One of science's more frustrating endeavours has been the quest to find other intelligent species. Dolphins and whales communicate with squeaks, while chimpanzees and orang utans use tools for various purposes - usually dinner. This is doubly tantalising - humans aren't all that unique, but neither of these lifeforms offers much in the way of philosophical dialogue. The Search for Extra-Terrestrial Intelligence was founded a half-century ago to search elsewhere for somebody to talk to. The search was among the stars.

In this well-conceived and executed tale, Robert J. Sawyer has speculated on the possible results of "listening in" on the Cosmos. A major problem in interstellar communication is that distance equals time. If a planet circling a star 18.8 light years distant wants to chat, it's 37.6 years between responses. SETI had triggered a "first contact" which was translated by Canadian astronomer Sarah Halifax and a reply transmitted. Now, nearly four decades later, whoever lives near Sigma Draconis has answered back. For some reason, the "Dracons" have encrypted the message. Sarah is in her eighties, yet it's clear that she's the best candidate to deal with the new message. At her age can she cope with the intense labour involved in the exercise?

Help is at hand from the science studying aging. An entrepreneur interested in SETI has agreed to fund the means to extend Sarah's life so that she can work on the encrypted message. Sarah, and her husband Don will have their aged bodies "rolled back" to a more youthful physical age. It's like starting life over with almost endless possibilities. The "rollback" process, though tried on only a couple of hundred people, is "foolproof". But while it works on Don, it fails on the person needing it most - Sarah.

Sawyer examines the many practical and philosophical issues surrounding the possibility of extended life. The first, and most obvious, is where Don's restored libido might lead him. Another aspect is the realisation that age may bring wisdom, but what is its worth in terms of employability. Moore's Law says computer power will double every 18 months. Translate that into terms a man retired for twenty years confronts when he seeks a job. Rollback is an expensive process - not everybody can afford it. How does a man deal with his children who are "older" than he and that he's certain to outlive? These are the types of questions Sawyer has a superlative talent in posing and addressing. His ability to develop real characters who must deal with such issues is without peer. Underlying these capabilities is a firm foundation in the relevant sciences. "Rollback" may be speculative, but only in the narrowest definition of the term. Sawyer didn't place this story only a generation in the future just to avoid extravagant surroundings. The science he depicts is almost there. Only the Dracons are missing . . . [stephen a. haines - Ottawa, Canada]

For nit-pickers: The question of how Don's brain, which has been adjusting to his advancing years, would react to the sudden reversal of the remainder of the body's effective age to 25. Whatever the results to his libido, there's as good an argument for his going insane as there is for Sawyer's scenario of the resetting of his chronological clock. Yet another philosophical question raised by this excellent author. - sah