Time: It is a mathematical dimension to measure the change of state (any motion) of Existence (includes universe/multiverse/entire creation).
In order to travel in Time, one has to change the state of entire existence to the previous/future state which is impossible.
We need to consider our time measurement techniques again. Should we consider time dilation shown on our clocks as actual time dilation?
The laws of existence affect all the physical entities in a different way. All the physical entities have a different effect of gravity and velocity on them depending on their nature. It is not necessary that our biological clock of living beings and other physical phenomena would be affected in the same time measurement scale as it affects the normal clocks and atomic clocks.
Please elaborate and correct me if I am wrong... Thank you