A Computer's Arrow of Time

A compromised arrow of time

The second law of thermodynamics—the usual statement of the arrow of time—has been called the most fundamental law of physics. It is thus difficult to conceive that a single dynamical system could contain subsystems, in significant mutual contact, possessing opposite thermodynamic arrows of time. By examining cosmological justification for the usual arrow it is found that a consistent way to es...

A subquantum arrow of time

The outcome of a single quantum experiment is unpredictable, except in a purestate limit. The definite process that takes place in the apparatus may either be intrinsically random or be explainable from a deeper theory. While the first scenario is the standard lore, the latter implies that quantum mechanics is emergent. In that case, it is likely that one has to reconsider radiation by accelera...

A Computer's Arrow of Time

Some researchers believe that the psychological or consciousness arrow of time is a consequence of the thermodynamic arrow. Some don’t. As for many issues in this area, the disagreement revolves about fundamental and undebatable assumptions. As a contribution to this standoff I consider the extent to which a computer—presumably governed by nothing more than the thermodynamic arrow—can be said t...

The Arrow of Time

A Microscopic Liouville Arrow of Time

We discuss the treatment of quantum-gravitational fluctuations in the space-time background as an ‘environment’, using the formalism for open quantum-mechanical systems, which leads to a microscopic arrow of time. After reviewing briefly the open-system formalism, and the motivations for treating quantum gravity as an ‘environment’, we present an example from general relativity and a general fr...