Today I was riding my bike, when suddenly I got this weird feeling. About gravity.
So I'm riding along, and suddenly I imagine that I am motionless. My bike is pushing the earth underneath me. The harder I ride, the harder my tires push against the road glued onto the earth, and the faster it moves underneath me. I start a climb and the earth presses harder on my tires, and gets heavier (harder to move). I crest the hill and the earth falls away slightly, and lightens (becomes easier to move). I lean to the right, and the earth spins counterclockwise beneath me. I straighten, and it stops spinning.
And then I imagine gravity, not as an attractive force from below, but as a repulsion from above! It is pressing me away, into the earth. As I go uphill the force becomes stronger, pushing me into the street. My tires resist and my legs spin the earth beneath me. As I go downhill the force weakens, and I'm freed a little from the pressure. I reach a steep decent and gravity shoves me downward - whee! - and the earth slides easily along under my bike, tires spinning, legs resting. I begin another climb and suddenly I am pressed back into the street, the earth groans and resists the puny efforts of my tires to push it along.
Very cool. All physicists should ride bikes.