This is a column about the edges and borders and boundaries. Many people think of boundaries in terms of separation and division, but that—as you will soon see—is only one way to look at them. We regard edges as places where interesting things happen.

"What does this have to do with fantasy and science fiction?" you ask. We'll get to that later—really we will. But before we get to that, we're going to tell you how to do some weird and frightening experiments with eggs and osmosis and we're going to show you how your eyes act to exaggerate an edge, a tendency important to how we perceive the world. Then we'll get to matters that concern science fiction and fantasy.

About Edges and the Egg

At first glance, you might think an egg, a smoothly rounded object, has no edge. That's true if you are thinking of an edge as something sharp and hard. If you think of an edge as a boundary, then the egg has a definite edge. The shell of an egg and the membrane just inside that shell form a boundary that separates what's inside the egg from what's outside.

To experiment with this boundary, you must remove the egg's shell without breaking the membrane. It's easy to do, and it's one of Pat's favorite odd science activities.

You'll need a few eggs, some white vinegar, a container big enough to hold your eggs, a cover for that container, and a big spoon. Put your eggs in the container so that they are not touching, then add enough vinegar to cover the eggs.

Bubbles immediately start to form on the eggs. The acid in the vinegar reacts with the calcium carbonate of the eggshell. In this reaction, the solid calcium carbonate crystals break apart to form calcium ions that float free in the liquid and carbon dioxide, which makes the bubbles that you see.

Cover the container, put it in the refrigerator, and let the eggs sit in the vinegar for 24 hours. After 24 hours, use your big spoon to scoop the eggs out of the vinegar. Be careful: the eggshell has been dissolving and the egg is very fragile.

Now dump out the vinegar. Put the eggs back in the container and cover them with fresh vinegar. Leave the eggs in the refrigerator for another 24 hours.

At this point, the eggshells are probably completely gone. Scoop the eggs out of the container again and rinse them carefully. If any of the membranes have broken, letting the egg ooze out, throw those eggs away.

Voila! You have a naked egg, an egg without a shell. It looks like an egg, but it's translucent. All that's holding it together is the membrane that's just inside the eggshell. This membrane flexes when you squeeze it.

Pat thinks that naked eggs are very cool, but Officer Dave, Pat's husband, thinks they are rather scary. Officer Dave is with the San Francisco Police Department and he's used to mixing it up with the local criminal element. But he finds the sight of a shelless egg—an organic blob swelling in its translucent skin—a tad unnerving. (At least that's what he says when there's a bowl of naked eggs in the refrigerator beside the beer.)

What is a naked egg good for, other than disturbing members of the local constabulary? Well, here are a few ways to experiment with your naked eggs.

Take one naked egg and put it in a small container. (Pat uses a coffee cup.) Fill the container with water. Take another naked egg, put it in another small container, and fill that container with corn syrup. Leave the eggs overnight after warning your significant other that a scientific experiment is underway in the refrigerator.

In the morning, compare the two eggs. The egg that was in the water will be plump and firm and larger than it was before. The egg that was in the corn syrup will be shriveled and flabby.

You are observing the results of osmosis, the movement of water through a semipermeable membrane. The membrane that surrounds the egg is selectively permeable, which means it lets some molecules move through it and blocks other molecules. Water moves through the membrane easily. Bigger molecules—like the sugar molecules in the corn syrup or the proteins of the egg white—don't pass through the membrane.

When you put a naked egg in corn syrup, you are creating a situation where the egg membrane separates two solutions of different concentrations. The egg white is about 90% water; corn syrup is about 25% water. In this situation, random movements of water molecules cause them to move from the side of the membrane where they are more abundant to the side where they are less abundant. So water migrates from inside the egg to outside the egg, leaving the egg limp and flabby.

The same osmotic migration that makes the egg flabby helps preserve certain foods. When fruit is canned, the fruit sugars are concentrated. Any water-containing microorganism that tries to invade the fruity sugar syrup will lose its water to the syrup (like the flabby egg) and will die of dehydration.

