What If?: Serious Scientific Answers to Absurd Hypothetical Questions

“Nearly everyone would die. Then things would get interesting.”

For scientists, the most fascinating aspects of physics often involve lethal things. Throughout the book, examples meant to illustrate the immense size of the possible usually result in massive die-offs of humanity. It can be awkward to discuss with enthusiasm phenomena that would kill most people; thus, the author pokes fun at himself. At the same time, he invites readers with fearless senses of humor to join him in exploring the extremely unusual possibilities, some of them grimly funny, in our universe.

“Eventually, humans will die out. Nobody knows when, but nothing lives forever. Maybe we’ll spread to the stars and last for billions or trillions of years. Maybe civilization will collapse, we’ll all succumb to disease and famine, and the last of us will be eaten by cats. Maybe we’ll all be killed by nanobots hours after you read this sentence. There’s no way to know.”

The author treats every topic, even humanity’s possible extinction, with a dose of humor. It’s a detached, bird’s-eye view of a world whose features may sometimes appear horrifying but always are interesting. This fascination with facts of all kinds is a characteristic of the scientific mind. A cool head and an occasional sardonic chuckle perhaps make for the best attitude to bring along when exploring a universe filled with both good and bad attributes.

“A world of random soul mates would be a lonely one. Let’s hope that’s not what we live in.”

Humans have trouble with large numbers; sometimes, we don’t realize how small are our chances of finding unique things that we want. If everyone has a single soul mate, the odds of such a person even being alive when we are is hugely remote. Simple statistics, then, suggest that we modify our search to permit a much larger number of people who might bring happiness to our lives.

“I wonder how high this dial goes.”

This might be considered the book’s motto. The author constantly tweaks the power rating, size, or other quality of a thing under discussion until it changes absurdly in dimension. His purpose is to present a scale of the possibilities for various physical processes so that readers get a sense of how physics works at different sizes and volumes. The results usually are absurd, often massively destructive, and certainly nothing anyone would want to try, even if they could. Still, curiosity is the hallmark of science, and scientists can’t help wondering what might happen if things got dialed up.

“They say lightning strikes the tallest thing around. That’s the kind of maddeningly inexact statement that immediately sparks all kinds of questions. How far is ‘around’? I mean, not all lightning hits Mount Everest.”

The author points out that science can’t answer questions asked in too general a way. Many common-sensical ideas aren’t scientific: they’re not specific enough for scientists to tackle. Whether lightning strikes tall things depends on how many other objects stand nearby, what they’re made of, the direction of the wind and weather, and so on. Nature is complicated, and its effects aren’t always easy to calculate.

“So we shouldn’t worry too much about when computers will catch up with us in complexity. After all, we’re caught up to ants, and they don’t seem too concerned. Sure, we seem like we’re taken over the planet, but if I had to bet on which one of us would still be around in a million years—primates, computers, or ants—I know who I’d pick.”

Science and technology create wonders, but they don’t remove the inherent dangers of being the creatures who generate the wonders and their terrible side effects. The author caps this comment with an illustration of a computer, broken and rusted, with ants crawling on it.

“Traditionally, the optimist sees the glass as half full while the pessimist sees it as half empty. This has spawned a zillion joke variants—for example, the engineer sees a glass that’s twice as big as it needs to be, the surrealist sees a giraffe eating a necktie, etc.”

For the author, science is half full of humor. He looks at scientific questions from all angles, including the silly and the ridiculous; this gives him a creative perspective on those questions that permits him to come up with surprisingly imaginative ways to answer them. This trait is highly valuable in science as much as it is in the arts since it enables researchers to see beyond their usual view of things and, sometimes, pluck useful answers from odd perspectives.

“Even a vacuum arguably isn’t truly empty, but that’s a question for quantum semantics.”

Everything, including empty space, contains virtual particles that appear and disappear in accordance with Heisenberg’s uncertainty principle, by which even extremely unlikely things—like the sudden appearance out of nowhere of subatomic particles—have specific odds of happening. The uncertainty principle is a pillar of Quantum Mechanics, a part of physics that also poses deeply puzzling philosophical questions about the nature of reality. The author deliberately misnames it “quantum semantics” as a sardonic comment on how hard it is even for physicists to define nothing.

