Knowledge is cheap. A few taps on a smartphone and anyone can dive into the works of Plato and Einstein, watch a lecture at Harvard or Princeton, or look up a recipe for cauliflower pizza crust, without spending a penny.

Yet for all these wonders, for all the wealth generated in the name by making information free, the Internet has done little to improve the prospects of poor kids growing up in America, Robert Putnam says in his new book, “Our Kids: The American Dream in Crisis.”

“ Advances in technology have ‘not leveled the playing field at all in terms of the difference between rich kids and poor kids.’ ” — Robert Putnam

Social and mobile technologies, he says, do almost nothing to improve social mobility.

“It has not leveled the playing field at all in terms of the difference between rich kids and poor kids,” Putnam told MarketWatch. Though it’s not the fault of the technology — or the kids, he adds.

Putnam’s research explores why the divide between the prospects of rich and poor kids in the U.S. has grown so much since the 1950s, and how changes in family structure, geographical and social-class segregation exacerbated the problem.

As for technology, most of the kids Putnam profiles in the book had smartphones, but the poorest ones tended to use the devices “in completely different, mindless ways,” he said. “Not that this is their fault.”

Also see: Why the American Dream is unraveling, in four charts

“Compared to their poorer counterparts, young people from upper-class backgrounds (and their parents) are more likely to use the Internet for jobs, education, political and social engagement, health and newsgathering, and less for entertainment and recreation,” Putnam writes. “Affluent Americans use the Internet in ways that are mobility-enhancing, whereas poorer, less educated Americans typically use it in ways that are not.”

This is not to say the wealthier kids are using their iPhones to watch lectures on thermodynamics. They also send spend much of their Internet time sending off Snapchats, playing games and watching YouTube videos. But since social networks online tend to reflect social networks in real life, the wealthier kids have more people to draw on digitally to help advance their education and careers. (Parents in the top fifth of the economic hierarchy have 20% to 25% more friends than parents in the bottom fifth, and they know people in a far wider range of occupations, studies show.)

In fact, the social connections common to the wealthy may be even more important in an age where everyone can freely download all the world’s information, Putnam says. “Just because teens can get access to a technology that can connect them to anyone anywhere does not mean that they have equal access to knowledge and opportunity.”

A technology that reduces all the world’s information to ones and zeroes may exacerbate our division into haves and have-nots, Putnam says. “At least at this point in its evolution, the Internet seems more likely to widen the opportunity gap than to close it.”