A steak dropped from 39 kilometers will, unlike Felix, probably stay below the sound barrier. It also won’t be appreciably heated. This makes sense—after all, Felix’s suit wasn’t scorched when he landed.
Steaks can probably survive breaking the sound barrier. In addition to Felix, pilots have ejected at supersonic speeds and lived to tell about it.
To break the sound barrier, you’ll need to drop the steak from about 50 kilometers. But this still isn’t enough to cook it.
We need to go higher.
If dropped from 70 kilometers, the steak will go fast enough to be briefly blasted by 350°F air. Unfortunately, this blast of thin, wispy air barely lasts a minute—and anyone with some basic kitchen experience can tell you that a steak placed in the oven at 350 for 60 seconds isn’t going to be cooked.
From 100 kilometers—the formally defined edge of space—the picture’s not much better. The steak spends a minute and a half over Mach 2, and the outer surface will likely be singed, but the heat is too quickly replaced by the icy stratospheric blast for it to actually be cooked.
At supersonic and hypersonic speeds, a shockwave forms around the steak that helps protect it from the faster and faster winds. The exact characteristics of this shock front—and thus the mechanical stress on the steak—depend on how an uncooked 8-ounce filet tumbles at hypersonic speeds. I searched the literature, but was unable to find any research on this.
For the sake of this simulation, I assume that at lower speeds some type of vortex shedding creates a flipping tumble, while at hypersonic speeds it’s squished into a semi-stable spheroid shape. However, this is little more than a wild guess. If anyone puts a steak in a hypersonic wind tunnel to get better data on this, please, send me the video.
If you drop the steak from 250 kilometers, things start to heat up; 250 kilometers puts us in the range of low Earth orbit. However, the steak, since it’s dropped from a standstill, isn’t moving nearly as fast as an object reentering from orbit.
In this scenario, the steak reaches a top speed of Mach 6, and the outer surface may even get pleasantly seared. The inside, unfortunately, is still uncooked. Unless, that is, it goes into a hypersonic tumble and explodes into chunks.
From higher altitudes, the heat starts to get really substantial. The shockwave in front of the steak reaches thousands of degrees (Fahrenheit or Celsius; it’s true in both). The problem with this level of heat is that it burns the surface layer completely, converting it to little more than carbon. That is, it becomes charred.
Charring is a normal consequence of dropping meat in a fire. The problem with charring meat at hypersonic speeds is that the charred layer doesn’t have much structural integrity, and is blasted off by the wind—exposing a new layer to be charred. (If the heat is high enough, it will simply blast the surface layer off as it flash-cooks it. This is referred to in the ICBM papers as the “ablation zone.”)
Even from those heights, the steak still doesn’t spend enough time in the heat to get cooked all the way through.2 We can try higher and higher speeds, and we might lengthen the exposure time via dropping it at an angle, from orbit.
But if the temperature is high enough or the burn time long enough, the steak will slowly disintegrate as the outer layer is repeatedly charred and blasted off. If most of the steak makes it to the ground, the inside will still be raw.
Which is why we should drop the steak over Pittsburgh.
As the probably apocryphal story goes, steelworkers in Pittsburgh would cook steaks by slapping them on the glowing metal surfaces coming out of the foundry, searing the outside while leaving the inside raw. This is, supposedly, the origin of the term “Pittsburgh Rare.”
So drop your steak from a suborbital rocket, send out a collection team to recover it, brush it off, reheat it, cut away any badly charred sections, and dig in.
Just watch out for salmonella. And the Andromeda Strain.
1I mean, intact. Not necessarily fine to eat.
2I know what some of you are probably thinking, and the answer is no — it doesn’t spend enough time in the Van Allen belts to be sterilized by radiation.
Hockey Puck
Q. How hard would a puck have to be shot to be able to knock the goalie himself backward into the net?
—Tom
A. This can’t really happen.
It’s not just a problem of hitting the puck hard enough. This book isn’t concerned with that kind of limitation. Humans with sticks can’t make a puck go much faster than about 50 meters per second, but we can assume this puck is launched by a hockey robot or an electric sled or a hypersonic light gas gun.
The problem, in a nutshell, is that hockey players are heavy and pucks are not. A goalie in full gear outweighs a puck by a factor of about 600. Even the fastest slap shot has less momentum than a ten-year-old skating along at a mile per hour.
Hockey players can also brace pretty hard against the ice. A player skating at full speed can stop in the space of a few meters, which means the force they’re exerting on the ice is pretty substantial. (It also suggests that if you started to slowly rotate a hockey rink, it could tilt up to 50 degrees before the players would all slide to one end. Clearly, experiments are needed to confirm this.)
