Anthropic credited Claude Fable 5.2 with a calculation on a theoretical phase transition associated with black-hole physics, while the preprint leaves the version of the system that performed it unidentified.
A version-one preprint dated Nov. 7 reports a quartic coefficient of b = −1.48 × 10⁻³ λ². It places the calculation in a weak-coupling setting. The work concerns theoretical physics, not observations of astronomical events.
The question follows a 2003 study that described two possible outcomes: two continuous transitions or one first-order transition. The new calculation examines the alternatives in the weak-coupling regime.
The preprint identifies the calculating system only as an internal Claude research model. It says a physicist checked several known cases and that another Claude calculation, using a different method, reached the same result.
Anthropic separately credited Fable 5.2 with the result. Its Nov. 9 announcement listed the model as available across the company’s platforms; the preprint does not specify a model version for the calculation.
