Spotting an AI-generated photo, song or paragraph by eye is getting close to impossible. Google DeepMind's answer is not a better guessing machine but a signature baked in at the moment of creation: SynthID, an invisible watermark now stamped on a remarkable volume of content. In October 2026 Google opened its SynthID Detector to everyone, and the company says it has already watermarked more than 180 billion images and videos, plus the equivalent of 240,000 years of audio (Google, October 2026)...