The ultimate physical limits to reversibility

TL;DR

This paper establishes fundamental physical limits on the reversibility of an object's dynamics, showing that the size of objects whose evolution can be reversed is bounded by the universe's information capacity, with implications for quantum measurement devices.

Contribution

It introduces a universal bound on reversibility based on the holographic principle, linking object size, information tracking, and the universe's computational limits.

Findings

Objects larger than ten microns cannot have their dynamics reversed since the universe's information capacity is insufficient.

Reversible computation of an object's history requires it to be smaller than this universal bound.

Irreversible processes imply even smaller size constraints for quantum measurement devices.

Abstract

We argue that if, in order to reverse an object's dynamics, we need to be able to keep track of it with enough precision, then there is an upper bound on the size of the object whose dynamics we can reverse - even using all the available resources of the universe. Using a bound from the holographic principle and treating the universe as the ultimate quantum computer, we show that if we want to reverse the dynamics of an object which has evolved since the beginning of time, its radius cannot exceed ten microns. If this computation is performed irreversibly, the object must be much smaller. This places a lower bound on the size of the smallest possible quantum measurement device.