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Artificial life acknowledges new lifes and a new definition of life. "New" life is an old force that organizes matter and energy in new ways. Our ancient ancestors were often generous in deeming things alive. But in the age of science, we make a careful distinction. We call creatures and green plants alive, but when we call an institution such as the post office an "organism," we say it is lifelike or "as if it were alive."

We (and by this I mean scientists first) are beginning to see that those organizations once called metaphorically alive are truly alive, but animated by a life of a larger scope and wider definition. I call this greater life "hyperlife." Hyperlife is a particular type of vivisystem endowed with integrity, robustness, and cohesiveness -- a strong vivisystem rather than a lax one. A rain forest and a periwinkle, an electronic network and a servomechanism, SimCity and New York City, all possess degrees of hyperlife. Hyperlife is my word for that class of life that includes both the AIDS virus and the Michelangelo computer virus.

Biological life is only one species of hyperlife. A telephone network is another species. A bullfrog is chock-full of hyperlife. The Biosphere 2 project in Arizona swarms with hyperlife, as do Tierra, and Terminator 2. Someday hyperlife will blossom in automobiles, buildings, TVs, and test tubes.

This is not to say that organic life and machine life are identical; they are not. Water striders will forever retain certain characteristics unique to carbon-based life. But organic and artificial life share a set of characteristics that we have only begun to discern. And of course there easily may be other types of hyperlife to come that we can't describe yet. One can imagine various possibilities of life -- weird hybrids bred from both biological and synthetic lines, the half-animal/half-machine cyborgs of old science fiction -- that may have emergent properties of hyperlife not found in either parent.

Man's every attempt to create life is a probe into the space of possible hyperlifes. This space includes all endeavors to re-create the origins of life on Earth. But the challenge goes way beyond that. The goal of artificial life is not to merely describe the space of "life-as-we-know-it." The quest that fires up Langton is the hope of mapping the space of all possible lifes, a quest that moves us into the far, far vaster realm of "life-as-it-could-be." Hyperlife is that library which contains all things alive, all vivisystems, all slivers of life, anything bucking the second law of thermodynamics, all future and all past arrangements of matter capable of open-ended evolution, and all examples of a type of something marvelous we can't really define yet.

The only way to explore this terra incognita is to build many examples and see if they fit in the space. As Langton wrote in his introduction to the proceedings of the Second Artificial Life conference, "If biologists could 're-wind the tape' of evolution and start it over, again and again, from different initial conditions, or under different regimes of external perturbations along the way, they would have a full ensemble of evolutionary pathways to generalize over." Keep starting from zero, alter the rules a bit and then build an example of artificial life. Do it dozens of times. Each instance of synthetic life is added to the example of Earth-bound organic life to form the complete ensemble of hyperlife.

Since life is a property of form, and not matter, the more materials we can transplant living behaviors into, the more examples of "life-as-it-could-be" we can accumulate. Therefore the field of artificial life is broad and eclectic in considering all avenues to complexity. A typical gathering of a-life researchers includes biochemists, computer wizards, game designers, animators, physicists, math nerds, and robot hobbyists. The hidden agenda is to hack the definition of life.

One evening after a late-night lecture session at the First Artificial Life Conference, while some of us watched the stars in the desert night sky, mathematician Rudy Rucker came up with the most expansive motivation for artificial life I've heard: "Right now an ordinary computer program may be a thousand lines and take a few minutes to run. Artificial life is about finding a computer code that is only a few lines long and that takes a thousand years to run."

That seems about right. We want the same in our robots: Design them for a few years and then have them run for centuries, perhaps even manufacturing their replacements. That's what an acorn is too -- a few lines of code that run out as a 180-year-old tree.

The conference-goers felt the important thing about artificial life was that it not only was redefining biology and life, but it was also redefining the concept of both artificial and real. It was radically enlarging the realm of what seemed important -- that is, the realm of life and reality. Unlike the "publish or perish" mode of academic professionalism of yesteryear, most of the artificial life experimenters -- even the mathematicians -- espoused the emerging new academic creed of "demo or die." The only way to make a dent in artificial and hyperlife was to get a working example up and running. Explaining how he got started in life-as-it-could-be, Ken Karakotsios, a former Apple employee, recalled, "Every time I met a computer I tried to program the Game of Life into it." This eventually led to a remarkable Macintosh a-life program called SimLife. In SimLife you create a hyperlife world and set loose little creatures into it to coevolve into a complexifying artificial ecology. Now Karakotsios seeks to write the biggest and best game of life, an ultimate living program: "You know, the universe is the only thing big enough to run the ultimate game of life. The only problem with the universe as a platform, though, is that it is currently running someone else's program."

