What If? 2: Additional Serious Scientific Answers to Absurd Hypothetical Questions

Question: “How tall can a swing set be while still being powered by a human pumping their legs? Is it possible to build a swing set tall enough to launch the rider into space if they jump at the right time?” (79).

Pumping one’s legs, or “driven oscillation,” works by pushing around the pivot of the crossbar. Pumping becomes less efficient as the swing set becomes taller because each pump adds less twist to the whole system, while air resistance becomes more significant. The ideal swing to propel by pumping is 10-15 feet tall, which is the height of a normal playground swing set.

Question: “My friend is a commercial airline pilot. She says that a significant amount of fuel is spent on takeoff. To save fuel, why couldn’t we launch airplanes using catapult systems like on aircraft carriers (calibrated to normal human accelerations)? Could significant amounts of fossil fuels be saved if the catapults could be run by some other clean energy? I’m imagining a rope…one end tied to the airplane, the other tied to a large boulder at the edge of a cliff. Just push the boulder off the cliff!” (83).

The catapult could aid acceleration only while the airplane is on the ground, not during the costly climb to cruising altitude. The initial takeoff is brief enough that it consumes only a small portion of an airplane’s fuel and altering that would require runways to take up too much space. Catapult systems have been proposed and tested but have never been implemented because the prohibitive overhead expenses generally outweigh any benefits in saved fuel. (Munroe proposes that a complex pully system could be rigged to use the Washington Monument as the weight to catapult a plane forward.)

In this chapter, Munroe answers several user-submitted questions via a brief written answer, a short comic, or both.

Question: “Billy the Clown is running out of cash, so in order to raise money, he devises his newest trick: He will inflate, by mouth, a standard-size party balloon until the material (some form of indestructible rubber) is just one atom thick. How large would the inflated party balloon be?” (88).

The author ironically comments on the “mystery” of why the clown is running out of cash.

Question: “How many leaf blowers would it take to move a standard SUV?” (89).

A total of 12-24 leaf blowers would suffice to propel a car in neutral on level ground, though more would be needed to accelerate quickly.

Question: “If you put a vacuum at extremely high suction power and aimed it at a normal BMW sedan, what would happen?” (89).

A comic shows bystanders objecting, while the car is unaffected.

Question: “On a warm summer evening, when you sit outside with a light on, you can be quite sure that bugs would be attracted to the light. Then why is it that these same bugs don’t fly toward the biggest and strongest lamp of them all, namely the Sun, during the day?” (90).

It’s uncertain why insects fly toward lamps at night, but the reason they don’t fly toward the sun during the day is that any insects that did so would die without reproducing, preventing their genes from being passed on.

Question: “If you collected all the guns in the world and put them on one side of the Earth, then shot them all simultaneously, would it move the Earth?” (91).

No, but the author would welcome the removal of all guns to the opposite side of the world.

Question: “What would happen if you microwaved a smaller microwave, while the smaller one was on as well?” (91).

You’d be banned from the Ikea in which you were presumably conducting the experiment.

Question: “If you’re jumping on a trampoline, how fast would your body have to be going to: A. Break all bones on impact B. Make your body go through the tiny holes of the mesh” (92).

In scenario A, you’d be going so fast that the presence of the trampoline wouldn’t matter. Scenario B is impossible.

Question: “I have a Nothing Grenade. When detonated, it instantly replaces itself with a sphere of perfect vacuum 2 meters across. What would actually happen when it went off?” (93).

The vacuum would collapse and the energy radiating outward would have an effect similar to that of a normal grenade.

Question: “Is space hot or cold?” (93).

The molecules in space are all high energy, so space is technically hot. However there are so few molecules that their total heat energy is low, so you would nonetheless freeze to death in space.

Question: “How many bones can you remove from the human body while allowing the human to continue living? Asking for a friend” (94).

The author notes that the “friend” in question is likely not a real friend.

Question: “What would happen if you put a human under a g-force of 417 Gs for twenty seconds?” (94).

The person would die.

Question: “Where or how can one commit a murder and not be prosecuted for it?” (95).

Some claim that felonies committed in a particular area of Yellowstone National Park wouldn’t be prosecuted due to jurisdictional conflicts, but a federal prosecutor dismisses this as untrue.

Question: “I read today that insects make at least $57 billion a year for the US economy. If we were to pay every single insect in the United States equally for their economic contribution, how much would each insect get?” (96).

