There are many time travel novels & some of them have been made into movies, or get movies based on them. Depending on your homework assignment you need to be careful not to do a report on a book, where your primary source is the movie.

When people travel in time, sometimes they use some kind of a machine, a worm hole, a way not explained to the readers.

Some are one way trips. Some methods make it possible for other people to use the system. For example in one of the sequels to H.G. Wells Time Machine, it ends up in a Museum, where it gets borrowed by a modern day person to be Jack the Ripper

In this one self-hypnosis is attempted as the way to get back.

For what purpose do people seek to travel or communicate in time?

* curiousity

* research

* tourism

* meddle … like save Christ from Crucifiction, then the whole religion of Christianity never be born … prevent 9/11

* romance … pursue fantasy interest in some past person

* solve crimes

* military … go back in time, send modern army through ancient lands, then attack enemy from the past

* get at the DNA of Einstein or other key people

In this book, their interest is a combination of curiousity and research, to try to figure out some mysteries

If someone goes into the past and due to their actions change what happens in history, won’t the people in the present day now experience the new version of reality and be unable to tell what got changed?

When they been changing the past, we can expect that their version of history is different from ours.

If our version of history disagrees, is it because our study of history is flawed, the writers biased, or time travelers involved?

In some time travel stories, there is theory that the past cannot be changed (the grandfather paradox, and other paradoxes) but perhaps there is more than one universe, and what has happened is we have traveled into a universe that is the same as our old one, except for the changes we made … we can never return to the original one.