What If? Read online

  4Also known as catamounts.

  5Also known as panthers.

  6Also known as painted cats.

  7Although you might not see the clouds of trillions of pigeons encountered by European settlers. In his book 1491, Charles C. Mann argues that the huge flocks seen by European settlers may have been a symptom of a chaotic ecosystem perturbed by the arrival of smallpox, bluegrass, and honeybees.

  8That is, the current site of Yonkers. It probably wasn’t called “Yonkers” then, since “Yonkers” is a Dutch-derived name for a settlement dating to the late 1600s. However, some argue that a site called “Yonkers” has always existed, and in fact predates humans and the Earth itself. I mean, I guess it’s just me who argues that, but I’m very vocal.

  9Though with fewer billboards.

  10Well, had been. We’re putting a stop to that.

  11If anyone asks, total coincidence.

  12If you do, email me.

  Soul Mates

  Q. What if everyone actually had only one soul mate, a random person somewhere in the world?

  —Benjamin Staffin

  A. What a nightmare that would be.

  There are a lot of problems with the concept of a single random soul mate. As Tim Minchin put it in his song “If I Didn’t Have You”:

  Your love is one in a million;

  You couldn’t buy it at any price.

  But of the 9.999 hundred thousand other loves,

  Statistically, some of them would be equally nice.

  But what if we did have one randomly assigned perfect soul mate, and we couldn’t be happy with anyone else? Would we find each other?

  We’ll assume your soul mate is chosen at birth. You don’t know anything about who or where they are, but—as in the romantic cliché—you recognize each other the moment your eyes meet.

  Right away, this would raise a few questions. For starters, would your soul mate even still be alive? A hundred billion or so humans have ever lived, but only seven billion are alive now (which gives the human condition a 93 percent mortality rate). If we were all paired up at random, 90 percent of our soul mates would be long dead.

  That sounds horrible. But wait, it gets worse: A simple argument shows we can’t limit ourselves just to past humans; we have to include an unknown number of future humans as well. See, if your soul mate is in the distant past, then it also has to be possible for soul mates to be in the distant future. After all, your soul mate’s soul mate is.

  So let’s assume your soul mate lives at the same time as you. Furthermore, to keep things from getting creepy, we’ll assume they’re within a few years of your age. (This is stricter than the standard age-gap creepiness formula,1 but if we assume a 30-year-old and a 40-year-old can be soul mates, then the creepiness rule is violated if they accidentally meet 15 years earlier.) With the same-age restriction, most of us would have a pool of around half a billion potential matches.

  But what about gender and sexual orientation? And culture? And language? We could keep using demographics to try to narrow things down further, but we’d be drifting away from the idea of a random soul mate. In our scenario, you wouldn’t know anything about who your soul mate was until you looked into their eyes. Everybody would have only one orientation: toward their soul mate.

  The odds of running into your soul mate would be incredibly small. The number of strangers we make eye contact with each day can vary from almost none (shut-ins or people in small towns) to many thousands (a police officer in Times Square), but let’s suppose you lock eyes with an average of a few dozen new strangers each day. (I’m pretty introverted, so for me that’s definitely a generous estimate.) If 10 percent of them are close to your age, that would be around 50,000 people in a lifetime. Given that you have 500,000,000 potential soul mates, it means you would find true love only in one lifetime out of 10,000.

  With the threat of dying alone looming so prominently, society could restructure to try to enable as much eye contact as possible. We could put together massive conveyer belts to move lines of people past each other . . .

  . . . but if the eye contact effect works over webcams, we could just use a modified version of ChatRoulette.

  If everyone used the system for eight hours a day, seven days a week, and if it takes you a couple of seconds to decide if someone’s your soul mate, this system could—in theory—match everyone up with their soul mates in a few decades. (I modeled a few simple systems to estimate how quickly people would pair off and drop out of the singles pool. If you want to try to work through the math for a particular setup, you might start by looking at derangement problems.)

  In the real world, many people have trouble finding any time at all for romance—few could devote two decades to it. So maybe only rich kids would be able to afford to sit around on SoulMateRoulette. Unfortunately for the proverbial 1 percent, most of their soul mates would be found in the other 99 percent. If only 1 percent of the wealthy used the service, then 1 percent of that 1 percent would find their match through this system—one in 10,000.

  The other 99 percent of the 1 percent2 would have an incentive to get more people into the system. They might sponsor charitable projects to get computers to the rest of the world—a cross between One Laptop Per Child and OKCupid. Careers like “cashier” and “police officer in Times Square” would become high-status prizes because of the eye contact potential. People would flock to cities and public gathering places to find love—just as they do now.

  But even if a bunch of us spent years on SoulMateRoulette, another bunch of us managed to hold jobs that offered constant eye contact with strangers, and the rest of us just hoped for luck, only a small minority of us would ever find true love. The rest of us would be out of luck.

