When movies or TV shows create various laws about traveling through time, there is going to be some fundamental mistakes that crop up within the respective show or movie.

Let’s take “Time Machine” by H.G. Wells for instance; the law within this movie/book was that the inventor of the time machine could not prevent the death of his wife in the past no matter how much he tried. Yet, at the end of the show [spoiler] he is able to change future’s history by saving one version of humanity against another.

So what’s wrong with the time traveling law? Basically, if a man from the past can change the future, then any one from his past could save his wife in the future. It certainly creates a lovely paradox (for why would he then need to build a time machine if she did not die).

If a sci-fi show (that wants to have some semblance of following scientific laws) is going to have to create some kind of time traveling law, be sure to run it by a whole variety of people (scientists, children, etc.) first to make sure it is sound proof so as not to defeat the whole point of the show’s plot.