Complexity: Plain and simple

✍ Scribed by Seth Lloyd

• Book ID: 101275031
• Publisher: John Wiley and Sons
• Year: 1999
• Tongue: English
• Weight: 28 KB
• Volume: 4
• Category: Article
• ISSN: 1076-2787
• DOI: 10.1002/(sici)1099-0526(199903/04)4:4<72::aid-cplx9>3.0.co;2-g

✦ Synopsis

Plain and Simple

I n all the fields in which I have worked-from math to philosophy to physics to engineering-my research has focused on the role of information. How do physical systems register information and move it about? How is information transformed and processed? And, most importantly, how do the ways in which a system transfers and transforms information determine its behavior?

When I was a graduate student, I was sitting at my desk attempting to analyze the role of information in quantum gravity when my supervisor, Heinz Pagels, walked in. "Seth," he said, "we need to define a physical measure of complexity." I responded that complex systems were exactly those that resisted a simple analysis in terms of a single number. But he insisted. Eventually, after studying the work of Rolf Landauer on physics of information processing and of Charlie Bennett on computational measures of complexity, we were able to define a reasonable physical measure of complexity in terms of the amount of thermodynamic resources required to perform a given task.

Subsequently, I became a collector of measures of complexity: Despite the proliferation of apparently disparate methods for quantifying the complex, I have been able to show that most such measures are closely related to each other. In fact, all measures that I have come across measure either information-the difficulty of describing a thing-or effort-the difficulty of accomplishing a task-or both.