# Gravity and Gravitation - The History Of Gravity, Newtonian Gravity, General Relativity

Science EncyclopediaScience & Philosophy: *Glucagon* to *Habitat*

Gravity is a **force** of attraction that exists between every pair of objects in the Universe. This force is proportional to the **mass** of each object in each pair, and inversely proportional to the square of the **distance** between the two; thus,

where *m*_{1} is the mass of the first object, *m*_{2} is the mass of the second object, *r* is the distance between their centers, and *G* is a fixed number termed the gravitational constant. (If *m*_{1} and *m*_{2} are given in kilograms and *r* in meters, then *G* = 6.673 × 10^{-11}N m^{2}/kg^{2}.)

## Additional topics

- Gravity and Gravitation - The History Of Gravity
- Gravity and Gravitation - Newtonian Gravity
- Gravity and Gravitation - General Relativity
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