Summary from Goodreads:
Galileo. Newton. Salk. Oppenheimer. Science can change the world...but can it go too far? Eleven-year-old Ellie has never liked change. She misses fifth grade. She misses her old best friend. She even misses her dearly departed goldfish. Then one day a strange boy shows up. He’s bossy. He’s cranky. And weirdly enough...he looks a lot like Ellie’s grandfather, a scientist who’s always been slightly obsessed with immortality. Could this pimply boy really be Grandpa Melvin? Has he finally found the secret to eternal youth?