I just finished reading the trilogy, "The Sylo Chronicles," by D.J. MacHale. A very good read. I'd suggest that a different ending could be produced where the main characters, when they end up in 1952, could have a vial of Magic Medicine, with them. If not a vial than they could have blood tests done and perhaps produce the medicine from their blood--remnants of the medicine could still be in their systems. If the technology wasn't available they could develop it. I would also post that it would be interesting to discover that taken in weak doses could extend one's life significantly. This would allow the primary characters to really make a difference over the long run. I would also suggest that this extended length of life would benefit them if they used their knowledge to expand out into space and possible into the universe. Just thoughts, keep up the good work.