Now, instead of pie-in-the-sky estimates for products that may never become reality, the focus is on more mundane issues like costs and profit margins. Research and development costs grew to about 12 percent of gross revenue last year, the highest share since the company went public in 2004. That includes the vast majority of engineers and technical expenses at the company.

The most unusual projects are at Google X, in a brick building about a half-mile from the main company campus in Mountain View, Calif. Google X focuses on technologies that are likely to be five to 10 years away from being commercialized. Its leader, Astro Teller, whose business card reads “Captain of Moonshots,” is a polymathic computer scientist who moonlights as a novelist and used to manage a hedge fund.

In an interview, Mr. Teller said that his division’s responsibility was to produce financial results on par with what a venture capitalist might expect when putting money into a new company. “Because risk abounds, we owe a very strong return,” he said.

Google X’s best-known projects are Glass and the self-driving car, but inside there is much more, like an effort to make wind power with kites, or a project to deliver packages with drone aircraft. And all across the Southern Hemisphere, the company has stratospheric balloons that aim to connect people to the Internet. Add this to the list of things Google X has tinkered with — jet packs, hovering skateboards — and it is easy to see why investors are getting antsy.

Image Google’s experimental self-driving car at the company’s headquarters in Mountain View, Calif. A camera mounted to the roof, along with various sensors, help the vehicle drive itself. Credit... Justin Sullivan/Getty Images

As out there as the projects sound, Google is going down a familiar road. Today, Google is so dominant in search advertising that it has almost no choice but to spend lavishly in search of future businesses.

“If you think historically, go back 30 or 35 years, the organizations with big R.&D. divisions were AT&T, IBM and Xerox,” said Ed Lazowska, a computer science professor at the University of Washington. “Notice that each of those companies had a de facto monopoly.”