Definition · Plain-language
Gravity
Gravity is the natural force of attraction that draws together any two objects that have mass.
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A universal attraction
Gravity is the attraction that exists between every pair of objects that have mass, from atoms to galaxies. Newton’s law of universal gravitation captures the everyday picture: the force grows with the masses involved and weakens rapidly with distance, falling off as the square of the separation. It is by far the weakest of the four fundamental forces — you can overcome Earth’s entire gravity just by jumping — yet because it always attracts and reaches across vast distances, it dominates the universe at large scales, shaping stars, planets and galaxies.
Weight, falling and orbits
On Earth, gravity gives every object its weight — the downward force equal to its mass times the gravitational field strength, about 9.8 newtons per kilogram. It also makes objects fall, accelerating them at about 9.8 metres per second squared regardless of their mass, so a feather and a hammer fall together where there is no air. The same force keeps satellites, the Moon and the planets in orbit: they are continually falling toward the body they circle, but moving sideways fast enough that they keep missing it.
Einstein’s deeper picture
Newton described how gravity behaves but not what it is. In 1915 Einstein’s general relativity offered a deeper account: mass and energy curve the fabric of spacetime, and objects simply follow the straightest available paths through that curved geometry. What we feel as a gravitational pull is the effect of this curvature. The picture predicts subtle effects Newton’s does not, such as light bending near the Sun and clocks running slower in stronger gravity, all of which have been confirmed by experiment.
Key facts
At a glance
- Definition: the attractive force between objects with mass
- Strength rule: grows with mass, weakens with the square of distance
- Weakest force: the weakest of the four fundamental forces
- On Earth: gives weight; objects fall at about 9.8 m/s²
- Keeps orbits: holds moons, planets and satellites in their paths
- Einstein’s view: the curvature of spacetime by mass and energy
Common misconceptions
What people often get wrong
Often heard: Heavier objects fall faster than lighter ones.
Actually: Ignoring air resistance, all objects fall at the same rate regardless of mass. A feather and a hammer dropped in a vacuum land together; air resistance, not gravity, is what usually slows the feather.
Often heard: There is no gravity in space.
Actually: Gravity reaches everywhere and is what keeps satellites and the Moon in orbit. Astronauts feel weightless because they are in free fall around the Earth, not because gravity is absent.
Often heard: Gravity is the strongest force in nature.
Actually: Gravity is actually the weakest of the four fundamental forces. It dominates on large scales only because it always attracts and acts over enormous distances, unlike forces that can cancel out.
Going deeper
