Brief Answers to the Big Questions

The main topic of Hawking’s research was black holes. A black hole forms when a large star at the end of its life collapses down to a point. All its mass is contained in that single point, and anything that comes within a certain distance of it, including light, becomes trapped by its intense gravity and gets sucked down into the point. The point is called a singularity; the distance around the point within which matter and energy become trapped is called the event horizon.

The first black holes discovered were called quasars because of their “quasi-stellar” brightness. The light came from matter swirling down toward the black hole, emitting high-energy photons while being torn apart by the intense gravity. The author discovered that black holes radiate a small amount of matter and energy: Virtual particles, as postulated by quantum mechanics, form and vanish everywhere, and the ones that do so at a black hole’s event horizon may become separated by the horizon. One member of such a pair escapes into space. This ongoing process causes the black hole to slowly evaporate.

The author wondered whether the information lost to the black hole would return to the outside universe along with the slowly evaporating hole. He determined that black holes contain many “symmetries”—quantities that don’t vary. (Examples of symmetries outside of black holes are things that don’t change over time, like the speed of light or the shape of a sphere as it’s rotated.) These symmetries could contain the information that was crushed, along with matter and energy, into the black hole’s singularity. Thus, black holes do retain information about all the things that fall into them. Through his work on black holes, Hawking developed theories about the origin of our universe, which itself was a kind of black hole in reverse, spewing its contents outward in a cataclysm of birth.

Hawking mentions God several times in the book, most often in Chapter 1 when he disposes of God as an active agent controlling the universe. He doesn’t strictly define God but addresses the common belief in a personal being of immense power who created and/or manipulates the cosmos. His view is controversial and defies the tacit convention between religionists and scientists that each holds views that are valid in their own way. However, he makes a peace offering to religionists: “I use the word ‘God’ in an impersonal sense, like Einstein did, for the laws of nature, so knowing the mind of God is knowing the laws of nature” (28).

Beyond that definition, Hawking doesn’t believe in a separate being, a personal God, who maintains the universe. Instead, he thinks the universe created itself and currently is doing just fine, with no need for outside intervention. Hawking thus questions whether a universe that erupts spontaneously out of nothing, as he believes ours did, needs a God at all.

At age 20, Hawking experienced a series of physical falls from which he had trouble rising. Doctors diagnosed his affliction as amyotrophic lateral sclerosis (ALS), also known as Lou Gehrig’s disease, a form of motor neuron dysfunction that causes a rapid onset of muscle weakness and paralysis. ALS thus dramatically shortens a patient’s life expectancy: “My illness seemed to progress rapidly. Understandably, I became depressed” (11).

For Hawking, it was a wake-up call that challenged him to redouble his efforts in physics. When his symptoms stabilized, Hawking took renewed interest in his PhD studies and appreciated every day left to him. Aided and inspired by Jane Wilde, who became his wife, he finished his degree, became a professor at Cambridge, and, with Jane, raised three children. With her help and that of others, Hawking accomplished an astounding amount of pivotal scientific work. He lived with ALS for 56 years and died at age 76, an astonishingly long life given that individuals who have the illness often die within a few years.

A foundation of quantum mechanics, the uncertainty principle states that the exact position and velocity of a subatomic particle can never be known. This is because such particles are observed by other particles that transfer an unknown amount of energy to the particle for observation. The more precisely such an experiment can determine the position of a particle, the less it knows about the particle’s energy state, and vice versa. Instead, scientists calculate a “wave function,” which describes particles as waves of energy centered on a few tall waves that roughly define the particle’s probable location at the moment of observation.

The uncertainty principle makes it possible for “virtual particles” to exist temporarily. Such particles appear out of nowhere, wiggle around for a tiny moment, and then disappear. These particles have been shown to exist through the Casimir effect, by which virtual particles that surround closely aligned parallel metal plates exert pressure on the plates, pushing them closer together. At the visible edge of a black hole, the event horizon may separate virtual particles that form—one dropping back into the hole and the other escaping. Over time, this process causes the total mass and energy of the hole to gradually dissipate.

The uncertainty principle serves as an upper limit to what scientists can predict about humanity and the universe. Ultimately, knowing everything about our cosmos is impossible; on the other hand, the uncertainty allows, on occasion, strange and even miraculous events to occur.