In reality objectal events outside the vehicle don't change. Due to the vehicles momentum cycle the time machines reaches light momentum that at light speed momentum the vessel passes through time manually coordinated. This occurrence happens in the vessel not the scene outside. The machine journey does not affect the outside reality because it is the outside reality from which it journeys through. Any changing occurrences are the event of the traveler and thus neither the traveler nor his activity can change the Time Stream and not reverse. Since it is the machine that travels back or forth through TIME. It is not the outside scenery that is interchangeable but only the reality and time coordinates of the vessel the traveler is carried in.

Earth's TIME history is a measurement of a planetary orbit. The Universe's time trek is the measurement of the expansion. A planet or systems of planets rotate at a specific velocity and we measure time by this activity as days, months, decades, years and the seasons. The arrow of time is directed by this same flow of motion activity. A glass from the table drops to the floor and your wife picks it up. This is the arrow of time flowing forwards. The Universe was set in motion in the beginning by a big bang. After a while things cooled and slowed down. The Universe's orbit on an axis and everything in it followed. Stephen Hawking suggested in his book on black holes that if the Universe was in the direction of attraction and collapse that we wouldn't even know it but it would affect the arrow of times direction of flow. Instead of the glass on the table falling - it would rise and clack together rising back atop the table instead of falling down to the floor and a part. Time in essence would be flowing backwards. In reference to are traveler he is the one experiencing momentum not the Universe that in which is the only means to redirection the arrow of time that which controls the activity of time and its direction. Yes, he just took a trip down 35th Avenue in 1905 and made a mistake.

So the question is raised ' The grandfather paradox ' again. He didn't vanish as he thought he would. He didn't reverse the rotation of the planet to change the flow of time as he thought he would. He did travel backwards through a wormhole event created by his time machine ship. He did kill his grandfather. And he did change his history. He went to jail for murder and spent the rest of his life trying to understand what I have just told you.

That is - you cannot change history no matter what.

These are the reasons Einstein asserted traveling backwards through fourth dimension space was not possible, that a side from these conclusions - you have to travel faster then light and this to him was not possible. Quanta Physics asserts the differences in physics illustrate a time travel coordinates theory in full volume with the past, present and future and back again based on the standard model. Q.P.T. study on faster then light analogy is not based on the light constant as relativity was but rather the fabric of space itself. The Michael Alcubierre warp drive theory is another supraliminal theory but he does not assert faster then light travel or the evidence for it in his theory that the technology is feasible. So the discussion sits here in the tread of thought between all the theories in Terra physics to answer as an expansion for future space exploration technology and basic analogy for the development.