“I’ve never seen the Icarus story as a lesson about the limitations of humans. I see it as a lesson about the limitations of wax as an adhesive.”

In the Greek parable, Icarus, anxious to achieve flight, flies too close to the sun, and his waxed wings fail. In his humorous way, the author enlists the eternal optimism of science and technology, which always search for ways to overcome physical restrictions. Perhaps the real lesson is to avoid not inventions but hubris.

“Avoiding a high-speed landing is, unsurprisingly, the key to survival. […] ‘It’s not the fall that kills you, it’s the sudden stop at the end.’”

Sometimes, darkly humorous jokes provide clues on how to think about important topics. Death is important, and avoiding it sometimes requires careful thought: If we neglect to think carefully through all the consequences of our risky actions, sometimes we miss the obvious and suffer for it.

“Neutrinos are ghostly particles that barely interact with the world at all. Look at your hand—there are about a trillion neutrinos from the Sun passing through it every second. Okay, you can stop looking at your hand now. The reason you don’t notice the neutrino flood is that neutrinos mostly ignore ordinary matter. On average, out of that massive flood, only one neutrino will ‘hit’ an atom in your body every few years.”

The strangeness of the author’s answers isn’t always caused by his unusual take on the topics he covers. A large part of it is simply due to the enormously strange nature of our universe. Some aspects of physics have the quality of fantasy or magic, yet they’re quite true. In their methodically careful way, scientists have discovered facts about reality that far surpass the most fantastic myths dreamed up by humans.

“Space is about 100 kilometers away. That’s far away—I wouldn’t want to climb a ladder to get there—but it isn’t that far away. If you’re in Sacramento, Seattle, Canberra, Kolkata, Hyderabad, Phnom Penh, Cairo, Beijing, central Japan, central Sri Lanka, or Portland, space is closer than the sea.”

A recurring theme is that things are stranger than we might think. It’s easy, for example, to gaze at a mountain 60 miles away, but it’s not intuitively obvious that the same distance straight up ends in outer space.

“High up in the North in the land called Svithjod, there stands a rock. It is a hundred miles high and a hundred miles wide. Once every thousand years a little bird comes to this rock to sharpen its beak. When the rock has thus been worn away, then a single day of eternity will have gone by. —Hendrik Willem Van Loon”

The author quotes Van Loon to illustrate the unbelievable immensity of large numbers. He then shows that it would take a year of eternity days for even a 1-in-10,000 chance that a single student out of 4 million SAT test-takers, filling in the math section with random answers a million times every day for 5 billion years, might get a perfect score. This analogy demonstrates that some things are hopelessly beyond our ability to conceive them, yet they’re quite real.

“Suppose that the bird scrapes off a tiny bit of rock from the mountain when it visits every thousand years, and it carries away those few dozen dust particles when it leaves. (A normal bird would probably deposit more beak material on the mountaintop than it would wear away, but virtually nothing else about this scenario is normal either, so we’ll just go with it.)”

The comment reminds readers that most of the book’s scenarios have defects. If they behaved perfectly, the events described would be expected to come about, but the sheer implausibility of the starting assumptions assures us that such happenings are extremely unlikely. This, of course, can be cause for relief.

“While 140 characters may not seem like a lot, we will never run out of things to say.”

The author refers to the social media app Twitter, whose extremely limited space still allows for more distinct comments than can be read aloud in trillions of years. It’s a commentary not only on the remarkable efficiency of language but also on the extraordinarily vast opportunities for human thought.

“[E]nthusiasts will point out it should be written ‘LEGO.’ Actually, the LEGO Group® demands that it be styled ‘LEGO®.’ On the other hand, writers have no legal obligation to include the trademark symbol. The Wikipedia style guide mandates that it be written ‘Lego.’ The Wikipedia style is not without its critics. The talk page argument over this issue featured many pages of heated arguments, including several misguided legal threats. They also debate the italics.”

