- Gravity (Wikipedia)
In physics, gravity (from Latin gravitas ‘weight’) is a fundamental interaction which causes mutual attraction between all things that have mass. Gravity is, by far, the weakest of the four fundamental interactions, approximately 1038 times weaker than the strong interaction, 1036 times weaker than the electromagnetic force and 1029 times weaker than the weak interaction. As a result, it has no significant influence at the level of subatomic particles. However, gravity is the most significant interaction between objects at the macroscopic scale, and it determines the motion of planets, stars, galaxies, and even light.
Gravity is a habit that is hard to shake off.
Terry Pratchett, Small GodsI used to think that I was stupid, and then I met philosophers.
Terry Pratchett, Small GodsI was sitting in a chair in the patent office at Bern when all of sudden a thought occurred to me: If a person falls freely he will not feel his own weight. I was startled. This simple thought made a deep impression on me. It impelled me toward a theory of gravitation.
Albert Einstein- There is no difference in the gravitational behavior of matter and antimatter. In other words, antimatter falls down when dropped, not up.