with this revelation just yet. So while there is suspicion of a fifth fundamental force, we cannot conclude it just yet. Research will obviously continue. The physicist Jonathan Feng said that since the particle is quite light, there are many laboratories which are capable of performing the experiment to search for it and according to him, many have already joined this task-force.