In this hard-boiled detective novel set in the future, Brin gleefully plays with the concepts of identity and immortality. In this future, we have figured out how clone short-lived, clay versions of ourselves, which can then go out and do the work while the originals enjoy lives of leisure. Since the copies are expendable, they are often assigned risky tasks or sent out to do chores or other drudgery. But since the copies possess all the memories and consciousness of the original, they are cursed with a knowledge of how brief their lives are, and their only fulfillment comes from making it back home to download their memories into the original, in that way achieving a kind of afterlife. Layered on top of all that is a mystery told from the points of view of a private investigator and several of his copies unraveling a complicated conspiracy case culminating in a plot by a mad scientist to achieve godhood, and this becomes a very complicated plot indeed. Good thing Brin tells it with a sense of fun and humor.

As a detective story, this novel is pretty good. However, where it really shines is in the premise, a world in which people can create “dittos,” or expendable clay copies of themselves. The copies last one day and then their memories can be uploaded into the original’s mind.

Anyway, the idea that I really liked was that of the “standing wave,” the metaphor characters in this novel use to describe continuity of consciousness. This idea really makes clear the distinction between self and memory. That is, another entity could share my memories and appear to be me. However, if this being did not continue my standing wave, didn’t continue my original consciousness, it wouldn’t really be me.

The standing wave varies from person to person. Since the dittos are offshoots of the original, their memories can be uploaded. However, one cannot upload someone else’s dittos memories because, as it turns out, every person’s experience of reality is totally different. The ditto’s memories would be nonsense.

Anyway, I have been trying to come up with a suitable explanation for why I have a problem with SF technologies like the transporter in Star Trek or with Kurzweil-style “uploading.” The standing wave metaphor really makes it clear. If it breaks or interrupts the standing wave, my copy isn’t really me!

My review is here.

An entertaining mystery with many plot twists.