Time is not a constant

Time is not a constant

Some theorists explain the apparent passage of time as an illusion of flow caused by perceptual processes that attribute apparent motion to events that happen in sequence. Another, compatible approach considers the way that evolutionary pressures might have shaped emotions and cognitive heuristics to give us a strong past/future distinction in our reasoning. 

A is on the moving train 

and B is standing on the platform

. For our purposes, a reference frame is nothing more than a coordinate system that is used to identify the same point in space at different times. Someone on a steadily moving train, for instance, will naturally use a reference frame that is different from someone who is standing on the station platform, since it is natural for the person on the train to think of themselves as stationary, while for the person on the platform it seems obvious that they are moving.

Astronaut returns to Earth 'younger' than his twin brother after spending a year in space

Someone living on top of mountain over 'time' will be younger than

his twin brother living at ground level.

Some B-theorists explain the apparent passage of time as an illusion of flow caused by perceptual processes that attribute apparent motion to events that happen in sequence. Another, compatible approach considers the way that evolutionary pressures might have shaped emotions and cognitive heuristics to give us a strong past/future distinction in our reasoning.