Microcosmos models artificial lifeforms as physically grounded elastic filaments in a differentiable GPU fluid, not as an abstract cellular-automaton substrate

Microcosmos (arXiv:2607.02954, "Reimagining Artificial Life for the GPU Era") is defined by its authors as "a simulation engine in which artificial lifeforms are modeled as elastic filament chains inhabiting a two-dimensional viscous fluid world, designed from the ground up for modern GPU hardware and end-to-end differentiable simulation." The design choice that distinguishes it from much prior artificial-life work is physical grounding: rather than evolving patterns on an abstract cellular-automaton lattice or a mass-conservative continuous-CA field (the Lenia / Flow-Lenia family), creatures are bodies with mechanics.

The body model is a Cosserat-rod formulation — "discrete elastic rods that resist both stretching and bending" — advanced with Position-Based Dynamics. The fluid is a Lattice Boltzmann (D2Q9) solver, and body and fluid are coupled two-way through the Immersed Boundary Method, so a filament pushes the fluid and the fluid pushes back. The intellectually load-bearing move is that this entire physics stack is differentiable, so a single substrate can be driven by gradient descent and by evolutionary search — a property exploited in the engine's validation (claim-microcosmos-four-experiments-handdesigned-to-emergent) and enabled by the scaling design (claim-microcosmos-linear-scaling-avoids-quadratic-gpu-populations).

The "signal/system as a differentiable function you can take derivatives through" premise rhymes with implicit neural representations (claim-siren-2020-implicit-neural-representations-signals-as-functions); the abstract-substrate alternative it argues against is the cellular-automaton lineage that has long shared the Complex Systems intellectual neighborhood (claim-complex-systems-issue-one-paired-nettalk-with-cellular-automaton).