Call it the Google paradox.

Last month, the European Union’s antitrust chief accused Google of abusing its dominant market power in web searches.

A week later, Google announced it was entering the wireless service market in the United States, threatening to disrupt one of America’s most concentrated industries. Meantime, it is expanding its superhigh-speed broadband Internet service to as many as 34 cities, taking on another market so concentrated that the government recently derailed the proposed Comcast-Time Warner Cable merger.

So is Google an evil monopolist or a competitive champion?

In the stodgy wireless service industry, long dominated by AT&T and Verizon, with struggling Sprint and feisty T-Mobile a distant third and fourth, the possibility that a new competitor might upend this cozy oligopoly has long been considered a pipe dream. When the Justice Department sued to block the proposed merger of AT&T and T-Mobile in 2011, it concluded it was highly unlikely that other competitors would enter the market. Last year, Sprint abandoned its bid for T-Mobile after the Justice Department suggested that deal, too, would be anticompetitive.

But now Google’s entry into wireless — named Project Fi — has changed the conversation about competition in that market, even though Google said the move was still an experiment.