From estimates of collision speeds in hockey videos, and some guidance from a hockey player, I estimated that the 165-gram puck would have to be moving somewhere between Mach 2 and Mach 8 to knock the goalie backward into the goal—faster if the goalie is bracing against the hit, and slower if the puck hits at an upward angle.
Firing an object at Mach 8 is not, in itself, very hard. One of the best methods for doing so is the aforementioned hypersonic gas gun, which is—at its core—the same mechanism a BB gun uses to fire BBs.1
But a hockey puck moving at Mach 8 would have a lot of problems, starting with the fact that the air ahead of the puck would be compressed and heated very rapidly. It wouldn’t be going fast enough to ionize the air and leave a glowing trail like a meteor, but the surface of the puck would (given a long enough flight) start to melt or char.
The air resistance, however, would slow the puck down very quickly, so a puck going at Mach 8 when it leaves the launcher might be going a fraction of that when it arrives at the goal. And even at Mach 8, the puck probably wouldn’t pass through the goalie’s body. Instead, it would burst apart on impact with the power of a large firecracker or small stick of dynamite.
If you’re like me, when you first saw this question, you might’ve imagined the puck leaving a cartoon-style hockey-puck-shaped hole. But that’s because our intuitions are shaky about how materials react at very high speeds.
Instead, a different mental picture might be more accurate: Imagine throwing a ripe tomato—as hard as you can—at a cake.
That’s about what would happen.
1Though it uses hydrogen instead of air, and when you shoot your eye out, you really shoot your eye out.
Common Cold
Q. If everyone on the planet stayed away from each other for a couple of weeks, wouldn’t the common cold be wiped out?
— Sarah Ewart
A. Would it be worth it?
The common cold is caused by a variety of viruses,1 but rhinoviruses are the most common culprit.2 These viruses take over the cells in your nose and throat and use them to produce more viruses. After a few days, your immune system notices and destroys it,3 but not before you infect, on average, one other person.4 After you fight off the infection, you are immune to that particular rhinovirus strain—an immunity that lasts for years.
If Sarah put us all in quarantine, the cold viruses we carry would have no fresh hosts to run to. Could our immune systems then wipe out every copy of the virus?
Before we answer that question, let’s consider the practical consequences of this k
ind of quarantine. The world’s total annual economic output is in the neighborhood of $80 trillion, which suggests that interrupting all economic activity for a few weeks would cost many trillions of dollars. The shock to the system from the worldwide “pause” could easily cause a global economic collapse.
The world’s total food reserves are probably large enough to cover us for four or five weeks of quarantine, but the food would have to be evenly parceled out beforehand. Frankly, I’m not sure what I’d do with a 20-day grain reserve while standing alone in a field somewhere.
A global quarantine brings us to another question: How far apart can we actually get from one another? The world is big,[citation needed ] but there are a lot of people.[citation needed ]
If we divide up the world’s land area evenly, there’s enough room for each of us to have a little over 2 hectares each, with the nearest person 77 meters away.
While 77 meters is probably enough separation to block the transmission of rhinoviruses, that separation would come at a cost. Much of the world’s land is not pleasant to stand around on for five weeks. A lot of us would be stuck standing in the Sahara Desert,5 or central Antarctica.6
A more practical—though not necessarily cheaper—solution would be to give everyone biohazard suits. That way, we could walk around and interact, even allowing some normal economic activity to continue:
But let’s set aside the practicality and address Sarah’s actual question: Would it work?
To help figure out the answer, I talked to Professor Ian M. Mackay, a virology expert from the Australian Infectious Diseases Research Centre at the University of Queensland.7
Dr. Mackay said that this idea is actually somewhat reasonable, from a purely biological point of view. He said that rhinoviruses—and other RNA respiratory viruses—are completely eliminated from the body by the immune system; they do not linger after infection. Furthermore, we don’t seem to pass any rhinoviruses back and forth with animals, which means there are no other species that can serve as reservoirs of our colds. If rhinoviruses don’t have enough humans to move between, they die out.
We’ve actually seen this viral extinction in action in isolated populations. The remote islands of St. Kilda, far to the northwest of Scotland, for centuries hosted a population of about 100 people. The islands were visited by only a few boats a year, and suffered from an unusual syndrome called the cnatan-na-gall, or “stranger’s cough.” For several centuries, the cough swept the island like clockwork every time a new boat arrived.
The exact cause of the outbreaks is unknown,8 but rhinoviruses were probably responsible for many of them. Every time a boat visited, it would introduce new strains of virus. These strains would sweep the islands, infecting virtually everyone. After several weeks, all the residents would have fresh immunity to those strains, and with nowhere to go, the viruses would die out.
The same viral clearing would likely happen in any small and isolated population—for example, shipwreck survivors.
If all humans were isolated from one another, the St. Kilda scenario would play out on a species-wide scale. After a week or two, our colds would run their course, and healthy immune systems would have plenty of time to clear the viruses.
