With this volume, Robert Sawyer shores up what was already a solid claim to a spot, maybe even the top spot, on the short list of best hard SF writers writing today. By today's standards, this is a fairly short novel, and it's not difficult reading, but that's not at all because there's nothing but fluff. Sawyer takes on two important topics for hard SF speculation -- SETI and life extension -- and comes up with profound and original (or at least not known to me) philosophical ideas about both of them. In passing, he rebuts Stross' prediction of the Singularity (presenting a future that's far less scary than Accelerando or even Vinge's Rainbows End) and tosses out a position on the abortion debate that I'm really going to have to chew on. And he does all this in the course of a fast-moving, emotionally moving, satisfying story and even works in a few good laughs.
As I reflect, I think I'm recognizing a hint of the level of craft in this book. The prose is not poetic; I don't think there are individual sentences that people are going to fall in love with. But every paragraph, possibly even every word, is there for a good reason and moves the book forward. I think there's real skill in whittling this big a story down to a modest sized novel and writing it so that even a painfully slow reader such as I can get through it effortlessly but still think some pretty deep thoughts along the way. The characters and their interactions are not realized with the color and depth that they might be in a different sort of novel, but they are quite sufficient for a book that really is about ideas. They're not faceless cardboard cutouts going through ludicrous motions. The plot itself stretches believability, but in the sense of some coincidences that are just a little too convenient, not in the sense of "you moron, physics doesn't work that way!" that we too often see in SF novels written by people who are mostly worried about the character interactions, or even in the sense of "you moron, people don't work that way!" that we sometimes find when authors are too caught up in getting getting the plot to the right place. Sawyer's characters make some mistakes, but they're very human mistakes, and they're realized just deeply enough that we can appreciate the main themes of the story, which are bigger than the characters.
This is the kind of book that I read science fiction for. 10 out of 10.
**** PLOT SUMMARY -- MASSIVE SPOILERS ****
It's 2048. Don and Sarah Halifax are celebrating their 60th wedding anniversary with their children and grandchildren. There are a few changes, but the world doesn't seem too different yet; Don and Sarah are both 87, and that's still quite old; they're thinking about how this may be the last time they're both there for a family gathering, and contemplating that they've had a good life, when the phone rings. The aliens are answering. Sarah, it seems, was a SETI researcher when a real signal came in from Sigma Draconis in 2009, and it was Sarah who figured out that the main part of the message was a survey about ethics. The aliens asked earth to reply with 1000 individuals' responses. Sarah is excited, but at this stage of her life the family celebration is more important than either watching the message as it comes in or giving interviews. The next morning, they review a phone message which reveals that the new message is encrypted. The first part describes an encryption algorithm, but the rest is gibberish, presumably encrypted, and the key is not obvious.
A couple of days later, a humanoid robot drives up to their house and rings the doorbell. (This is emblematic of how tech has progressed but not changed society that much.) The Halifaxes still aren't answering the phone, but someone really wants to get in touch, so he sent a robot. And the someone is Cody McGavin. He invented a lot of the technology that made the robot possible, and he is now one of the world's richest men. He's also a patron of SETI research. And he believes Sarah will be the one to figure out the key, and he wants her to answer the message. And further, he wants Sarah to be around to continue the conversation. A rejuvenation technology -- the rollback of the title -- has been developed, but it still costs billions of dollars per person. McGavin is offering it to Sarah. Don and Sarah discuss it, and agree, on the condition that Don gets a rollback too. McGavin doesn't like this; even for him, it's a LOT of money. But he goes along. The rollback starts with fixing a few immediate problems that would get in the way of surviving the process, but the main treatment involves administering some carefully-programmed nanotech and waiting. After a few weeks, Don's hair starts to come back; his rollback is proceeding normally. But something is wrong with Sarah's. Eventually they learn that when Sarah had cancer decades earlier, an experimental treatment they'd tried, which hadn't helped the cancer, had somehow bollixed up her biology so that the rollback fizzled.
