What do you consider to be "the past"? If "the past" refers to "that which has happened", then, how could the "time traveller" make changes to it?
The machine travels in time to the birth of the Solar system.
The gravity of the machine (and its presence there whatsoever) changes the movement of some particles.
Right now, there are two timelines. The machine's timeline, where there were no changes, and the alternative timeline, where the changes the machine made at the birth of the Solar system take effect.
In fact, the alternative timeline branches from the machine's timeline at the moment of the machine's arrival to the birth of the Solar system.
So, since the machine entered the alternative timeline at the moment it arrived to the birth of the Solar system, when it tries to return to the present, it follows the timeline it's already in, which is the alternative timeline.
Also, what do you think of this theory?
Extremely interesting. If you liked those I'd urge you to follow up with:
Aren't there really 11 dimensions?
