Anthropic found a hidden space where Claude puzzles over concepts

What's happening

Anthropic published research and released tooling that reveals a hidden internal workspace inside large language models, which they call J-space or the Jacobian lens. The company shows that Claude runs silent, stepwise concept manipulations in J-space that never appear in its text output (for example internal chains like 21 -> 42 -> 49 while the model outputs 49). Anthropic and community contributors released the J-Space lens code, demos applying it to Qwen 3.6 27B and Qwen3-8B, and follow-up experiments that use J-space entropy as a signal to detect hallucinations across datasets including TriviaQA and GSM8K (one test ran ~11,400 examples on Qwen3-4B). Independent builders also made web tools to view and edit what models "think" before answering.

Why it's trending

Because Anthropic published the Jacobian lens and people are already running it on open models (Qwen variants), generating immediate demos and replication experiments about silent reasoning and hallucination signals.

SignalHolding at its usual pace, confirmed across 3 independent source types.