Seite 3: Existence

What is reality, anyway? The idea of a simulated existence is the first link in a disturbing chain of thought. Just as a literary description of a place can exist in different languages, phrasings, printing styles and physical media, a simulation of a world can be implemented in radically different data structures, processing steps and hardware. If one interrupts a simulation running on one machine and translates its data and program to carry on in a totally dissimilar computer, the simulation's intrinsics, including the mental activity of any inhabitants, continue blithely to follow the simulated physical laws. Only observers outside of the simulation notice if the new machine runs at a different speed, does its steps in a scrambled order, or requires elaborate translation to make sense of its action.

A simulation, say of the weather, can be viewed as a set of numbers being transformed incrementally into other numbers. Most computer simulations have separate viewing programs that interpret the internal numbers into externally meaningful form, say pictures of evolving cloud patterns. The simulation, however, proceeds with or without such external interpretation. If a simulation's data representation is transformed, it steps through an entirely different number sequence, though a correspondingly modified viewing program will produce the same pictures. There is no objective limit to how radical the alteration can be, and any simulation can be represented by almost any sequence, and still be viewable given the right interpretation. A simple clock simulates the evolving state of a complex world, when interpreted via a world-describing playbook or movie sequence keyed to clock ticks. Even the clock is superfluous, since an external observer can read the book or watch the movie at leisure. If the interpretation of a simulation is a dispensable external, while its core implementation can be transformed away to nothing, in what sense can a simulated world be said to exist at all?

Mathematical realism, a philosophical position advocated by Plato, addresses this problem's vexing intangibles. Just as physical objects are seen by the senses, mathematical objects like numbers and shapes can be observed via abstract thought, to reveal objectively verifiable features. To Plato, mathematical concepts were as real as physical objects, just invisible to the external senses as sound is imperceptible to the eyes.

Computer simulation brings mathematical realism neatly full circle. Plato's unaided mind could handle only simple mathematical objects, leading do such dichotomies as the idea of a perfect sphere compared to a mottled, scratched marble ball in the hand. Computer simulation, like a telescope for the mind's eye, extends vision beyond the nearby realm of simple objects, to details of distant worlds, some as complex as physical reality, potentially full of living beings, warts, minds and all. Our own world is among this vista of all conceivable ones, defined by the abstract relationships we call physical law as any simulation is defined by its internal rules. The difference between physical and mathematical reality is an illusion of vantage point: the physical world is simply the particular abstract world that happens to contain us.

The Platonic position on simulation puts a handle on the vexingly intangible: without it an interpretation is meaningful only in context of another interpretation. It defuses various worries about intelligent machinery. Some critics argue that a machine cannot contain a mind since a machine's function is entirely an outside interpretation, unlike human minds, which supply their own sense of meaning. The Platonic position answers that the abstract relationships that constitute the mind, including its own self interpretation, exist independently, and a robot, a simulator or a book describing the action, no less than a biological brain, is a way of viewing them. Other critics worry that future robots may act like intelligent, feeling beings without having an internal sense of existence--that they will be unconscious, mindless zombies. Platonism replies that while there are indeed interpretations of any mechanism (including the human brain) as mindless, there are others under which it has a real, self-appreciating mind. When a robot (or a person) behaves as if it has beliefs and feelings, our relationship with it will usually be facilitated if we choose a has a mind interpretation. Of course, when working on the internals, a robotics engineer (or a brain surgeon) may be best served by temporarily slipping into a mindless mechanism interpretation.

Platonism puts on the same footing mechanical simulations that precisely mimic every interaction detail, rough approximations, cinematic reconstructions, literary descriptions, idle speculation, dreams, even random gibberish: all can be interpreted as images of realities, the more detailed presentations simply have a sharper focus, blurring together fewer alternative worlds. But isn't there a huge difference between a conventional live simulation of a world, and a simulation transformed to nothing, requiring a "recorded" book or movie to relate the unfolding events? Isn't it possible to interact with a running simulation, poking one's finger into the action, in a way impossible with a static script?

In fact, a meaningful interaction is possible in either case only via an interpretation that connects the simulated world to the outside. In an interactive simulation, the viewing mechanism is no longer passive and superfluous, but an essential bidirectional conduit that passes information to and from the simulation. Such a conduit can exist for books and movies if they contain alternative scenarios for possible inputs. Programmed learning texts popular in previous decades were of this form, with instructions like if you answered A, go to page 56, if you answered B, go to page 79, ...

Some laser disk video games give the impression of interactive simulation by playing video clips contingent on the player's actions. Mathematically, any interactive mechanism, even a robot or human, can be viewed as a compact encoding of a script with responses for all possible input histories. Platonism holds that the soul is in the abstract relationships represented, not the mechanics of the coding.

