Virtual and Real Worlds: How Computer Simulation is Changing the Boundaries of Science

Author: John L. Casti
Translator: Wang Qianxiang
Rights: Ning Qing
Publisher:
Publish Date: 1999-05-01
Features: As a computer simulation that is triggering a scientific revolution, it is not based on direct observation experiments but on the mapping from the real space to the virtual space. From artificial life to geopolitical games, from stock market psychology to the president nomination paradox, The Virtual World will guide you through the siliconized world and explore the new frontiers of complex adaptive systems. This book is a powerful work on simulation by the "contemporary great science writer" Casti. Whether the computer simulation world is "real" and to what extent it can be real, answering these fascinating questions will open up a new world of scientific discovery in the 21st century.
Detailed Introduction: In the ever-changing world of science, new tools often lead to major discoveries, dramatically changing our understanding. Today, with the help of a new tool, scientists are a scientific revolution, whose profound significance is akin to the revolution triggered by Galileo's telescope. From the bits and bytes in computer memory, researchers are creating a silicon substitute for the real world—a refined "artificial world," which allows them to conduct experiments that are impractical, too costly, or sometimes too dangerous in the "physical form." From the simulation testing of new drugs to the creation models of planets and galaxies, and the digital life forms growing in computerized petri dishes, these future laboratories are an important tool for the controversial new scientific method. This new method is not based on direct observation and experimentation but on the mapping from the real space to the virtual space. Here, a new discipline—simulation—has emerged. The artificial (virtual) world mapped is a truly exciting field, the new frontiers of "complex adaptive systems." These systems (from environmental ecosystems to market economy systems) involve living "agents" that continuously change their behavior in various ways, which cannot be predicted and measured by the old scientific rules. The exploration of scientists represents a new vision for scientific discovery in the 21st century, and the simulation world is mapping the course.
In The Virtual World, the popular science writer John L. Casti takes us on a fascinating journey through many unusual siliconized micro-worlds, showing us how they are used to establish important new theories and solve practical problems. We visit "Tierra," a "computational box" where artificial life forms, grows, and mutates biological shapes, revealing new perspectives on natural selection and evolution. We play a game of "Balance of Power," a simulation program that characterizes the complex forces of geopolitics. We also drive through "TRANSIMS," a model of Albuquerque, New Mexico, to find the roots of traffic congestion and traffic accidents. Along this path, Casti explores answers to some profound questions raised by the new simulation in these "virtual worlds." If we can create worlds freely in computers, how real can they be? Can they uncover the most elusive mysteries of our world, or can they only reveal the laws of another reality? How "real" must these models be? And to what extent can they be real? The answers to these questions may completely change the face of science.
Excerpt: The Meaning of Virtual Reality
The 1966 film The Incredible Journey depicts the strange effects you might see if you were to move around inside the human body, assuming you were only as big as a blood cell. It was not only Raquel Welch's first film but also renowned for its special effects. Like this film, it is interesting to speculate from a hypothetical standpoint what the human body would look like if people observed it from the inside. This experiment on human nanotechnology missed a very favorable opportunity and did not address the fundamental questions of what we now call "internal physics": Are the laws governing the behavior of a system different when observed from within (e.g., inside the human body) compared to when observed from the outside? More precisely, does the law governing the brainwave pulses that Welch sees while wearing her white spandex suit differ from the law her normal-sized colleagues observe using microelectrodes from the outside? There is a fundamental issue to resolve: the difference between the physics observed from the inside and the physics observed from the outside. This reflects the basic duality of nature and life, the distinction between the inside and the outside of things—buildings, nations, societies.
The same question lies at the heart of what can be learned from the virtual worlds considered in this book. Therefore, we will discuss this fundamental issue by examining several examples of the inside/outside distinction in science.
Relativity
When asked how he discovered the theory of relativity, Einstein replied that he imagined what the world would look like if he were traveling along a beam of light. Here we get a perfect example of the idea of internal physics, where Einstein drew the astonishing conclusion that if you observe physical phenomena from a beam of light, it is indeed different from just watching the beam of light pass through the air. In particular, you know you are traveling at a definite, finite speed, which in turn causes the contraction of space and time in other systems. These space-time contractions are now familiar to us from observations outside the beam of light. But from the perspective of the beam of light itself, you see nothing unusual—just traveling at the normal speed of light from one location to another.
G?del's Theorem
The key idea behind G?del's famous incompleteness theorem is that in any logical system powerful enough to express any statement about integers, there exists a statement that, using the rules of that specific logical system, cannot be proven nor disproven. However, if we step outside the system, we find that these statements are indeed true. They are simply not provable using the reasoning rules contained within the given logical framework. From the perspective of internal physics, G?del's result is saying that arithmetic is incomplete—when viewed from the inside. Yet, it can be argued that if we look at the same system from the outside, from an external physics perspective, it is complete. Thus, the laws of arithmetic are indeed different, depending on whether you view the specific logical system from the inside or the outside.
The Genetic Code
One of the groundbreaking achievements of modern molecular biology is the work of Francis Crick and Sydney Brenner in the late 1950s, which revealed the genetic code. This code translates certain three-character combinations of nucleotide bases (A—adenine, G—guanine, C—cytosine, and T—thymine) into the 20 amino acids that make up all known life forms. This translation process begins with the passive replication of a DNA strand into a messenger RNA (mRNA) strand, which is then read by ribosomes moving along the strand, one three-base pair at a time, like a tape head moving along a tape. As it moves from one end of the mRNA to the other, the ribosome decodes the symbols written on the mRNA strand, capturing amino acids encoded by the corresponding triplets from floating transfer RNA fragments in the cytoplasm. This is a simple description of the processes of gene transcription and translation.
Following Einstein's line of thought, let's consider such a scenario from the perspective of external physics: Suppose we ride on a ribosome as it moves from one end of the mRNA strand to the other. What would we see? The result is nothing new. More precisely, we might expect to see a clear distinction between the purely syntactic operations of information replication during transcription and the semantically meaningful decoding operations during translation. However, we clearly do not see this distinction from the "molecular eye" perspective. In both cases, what we see are only simple chemical operations and transformations. Only when we step outside the system do we discover the syntactic/semantic distinction between these two operations. From the inside, there is only biochemistry; from the outside, there is a meaningful world of proteins.
Behavior and Cognition
In the 1920s, John Watson proposed a radical view that human behavior patterns do not have mental causes. More specifically, Watson's argument was that the claim that unmeasurable mental states in the brain produce observable behavior is unscientific. This gave rise to the school of behaviorism, which focused on external, observable input/output or stimulus/response behavior patterns as the raw material for building theories of mind and behavior. In contrast, cognitive psychologists argue that only by assuming the existence of internal states (i.e., neural patterns) in the brain can we hope to establish a true scientific theory of human behavior. From a cognitive perspective, the task of psychologists is to infer the characteristics of these internal states from observed behavior and to build predictive theories of human behavior based on the assumed relationships between these internal states in the brain. From the perspective of an internal physicist, we find that the hardware in the brain transforms itself into different states composed of rapidly switching neurons, which in turn lead to thoughts and behavior. But an external physicist would argue that such states do not exist as the basis of thought power. This distinction precisely reflects the two opposing views on artificial intelligence. Those who support artificial intelligence (and are also external physicists) argue that for any object, if it thinks like a brain, it is a brain. Those who oppose artificial intelligence reply that one cannot judge a brain by its appearance. Research on these opposing views has been thoroughly discussed elsewhere, and the materials listed in the appendix can also be consulted.