Gravity is the invisible force that keeps our feet on the ground, makes apples fall from trees, and governs the motion of celestial bodies. But who discovered gravity? Most people immediately think of Sir Isaac Newton — and rightly so, but the full story of the discovery of gravity spans centuries and involves more than one brilliant mind.
In this post, we’ll explore the history of gravity, highlight key figures like Isaac Newton and Albert Einstein, and understand how our knowledge of this fundamental force has evolved.
What Is Gravity?
Before diving into who discovered gravity, let’s define it. Gravity is the force by which a planet or other body draws objects toward its center. It is responsible for the structure of the universe — from falling objects on Earth to the orbits of planets around the Sun.
The Ancient Understanding of Gravity
Long before Newton, ancient civilizations had their own interpretations of why objects fall.
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Aristotle (384–322 BC) believed that objects had a natural place. Heavy objects, like rocks, naturally moved toward the center of the universe — which he thought was Earth.
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Indian astronomers and thinkers like Aryabhata (5th century) also hinted at gravitational ideas, suggesting that the Earth attracts objects and doesn’t fall itself due to being surrounded by space on all sides.
While these early ideas weren’t scientifically correct, they set the stage for future inquiry.
Who Really Discovered Gravity? Enter Isaac Newton
The name most associated with gravity is Sir Isaac Newton (1642–1727). His groundbreaking work in the late 17th century forever changed science.
The Famous Apple Story
Legend has it that Newton observed an apple falling from a tree and asked, “Why does the apple always fall straight down?” This moment sparked his curiosity about the force that governs falling objects and planetary motion.
Newton's Law of Universal Gravitation
In 1687, Newton published the Principia Mathematica, where he introduced the Law of Universal Gravitation. It stated that:
"Every mass attracts every other mass in the universe with a force directly proportional to the product of their masses and inversely proportional to the square of the distance between them."
This was revolutionary. Newton didn’t just explain why apples fall — he explained why planets orbit the Sun, why the Moon doesn’t fly off into space, and much more.
Einstein Redefines Gravity
Fast forward to the 20th century — Newton’s laws held up well, but they weren’t perfect. Albert Einstein, in 1915, introduced the General Theory of Relativity, which offered a new perspective.
Instead of gravity being a force, Einstein described it as a curvature in space-time caused by mass and energy. Massive objects like Earth bend the space around them, and other objects move along these curves.
Einstein’s theory was confirmed by observations, like the bending of light around the sun — something Newton’s model couldn’t explain.
Other Contributors to the Understanding of Gravity
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Galileo Galilei (1564–1642): Conducted early experiments on falling bodies and showed that objects fall at the same rate regardless of mass.
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Johannes Kepler: Developed the laws of planetary motion that Newton later used as a foundation.
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Cavendish Experiment (1797–1798): Henry Cavendish measured the actual force of gravity between two masses, determining the value of the gravitational constant (G).
Why Newton Gets Credit for the Discovery of Gravity
While many thinkers contributed, Isaac Newton is credited with discovering gravity because he was the first to:
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Formulate a universal law that applies to all objects.
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Combine terrestrial and celestial physics.
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Provide a mathematical framework to predict gravitational effects.
His ideas laid the groundwork for modern physics, and his laws are still widely used today in engineering, astronomy, and everyday calculations.
Final Thoughts: Gravity Is Still a Mystery
Even with Einstein’s theory, scientists are still uncovering gravity’s secrets. Questions like:
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Why is gravity so much weaker than other forces?
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Is there a "graviton" — a particle responsible for gravity?
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How does gravity behave near black holes?
...are still being explored.
Conclusion: Gravity’s Discovery Was a Journey
So, who discovered gravity? The answer is layered:
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Ancient thinkers observed it.
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Galileo experimented with it.
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Kepler mapped its celestial effects.
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Newton defined and explained it.
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Einstein reimagined it.
Understanding gravity wasn’t a single discovery — it was a journey through centuries of curiosity and genius. Thanks to these brilliant minds, we not only know why apples fall, but also why planets dance around stars in cosmic harmony.