Yes, real. Harvard/MIT-led paper (arXiv:2608.04205, Aug 2026) introduces MatrAIx: Persona 8B with 8.3B records across 1290 dimensions (1M coreset released). LLM agents run in survey/chat/web/app envs for product eval. 91.5% persona adherence in tests. Infrastructure for simulated users, not a persistent full-Earth sim.