Unfortunately, there’s one catch, and it’s enough to unravel the whole plan: We don’t all have healthy immune systems.
In most people, rhinoviruses are fully cleared from the body within about ten days. The story is different for those with severely weakened immune systems. In transplant patients, for example, whose immune systems have been artificially suppressed, common infections—including rhinoviruses—can linger for weeks, months, or conceivably years.
This small group of immunocompromised people would serve as safe havens for rhinoviruses. The hope of eradicating them is slim; they would need to survive in only a few hosts in order to sweep out and retake the world.
In addition to probably causing the collapse of civilization, Sarah’s plan wouldn’t eradicate rhinoviruses.9 However, this might be for the best!
While colds are no fun, their absence might be worse. In his book A Planet of Viruses, author Carl Zimmer says that children who aren’t exposed to rhinoviruses have more immune disorders as adults. It’s possible that these mild infections serve to train and calibrate our immune systems.
On the other hand, colds suck. And in addition to being unpleasant, some research says infections by these viruses also weaken our immune systems directly and can open us up to further infections.
All in all, I wouldn’t stand in the middle of a desert for five weeks to rid myself of colds forever. But if they ever come up with a rhinovirus vaccine, I’ll be first in line.
1“Virii” is used occasionally but discouraged. “Viræ” is definitely wrong.
2Any upper respiratory infection can actually be the cause of the “common cold.”
3The immune response is actually the cause of your symptoms, not the virus itself.
4Mathematically, this must be true. If the average were less than one, the virus would die out. If it were more than one, eventually everyone would have a cold all the time.
5(450 million people).
6(650 million people).
7I first tried to take the question to Boing Boing’s Cory Doctorow, but he patiently explained to me that he’s not actually a doctor.
8The residents of St. Kilda correctly identified the boats as the trigger for the outbreaks. The medical experts of the time, however, dismissed these claims, instead blaming the outbreaks on the way the islanders stood around outdoors in the cold when a boat arrived, and on their celebrating the new arrivals by drinking too much.
9Unless we ran out of food during the quarantine and all starved to death; in that case, human rhinoviruses would die with us.
Glass Half Empty
Q. What if a glass of water was, all of a sudden, literally half empty?
—Vittorio Iacovella
A. The pessimist is probably more right about how it would turn out than the optimist.
When people say “glass half empty,” they usually mean a glass containing equal parts water and air.
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.
But what if the empty half of the glass were actually empty—a vacuum?1 The vacuum would definitely not last long. But exactly what happens depends on a key question that nobody usually bothers to ask: Which half is empty?
For our scenario, we’ll imagine three different half-empty glasses, and follow what happens to them microsecond by microsecond.
In the middle is the traditional air/water glass. On the right is a glass like the traditional one, except the air is replaced by a vacuum. The glass on the left is half full of water and half empty—but it’s the bottom half that’s empty.
We’ll imagine the vacuums appear at time t=0.
For the first handful of microseconds, nothing happens. On this timescale, even the air molecules are nearly stationary.
For the most part, air molecules jiggle around at speeds of a few hundred meters per second. But at any given time, some happen to be moving faster than others. The fastest few are moving at over 1000 meters per second. These are the first to drift into the vacuum in the glass on the right.
The vacuum on the left is surrounded by barriers, so air molecules can’t easily get in. The water, being a liquid, doesn’t expand to fill the vacuum in the same way air does. However, in the vacuum of the glasses, it does start to boil, slowly shedding water vapor into t
he empty space.
While the water on the surface in both glasses starts to boil away, in the glass on the right, the air rushing in stops it before it really gets going. The glass on the left continues to fill with a very faint mist of water vapor.
After a few hundred microseconds, the air rushing into the glass on the right fills the vacuum completely and rams into the surface of the water, sending a pressure wave through the liquid. The sides of the glass bulge slightly, but they contain the pressure and do not break. A shockwave reverberates through the water and back into the air, joining the turbulence already there.
The shockwave from the vacuum collapse takes about a millisecond to spread out through the other two glasses. The glass and water both flex slightly as the wave passes through them. In a few more milliseconds, it reaches the humans’ ears as a loud bang.
Around this time, the glass on the left starts to visibly lift into the air.
The air pressure is trying to squeeze the glass and water together. This is the force we think of as suction. The vacuum on the right didn’t last long enough for the suction to lift the glass, but since air can’t get into the vacuum on the left, the glass and the water begin to slide toward each other.
The boiling water has filled the vacuum with a very small amount of water vapor. As the space gets smaller, the buildup of water vapor slowly increases the pressure on the water’s surface. Eventually, this will slow the boiling, just like higher air pressure would.
What If? Page 9