What causes Gravity?

[Althalus]

on a lighter note, i think it should have been called Grabbity, sounds so much better, but then I have been watching a bit to much Rugrats for my own good lately.

[j6p]

Alt..you may be on to something here. Lets see, A shuttle booster rocket has "Trust" because you had better have trust or get your butt outa there. Then there is "proPUSHion" cause thats what it does and of coarse, "grabbity". I like that.

[CASTOR]

everything has gravity. Mass is the key component. F = G * ((m1 * m2) / r squared) is the formula you are needing. The F is the force accumulated by gravitational pull. The G is a constant 6.67 * 10 to the -11th power. The units for G are Nm2/kg squared. The main contributing factor to gravitational pull, however, is the distance between the objects. This is the r in the equation. The centrifugal force from the spinning of the earth is also a contributing factor in its case. mass is what is the main thing here. like a black hole has infinite mass and density. so that means that it will pull everything including light. that is gravity!

[Hobo]

just a wild theory, but what if gravity was a reflection of the expansion of the universe. the larger the collection of mass the larger the reflection. also if the big crunch occures insted of the universe expanding and its contents attracting eachother the universe would contract and its contents would repell eachother.