Time is a measurement of change. Time as we human defined it was born out of the human need to determine night and day. To differentiate between one state and another. As such, time, is just a measurement. It does not matter which scientific belief you go by, presentist, eternalist, quantum thery, relativity and all the theories out there that compete like religions for believers. Time does not exist for itself, it is wholly dependant on existence itself. Change is immutable, if a body changes, it cannot "reverse" the change, all it can do is change into something similar to what it was but that is not the original state, it did not "go back through "time"" it did not reverse its state, all it did was change from one state to another. Time measures that change and time is therefore relative to the change itself. To put it simply, we dont need to describe time in terms of solar measurements, we can make time a measurement that is defined only by the individual change relative to what it was and what it is.