The gravitational constant, called G in physics equations, is an empirical physical constant. It is used to show the force between two objects caused by gravity. The gravitational constant appears in Newton's universal law of gravitation.
G is about 6.67408 ×10−11 N⋅m2/kg2, and is denoted by letter G.
It usually appears in Sir Isaac Newton's law of universal gravitation, and in Albert Einstein's general theory of relativity. It is also known as the universal gravitational constant, Newton's constant, and colloquially as Big G. It should not be confused with "small g" (g), which is the local gravitational field of the Earth (equivalent to the free-fall acceleration).
- Gundlach, Jens H.; Merkowitz, Stephen M. (2002-12-23). "University of Washington Big G Measurement". Astrophysics Science Division. Goddard Space Flight Center.
Since Cavendish first measured Newton's Gravitational constant 200 years ago, "Big G" remains one of the most elusive constants in physics.
- Halliday, David; Walker, Jearl; Resnick, Robert (2007). WIE ASE Fundamentals of Physics Extended, Eighth Edition, Asian Student Edition. p. 336. ISBN 978-0-470-04618-0.