Elon Musk’s artificial-intelligence company xAI is internally testing Grok 3.5, the next version of its large language model, according to company messages and Musk’s own social-media posts. The upgrade is being trialed on the Grok web platform and, for the first time, includes a voice capability that allows users to converse with the system rather than rely solely on text. Musk said Grok 3.5 aims to "reason from first principles," applying physics-based tools across a range of topics, and added that he is "increasingly confident" the model will be "by far the smartest AI." A limited group of testers already has access, but xAI has not announced a formal launch date, signaling only that public availability is expected soon.