Baidu chief scientist Andrew Ng said Wednesday that he was leaving the company to explore “a new chapter” in artificial intelligence, without providing details. In a statement posted online, Mr. Ng said he had been “privileged to learn from both the US and Chinese AI communities—both of which are powerhouses.” A Stanford University adjunct professor, Mr. Ng was brought on to help the Chinese search-engine firm build out its artificial-intelligence capabilities. He headed four Baidu research labs, including one in Silicon Valley and Baidu’s big-data and speech-technology groups. He split his time between Beijing and Sunnyvale, California. “This is a big blow to Baidu’s strategy on artificial intelligence and a setback of the company’s internationalization,” Fang Xingdong, founder of internet strategy think tank Chinalabs, told The Wall Street Journal.