Space: My Final Frontier?

Since I was a small boy growing up in southern Florida I have always been interested in space and what mysteries it holds.  I used to watch the space shuttle launch every chance I could and even had my own small telescope to gaze at the moon and stars.  My interest even went so far as me majoring in Astrophysics in college; although my desire to party won the battle thus making my tenure in college very short.  So now I find myself with many questions of which I either do not have the answer to or that I have not found (probably due to not thoroughly looking) remain unanswered.

     Case in point, just the other night I began to contemplate the complexities of gravity.  What is it?  How does it affect the movement of celestial bodies?  so on and so forth.  So I surmised in my little word of reality that if gravity is constant and is one of the fundamental forces, then gravity should be infinite insomuch that every object affects every other object in the universe.  Now that is not to say that I think that the Earth's gravitational influence on say the galaxy Andromeda is the same as me being held down to the ground, but that the Earth still has a gravitational influence on everything.  Likewise everything else has a gravitational influence on us.  I envisioned it as a string attached to an object.  The further away the object from another objects center of mass, the longer the string.  If you take a string and attach one end to a stationary point and attach the other end to a ball and then roll the ball until you have a 20 degree angle from it's starting point, the distance traveled would be less for a shorter string that one that is longer.  If that is the case then the amount of energy required for the ball to move through the angle would increase as the distance from the center point increases.  So if you continue to lengthen that string to billions of miles, the amount of energy that is required to move the ball would so much that any other object that also has greater mass that is closer to the ball would have a greater effect on it.  This however does not negate the string from the original center point, it just makes the string irrelevant. 

    What do you guys think?  Am I nuts, or just under informed?  LOL!!!!