I found this spacetime diagram at https://en.wikipedia.org/wiki/Proper_acceleration with an accelerating traveler, resulting in "curved" hyperplanes of simultaneity. Notice how the simultaneity planes are angled "normally" (The faster the steeper the slope and no slope when stationary) but only when close to the traveler. However the simultaneity planes get distorted in farther space, obviously due to acceleration. Also in the pink area, where the traveler is stationary, the simultaneity planes are horizontal close to the traveler like a normal spacetime diagram, however in farther space the simultaneity planes are CURVED, which can only be explained by "the result of future acceleration that has not yet happened". Also in the yellow area, the traveler finished the journey and is stationary, but the simultaneity planes are curved in farther space, if interpreted literally, due to past acceleration. Now I see why Einstein told Besso's family that "time is a stubborn illusion" after he had died. Or am I completely mistaken?????