Computational capacity of life in relation to the universe.

As physical systems, all life in the universe processes information according to physical laws. Estimates for the computational capacity of living systems generally assume that the fundamental information-processing unit is the Hodgkin-Huxley neuron, thereby excluding aneural organisms. Assuming the laws of quantum mechanics, the relativistic speed limit set by light, a universe at critical mass-energy density, and a recent experimental demonstration of single-photon superradiance in cytoskeletal protein fibers at thermal equilibrium, it is conjectured that the number of elementary logical operations that can have been performed by all eukaryotic life in the history of Earth, which is shown to be approximately equal to the ratio of the age of the universe to the Planck time, is about the square root of the number by the entire observable universe from the beginning. The existence of ultraviolet-excited [Formula: see text] states in these protein fibers, operating within two orders of magnitude of the Margolus-Levitin speed limit, motivates state-of-the-art performance comparisons with contemporary quantum computers.