Larry Yaeger, a current Apple employee, once handed me his business card. It ran: "Larry Yaeger, Microcosmic God." Yaeger created Polyworld, a sophisticated computer world with organisms in the shape of polygons. The polys fly around by the hundreds, mating, breeding, consuming resources, learning (a power God Yaeger gave them), adapting, and evolving. Yaeger was exploring the space of possible life. What would appear? "At first," said Yaeger, "I did not charge the parents an energy cost when offspring was born. They could have offspring for free. But I kept getting this particular species, these indolent cannibals, who liked to hang around the corner in the vicinity of their parents and children and do nothing, never leave. All they would do was mate with each other, fight with each other, and eat each other. Hey, why work when you can eat your kids!" Life of some hyper-type had appeared.

"A central motivation for the study of artificial life is to extend biology to a broader class of life forms than those currently present on the earth," writes Doyne Farmer, understating the sheer, great fun artificial life gods are having.

But Farmer is onto something. Artificial life is unique among other human endeavors for yet another reason. Gods such as Yaeger are extending the class of life because life-as-it-could-be is a territory we can only study by first creating it. We must manufacture hyperlife to explore it, and to explore it we must manufacture it.

But as we busily create ensembles of new forms of hyperlife, an uneasy thought creeps into our minds. Life is using us. Organic carbon-based life is merely the first, earliest form of hyperlife to evolve into matter. Life has conquered carbon. But now under the guise of pond weed and kingfisher, life seethes to break out into crystal, into wires, into biochemical gels, and into hybrid patches of nerve and silicon. If we look at where life is headed, we have to agree with developmental biologist Lewis Held when he said, "Embryonic cells are just robots in disguise." In his report for the proceedings of Second Artificial Life Conference Tom Ray wrote, "Virtual life is out there, waiting for us to create environments for it to evolve into." Langton told Steven Levy, reporting in Artificial Life, "There are these other forms of life, artificial ones, that want to come into existence. And they are using me as a vehicle for its reproduction and its implementation."

Life -- the hyperlife -- wants to explore all possible biologies and all possible evaluations, but it uses us to create them because to create them is the only way to explore or complete them. Humanity is thus, depending on how you look at it, a mere passing station on hyperlife's gallop through space, or the critical gateway to the open-ended universe.

"With the advent of artificial life, we may be the first species to create its own successors," Doyne Farmer wrote in his manifesto, Artificial Life: The Coming Evolution. "What will these successors be like? If we fail in our task as creators, they may indeed be cold and malevolent. However, if we succeed, they may be glorious, enlightened creatures that far surpass us in their intelligence and wisdom." Their intelligence might be "inconceivable to lower forms of life such as us." We have always been anxious about being gods. If through us, hyperlife should find spaces where it evolves creatures that amuse and help us, we feel proud. But if superior successors should ascend through our efforts, we feel fear.

Chris Langton's office sat catty-corner to the atomic museum in Los Alamos, a reminder of the power we have to destroy. That power stirred Langton. "By the middle of this century, mankind had acquired the power to extinguish life," he wrote in one of his academic papers. "By the end of the century, he will be able to create it. Of the two, it is hard to say which places the larger burden of responsibilities on our shoulders."

Here and there we create space for other varieties of life to emerge. Juvenile delinquent hackers launch potent computer viruses. Japanese industrialists weld together smart painting robots. Hollywood directors create virtual dinosaurs. Biochemists squeeze self-evolving molecules into tiny plastic test tubes. Someday, we will create an open-ended world that can keep going, and keep creating perpetual novelty. When we do we will have created another living vector in the life space.

When Danny Hillis says he wants to make a computer that would be proud of him, he isn't kidding. What could be more human than to give life? I think I know: to give life and freedom. To give open-ended life. To say, here's your life and the car keys. Then you let it do what we are doing -- making it all up as we go along. Tom Ray once told me, "I don't want to download life into computers. I want to upload computers into life."