Instructional Information Processing:Replies Considered

摘要

Wolf and White address different aspects of the paper, and in this present reply, space only permits making two brief remarks. Starting with White's intriguing observation, digital computation without erasing information is possible. This clearly has important implications for real-world digital computing systems, since they can be designed and constructed in a more energy-efficient manner, if information erasure operations are kept to a minimum. Yet, avoiding information erasure operations completely in the course of computation is another matter. At least prima facie, this introduces difficulties relating to memory storage. Information is conveyed by data and (particularly persistent) data in computing systems occupy space. However, computation that only adds new information without erasing any will inevitably require an infinite memory space. Whilst idealised Turing machines have this capacity by definition, real-world computing systems do not.