??light-like curve in 2+1 conformal spacetime ... ???... ???something about ... ???nails and gimbal moving simultaneously... instantaneous swiveling, and instantaneous

??arrow of time on gimbal .... ??helping to visualize cone shape ... ??or something ??

???something about ... for a particular event, "time" as the tangent space of the gimbal at the nail(s??) (??which maybe we can also sort of canonically (???) identify with the "most distant" diameter of the gimbal ?? ... ???hmm, what about whether certain identification here is conformal ... ???or something ??....) and "space" as the tangent space of the globe at the nail ... ???or something??? ....