What is the 'fifth force' of nature?

A new search for the 'fifth force' or otherwise referred to as the 'dark force' of nature, is about to be launched by scientists.

In recent decades, the search for the 'dark force' has become popular amongst the scientific community, due to findings that the majority of the mass of the universe is made of 'dark matter'.

However, it is argued amongst physicists as to what 'dark matter' actually is. Some believe that 'dark matter' is a new subatomic particle (this can refer to any unit of matter below the size of an atom). Some physicists believe that 'dark matter' could be related to an unknown fundamental force (the majority of scientists conventionally excepts four fundamental forces).

The importance of these forces is that they provide the basis of our known interactions in nature.

• Gravity - is the force that pulls the body to the centre of the Earth, this allows us to keep our feet on the ground. Gravity also describes the attraction to any other physical body having mass. 

• Electromagnetism - is the force that relates to electric and magnetic fields, their relationship with each other, with other currents and electric charges. Electromagnetism holds atoms together. And it generates light in computer monitors so that you can read it.  

• The Strong Force - is the force that holds the nucleus, the positive central core of an atom, together.

• The Weak Force - is the force that causes beta decay (a type of radioactive decay where an electron is emitted).

However, some physicists theorise that a form of 'dark energy', 'Quintessence', could be the fifth force. 'Quintessence' is the hypothetical energy that has caused the acceleration of the expansion of the universe. 

Therefore, the search for this 'fifth force' could, thus, reveal forces of nature that are unknown to the scientific community. But there is a possibility that not all the answers to the universe will be revealed. The best theory used by physicists (the theory of reality), only explains 4% of the perceptible universe.