gravity "timmer doesn't believe in gravity." or so the misquote goes. my actual position is that the force of gravity is imaginary. what?!?! it all has to do with equilibrium and human ego. equilibrium is defined as being at rest, ie there are no external foces applied to you. am i at equilibrium right now sitting at my desk typing this blog? human ego, anthrocentricity, and high school physics, demand that i AM at equilibrium. but if i build a real (or imaginary) accelerometer it would show that i am accelerating upwards at 1.0 g's. ergo, i'm not really at equilibrium. high school physics class supports its position by teaching you to draw force diagrams with a vector pointing down labeled "weight". is this wrong? well, yes and no. it's an easy way for phsyics students to get the right answers. unfortunately, the understanding of the underlying principles is lost and leads to more confusion when you start talking about objects in space stations and rocket ships far from earth which really are at equilibrium. if i really am at equilibrium then i, my chair, my desk, and all the other junk in my office should be floating around the room just like it would be if i and it were lost in deep space.

so what should be done? well, F=ma asserts the equivalence of forces and accelerations. rewrite the equation as F-ma=0. introduce an imaginary force called W for weight equal to -mg and voilá we have F+W=0 which looks a whole lot like the equation for an object at equilibrium. so the next time you find yourself drawing force diagrams on the blackboard of a high school physics class draw the weight force vector dotted (or with a different color) and label it "-mg" instead of "W" to remind yourself that it's not a real force and to demonstrate that you are smarter than everyone else in the room. ;->  ¶ 10:04 AM