When you put a naked egg in plain water, random movements of water molecules cause them to move from outside the egg, where they are more abundant, to inside, where they are less abundant. Under these circumstances, water moves into the egg, making it swell.

This naked egg feels plump because of the higher pressure inside the egg. As water moved across the membrane into the egg, the pressure inside the egg increased, stretching the membrane out to enclose the new, larger volume. If the membrane stretches to its breaking point then it will burst in what Paul calls an "osmotic bomb."

You can do other experiments with your naked eggs—putting them in salt solution or in solutions of food coloring. You can even boil them, solving that nasty problem of the eggshell that sticks to the egg. No shell, no problem.

Now we could make an analogy here, comparing the naked egg drifting in a cup of water to the genre of science fiction floating in the sea of popular culture. Some science fiction elements migrate out of the field into the mainstream—but wait! It's not time for that yet. First, we have talk a bit about another edge—an edge created by your eye.

About Edges and Your Eye

We'll start with another experiment—a quick and easy one that reveals something profound about how your eyes work. You'll need two pieces of 8-1/2" x 11" paper, a couple of pieces of tape, and a white wall.

Roll the sheets of paper into paper tubes that are 11 inches long (that's 28 cm, for those who prefer metric) and about 1/2 inch (that's 1.3 cm) in diameter. Use the tape to keep the tubes from unrolling.

With both eyes open, look at the white wall through one of the tubes. Notice that the spot of light that you see through the tube looks brighter than the surrounding wall, seen without the tube.

That's weird. The wall is the same, whether you are looking through a tube or not. Why does it look brighter through the tube?

But you can make the situation even weirder, if you like (and since you are a reader of science fiction and fantasy, we are confident that you would). Put one tube up to each eye, keep both eyes open, and look through the tubes at the white wall. Notice that both eyes now see bright spots.

Move the tubes so that the two spots overlap by just a little bit (like the circles in a Venn diagram. The place where the circles overlap will be brighter than either of the two spots.

Now overlap the two spots completely. Does the combined spot look brighter than either spot alone? You can find out by closing one eye. To us, it looks the same viewed with both eyes or viewed with one eye.

What's going on here? Well, if you read our column on seeing in the dark ("Nightfall Revisited," March 2000), you know that you see because light stimulates the light-sensitive cells in your eye. These cells are called photoreceptors--"photo" is the Greek word for "light." The photoreceptors of your eye are part of the retina, a layer of cells at the back of your eyeball. The photoreceptors detect light and the patterns that it forms on the retina, then sends this information to your brain via the optic nerve.

But, as Paul likes to say, "it's not quite as simple as that." There are about 100 million photoreceptors in each eye, and yet there are only one million neurons in the optic nerve. So the visual information sent down the optic nerve must be processed (Paul says that 99% of the information in the image on one retina is discarded, then 1% is sent on to the brain where your perception of the world is created.) The most important information is contained in edges, places where brightness changes rapidly. Less important are regions where brightness is changing gradually.

How does your eye make sure that your brain takes note of edges? Photoreceptors in your eyes send signals to your brain, but they also send signals to surrounding receptors. A receptor receiving light also sends signals to neighboring receptors, telling them to turn down their own sensitivity to light. Basically, a photoreceptor that is sensing light inhibits the surrounding receptors. This is known as lateral inhibition.

When you look at the white wall without a tube, you see a uniform field of brightness because all the receptors are equally inhibited by their neighbors. When you look through the tube, the spot of light is surrounded by the dark ring of the tube. The spot appears brighter than the rest of the wall because the receptors in the center of your retina are not inhibited by signals from surrounding receptors--the dark ring of the tube prevents this inhibition.

Lateral inhibition acts to enhance edges and boundaries. If you are looking at a white shape bordering on a gray shape, lateral inhibition will make the white shape brighter and the gray shape, by contrast, darker. Through lateral inhibition, your eyes and brain work together to draw a boundary more distinct and clear than the boundary that actually exists.

Your brain uses the brightness at the edges of a region to figure out the brightness of that region. When you look through the tube, the bright wall of the room looks brighter because it is next to the dark wall of the tube. Your eye and brain then assign this brighter value to the entire circle of light viewed through the tube.

