Decisive test that a cellular body forms by phase separation
In plain words
Many cellular structures look like droplets, but similar clusters can form by simple binding to a scaffold without any phase transition. A reliable experimental signature that tells them apart is needed.
Precise statement
Phase separation of a single component predicts concentration buffering (dilute-phase concentration fixed at $c_{\mathrm{sat}}$ as total concentration rises), a sharp threshold for droplet appearance, and coexistence behavior, while multicomponent condensates weaken buffering (Riback and co-workers, 2020). Formulate criteria that discriminate phase separation from saturable binding to scaffolds, valid for multicomponent systems, and apply them to standard examples in vivo.
What would settle it
Criteria derived from multicomponent thermodynamics and tested in vivo on systems where the answer is known independently.