Let's say we have a blank universe and have a 1kg mass. At some point in time, this is near-instantaneously replaced by a heavier mass. Both masses are stationary. Will the lighter mass, before it is replaced, see effects due to the heavier mass existing in the future? In turn, will the heavier mass see effects due to the lighter mass existing in the past? More importantly, why or why not? Since, according to Einstein, a stationary object travels through time at c, the distance between these two masses in time would rapidly increase, likely making the effects very small. Also, I'm not sure about what this would cause, and I don't want to get into too much speculation right now, but it could lead to an increase or decrease in mass of some objects at certain points in time.