SLIPSTREAMING

The characteristic of fluids that most interested Leonardo Da Vinci was turbulence. He lived in a politically turbulent age. He had a turbulent, restless mind. The world he lived in felt most strongly the cultural turbulence of new discoveries and new ideas, and he was driven by the desire to be part of what we look back on as ‘the rebirth’ of an intellectual freedom that Europe had not seen since the collapse of the Roman Empire more than a millennium before. The effect of this freedom on the intellectually repressive, dogmatic stasis of the Middle Ages was like the turbulence of a waterfall on a placid pond, or of a thunderstorm breaking suddenly in calm skies. Da Vinci’s drawings capture the drama of such violent events but were not mere illustrations of them. Rather, their rigorous analyses of how the complex interplay of forces actually worked were events in themselves, the first stirrings of scientific and technological imagination that would, over the next few centuries, transform the world.

And then:

The turbulence that most interests us today is of a different order than that which fascinated Da Vinci and characterized his time. It is the turbulence called a slipstream, created by a body—either fluid or solid—moving rapidly within a larger fluid body, which may itself be moving or at rest. The historically recent advent of propulsion systems capable of moving aircraft, boats, cars, and pulses of gas, fluids, or solids at high speed has resulted in the creation of a new type of turbulent space in their wake.

The slipstream is a highly dynamic space active with forces that impel a direction and that itself moves, together with the moving body continuously creating it. Its boundaries are variable, depending on the velocity and shape of that moving body, and also the characteristics—density, viscosity, and the like—of the fluid through which it moves. All of this can be described precisely with mathematics. However, as with all descriptions, they cannot bring us to full analytical understanding. We need other perspectives, and for that must turn to the analog.

The analog emphasizes some aspects of a slipstream space, while it ignores others. In effect, it creates a fictional construct based on facts, or at least selected ones. However, it is important to realize that every description—even the most rigorous scientific one, backed up by mathematics—is fictional. Every theory that has been widely accepted enough to become a ‘law,’ is an invention by human beings who emphasize what they consider the most salient characteristics of phenomena. In a sense, all of science is an analog of nature, of the reality of the world. Its relative success or failure depends not on absolute truth—who possesses such?—but on human consensus. How many colleagues are willing to endorse your fiction? That will of course depend on how well it fits into their fictions or theoretical constructs and therefore how useful it is in a particular scientific context. Rarely, someone invents a new theory that forces everyone to change their theories, such as Copernicus’ theory of the solar system, or Newton’s theory of gravity.

Slipstream space can be inhabited by people and sometimes is. Auto racers get extra speed while spending less fuel by following fast cars in front of them, as do drivers of eighteen-wheelers, whose boxy trailers create exceptionally violent turbulence and powerful slipstreams, which is why you will often see, on the highway, two or more of these trucks following each other in a tightly spaced line. Separated from the slipstream space by their vehicles’ enclosure surfaces these drivers do not experience the space directly, but only through the instruments of their machines. Modern technological living provides many such indirectly experienced spaces, perhaps most prominently cyberspace. Its virtuality is, on an experiential level, analogical, and in exactly the terms of selectiveness described here. Virtual and analog experiences emphasize some characteristics of a phenomenon while ignoring others. That is the price to be paid for vastly expanding the boundaries of our experience, and for exploring the imaginary in the real.

LW