Now that Don is fully rejuvenated and physically 25, he starts trying to get a job, but he discovers that the CBC (where he retired 20 years previous from his position as a top-notch recording engineer) isn't interested in him at all. He starts to feel depressed. He's also sexually frustrated, because his new, rejuvenated self is too vigorous for Sarah; they try to have sex but she can't handle it. As Don is going through these things, Sarah sends him to the university to pick up some paper records she needs for her work (she's doing her best to try to find the key despite her rollback not working), and he meets Lenore, the graduate student who initially called on their anniversary with the news. When he says he's come for the papers, she figures he must be Sarah's grandson, and he fails to correct her. And then the sparks start flying, and the next thing Don knows, she's dragged him off to bed. Mentally, she's very much like Sarah was when Don first met her, interesting to talk to unlike her fellow grad students who seem very shallow, and she's a serious Scrabble player like Don. After a few weeks, Don admits that he's not Sarah Halifax's grandson, but her husband. Lenore is furious. But after a few days, she realizes that she really likes Don, and they get back together. On his way home after a date after they reconcile, Don has some sort of a premonition and phones home, and Sarah doesn't answer. Fearing the worst, he rushes as much as he can (the trip is mostly on public transit), and finds that Sarah has fallen and broken a leg. Don feels terribly guilty. He decides that he really needs to be home with Sarah to help her. But Cody McGavin comes to the rescue, providing a domestic robot who is an excellent helper for Sarah and who projects enough of a personality that the Halifaxes become attached. Don genuinely loves Lenore, but he also loves Sarah, and even though there is some hint that Sarah knows what's going on and might even approve, he won't tell her. Finally he can't take it and breaks up with Lenore. And Sarah figures out the key. It seems that the key is Sarah's answers to the survey (of the 1000 answers were sent to Sig Drac, 999 were selected randomly from all the people who submitted surveys, but Sarah, as the leader of the effort, got to include hers. The reason this relatively obvious answer hadn't been tried before is that when Sarah had done the survey, she'd been troubled by one of the questions, and she'd changed her answer at the last minute. The published version of the message had her old answer, but the one she actually sent when she plugged her laptop in to the radiotelescope and hit the send button was her new answer. No one else even knew, and she'd forgotten about it until now.
Once they could read the message, they figured out why it was intended to be private to the one person whose answers were most suitable. The message the aliens had sent was the complete genome of two Dracons and the instructions to build a uterine replicator. The message was interviewing for a suitable foster parent. Unfortunately, the foster parent they'd selected was about to die of old age, but Sarah has Don take the test and compares his answers to hers with a special program (since the answers are more fine-grained than yes/no, deciding how close two sets are is a bit tricky), and they turn out to be a very close match. Don has just visited with his 13 year old grandson, who observed that since Don is looking for a new job now, he should make it something important. And Don and Sarah decide that they want him to be the foster parent of the Dracon children. So, rather than releasing the message, they contact Cody McGavin in private. He doesn't like not being in control, but goes along with the deal, which is a reasonable business decision because, while it will be a major technical effort (and expense) to actually build the replicator, it will give him first crack at exploiting the alien tech.
While the aliens are gestating in the finished replicator, Sarah's un-rolled-back body finally gives out. A few days later, McGavin Robotics sends a tech over "for routine maintenance" on Gunter, but Gunter proves that he's both quicker on the uptake than Don, and also more of a person than anyone expected and more loyal than Don knew, because the tech finds Gunter motionless on the floor. The robot wiped his own memory -- suicide, for all practical purposes -- to keep McGavin from stealing the decryption key.
A few weeks before the Dracons are to be decanted, Don flies to Canterbury University in Christchurch, New Zealand, where Lenore has started work on her doctorate. He's still in love with her, and it seems that she hasn't hooked up with anyone else. He offers her a remarkable new thesis project: co-parent of the alien children. She counter-offers that she'd want some of her own. Don agrees.
We now cut to the epilogue, where the whole family -- Don, Lenore, the Dracons Amphion and Zethus, the human child Gillian, and Gunter -- are visiting the 2067 Canadian World's Fair. There's a little description of the Dracons, who stand 2.5m tall on 3 legs, possess four eyes with different frequency response, 3 fingered hands on their two arms, and some undescribed gravitic sense, and have to use a filter mask because the CO2 levels in our air are toxic, but still don't seem that alien. And there are some hints of further technological marvels, some of which were inspired by the alien reproductive technology.