The Last Theorem , which grew from 100 pages of notes scribbled by Clarke, is more than a futuristic tale about a mathematician who discovers a proof to a centuries-old mathematical puzzle.
The novel, released Aug. 5, represents a historic collaboration between two of the genre's most influential writers in the twilight of their careers. Clarke, best known for his 1968 work, 2001: A Space Odyssey , died in March at age 90; Mr. Pohl is 89.
"As much as anything, it'll be a historic artifact," says Robin Wayne Bailey, a former president of Science Fiction Writers of America and a writer. "This is a book between two of the last remaining giants in the field."
Clarke originally intended The Last Theorem to be his last solo project, and he began writing it in 2002.
Progress was slow because of his poor health, and he missed the book's original 2005 publication deadline. Worried that the book wouldn't be published, he searched for a co-author.
While the search was under way, Clarke would often tell his aides, "I hope The Last Theorem won't become the lost theorem!" Nalaka Gunawardene, one of Clarke's aides in Sri Lanka, said by e-mail.
Mr. Pohl said he volunteered for the job and set about making sense of 100 pages of notes Clarke left him. About 40 or 50 pages of scenes were fully written, but the rest contained undeveloped ideas. On some pages, there were only one or two lines of text, he said.
Clarke, who lived in Sri Lanka until his death and had battled post-polio syndrome for decades, became bedridden after breaking bones in his lower back. Difficulties with memory meant he couldn't recall enough about what he'd written in his notes to help Mr. Pohl decipher them.
"I started out by asking him for information on things in the book," Mr. Pohl said. "And he e-mailed me back and said, 'I don't know. I have no idea what I was thinking of when I wrote that.' It had just gone right out of his head."
Mr. Pohl has his own troubles. He suffers from poor muscle response in his hands and feet. He wrote much of the novel on pen and pad, with his wife, Betty, transcribing the scribbles onto a computer; but his handwriting is now illegible. Typing, too, is difficult because his right hand remains bent and does not unfold properly.
Together, the two longtime friends worked through the novel.
Clarke is known for predicting scientific inventions in his novels: In 1945, he predicted the invention of communications satellites, 12 years before the launch of the first artificial satellites. As a result, geosynchronous orbits, which keep satellites in a fixed position relative to the ground, are called Clarke orbits.
The Last Theorem includes a weapon called Silent Thunder, which neutralizes all electronic activity in a given area to harmlessly disarm entire nations. Another is the space elevator, a cord suspended from an orbiting object in space that can pull objects from Earth, rather than rely on rocket power to launch them.
Mr. Pohl said his research and conversations with friends who are scientists convince him both will one day exist.
"If we can somehow figure out what possible futures there might be," he said, "you can try to encourage the ones you like and avoid the ones you don't."