The premise for this thought experiment is simple: mankind disappears tomorrow, all at once.  Whether by plague or rapture, it makes no difference.  What is important is how the world gets on without us.

Pretty well would seem to be the answer.  Even though the pressure exerted by our presence on the global biosphere is approaching whatever stress resulted in the great Permian extinction some 251 million years ago, life would soon fill in the gaps in our absence, even as it has rushed in to the human-less vacuums left around Chernobyl or in the demilitarized zone between North and South Korea.

Each chapter is filled with fascinating details, from how the New York subways would flood within 24 to 36 hours after our disappearance to how  the average house decays into a sunken basement filled with rubble within half a century. There is the endless lifespan of plastics to consider.  They may have to wait for the expanding sun to recycle them and Earth too (or for a life form to evolve that can munch all our soft drink bottles).

We are not used to thinking in terms of geologic time, but in our absence as the eons roll by, not a city or human artifact will eventually be spared.  One of our longest lasting artifacts may be the simple penny, at least the ones made mostly of copper.  Something about their chemistry, being close to that of bronze, makes them pretty durable tokens of our civilization.  Radiation is another durable gift for the future, as our over 400 nuclear plants and countless missile warheads need constant fussing.  But life will get over that too.

Of course in a book about being gone, there is some question about how long we have to stay.  Every species goes extinct after all, and it is not clear that humans are clever enough to stave off the inevitable (although there seems evidence we are foolish enough to hasten it along). 

Perhaps the central question is: if we truly pave over the planet, and wipe out everything but the few animal and plant species necessary to our survival, will we in fact survive? 

I tend to think the answer is "yes," although Mr. Weisman might disagree.  I'm not saying that's a good alternative, or that the world would be a happy place in the absence of its "natural" biosphere. I just see our rapidly increasing technical prowess providing us with a kind of mastery over the material world we have yet to understand.

This century alone will be host to many of the ultimate conflicts between man and nature that could result in The World Without Us.  While we wait to see how it turns out, I can highly recommend Mr. Weisman's study of the subject.  It should be required reading for aspiring Science Fiction and Fantasy writers.  Well, maybe just required reading.  Period.