I am not a man of Physics so my post is more philosophical than scientific. But it occurred to me that all observations are made in the present so a logical frame of reference for the passage of time would also be the present (at least philosophically if not mathematically). With such a frame of reference, an object would not "move" forward in time, but rather it's past would propagate (?) further back in time from the present. And if two objects can occupy the same space as long as they are separated by time, then how much time need elapse before this could occur. If it is infinitesimal then could an object which is infinitesimally separated from the present, time wise still have observable effects in the present. I've been trying to reconcile the observations in quantum physics where a photon can seemingly go back in time and change it's properties from a particle to a wave and vice-versa. And if time does indeed propagate negatively from the present when viewed from a present frame of reference, then it might be possible that an object can exert a force on the present while existing ever so slightly in the past. Could that be dark matter? Could that be plausible mathematically?