Brief Answers to the Big Questions

The chapter and the final three chapters speculate on humanity’s future. Here, Hawking sets forth his final call to the world, hoping that we finally wake up to the dangers and their remedies. He warns that selfishness can lead to disaster but holds out the hope that if we survive our own foolishness, we’ll be able to construct a civilization that’s wonderful beyond our dreams.

In this chapter, Hawking ponders the extremes to which technology has advanced our ability to create and destroy—and the catastrophic risks that result. His concerns center on two major dangers: (1) climate disruption and ecological destruction and (2) nuclear war. He believes that we’re highly likely, sometime during the next several centuries, to damage or destroy ourselves via war or environmental collapse. (Hawking adds to this the dangers posed by artificial intelligence machines, but he addresses this risk separately in Chapter 9.) These worries underlie the book’s theme of The Dangers of Modernity.

Hawking’s fears about a climate disaster are based on the idea that increasing world temperatures might lead to a self-reinforcing runaway temperature rise, such as what happened to the planet Venus, which today has surface temperatures several hundred degrees higher than Earth’s. Rising temperatures here may cause even more carbon dioxide to be released as forests wither, while melting ice caps would no longer deflect some of the sunlight and thus cool the planet.

The author’s worries about nuclear war have merit: As long as atomic weapons remain at the ready and on hair-trigger alert, eventually a glitch, accident, hacking, or wartime crisis will cause the weapons to be unleashed. Many researchers estimate that the odds of a nuclear exchange in a given year hover around 1%; these odds, multiplied across 100 years, raise the probability to more than 63%. It’s like a roulette wheel that has 100 slots, one of them a green-zero that takes all bets, which is spun 100 times: The ball will likely land on green-zero during those spins. These are simple statistics, and the implications are devastating for civilization, but we don’t trust each other enough to stop the game. Hawking is right to sound an alarm.

Chief among his suggestions for escaping total disaster is to colonize other moons and planets. This would spread people out somewhat; the colonies could serve as human back-ups, similar to how an external drive can back up a computer in case it fails. Hawking mentions Elon Musk’s plans for colonizing Mars, which would go some distance toward addressing this issue.

Assuming that we survive the dangers we face, Hawking predicts that eventually we’ll answer the fundamental questions about the nature of reality. In particular, scientists will complete the long-sought-after unification of quantum mechanics and relativity theory. Such a merger would settle many questions about the nature of space and time; it also would open up new technical opportunities for improving society, and it would improve our ability to explore deeper into the cosmos.

Hawking mentions Switzerland’s Large Hadron Collider, a circular tunnel nearly 20 miles in circumference that smashes together subatomic matter in search of elusive high-energy particles. Hawking adds that delving into the subatomic realm down to the smallest possible size, the Plank length, would require atom smashers “larger than the solar system” (155). It’s ironic that studying the truly tiny requires building gigantic scientific tools.