What If?: Serious Scientific Answers to Absurd Hypothetical Questions

Question: “What is the longest possible sunset you can experience while driving […]?” (228).

Near the poles, the sun can set in odd ways. The furthest-north decent road is Norway’s Route 69, on which, driving north as the sun begins to set, you can stretch out the sunset to 95 minutes.

Question: “If you call a random phone number and say ‘God bless you,’ what are the chances that the person who answers just sneezed?” (233).

Research suggests that the average person sneezes roughly once a day. The odds that, when you call, they’ve just sneezed are one in 40,000. The chances also are about one in 10 million “that you’ll get someone who—just that day—published an article on sneezing” (235).

Question: “What is the probability that if I am stabbed by a knife in my torso that it won’t hit anything vital and I’ll live?” A cartoon stick figure, holding a knife, texts, “Asking for a friend. Former friend, I mean” (236).

Question: “If I were on a motorbike and do a jump off a quarter pipe ramp, how fast would I need to be moving to safely deploy and land using the parachute?” (236). No comment.

Question: “What if every day, every human had a 1 percent chance of being turned into a turkey, and every turkey had a 1 percent chance of being turned into a human?” (236). No comment.

Question: “How long would it take for people to notice their weight gain if the mean radius of the world expanded by 1 cm every second?” (237).

For the first couple of years, little would change. (After a few months, the orbiting International Space Station would have to be abandoned because the increased gravity and rising atmosphere pull it out of orbit.) After five years, roads and bridges begin to suffer damage as the ground under them expands. At 40 years, Earth’s gravity is triple-strength, trees collapse, and only the strongest people can walk. At 100 years, six Gs of gravity make breathing difficult, and the highly dense oxygen becomes a poison. At 300 years, the Moon is pulled so close to Earth that it’s torn up into rings around the planet.

Question: “Assuming a zero-gravity environment […], how long would it take the friction of air to stop an arrow fired from a bow?” (244).

Professional archers can shoot arrows as far as one kilometer. In normal still air and zero gravity, an arrow could travel as much as five to 10 kilometers depending on its exact shape. The projectile would take a few hours to slow to a stop.

Question: “What would happen to the Earth if the Sun suddenly switched off?” (248).

This is the most popular question in What If? If the sun went out, several benefits would accrue. There’d be no more solar flares to damage electrical infrastructure; satellite service and astronomical research would no longer be interrupted by solar light and noise; bridges could be replaced by asphalt over ice; a single time zone would simplify commerce; fighter pilots wouldn’t sneeze in direct sun during combat.

On the bad side, “We would all freeze and die” (250).

Question: “If you had a printed version of the whole of (say, the English) Wikipedia, how many printers would you need in order to keep up with the changes made to the live version?” (252).

A printed version of Wikipedia would fill many bookshelves. In 2014, the entire encyclopedia, printed out, would take up 300 cubic meters of space. To keep up with the continuing edits, only six inkjet printers, working continuously, could do the job. This would require 100,000 sheets of paper per day, totaling $6,000 per day for paper and ink, not counting printing costs for images.

Question: “When, if ever, will Facebook contain more profiles of dead people than of living ones?” (255).

By 2014, between 10 and 20 million Facebook users had already died, but most Facebook participants are relatively young. If Facebook retains all its data and its usage stabilizes for generations, the crossover won’t happen until the “mid-2100s.”

Question: “When (if ever) did the Sun finally set on the British Empire?” (259).

Around 1800, the expanding British Empire added Australia to its worldwide list of colonies; after that, the sun always shone on some part of the empire. Britain lost most of its colonies during the mid-1900s, but there are enough remnants—mostly islands, including Pitcairn Island in the remote Pacific—that the sun still shines continuously on British possessions.

Eventually, a total solar eclipse over Pitcairn Island will end the streak, but not for 1,000 years.

Question: “Would I be able to boil a cup of water by stirring?” (262).

It takes 700 watts of power to boil a cup of water. A microwave can do this in about two minutes; certain types of blenders can warm the tea somewhat. Stirring rapidly by hand has almost no effect. The amount required, “tens of thousands of stirs per second” (265), would cause vacuums in the tea, or cavitation, which would cause the tea to splash upward, lose heat, and cause a mess.

