Isn't it strange that scientists went all the way to Mars--only to discover that the rocks there are named for familiar cartoon characters on Earth? Scoobie Doo, Casper, Calvin and Hobbes.
Alas, it's an old story in science. The late physicist Arthur Eddington told of the astronomer who gave a lecture on stars. Afterward, a student complained that while he could understand how astronomers had discovered the temperatures, masses and distances to the stars, he couldn't understand how the scientists found out their names.
We chuckle, because we know that people give the stars their names; we know that people--even scientists--invent aspects of the outside world based on the images already in their heads.
When Mars Pathfinder scientists report that the Sojourner rover "did a wheelie, it was so excited," we know that the robot isn't excited; the scientist is. Yet it's easy to confuse the world that is with the world we make up.
As the year 2000 approaches, many people are obsessed with the idea of the approaching millennium. The year 2000 (or 2001, more correctly) seems to signify something profound. But there's nothing special about a thousand. It's an arbitrary point in time with no meaning at all in the natural world.
In fact, the whole idea of time is just such an artificial concept. When you cross the international date line, your plane doesn't go bump in the night. Time only tells us the position of the Earth relative to the sun, or the number of sand grains that have run through the egg timer, or the number of vibrations of a quartz crystal in a watch.
People made up the millennium just as they made up seconds and minutes--or, for that matter, numbers. The number zero is a fairly recent human invention. It makes much of mathematics easier, but 10 apples plus 10 apples is 20 apples whether we have zero in our number system or not. We could say the same thing in Roman numerals.
Tools like numbers are useful fictions. They play an invaluable role in revealing connections and discovering aspects of the physical world. They bring a semblance of order to the universe, making it simpler, clearer, easier to grasp.
Likewise, Scoobie Doo is easier to remember than rock #xpz15r. But the name tells us more about ourselves than about the rock.
Consider the constellations. The stars that we stitch together into outlines of dippers or twins or warriors may be far removed from each other in space and look totally unconnected from other (non-earthbound) perspectives. We connect the stars for our own convenience.
Tellingly, the constellations in the Northern Hemisphere resemble gods and beasts and royals who mattered to the Greeks who named them, while southern constellations reflect the more modern interests of the first global navigators--instruments and geometric figures.
"The division of the stars into constellations tells us very little about the stars," wrote the late physicist James Jeans, "but a great deal about the minds of the earliest civilizations."
Some of the useful fictions scientists invent to help them get a handle on the familiar world later turn out to be real. Molecules, quarks and electric charges all started out as metaphors for the unfathomable. Only years later did technology allow scientists to see that they actually existed.
Albert Einstein is famous for inventing such an arbitrary factor to make his equations mesh more smoothly with reality. He called it the "cosmological constant," and later said it was the biggest blunder of his life. Lately, however, the cosmological constant appears to be making a comeback. Cosmologists think it might be a real kind of anti-gravitational force that accounts for the "missing matter" in the universe.
It's a fine line, sometimes, between discovering something and making it up. Scientists continually have to pinch themselves to see whether they're really looking into a mirror when they think they're looking through a window at the outside world.
Nobody said it better than Eddington: "When science has progressed the furthest, the mind has but regained from nature what the mind has put into nature. We have found a strange footprint on the shores of the unknown. We have devised profound theories, one after another, to account for its origin. At last, we have succeeded in reconstructing the creature that made the footprint, and lo! it is our own."