FUNDAMENTAL FORCES IN NATURE

FORCES IN NATURE

Fundamentals forces govern many aspects of our lives, from the motion of celestial bodies to the behavior of subatomic particles. They are responsible for the production of energy in stars and galaxies and even act on the smallest scales in biology and chemistry. These forces are essential to our understanding of the universe, and it is important to study them in depth. By learning about these phenomena, we are able to gain a deeper insight into the laws that govern the universe and perhaps develop new technologies.

Gravitational Force

One of the four fundamental forces in nature is gravity, which is the force that attracts two objects to each other. This force is responsible for the bending of light and the formation of galaxies, stars and planets. Despite its ubiquity, gravity has been difficult to understand and describe precisely due to its extremely weak nature. Scientists have developed new theories that attempt to explain this phenomenon, such as the recently discovered General Theory of Relativity.

Electromagnetic Force

The electromagnetic force is the force between charged particles. In the simpler case when charges are at rest, the force is given by Coulomb’s law: attractive for unlike charges and repulsive for like charges. Charges in motion produce magnetic effects and a magnetic field gives rise to a force on a moving charge. Electric and magnetic effects are, in general, inseparable – hence the name electromagnetic force. Like the gravitational force, an electromagnetic force acts over large distances and does not need any intervening medium. It is enormously strong compared to gravity. The electric force between two protons, for example, is 1036 times the gravitational force between them, for any fixed distance.

Strong Nuclear Force

The strong nuclear force binds protons and neutrons in a nucleus. It is evident that without some attractive force, a nucleus will be unstable due to the electric repulsion between its protons. This attractive force cannot be gravitational since the force of gravity is negligible compared to the electric force. A new basic force must, therefore, be invoked. The strong nuclear force is the strongest of all fundamental forces, about 100 times the electromagnetic force in strength. It is charge-independent and acts equally between a proton and a proton, a neutron and a neutron, and a proton and a neutron. Its range is, however, extremely small, of about nuclear dimensions (10–15m). It is responsible for the stability of nuclei. The electron, it must be noted, does not experience this force.

Recent developments have, however, indicated that protons and neutrons are built out of still more elementary constituents called quarks.

Weak Nuclear Force

The weak nuclear force appears only in certain nuclear processes such as the β-decay of a nucleus. In β-decay, the nucleus emits an electron and an uncharged particle called neutrino. The weak nuclear force is not as weak as the gravitational force, but much weaker than the strong nuclear and electromagnetic forces. The range of weak nuclear force is exceedingly small, of the order of 10–16 m.

Towards Unification of Forces

We remarked in section 1.1 that unification is a basic quest in physics. Great advances in physics often amount to the unification of different theories and domains. Newton unified terrestrial and celestial domains under a common law of gravitation. The experimental discoveries of Oersted and Faraday showed that electric and magnetic phenomena are in general inseparable. Maxwell unified electromagnetism and optics with the discovery that light is an electromagnetic wave. Einstein attempted to unify gravity and electromagnetism but could not succeed in this venture. But this did not deter physicists from zealously pursuing the goal of unification of forces.