A multitude of forces act on everything present in the universe in one way or another. There are dozens of forces, but if we break them down to their basic levels, we will find that all these forces are essentially a form of four forces. These four forces, together, are called the fundamental forces of nature. They are:
- Gravitational force- It is an attractive force which exerted by anything that has mass. We think of it gravity on a large scale basis, such as planetary gravity, which acts on things on or around any planet or gravity of stars which keeps the planet together. But the fact is that even the smallest particles in the universe exert gravity, however small in magnitude.
- Electromagnetic force- It is the force that is present between two electrically charged particles. Like forces repel each other and opposite forces attract. Take, for example, two bars of magnet. If you place them close by, they will attract if the opposite poles are facing each other and repel if the like poles are facing each other.
- Strong nuclear force- This force is responsible for holding the nucleus of atoms together. Although very strong, it has a very limited range (10-13 cm). This force is essentially attractive in nature but if the distance between two particles is smaller than its range, it becomes repulsive. That is how it keeps the nucleus from collapsing into itself.
- Weak nuclear force- It is a short range (10-18 metre) and very weak force that causes radioactive decay. It is also responsible for neutrino emission and absorption.
Though it may seem unlikely, all other forces are different forms of these forces. For example, friction, which may appear to be a different force altogether, is actually a kind of electromagnetic force. All these forces, acting together, has shaped the universe as we know it.