In the Star Wars films, Obi-Wan Kenobi describes ‘The Force’ as “an energy field created by all living things. It surrounds us and penetrates us; it binds the galaxy together.” If that sounds exotic, wait until you hear how fundamental physics portrays the concept of ‘force’.
In high school, we learn that force is an agent that induces an object to change its velocity, according to Newton’s second law. Then our textbooks casually mention the astonishing fact that all the forces we have encountered – tension, friction, van der Waals force, weight, etc. – come from just four fundamental types of interactions between elementary particles.
Is this really so? Why, of all numbers, four? Are there more? Are there fewer?
