Allow me to introduce The n^th dimension : This is a separate page and can be accessed from the menu. For further information: https://iotatimesinfinity.wordpress.com/the-nth-dimension/
What exactly happens when a time traveller makes changes in the past?
Possibly, it is not possible. The person will not be able to make any changes due to cosmic censorship or and other reasons.
If changing the past is possible, what happens to the timeline?
Either an entirely new timeline is created (supported by the many-worlds interpretation) or the same timeline gets altered.
In case the same timeline gets altered with the past adapting to the changes made by the time traveller, where does the past go? Where can it possibly disappear if not into another timeline?
Also, what if two time travellers make different changes to the same instant in the past of the very same timeline simultaneously. I what way will the timeline be altered then?
Chances are timelines are not immortal and can indeed be murdered by time travellers but that is only if the law of conservation of timelines holds true: ” Timelines can neither be created nor destroyed but only transformed from one form to another.”
Until next time, we possibly don’t exist.