  Given all the stress and pressure, some people would fake it. They’d want to join the club, so they’d get together with another lonely person and stage a fake soul mate encounter. They’d marry, hide their relationship problems, and struggle to present a happy face to their friends and family.

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

  1xkcd, “Dating pools,” http://xkcd.com/314.

  2“We are the zero point nine nine percent!”

  Laser Pointer

  Q. If every person on Earth aimed a laser pointer at the Moon at the same time, would it change color?

  —Peter Lipowicz

  A. Not if we used regular laser pointers.

  The first thing to consider is that not everyone can see the Moon at once. We could gather everyone in one spot, but let’s just pick a time when the Moon is visible to as many people as possible. Since about 75 percent of the world’s population lives between 0°E and 120°E, we should try this while the Moon is somewhere over the Arabian Sea.

  We could try to illuminate either a new moon or a full moon. The new moon is darker, making it easier to see our lasers. But the new moon is a trickier target, because it’s mostly visible during the day—washing out the effect.

  Let’s pick a quarter moon, so we can compare the effect of our lasers on the dark and light sides.

  Here’s our target.

  The typical red laser pointer is about 5 milliwatts, and a good one would have a tight enough beam to hit the Moon—though it’d be spread out over a large fraction of the surface when it got there. The atmosphere would distort the beam a bit, and absorb some of it, but most of the light would make it.

  Let’s assume everyone has steady enough aim to hit the Moon, but no more than that, and the light spreads evenly across the surface.

  Half an hour after midnight (GMT), everyone aims and presses the button.

 
This is what happened:

  Well, that’s disappointing.

  It makes sense, though. Sunlight bathes the Moon in a bit over a kilowatt of energy per square meter. Since the Moon’s cross-sectional area is around 1013 square meters, it’s bathed in about 1016 watts of sunlight—10 petawatts, or 2 megawatts per person—far outshining our 5-milliwatt laser pointers. There are varying efficiencies in each part of this system, but none of it changes that basic equation.

  A 1-watt laser is an extremely dangerous thing. It’s not just powerful enough to blind you—it’s capable of burning skin and setting things on fire. Obviously, they’re not legal for consumer purchase in the US.

  Just kidding! You can pick one up for $300. Just do a search for “1-watt handheld laser.”

  So, suppose we spend the $2 trillion to buy 1-watt green lasers for everyone. (Memo to presidential candidates: This policy would win my vote.) In addition to being more powerful, green laser light is nearer to the middle of the visible spectrum, so the eye is more sensitive to it and it seems brighter.

  Here’s the effect:

  Dang.

  The laser pointers we’re using put out about 150 lumens of light (more than most flashlights) in a beam 5 arc-minutes wide. This lights up the surface of the Moon with about half a lux of illumination—compared to about 130,000 lux from the sun. (Even if we aimed them all perfectly, it would result in only half a dozen lux over about 10 percent of the Moon’s face.)

  By comparison, the full moon lights up the Earth’s surface with about 1 lux of illumination—which means that not only would our lasers be too weak to see from Earth, but if you were standing on the Moon, the laser light on the landscape would be fainter than moonlight is to us on Earth.

  With advances in lithium batteries and LED technology over the last ten years, the high-performance flashlight market has exploded. But it’s clear that flashlights aren’t gonna cut it. So let’s skip past all of that and give everyone a Nightsun.

  You may not recognize the name, but chances are you’ve seen one in operation: It’s the searchlight mounted on police and Coast Guard helicopters. With an output on the order of 50,000 lumens, it’s capable of turning a patch of ground from night to day.

  The beam is several degrees wide, so we would want some focusing lenses to get it down to the half-degree needed to hit the Moon.

  Here’s the effect:

  It’s hard to see, but we’re making progress! The beam is providing 20 lux of illumination, outshining the ambient light on the night half by a factor of two! However, it’s quite hard to see, and it certainly hasn’t affected the light half.

  Let’s swap out each Nightsun for an IMAX projector array—a 30,000-watt pair of water-cooled lamps with a combined output of over a million lumens.

  Still barely visible.

  At the top of the Luxor Hotel in Las Vegas is the most powerful spotlight on Earth. Let’s give one of them to everyone.

  Oh, and let’s add a lens array to each so the entire beam is focused on the Moon:

  Our light is definitely visible, so we’ve accomplished our goal! Good job, team.

  Well . . .

  The Department of Defense has developed megawatt lasers, designed for destroying incoming missiles in mid-flight.

  The Boeing YAL-1 was a megawatt-class chemical oxygen iodine laser mounted in a 747. It was an infrared laser, so it wasn’t directly visible, but we can imagine building a visible-light laser with similar power.

  Finally, we’ve managed to match the brightness of sunlight!

