Lab Notes
Godzillas in the Mist?

When a light ray strikes water, it bends. Stick a pencil in a glass of water and you can see this effect clearly: the pencil appears to kink sharply at the water's surface. This occurs because the water, being denser than air, has a higher index of refraction (technically speaking, because the speed of light is lower in a denser medium), so it acts as a prism. So what happens when the air is full of water? Nothing much, if it's in the form of vapor. As the amount of water in the air rises, though, a property called relative humidity (the amount of water in the air divided by the amount the air can actually hold) rises with it, and as this value approaches 100 percent, the water begins to condense into tiny droplets.

When this occurs in the sky, we call it a cloud. When it happens at ground level, we call it fog. Or "mist," although the strict meteorological definition of that word implies a very thin fog, with visibility between 1 and 2 kilometers. (Any thinner than that and it's simply called a "haze.") Still, most people use these terms interchangeably, so what the heck.

Thick fog—the kind we call "pea soup"—happens when a layer of humid air is trapped below a heavier layer of denser, colder air. This is known as a temperature inversion, and it doesn't usually happen unless the weather conditions are changing rapidly. And the sharper the temperature mismatch, the thicker and denser the fog will be. The clouds are literally squashed against the ground. Anyway, because it contains millions of tiny prisms, fog (or mist) can bend a light ray millions of times, scattering it in every possible direction. The result—even in full daylight—is a diffuse gray illumination that obscures details, baffles human senses and has fascinated writers and mythologists since the beginning of time.

(To a lesser extent, the same thing happens with sound waves; they get broken up and scattered as well. This is the source of fog's peculiar sound-deadening qualities, and the reason why the source of a noise can be hard to locate in the mist. Also, while humans aren't as reliant on the sense of smell as most other animals, fog can interfere with that as well, by making it more difficult for scent molecules to travel through the air.)

Fogged-in fantasy

Fog provides cover for armies, creates peril for drivers and pilots and lends an air of otherworldly mystery to even the most ordinary days. Still, it's unusual for a thick fog to persist day and night for several days. On Earth, this generally only happens at the seashore, where crashing waves put a lot of salt in the air. Salt is a desiccant, meaning water molecues like to stick to it, so when it's dispersed in the air, droplets tend to form around it, even when the humidity is less than 100 percent—sometimes even as low as 70 percent.

Other impurities in the air can have a similar effect. Fog machines, for example, heat a mix of water and glycerin that condenses into a thick, white mist under almost any conditions. In fact, some types of urban smog come together for the same reason: because droplets form around suspended smoke and hydrocarbons. Trees can do it, too; yes, they consume CO₂ and produce oxygen, but they also cough out all kinds of organic debris—resins and waxes, perfumes and pollen grains. As a result, forests and swamps can sometimes generate a thick, fragrant smog of their own.

So it isn't hard to imagine an atmosphere very similar to ours, but much richer with suspended plant gunk that attracts water and enhances the formation of mist, so it's really foggy all the time. You have to wonder what kind of plants would do that, though, and why spewing out such pollution is an evolutionary advantage for them. Are they signaling one another? Repelling hungry herbivores? Engaging in some sort of mutual chemical warfare? Or maybe just hiding themselves behind a cloak of protective mist? And if so, hiding from what?

Frank Darabont's new movie, The Mist (based on the 1980 Stephen King novella of the same name), provides a series of ever-more-disturbing answers to that question, when an electrical storm causes a military experiment to go awry, opening an accidental rift into a parallel universe where the ecology is, shall we say, more competitive than ours. This is also the starting point for the wildly popular video game Half-Life, and because it really is possible (astronomers recently claimed to have found physical evidence for the existence of parallel universes!), I thought some rules of thumb might be handy in case we ever need to survive this scenario for real.

Survival in a parallel universe

(1) The Food Chain Rule. If it can eat you, you can eat it. Our taste buds have evolved to recognize a narrow range of molecules as nutritious: sweets for energy, salts for electrolytes and mineral content, sours as a source of vitamins, and umami or "meaty" substances as a source of fats and protein. Everything else gets lumped into the broad category of "bitter" (a sensation our bodies use to warn us against potential toxins) or "tasteless" (a warning against substances that, while not directly harmful, do not contain any useful nutrients). Now, if an alien creature swallows one of your buddies and doesn't spit him out, that's a clue that its biochemistry is compatible, and if (God forbid!) it lays eggs inside him, and the larvae actually grow and devour him, then you'll know for sure: It's monster steaks for dinner tonight!

(2) The Venom Rule. If a creature's venom is rapidly fatal, you can eat the creature. This may sound strange, but there's sound biological reasoning behind it; inorganic toxins—even really nasty ones like hydrofluoric acid—rarely cause instant death. Instead, they disrupt the chain of reactions taking place inside your body, resulting in a slow (and often agonizing) cascade of system shutdowns. Death typically occurs in minutes or hours, not seconds. The same is true of random organic molecules; the vast majority of them are fatal only in large doses. To cause instant death, a substance needs to target one of a handful of truly vital processes taking place at the cellular level. And these processes vary significantly even between creatures from the same planet. Think of your household ant and roach spray: instantly fatal to insects but a much slower killer for spiders and scorpions. It's not good for humans either, but a whiff of it won't kill us.

So. If a creature has a venom that drops human beings in their tracks, it means the creature's diet includes something chemically similar to humans. Which means the creature itself is probably edible, as long as you take care to remove the venom sac without rupturing it.

(3) The Bait and Spike Rule. Biological compatibility also increases the odds that some Earthly toxin, like bug spray or rat poison, will kill the alien creatures if you use it correctly. If the aliens like meat (and they must, or you wouldn't be afraid of them!) try spiking some hamburger with assorted pesticides and leaving it out. When you find something that makes them sick, coat some pointy sticks with it and set up a defensive perimeter, or even some tiger traps.

(4) The Dandelion Rule. Chances are, our ecology is as pernicious to theirs as theirs is to ours. Some invasive species really take off (witness the success of the European dandelion and the Brazillian fire ant in North America), but a lot of them can't find a place in the food web and simply die out. It's hard to predict what will happen when two ecologies come into contact, but the total triumph of one over the other is not a likely outcome.

I don't mean to minimize the problems; when the mist rolls in and the hungry monsters roam free, there's bound to be a difficult transition period for the people in the way.

And yet.

Would you really bet against the human race? Whatever faults and foibles we may have, human beings certainly enjoy a brilliant track record of taming even the harshest wilderness, turning the plants into newspaper, the animals into dog food and clean water into untreated sewage. No ecology on Earth has escaped our influence, so why should some other planet be any luckier?

It's almost enough to make you feel sorry for the land squids, pizza bats and other Lovecraftian horrors that lurk on the other side of the rift. Hell, their universe won't know what hit it!

Sources:
The Internet Movie Database (www.imdb.com): The Mist
Wikipedia (en.wikipedia.org): "fog machine", "invasive species", "Great Smoky Mountains"
Encyclopedia Britannica 2008 Ultimate Reference Suite: "fog", "smog"
Dictionary.com: "haze"
Bridges, Andrew: "Here We Go Again! The Big 'Tree Pollution' Debate Is Back", CBS News, March 17, 2003
Gache, Gabriel: "Giant Cold Spot Evidence of Parallel Universe?", Softpedia News, Nov. 26, 2007