Question: “If all the lightning strikes happening in the world on any given day all happened in the same place at once, what would happen to that place?” (266).

Even in lightning-prone places like Florida and the Congo, sunlight delivers a million times as much power to the ground. If a million bolts all struck the same place at once, it would supply electricity equal to two Hiroshima a-bombs, enough to power the US for five minutes. It also would leave a crater the size of a basketball court and knock down or burn buildings and trees for miles around.

Question: “What is the farthest one human being has ever been from every other living person? Were they lonely?” (270).

During the lunar landings, the lone astronaut in the orbiter, while circling the Moon, got 3585 kilometers from the two astronauts on the surface. The only human who might have gotten farther away would have been a single person adrift at sea long ago in the Southern Ocean near Antarctica. This is no longer possible, as the southernmost continent is now continuously occupied by researchers.

The lone astronaut reported that he enjoyed the solitude.

Question: “What if everyone in Great Britain went to one of the coasts and started paddling? Could they move the island at all?” (273). No.

Question: “Are fire tornadoes possible?” (273). Yes.

Question: “What if a rainstorm dropped all of its water in a single giant drop?” (274).

A column of air from the ground up to space typically contains anywhere from zero to a few dozen centimeters of water. A storm 100 kilometers on a side with six centimeters of water, all of it condensed together, would produce a drop a kilometer wide. Falling at 200 miles per hour, the drop would strike the earth with a supersonic splash that destroys everything around it for 20 to 30 kilometers. The world would be horrified, but eventually, they’d get over it.

Question: “What if everyone who took the SAT guessed on every multiple-choice question? How many perfect scores would there be?” (278).

The odds of getting all 158 math questions right are one in 2.7x10^110, effectively zero. If 4 million students took the math test a million times a day for 5 billion years, the odds of one of them getting a perfect score would be 1 in 10,000. Basically, it’s never going to happen.

Question: “If a bullet with the density of a neutron star were fired from a handgun (ignoring the how) at the Earth’s surface, would the Earth be destroyed?” (280).

A neutron star is the crushed remnant of a giant star. Its material is made entirely of subatomic neutrons packed so tightly together that they become “a compact quantum-mechanical soup that’s in some ways similar to an atomic nucleus the size of a mountain” (281). If it were possible to make a bullet of material that dense, it would weigh as much as the Empire State Building. Fired at the ground, it would fall straight through to the Earth’s center and lodge there.

If the bullet could be put on a pedestal, its own gravity at 10 meters would cause a person to feel like they were on a slope leading toward the bullet. If the person touched the bullet, the fingers would be crushed against it, and blood would pour from their body. A better idea is to hose down the bullet until a sphere of water forms around it more than two meters wide, then adjust the water’s density with salt or vodka and reach in. If your hand is exactly the same density as the water, “you could touch the bullet and live to tell about it. Maybe” (287).

Question: “What if I swallow a tick that has Lyme disease? Will my stomach acid kill the tick and the borreliosis, or would I get Lyme disease from the inside out?” (289). The author suggests swallowing an insect to kill the tick, then an insect to kill that one, and so on.

Question: “Assuming a relatively uniform resonant frequency in a passenger jet, how many cats, meowing at what resonant frequency of said jet, would be required to ‘bring it down’?” (289). A cartoon stick figure calls the FAA and asks if there’s a passenger with cats on board a plane.

Question: “What if a Richter magnitude 15 earthquake were to hit America at, let’s say, New York City? What about a Richter 20? 25?” (290).

A category 15 quake would explode the Earth. A category 20 quake, 100,000 times bigger, would destroy the sun. Such quakes do occur in the superheavy material of neutron stars. Such an event would be what you’d get “if you packed the entire volume of the Earth with hydrogen bombs and detonated them all at once” (291).

The Richter Scale also goes below zero. Magnitude −3 equals a cellphone falling off a nightstand; −15 is a mote of dust landing on a table.

With such tiny examples in hand, the author notes that it’s pleasant, now and then, not to blow up the world.