The position seems to have scary moral implications. If simulation simply opens windows into Platonic realities, and robots and humans, no less than books, movies or computer models, are only images of those essences, then it should be no worse to mistreat a human, an animal or a feeling robot than to choose a cruel action in a video game or an interactive book: in all cases you are simply viewing preexisting realities. But choices do have consequences for the person making them, due to the mysterious contrivance of physical law and conscious interpretation that produces single threads of consciousness with unseen futures and unalterable pasts.

By our choices, we each thread our own separate way through the maze of possible worlds, bypassing equally real alternatives, with equally real versions of ourselves and others, selecting the world we must then live in. So is there no difference between being cruel to characters in interactive books or video games, and people one meets in the street? Books or games act on a reader's future only via the mind, and actions within them are mostly reversed if the experience is forgotten. Physical actions, by contrast, have greater significance because their consequences spread irreversibly. If past physical events could be easily altered, as in some time-travel stories, real life would acquire the moral significance of a video game. More disturbing is that any sealed-off activity, whose goings on can be forgotten, may be in the video game category.

Creators of hyperrealistic simulations - or even secure physical enclosures - containing individuals writhing in pain are not necessarily more wicked than authors of fiction with distressed characters, or myself, composing this sentence vaguely alluding to them. The suffering preexists in the underlying Platonic worlds, and authors merely look on. The significance of running such simulations is limited to their effect on viewers, possibly warped by the experience, and by the possibility of escapees - tortured minds that could, in principle, leak out to haunt the world in data networks or physical bodies. Potential plagues of angry demons surely count as a moral consequence. In this light, mistreating people, intelligent robots or individuals in high resolution simulations has greater moral significance than doing the same at low resolution or in works of fiction not because the suffering individuals are more real - they are not - but because the probability of undesirable consequences in our own future world is greater.

The most bizarre implication of this train of thought is that anything can be interpreted as possessing any abstract property. Given the right playbook, the thermal jostling of the atoms in a rock can be seen as the operation of a complex, self-aware mind. How strange. We see ourselves as having minds, and rocks not. But interpretations are often more ambiguous. One day's unintelligible sounds and squiggles may become another day's meaningful thoughts if one masters a foreign language in the interim. Is the Mount Rushmore monument a rock formation, or four presidents' faces? Is a ventriloquist's dummy a lump of wood, a human simulacrum, or a personality sharing some of the ventriloquist's body and mind? Is a video game a box of silicon bits, an electronic circuit flipping its own switches, a computer following a long list of instructions, or a large two-dimensional world inhabited by the Mario Brothers and their mushroom adversaries?

Sometimes we exploit offbeat interpretations: an encrypted message is meaningless gibberish except when viewed through a deliberately obscure decoding. Humans have always used a modest multiplicity of interpretations, but computers widen the horizons. The first electronic computer was developed by Alan Turing to find "interesting" interpretations of wartime messages radioed by Germany to its U-boats. As our thoughts become more powerful, our repertoire of useful interpretations will grow. We can see levers and springs in animal limbs, and beauty in the aurora: our mind children may be able to spot fully functioning intelligences in the complex chemical goings on of plants, the dynamics of interstellar clouds, or the reverberations of cosmic radiation. No particular interpretation is ruled out, but the space of all of them is exponentially larger than the size of individual ones, and we may never encounter more than an infinitesimal fraction.

The rock-minds may be forever lost to us in the bogglingly vast sea of chaotic rock-interpretations. Yet, those rock-minds make complete sense to themselves, and to them it is we who are lost in meaningless chaos. That we will encounter only a fraction of all possibleinterpretations is probably essential to our existence.

There is no content or meaning without selection. The realm of all possible worlds, infinitely immense in one point of view, is vacuous in another. Imagine a book giving a detailed history of a world similar to ours. The book is written as compactly as possible: rote details are left as homework for the reader. But even with maximal compression, it would be an astronomically immense tome, full of novelty and excitement. This interesting book, however, is found in the library of all possible books written in the Roman alphabet, arranged alphabetically - the whole library being adequately defined by the short, boring phrase in italics.

The library as a whole has so little content that getting a book from it takes as much effort as writing the book. The library might have stacks labeled A through Z, plus a few for punctuation, each forking into similarly labeled substacks, those forking into subsubstacks and so on, indefinitely. Each branchpoint holds a book whose content is the sequence of stack letters chosen to reach it. Any book can be found in the library, but to find it the user must choose its first letter, then its second, then its third, just as one types a book by keying each subsequent letter. The book's content results entirely from the user's selections, the library has no information to contribute.

Though content free overall, the library contains an infinitesimal fraction of individual books with fabulously interesting stories. Characters in some of those books, insulated from the vast gibberish that makes the library worthless from outside, can well appreciate their own existence. They do so by perceiving and interpreting their own story in a consistent way, one that recognizes their own meaningfulness - a prescription which is probably the secret of life and existence, and the reason we find ourselves in a large, orderly universe with consistent physical laws, possessing a sense of time and a long evolutionary history.