The Green Futures of Tycho
When eleven-year-old Tycho discovers that the mysterious egg-shaped object he dug up in his garden is a time travel device, he can't resist using his newfound power. Soon he is jumping back and forth in time, mostly to play tricks on his bossy older brothers and sister. But every time he uses the device, he notices that things are different when he gets back – and the futures he visits are getting darker and scarier. Then Tycho comes face-to-face with the most terrible thing of all: his grown-up self. Can Tycho prevent the terrible future he sees from coming true?
William Sleator
William Warner Sleator III (1945–2011), known as William Sleator, was an American science fiction author who wrote primarily young adult novels but also wrote for younger readers. His books typically deal with adolescents coming across a peculiar phenomenon related to an element of theoretical science, then trying to deal with the situation. The theme of family relationships, especially between siblings, is frequently intertwined with the science fiction plotline.