First, the good news: a new Pew Research Center report on the future of the internet is mostly optimistic. The research agency canvassed 1,400 technology experts for its 2014 Future of the Internet report, and a majority believed the internet wouldn't be significantly worse off by 2025 — although there were some strong dissenting opinions.

What are the greatest threats to a free and open web?

For the report, Pew asked the experts — who came from the media, nonprofits, corporations, and many other fields — a simple, yes-or-no question: "By 2025 will there be significant changes for the worse and hindrances to the ways in which people get and share content online compared with the way globally networked people can operate online today?" Of the respondents, 35 percent said yes, while 65 percent said no. (It's worth noting, however, that many respondents said they wished they could choose both yes and no, or said their response only represented hopes, not predictions.) But regardless of the answer, Pew also asked a followup question: what are the greatest threats to a free and open web? The answers are the most revealing part of the lengthy report. Pew grouped the responses into four horsemen of the digital apocalypse.

The first was a concern that governments will continue to crack down on the open web. In the midst of a revolution in 2012, Syria's internet went dark; China has spent years behind the so-called "Great Firewall." It may be only a matter of time before such tactics become the norm, and we see "more blocking, filtering, segmentation, and balkanization of the Internet," according to the report.

Many experts also voiced worries about pervasive internet surveillance

Many experts also voiced worries about pervasive internet surveillance, which might have a chilling effect on free speech. As respondent Peter S. Vogel, an internet law expert at lawfirm Gardere Wynne Sewell, put it to Pew: "Privacy issues are the most serious threat to accessing and sharing Internet content in 2014, and there is little reason to expect that to change by 2025, particularly given the cyber terror threats confronting the Internet users and worldwide businesses."

The next threat was the specter of corporations moving near-term profits ahead of a free internet. This was one of the broadest set of concerns. Included in it are the potential demise of net neutrality, telecom industries restricting access to the web, and litigious overprotection of copyrights. University of California-Los Angeles professor Leah Lievrouw put it most sharply when she told Pew: "There are too many institutional players interested in restricting, controlling, and directing ‘ordinary’ people’s ability to make, access, and share knowledge and creative works online — intellectual property rights holders, law enforcement and security agencies, religious and cultural censors, political movements and parties, etc."

The next fear was the most unexpected: that "efforts to fix the TMI (too much information) problem might over-compensate and actually thwart content sharing." In other words, a sea of information may drown us, but attempts to curb that problem may go overboard. Joel Halpern, a distinguished engineer at Ericsson, told Pew that Big Data may help, but "there are many limitations and risks (including mismatched incentives) with those tools."

There's always the risk of missing the mark when attempting to predict the future; the internet may be much more free by 2025, or could be assailed by another, as yet unknown threat. All four of these fears may make the web worse, or none of them may come to fruition. But like the best science fiction, reports like this tell us as much about the anxieties of today as about the fears for tomorrow.