How is There a Physics of Information? On Characterizing Physical Evolution as Information Processing

Abstract

We have a conundrum. The physical basis of information is clearly a highly active research area. Yet the power of information theory comes precisely from separating it from the detailed problems of building physical systems to perform information processing tasks. Developments in quantum information over the last two decades seem to have undermined this separation, leading to suggestions that information is itself a physical entity and must be part of our physical theories, with resource-cost implications. We will consider a variety of ways in which physics seems to affect computation, but will ultimately argue to the contrary: rejecting the claims that information is physical provides a better basis for understanding the fertile relationship between information theory and physics. Instead, we will argue that the physical resource costs of information processing are to be understood through the need to consider physically embodied agents for whom information processing tasks are performed. Doing so sheds light on what it takes for something to be implementing a computational or informationprocessing task of a given kind Contents 1 Introduction 2 Why is there a Physics of Information? 2.1 The Challenge of Landauer's

Interference experiment, anomalous weak value, and Leggett-Garg test of macrorealism

“…Proposals using weak measurement [27], quasiprobabilities [13] and continuous velocity measurements [28,29] have also been reported. But, a string of criticisms [23] have also been made regarding the viability of some of the approaches. It is argued that in negative result measurement the collapse from distance occurs and subsequent dynamics of the state is disturbed.…”

“…In their original paper, Leggett and Garg proposed ideal negative-result measurements to ensure the noninvasive measurability in QM which is adopted in recent experiments [21,22]. However, this approach is criticized by pointing out that collapse indeed occurs in negativeresult measurement procedure and eventually disturbs the system and its subsequent dynamics [23]. Another approach to tackle the non-invasive measurability in experiments is by using the technique of weak measurement [24].…”

“…In LG scenario, there are two subtle issues regarding the assumptions used to derive LGIs. For an excellent review with enticing discussion, we refer [23]. First, what exactly the 'state' implies in MRps assumption in a macrorealistic theory is unclear.…”

“…Note that, the statistical version of NIM condition -the operational non-invasivness (also well-known as no-signaling in time condition ), implies that prior measurements do not influence the statistics of future measurements. In two-time and three-time LG scenario they imply LGIs [11,12,15,23]…”

Computers in Abstraction/Representation Theory

“…Regarding the former, one has with AAR theory a better grip on which mathematical theories of computation can be considered more "physics-like" by understanding how they require simpler embeddings into the models of the physical computer (Sutner, 2018); when one considers a variety of theories besides classical mechanics, perhaps some mathematical theories will be more like specific physical theories than others. Regarding the latter, having an objective theory of when physical systems are computing opens the possibility for an objective and quantitative theory of physical computational complex-ity and information processing, i.e., the physical "costs" of performing computation or processing information (Maroney and Timpson, 2018).…”