But contemplating entropy is more fun anyway.
How long would this bridge stand if humans suddenly vanished, I wonder as I drive along. What would that neighborhood look like, maintenance-free, in 100 years? In 10,000 years? How would that cat, skittering across the road, fare on its own? How would the road fare on its own?
Science writer and journalism professor Alan Weisman thinks along the same lines in "The World Without Us."
Wisely, the author offers no mechanism to account for our collective outta here. Total nuclear war would take too much other stuff with it, he explains; that's another book, anyway. Ebola or some similar plague would wipe out at best 99.9% of us, which would still leave plenty of disease-resistant humans to regroup. (It'd be like discontinuing your antibiotics after only a few days, I guess.) The Rapture scenario works, but concomitant Other Plans for the Earth introduce unwieldy and unagreed-upon variables.
Things fall apart fast. Your house would probably topple in 100 years, with water acting as the primary catalyst for degradation. Newer buildings won't last nearly as long as a lot of old ones, as modern materials are cheaper and computer calculations allow for construction closer to real tolerances than was previously allowed, when margins of error had to be greater. Of all the items in your house, among the longest-lasting will be ... porcelain.
No one knows how long aluminum and plastic will endure, but Weisman's scariest chapter may be "Polymers Are Forever," in which scientists explain that plastics on the molecular level may be indestructible.
Weisman's look at animal life without us is trumped by both Peter Ward's "Future Evolution" (2001), which he mentions, and Dougal Dixon's more fanciful "After Man" (1998), which he doesn't. But Weisman does a tolerable job, explaining, for example, that cattle would make predators fat in Africa, but not for long because they won't last more than a few years; that dogs would provide a similar service for our predators; that cockroach and rat populations would decline; that our kittycats would do just fine.
As for the prospects of another intelligent species arising, Weisman of course looks to chimps and bonobos. But it didn't occur to him that any newly emerging civilization would be stymied by the lack of availability of metals that formed when the Earth was still molten. We've already mined 'em - picked the low-hanging fruit, leaving the tree all but barren for any apes-come-lately.
Weisman deals mostly with the next handful of thousands of years. In moments of environmental despair I like to leap forward 20, 30, 40 million years, when, long after our all-but-inevitable exit, the Earth will be pristine again - save for the occasional low-flush toilet, buried deep beneath what was once San Diego, waiting for an alien crew to uncover it and wonder, What the hell ...?
- Arthur Salm
