Gravity is one of the four fundamental forces in the universe. It's the force that attracts any two objects with mass toward each other. This invisible force is what keeps our feet on the ground and causes objects to fall when dropped.
Sir Isaac Newton formulated the law of universal gravitation in 1687. This law states that every particle 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 them. The gravitational constant G makes this relationship precise.
Gravity is everywhere in our daily lives. When you drop an apple, it falls because Earth's gravity pulls it downward. Gravity keeps us firmly planted on the ground and prevents us from floating away. It makes water flow downhill and creates ocean tides through the Moon's gravitational pull. On a larger scale, gravity keeps planets in orbit around the Sun and holds our atmosphere close to Earth.
Einstein's theory of general relativity completely changed how we understand gravity. Rather than being a force, gravity is actually the curvature of spacetime itself. Massive objects like stars and planets bend the fabric of spacetime, and other objects simply follow the curved paths created by this bending. This elegant theory explains phenomena that Newton's laws couldn't, such as black holes and gravitational waves.
Gravity truly is the universal force that shapes our cosmos. It forms stars and planets, creates the orbits that keep our solar system stable, and enables the conditions necessary for life on Earth. From the smallest interactions between particles to the largest structures in the universe, gravity is the fundamental force that governs cosmic evolution and makes our existence possible.