Introduction

In 1665, one of history’s greatest minds emerged: Sir Isaac Newton, the founder of differential and integral calculus, the Law of Gravity, and the Laws of Mechanics. Newton defined gravity as a force of attraction between objects based on their masses, with larger objects exerting a stronger pull on smaller ones. However, this understanding faced a major question: How does gravity travel through space? That puzzle remained unresolved until Albert Einstein’s revolutionary work in the early 20th century.

Gravity in the Middle Ages

Even Newton couldn’t explain how gravity acted between objects. What carried the force across the empty void? Newton’s followers proposed that space was filled with a mysterious substance called “ether,” which they believed transmitted gravity. This idea prevailed until 1887, when Albert Michelson and Edward Morley conducted an experiment that conclusively showed ether did not exist. The result threw the scientific world back into uncertainty about how gravity operated.

Perspective of Space-Time as a New Dimension

Einstein began solving this mystery in 1905 with his Special Theory of Relativity, introducing the famous equation E = mc², which showed that mass and energy are interchangeable. But it wasn’t until 1915, with his General Theory of Relativity, that Einstein addressed gravity in full. He rejected Newton’s force-based model and instead proposed that massive objects warp the fabric of space itself, creating what we now understand as space-time. Einstein’s radical idea that space is dynamic and curved by mass was confirmed in 1919 when astronomer Arthur Eddington travelled to Príncipe Island during a solar eclipse. He observed that light from stars appeared bent around the sun, exactly as Einstein had predicted. This discovery marked a major turning point and validated the idea of gravity as a geometric deformation of space-time.

The Future Through Light and Quantum

While Newton’s and Einstein’s theories explain gravity at medium and large scales, like for planets, stars, or black holes, they fail at the atomic level. Gravity doesn’t function properly when applied to subatomic particles like protons, neutrons, and electrons. At these scales, the electromagnetic force and the weak and strong nuclear forces dominate. These three are accounted for by quantum theory, which forms the basis of the Big Bang model. However, gravity remains the missing piece. To fully unify physics, scientists seek to include gravity in quantum theory through a process called renormalization. One proposed solution is the graviton, a hypothetical quantum particle that would function like a photon but for gravity. If proven, the graviton could help establish a “Theory of Everything,” merging all four fundamental forces into a single framework.

Conclusion

Newton’s discovery of gravity was a monumental breakthrough in physics, yet it sparked centuries of deeper inquiry. The question of what truly causes gravity evolved from ether to space-time, and now potentially to the graviton. Along this journey, the pursuit of understanding gravity has not only deepened our knowledge of the universe but also spurred advances across fields like medicine, technology, and computing. The search continues, with scientists pushing the boundaries of knowledge to unite the forces of nature under one grand theory.