How is gravitational force different from electromagnetic force?

Gravitational force is a universal attraction between masses, while electromagnetic force involves both attraction and repulsion between charged particles.

Gravitational force is a fundamental interaction that occurs between all objects with mass. It is always attractive, meaning it always seeks to pull objects together. This force is described by Newton's law of universal gravitation, which states that every particle of matter in the universe attracts every other particle with a force that is directly proportional to the product of their masses and inversely proportional to the square of the distance between their centres. However, gravity is the weakest of the four fundamental forces, and its effects are only noticeable on a large scale, such as between celestial bodies.

On the other hand, electromagnetic force is another fundamental interaction, but it occurs between charged particles. It can be either attractive or repulsive, depending on the nature of the charges involved. Like charges repel each other, while unlike charges attract. This force is much stronger than gravity—it's about 10^36 times stronger. Electromagnetic forces govern interactions at the atomic level and are responsible for holding atoms and molecules together. They also underlie the macroscopic forces of friction and tension.

Furthermore, the two forces operate over different ranges. Gravitational force acts over infinite distances, keeping planets in orbit around stars and forming the large-scale structure of the universe. Electromagnetic force, while also having an infinite range, is usually confined to smaller scales because positive and negative charges in the universe tend to balance out, making the net electromagnetic force zero over large distances.

Lastly, the two forces are described by different theories in modern physics. Gravity is described by Einstein's theory of general relativity, which portrays it as a curvature of spacetime caused by mass and energy. Electromagnetic force, meanwhile, is described by quantum electrodynamics (QED), a quantum field theory that portrays it as a result of the exchange of photons between charged particles. These differences in theoretical description reflect the fundamentally different natures of the two forces.