Living organisms don’t tolerate boiling or subzero temperatures, massive pressure or an environment too rich in salt, acid or toxic chemicals—or so we thought for centuries.
Biologists believed this until the mid 20th century, but they don’t believe it today, writes Toomey (English/Univ. of Massachusetts-Amherst; The New Time Travelers: A Journey to the Frontier of Physics, 2007) in this imaginative account of “life” in its broadest terms. The author begins by describing “extremophiles,” which thrive in wildly harsh conditions: chemical hot springs, inside sea ice, miles beneath the earth or at the ocean’s bottom. Having dealt with creatures that, however weird, exist, he proceeds to even stranger life that may exist on Earth, the planets, elsewhere throughout the universe, and in the minds of writers and philosophers. Along the way, he addresses surprisingly difficult questions, such as how to define life. Is it anything that grows, consumes, converts matter to energy, ages and dies? Stars and flames do that. Is it living if it can reproduce? Crystals reproduce, and mules don’t. How life originated remains elusive, but the good news is that it appeared so soon after the young Earth cooled that it may be part of the natural order and not a rare accident. As for the basics, life seems to require a backbone element that supports innumerable complex molecules. On Earth, this can only be carbon, but silicon may work at lower temperatures. Also essential is a liquid medium—water on Earth, but ammonia and methane might do elsewhere.
An ingenious overview of anything that might be alive. The author remains true to science while coming to delightfully bizarre conclusions.