## Problem 091 — rank:70

**Title:** Active cytoplasm as non-equilibrium matter

**Added binding assumptions (LaTeX):**

```latex
Fix Fourier conventions and one- or two-sided spectral densities. Infer the thermal spectrum from the dissipative response only under the stated equilibrium bath relation, and include cross-spectra if thermal and active forces are not independent. A stationary displacement process and a stable causal response are required. Probe transfer is restricted to a declared spatial and size regime, not assumed universal.
```

**Direct edits:** 0. **Fresh external checks:** None; supplied sources retained as provenance.