Morphological computational capacity of Physarum polycephalum

TL;DR

This paper estimates the maximum computational capacity of Physarum polycephalum, a unicellular organism, by analyzing its morphological dynamics and energy constraints, revealing it can perform up to 10^36 logical operations in a day.

Contribution

It introduces a novel framework to quantify the computational capacity of aneural organisms using morphological and energetic data, bridging biology and information theory.

Findings

Physarum can perform up to approximately 10^36 logical operations in 24 hours.

Morphological features correlate with information processing capacity.

The study provides bounds based on energy and morphological analysis.

Abstract

While computational capacity limits of the universe and carbon-based life have been estimated, a stricter bound for aneural organisms has not been established. Physarum polycephalum, a unicellular, multinucleated amoeba, is capable of complex problem-solving despite lacking neurons. By analyzing growth dynamics in two distinct Physarum strains under diverse biological conditions, we map morphological evolution to information processing. As the Margolus-Levitin theorem constrains maximum computation rates by accessible energies, we analyze high-throughput time-series data of Physarum's morphology--quantified through area, perimeter, circularity, and fractal dimension-to determine upper bounds on the number of logical operations achievable through its hydromechanical, chemical, kinetic, and quantum-optical degrees of freedom. Based on spatial distribution of ATP and explored areas, Physarum can perform up to ~$10^{36}$ logical operations in 24 hours, scaling linearly in the non-equilibrium steady state. This framework enables comparison of the computational capacities of life, exploiting either classical or quantum degrees of freedom.