Each insect would get a 1-in-3,500 share of a penny, and Munroe notes the division of wages between different categories of insect.

Question: “What, in today’s world and yesterday’s world, does it mean to be human, in all social and biological factors?” (97).

Munroe suggests that this question would be better submitted to a parody version of this book called Why If? that would deal with inane philosophical questions.

Question: “What if an object like the Chicxulub impactor hit Earth with a relatively low relative speed of (let’s say) 3 mph?” (98).

It wouldn’t cause a mass extinction event, but the object—which is more akin to gravel held together by frost and gravity than a boulder—would flow like liquid into a spreading disk. The landslide would cover approximately the same region as the original Chicxulub impact crater, and debris would flow into the sea, causing massive tidal waves and tsunamis.

Question: “What if Mercury (the planet) were entirely made of mercury (the element)? What if Ceres was made of cerium? Uranus made of uranium? Neptune made of neptunium? What about Pluto made of plutonium?” (103).

Mercury and Ceres would both get brighter and heavier, though the changes would be minor as viewed from Earth. If the most stable isotopes of Uranium and Neptunium were used, then both planets would be brighter, radioactive, and very hot, though they would not pose a threat to Earth. If unstable isotopes were used, then fission would occur in the core of Uranus, releasing a shockwave that would destroy Earth.

Question: “What would happen if the Earth’s rotation were sped up until a day only lasted one second?” (108).

Earth’s crust and mantel would break apart and the planet would be flattened into an ever-expanding disk. Earth’s equator would be traveling at over 10% of the speed of light and be flung outwards by centrifugal force. It would first impact Earth’s satellites and then travel through the solar system, emitting Gamma rays each time it hit an object. If the rotation were sped up as the Moon crossed the plane of Earth’s equator, the moon would be launched out of the solar system as a high-energy comet.

Question: “My daughter—4½—maintains she wants a billion-story building. It turns out not only is it hard to help her appreciate this size, I am not at all able to explain all of the other difficulties you’d have to overcome” (111).

Extremely tall buildings are impractical and prohibitively expensive. If a building were too tall, then it would be destabilized by strong winds at high altitudes, and its bottom floors would be crushed by the weight of the upper floors. (Munroe illustrates a series of increasingly tall skyscrapers to provide a sense of scale to the size of a billion-story building.)

Question: “What if Au Bon Pain lost their 2014 lawsuit and had to pay the plaintiff $2 undecillion?” (120).

Munroe illustrates how absurdly large this sum would be by showing how far it outstrips the total economic value of all goods and services ever produced by mankind, the total value of all Earth’s elements, and other extraordinarily costly hypothetical goods and services.

Question: “If every country’s airspace extended up forever, which country would own the largest percentage of the galaxy at any given time?” (124)

The Southern Hemisphere tilts toward the center of the galaxy, so it would have an advantage, and ownership would shift among countries as Earth rotated. Australia would win, owning more of the galaxy at its peak than any other nation.

Question: “Rubber tires on millions of cars and trucks start with about ½-in. tread and end up bald. Rubber should be everywhere, or at least our highways should be made thicker. Where’s the rubber?” (128).

The lost rubber from balding tires is a major source of microplastics in the environment. Rubber particles are blown away in the air or washed by rainwater into rivers, dirt, and oceans, affecting the chemical balance of the water and ending up in the lungs and bodies of both people and wildlife.

Question: “As plastic is made from oil and oil is made from dead dinosaurs, how much actual real dinosaur is there in a plastic dinosaur?” (131).

It would be very difficult to find out for certain. Some oil comes from terrestrial sources, though more is formed from marine life. Without tracing the manufacturing process of the plastic dinosaur back through to its sources there’s no way of knowing the origins of its components. All ocean water was once part of a dinosaur, given that the water cycle would have pulled it into the food chain at one point, so in a sense everything containing water is partly made up of dinosaurs.

In this chapter, the author answers several user-submitted questions via a brief written answer, a short comic, or both.

Question: “How long do you think two people would have to kiss continuously before they had no lips left?” (135).

Lips don’t erode when pressed against lips.

Question: “My college friend and I have had this debate for years now: If you put a million hungry ants in a glass cube with one human, who’s more likely to walk out alive?” (135).

There’s no reason to assume that they’d immediately fight each other. The glass cube and the person who put them in there would be their true unifying enemies.

