Stephen Wolfram, a 52-year-old scientist, software designer and entrepreneur, tends to go his own way — often with noteworthy results. He published his first physics paper at 15, earned his Ph.D. from Caltech at 20 and two years later won a MacArthur prize.

Less than three years ago, Dr. Wolfram created a new kind of search engine, called Wolfram Alpha. Unlike Google or Microsoft’s Bing, Wolfram Alpha does not forage the Web. It culls its own painstakingly curated database to find answers.

There was skepticism in 2009, when Wolfram Alpha arrived, with critics saying the approach was very limited, useful mainly for math and science facts. But the technology has come a long way, including delivering many answers for Siri, the question-answering personal assistant in the Apple iPhone 4S.

The new version of Wolfram Alpha arrives Wednesday afternoon. Its formal name is Wolfram Alpha Pro, and Dr. Wolfram calls “Step 2, the next step of what can be done with this approach,” which he describes as a “computational knowledge engine.” This is a premium version of the search engine: $4.99 a month, or $2.99 for students.