The student is expected to research and describe the historical development of the concepts of gravitational, electromagnetic, weak nuclear, and strong nuclear forces.
There are four fundamental forces of nature: gravitational force, electromagnetic force, weak nuclear force, and strong nuclear force.
The historical development of the concept of the four fundamental forces took a very long time. It took nearly 1700 years for the concept of gravitational force put forth by Aristotle to be correctly identified by Galileo and Newton. A hundred years after that, the electromagnetic force was explained. It took another hundred years for the weak nuclear and strong nuclear force to be understood.
All new scientific discoveries and interpretations must obey the fundamental laws of science. These laws are never defied but are sometimes refined. Scientific understanding of the gravitational force, electromagnetic force, weak and strong nuclear forces is based upon the historical development of previous knowledge and current technology.
The discovery of subatomic particles had a huge impact on the classical concepts of the fundamental forces of nature.
The strong nuclear force is the strongest force, then the electromagnetic, weak nuclear and gravity in order of decreasing strength.
The gravitational, strong and weak nuclear forces are always attractive, only the electromagnetic force can be either attractive or repulsive.
The range of the electromagnetic and gravitational forces is infinite, the range of the weak and strong nuclear forces is confined to atomic scales.
Four Fundamental Forces
It took human beings a very long time to correctly categorize different kinds of forces in nature. Although we encounter various forces in our daily life, for example friction, elastic force, buoyancy and so forth, only four fundamental forces exist. They are the gravitational force, the electromagnetic force, the weak nuclear force, and the strong nuclear force.
GRAVITATIONAL FORCE
Aristotle (4th Century): Aristotle approached the concept of gravitational forces from a scientific point of view about 1,700 years ago. He hypothesized that objects fall due to an intrinsic ‘heaviness’ rather than any external force. Furthermore, Aristotle stated that different objects accelerate at different rates. He stated heavier objects would have a greater acceleration and hence they would fall to the ground faster.
Galileo (17th Century): Galileo disproved Aristotle when he dropped balls of different masses and demonstrated that gravitational forces accelerated them with the same rate.
Newtonian Physics: Newton further developed the concept for gravitational forces quantitatively using mathematics through the inverse square law of universal gravitation. It states that the gravitational force between two objects is proportional to their masses and inversely proportional to the square of the distance between the two objects. Using this formula, Newton was able to derive Kepler’s laws of planetary motion. Astronomers observe planetary motion and are able to deduce the presence of orbiting moons based on gravitational disturbances of a planet’s orbit.
Einstein’s Theory of General Relativity: Einstein further developed the idea of gravity as acceleration into the theory of general relativity.
Many scientists from different eras contributed to the current understanding of gravity which acts on all masses in the universe. In general, new developments and discoveries in science are based on previous contributions of other scientists from all over the world.
ELECTROMAGNETIC FORCE
A hundred years after Newton’s work, people started to correctly explain the electromagnetic force, which occurs between charged particles and is associated with their electric and magnetic fields. Like gravity, it obeys the inverse square law of distance, but can be either attractive or repulsive.
STRONG NUCLEAR FORCE
A hundred years later, relying on advances in technology, people were able to understand strong and weak nuclear forces for the first time. The strong nuclear force binds the subatomic particles of the nucleus of an atom together.
WEAK NUCLEAR FORCE
The weak nuclear force is a weaker force that eventually leads to radioactive decay of subatomic particles. Nuclear forces do not obey the inverse square law.
Unifying Theories
All new scientific discoveries should be consistent with the fundamental laws of science. But laws are refined using more recent discoveries. For instance, the discovery of subatomic particles had a huge impact on the classical concepts of the fundamental forces of nature.
Although the four fundamental forces have many similarities, they are inherently different, especially when distances and strength are considered. Modern physics theories have been able to unify electromagnetic, weak and strong nuclear forces. To date, gravity is not included, and it is unclear whether a Theory of Everything can be achieved.