This series of footnotes amounts to a sidebar on the niceties of publishing. An author who understands infinitesimal concepts like 10^-34 has no problem noting and lampooning the posturing of corporate lawyers and the resulting fuss by writers, linguists, and historians. By extension, he’s also making fun of his obsessions with the details of his field of study, physics.

“It’s happened to all of us. You’re in the belly of a vast space station and you’re trying to shoot someone with a bow and arrow.”

This droll opening to a discussion of how air slows projectiles is a good example of the author’s odd sense of humor. He has a knack for setting up unusual scenarios to explain odd scientific facts and then making fun of the scenarios.

“Nothing lasts forever, and rapid change has been the norm for anything built on computer technology. The ground is littered with the bones of websites and technologies that seemed like permanent institutions ten years ago.”

Huge companies don’t always last a long time, especially during these days of constant change in the marketplace. The author points out that there are a few touchstones we can rely on in thinking about the future. The scientific mind takes a step back, removes all emotional blinders, such as personal devotion to an institution, and coolly estimates the likelihood that a given organization will be with us several decades from now.

“Right now, next of kin can convert a dead person’s Facebook profile into a memorial page. But there are a lot of questions surrounding passwords and access to private data that we haven’t yet developed social norms for. Should accounts remain accessible? What should be made private? Should next of kin have the right to access email? Should memorial pages have comments? How do we handle trolling and vandalism? Should people be allowed to interact with dead user accounts? What lists of friends should they show up on? These are issues that we’re currently in the process of sorting out by trial and error.”

Big changes in technology bring about big changes in society. New abilities present new ethical challenges; values once cast in stone begin to crumble when novel opportunities, and the moral dilemmas they cause, rise to challenge us. The first step is simply to be aware of the problem; after that, it’s difficult, but not impossible, to move forward in search of solutions that resolve the inevitable conflicts that arise with each new gadget or system.

“The basic pieces that make up a human life don’t change. We’ve always eaten, learned, grown, fallen in love, fought, and died. In every place, culture, and technological landscape, we develop a different set of behaviors around these same activities. Like every group that came before us, we’re learning how to play those same games on our particular playing field. We’re developing, through sometimes messy trial and error, a new set of social norms for dating, arguing, learning, and growing on the Internet.”

The author acknowledges that people today are feeling their way toward a future made more uncertain by constantly changing technology and social mores. Like most scientific minds, he is keenly aware that variables can mess up the most careful predictions. There are, however, several reasonably reliable constants in human behavior, and these can serve as signposts that help us navigate through the dimness of our ignorance.

“They say lightning never strikes in the same place twice. ‘They’ are wrong. From an evolutionary perspective, it’s a little surprising that this saying has survived; you’d think that people who believed it would have been gradually filtered out of the living population.”

Old myths die hard—this one perhaps because so few people get struck by lightning—and the author’s wry comment points out that ideas have their own evolution. In any case, it’s always important to retain a skeptical mind about anything one hears since human beliefs are only loosely connected to facts.

“In case you’re curious, yes, I did run some numbers on using passing tornadoes to run wind turbines […].”

The author’s enthusiasm exceeds even those of his most dedicated questioners. This explains why most of his answers contain not one but several solutions that speak to the main question and some alternative ones. Tornadoes, by the way, would be inefficient donors of energy.

“Apollo 11 command module pilot Mike Collins said he did not feel at all lonely. […] Introverts understand; the loneliest human in history was just happy to have a few minutes of peace and quiet.”

Aloneness can be a pleasure for shy people, especially those whose intellectual interests keep them busy. The lunar command-module astronauts, who got farther away from other humans than anyone in history, enjoyed their moments of solitude, though whether they’d like it if the experience lasted for days or weeks is another matter. The author hints that he’s one of them—his written ideas, if sometimes bizarre, are written in the gentle style of those not prone to loudness or anger but willing, with some diffidence, to express themselves and then return to their solitary studies.