Timescape

Another tale about sending information back in time; only in this instance people are trying to avoid creating paradoxes at all costs, especially the 'Grandfather Paradox', which is shorthand for anything that you do with the past that would have the result of preventing you from doing it. (Think about that for a moment. It's really cool!) The information they're wanting to send back by about 35 years is meant to warn people of impending ecological disaster if the world of the early 1960s continues on its course. The attempt works, but since it changes past history, a parallel time-stream is created and that severs the information link from the future. Meaning that in the original time-stream nothing changes. But you figured that out for yourself already, right? < Why it's on the list: Another good take on the 'send messages to the past' angle. Somewhat different to #6 on this list, taking a somewhat more 'global' view with strong eco-themes; but also taking recourse to 'parallel time-streams' speculations and the attendant consequences.