There is only one time and that is now. Trying to travel "back" in the past of into the "future" is not possible. Why?
Take a picture with a camera, it is an exact moment. There can be no subtraction or no addition.
In other words to go back in absolute time, you would have to spin the universe backward, and even if you were able to do that, that fact that you have the knowledge that the universe was spun back words would mean that you still did not go back in absolute time.
To get to this exact point in "time" or "now" (and the planet is our space ship), everything leading up to this point mush be exact down to the sequence of thoughts that each person has had in their mind. Take yourself for example, you have had a specific sequence of thoughts, that has led to a specific sequences of actions, that has led you to reading what I am writing now. If you did not think to ask the question and I did not choose to respond there would be a different series of events.
My time is no 9:25pm on my computer. This is exact relative to all existence. If someone tries to go back in time what they would do is create a delusion for themselves.
Absolute time has many ingredients that lay outside the ability of human beings to control. There is the physical, the mental, the astral planes, the spiritual (and each soul is unique and special), ethereal realms etc.
I hope this helps. If you think I have missed something please let me know.