K. C. Cole, formerly a writer at the Exploratorium and now writing for the Los Angeles Times, has compared this visual tendency to emphasize difference to the human tendency to draw boundaries in other areas: between different cultures, different races, different beliefs, different political views. She writes that people "seize on the differences between them, ignoring the differences within." She suggests that the existence of a boundary makes us focus on local differences and ignore similarities.

About Science Fiction and Fantasy

Among those who write and read and edit science fiction and fantasy, people are always talking about what is and what isn't science fiction and what is and what isn't fantasy. They talk about the difference between science fiction and fantasy-and the difference between these categories of fiction and what is out in the so-called "mainstream."

People seem to spend a lot of time trying to define the edge of the Field—what's included in science fiction and what isn't. People argue about it on on-line conferences and in bars at science fiction conventions. Some say that certain literary devices don1t belong in science fiction. Others complain that certain books in the mainstream are appropriating science fictional tropes.

These folks seem to be thinking about boundaries in terms of separation and division. When we started writing this column, Pat had two agenda: she wanted an excuse to include her favorite egg experiments in a column and she wanted to encourage people to think about the boundaries between science fiction and other fiction in a new way.

You can think about the border between science fiction and mainstream literature as a semipermeable membrane (like the membrane of the egg). Some fictional elements seem to cross the membrane quite easily. Biological thrillers, like Michael Crichton's Andromeda Strain with its extraterrestrial pathogens, are accepted by the mainstream quite handily, despite futuristic and scientific elements. The tropes of Cyberpunk have happily invaded the mainstream. And elements from mainstream fiction have also slipped across the boundary into science fiction. Back in the 1960s, the so-called New Wave introduced sex, drugs, and literary techniques into the science fiction field.

Or you can think of the border between science fiction and other types of literature as a perceptual illusion, like the bright spot that your eye sees when it looks through a paper tube. That spot on the wall is really no brighter than the rest of the wall, but your eye and brain have worked together to create the illusion that it's brighter.

"But wait!" we hear you protest. "Science fiction really is different from other kinds of fiction."

Is it? Pat has, in the past, taught a lecture course about science fiction at the University of California at Santa Cruz. She always begins the class with a lecture titled "What is Science Fiction?" since that's a question that invariably comes up early on.

In this lecture, Pat tells the class that she will read a few paragraphs from a book or story—and then the class will vote on whether these paragraphs are from a work of science fiction, fantasy, or mainstream literature. Then they will tell her why they voted as they did. Pat starts out easy—with an excerpt from an A. E. van Vogt story that includes anti-gravity, a ray gun, and a multi-eyed alien. Then she works her way around to works that are more subtly science fictional—from J. G. Ballard and Ray Bradbury. Her favorites, of course, are the ones that make the students stop and stare.

"As Gregor Samsa awoke one morning from uneasy dreams he found himself transformed in his bed into a gigantic insect." This, the opening line from Kafka's Metamorphosis, usually gets a laugh—the uneasy laughter of people who know they are being tricked. The students know the line is from Metamorphosis and they know that Kafka is shelved with literature, but they also know that the central event in the story—the transformation of Gregor-is a fantastic event, belonging to fantasy. Pat goes on to use other stories to challenge her students, such as Margaret Atwood's The Handmaid's Tale, Mark Twain's A Connecticut Yankee in King Arthur's Court, Carol Emshwiller's Carmen Dog, Toni Morrison's Beloved. By the end of the discussion, the students are raising examples of their own.

The lines are not firm; the edges are not clearly defined. And that, we think, is a good thing. The edge of the ocean, where the agitation of the surf mixes air and water in the presence of sunlight, is a biologically rich environment. The boundary where two cultures meet—whether it's at the border of a country, the border of a neighborhood, or the cultural clash of a first contact in a science fiction story-can produce interesting tensions. Interesting things happen at the edge.

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To learn more about Pat Murphy's science fiction writing, visit her web site at www.brazenhussies.net/murphy. For more on Paul Doherty's work and his latest adventures, visit www.exo.net/~pauld.