  We’re also drawing 5 petawatts of power, which is double the world’s average electricity consumption.

  Okay, let’s mount a megawatt laser on every square meter of Asia’s surface. Powering this array of 50 trillion lasers would use up Earth’s oil reserves in approximately two minutes, but for those two minutes, the Moon would look like this:

  The Moon would shine as brightly as the midmorning sun, and by the end of the two minutes, the lunar regolith would be heated to a glow.

  Okay, let’s step even more firmly outside the realm of plausibility.

  The most powerful laser on Earth is the confinement beam at the National Ignition Facility, a fusion research laboratory. It’s an ultraviolet laser with an output of 500 terawatts. However, it fires only in single pulses lasting a few nanoseconds, so the total energy delivered is equivalent to about a quarter-cup of gasoline.

  Let’s imagine we somehow found a way to power and fire it continuously, gave one to everyone, and pointed them all at the Moon. Unfortunately, the laser energy flow would turn the atmosphere to plasma, instantly igniting the Earth’s surface and killing us all. But let’s assume that the lasers somehow pass through the atmosphere without interacting.

  Under those circumstances, it turns out Earth would still catch fire. The reflected light from the Moon would be four thousand times brighter than the noonday sun. Moonlight would become bright enough to boil away Earth’s oceans in less than a year.

  But forget the Earth—what would happen to the Moon?

  The laser itself would exert enough radiation pressure to accelerate the Moon at about one ten millionth of a gee. This acceleration wouldn’t be noticeable in the short term, but over the years, it would add up to enough to push it free from Earth orbit . . .

  . . . if radiation pressure were the only force involved.

  Forty megajoules of energy is enough to vaporize a kilogram of rock. Assuming Moon rocks have an average density of about 3 kg/liter, the lasers would pump out enough energy to vaporize 4 meters of lunar bedrock per second:

  However, the actual lunar rock wouldn’t evaporate that fast—for a reason that turns out to be very important.

  When a chunk of rock is vaporized, it doesn’t just disappear. The surface layer of the Moon becomes a plasma, but that plasma would still block the path of the beam.

  Our laser would keep pouring more and more energy into the plasma, and the plasma would keep getting hotter and hotter. The particles would bounce off each other, slam into the surface of the Moon, and eventually blast into space at a terrific speed.

  This flow of material effectively turns the entire surface of the Moon into a rocket engine—and a surprisingly efficient one, too. Using lasers to blast off surface material like this is called laser ablation, and it turns out to be a promising method for spacecraft propulsion.

  The Moon is massive, but slowly and surely the rock plasma jet would begin to push it away from the Earth. (The jet would also scour the face of the Earth clean and destroy the lasers, but we’re pretending that they’re invulnerable.) The plasma would also physically tear away the lunar surface, a complicated interaction that’s tricky to model.

  But if we make the wild guess that the particles in the plasma exit at an average speed of 500 kilometers per second, then it will take a few months for the Moon to be pushed out of range of our laser. It would keep most of its mass, but escape Earth’s gravity and enter a lopsided orbit around the sun.

  Technically, the Moon wouldn’t become a new planet, under the IAU definition of a planet. Since its new orbit would cross Earth’s, it would be considered a dwarf planet like Pluto. This Earth-crossing orbit would lead to periodic unpredictable orbital perturbation. Eventually it would either be slingshotted into the Sun, ejected toward the outer solar system, or slammed into one of the planets—quite possibly ours. I think we can all agree that in this case, we’d deserve it.

  Scorecard:

  And that, at last, would be enough power.

  Periodic Wall of the Elements

  Q. What would happen if you made a periodic table out of cube-shaped bricks, where each brick was made of the corresponding element?

  —Andy Connolly

  A. There are
people who collect elements. These collectors try to gather physical samples of as many of the elements as possible into periodic-table-shaped display cases.1

  Of the 118 elements, 30 of them—like helium, carbon, aluminum, iron, and ammonia—can be bought in pure form in local retail stores. Another few dozen can be scavenged by taking things apart (you can find tiny americium samples in smoke detectors). Others can be ordered over the Internet.

  All in all, it’s possible to get samples of about 80 of the elements—90, if you’re willing to take some risks with your health, safety, and arrest record. The rest are too radioactive or short-lived to collect more than a few atoms of them at once.

  But what if you did?

  The periodic table of the elements has seven rows.2

  You could stack the top two rows without much trouble.

  The third row would burn you with fire.

  The fourth row would kill you with toxic smoke.

  The fifth row would do all that stuff PLUS give you a mild dose of radiation.

  The sixth row would explode violently, destroying the building in a cloud of radioactive, poisonous fire and dust.

  Do not build the seventh row.

  We’ll start from the top. The first row is simple, if boring:

  The cube of hydrogen would rise upward and disperse, like a balloon without a balloon. The same goes for helium.