Question: “What if all of humanity set all of their differences aside and work together to level out the Earth into a perfect sphere?” (136).

This proposition would cause new conflicts.

Question: “People talk a lot about a space elevator or a building that would reach into low orbit to save time and resources getting things into space. This is going to sound incredibly stupid, but why has no one proposed building a road into space? Since orbit is generally considered to be 62 miles out, would it be possible to build a 62-mile-high mountain somewhere in the United States? Colorado would be my suggestion since it has a low population density and is about a mile above sea level already” (137).

Sourcing the raw materials for the mountain would be a major issue since it would require millions of cubic kilometers of rock upon which many people already reside.

Question: “If I shot a rocket and a bullet through Jupiter’s center, would they come out the other side?” (138).

No.

Question: “What if Mount Everest magically turned into pure lava? What would happen to life; would we all die?” (138).

Large outpourings of lava have appeared on Earth’s surface before, typically during mass extinction events. The climate would be seriously affected by the outpouring of carbon dioxide. It would likely be catastrophic for humanity, although it would be less severe than the Permian Extinction, so life would persist on Earth.

Question: “Can you fall down into the Mariana Trench, or would you just swim over it?” (140).

Either is possible.

Question: “What if I struck a match on Titan? Would it light if there’s no oxygen?” (141).

Matches contain fuel and oxidizer in small amounts, so the match would spark briefly before going out due to the lack of oxygen.

Question: “I posted a question on social media asking what would be the smallest change that would create the biggest disaster. One of the responses I got said ‘if every atom gained 1 proton.’ So my question for you is, what would happen if every atom gained 1 proton?” (142).

That would not be a small change.

Question: “When I was a child, I discovered that if I took a container into the swimming pool, I could fill it with water and then bring the container (open-end down) to the surface of the water, and the water level in my container was higher than the water level in the pool. What would happen if you tried to do this with a giant container and the ocean? Could you create a giant aquarium on top of the water that the animals could swim in and out of freely? Maybe an irregularly shaped container that you would walk around on to get closer to the fish?” (143).

Water is suctioned into a protruding vessel as a consequence of air pressure affecting the water’s surface outside the vessel. An aquarium could be constructed using this principle to a maximum height of ten meters before the air pressure in the vessel would be too low and a vacuum would form above the water, boiling the water. This is the same principle by which barometers work. The pressure change in the aquarium could injure or damage fish by overinflating their swim bladders, and the lack of oxygen would suffocate any surfacing marine mammals in the vessel. In addition, the water level in the aquarium would drop over time.

Question: “If the Earth were a massive eye, how far would it see?” (149).

Simply scaling up the eye faithfully would not work, but if the larger eyeball could function like an ordinary eyeball, its main limit would be diffraction. It would have a resolution half a billion times better than that of a normal eyeball and would be able to see all the way across the universe—limited perhaps by the haze of space—though even starlight would be bright enough to burn its retina.

Question: “How many people would it take to build Rome in a day?” (154).

The number of people would not be the bottleneck for such a project; the issues would relate to logistics, coordination, and organization. One economic formula estimates that it would take 10-15 years to build Rome entirely anew. (However, Munroe shows, through various calculations, that from a labor perspective, the global population could easily build Rome in a single day.)

Question: “If I put an indestructible 20-meter-wide glass tube in the ocean that goes all the way down to the deepest part of the ocean, what would it be like to stand at the bottom? Assuming the Sun goes directly overhead.” (159).

The air pressure would be high because of being so far below sea level but it would be quite cool, even though the tube would reach three times deeper than the deepest mines. The sun would pass overhead only a couple of days a year, and the surrounding sea would be dark regardless, although a strong torch could illuminate immediate surroundings. Allowing a controlled flow of water into the tube could allow the observer to ascend on a fountain of deep ocean water.

Question: “What would be the most expensive way to fill a size-11 shoebox (e.g., with 64 GB Micro SD cards all full of legally purchased music)?” (164).

The highest total value is probably approximately $2 billion, whether the chosen filling is SD cards, legal or illegal drugs, or rare minerals/jewels, although a specially issued trillion-dollar coin from the US Treasury or a high-value check could exceed this amount. Allowing for different kinds of software—cryptocurrency or pay-to-play apps, for instance—could give the contents of the box practically unlimited value, although the actual value of such purchases is dubious.