The Future Is Listening
Why it is hard sci-fi
A father in 1969 and a son in 1999 establish radio contact across thirty years using a vintage ham radio during an unusually strong aurora borealis. The film commits to a single timeline that updates as the past changes, with photographs and newspaper clippings rewriting on screen. The cause-and-effect chains are tracked rigorously through both eras.
Science inside it
The aurora borealis is the conceit for the channel, and the film leans on real solar-storm physics to motivate the unusual propagation. The behaviour of the timeline follows a single-thread update model where memories and physical evidence rewrite together, which is one of two consistent ways to do time travel and the film picks one and sticks to it.