one such problem was the issue of wiggling : i will fit into the time machine pod like a fetus in a womb , and the pod will spin to produce the velocity that the observers will see ; the amount of wiggle room that i will have while in the pod will be a critical variable because even a few inches of slippage or physical indentation into the material of the pod ( produced by my footholds and other areas of pressure that i will be exerting on the pod ) would alter the location of my center of mass and ruin everything ( my center of mass is what will remain to be observed after the process of relativistic length contraction has asserted itself ) .