This book offers 50 possible solutions to Enrico Fermi's
famous question: "Where is everybody?" Fermi asked the question when lunching with
a bunch of his genius and the topic of alien civilizations came up. Fermi realized that in
a galaxy with 400 billion stars it seemed likely that there should be abundant alien
civilizations more advanced than our own. Just as humans have spread across the Earth,
these advanced aliens should have spread across the galaxy. The galaxy is billions of
years old, plenty of time for even one civilization to cover the entire galaxy. Yet we
see no sign of these aliens. If these civilizations are common, why can't we detect
Webb does a terrific job of clearly explaining, sometimes
amusingly, all sides of the argument. His 50 possible solutions to Fermi's question are
partitioned into 3 sets of answers: Aliens do exist, and they already HAVE contacted
Earth; aliens do exist, but we can't communicate with them; and aliens do not exist.
The answers for Aliens are already here are discussed and
quickly set aside. Webb fairly prevents the arguments that "aliens walk among us", but
then dismisses them - if aliens are deliberately hiding their presence from us, then
we will remain unable to detect them.
Much more interesting are the arguments that explain why alien
civilizations might exist, but be difficult to communicate with. Also, the section that
argues aliens simply do not exist is also informative. Webb conscisely summarizes each
argument, and then explains why it does not answer the paradox. For example, isn't it
possible that advanced alien species can't be bothered with communicating other species?
After all, we may be as simple as ants to them, and look at how poorly humans communicate
with ants. Of course, says Webb, that is a valid argument - but in a galaxy full of alien
civilizations, would you expect ALL advanced civilizations to make no attempt to communicate?
Because if even one civilization is trying to be seen/found, then that ought to be enough
for us to detect them. Webb covers SETI, the galatic habitable zone, the probability of
life appearing on other planets, doomsday war machines, space travel, the Drake equation,
and plenty more subjects. Each topic that he writes about is covered clearly, and quickly
without being boring. The reader gets a tour of all the reasons why life on Earth might be
unique, and the counterarguments as well. I really liked this book, it was informative and
fun. The 50th solution is the one Webb believes to be true. I won't reveal it here, but he
did a good job of convincing me that he is probably right.