Today in 1927, Philo T. Farnsworth, 21, succeeded in transmitting the image of a line through purely electronic means with a device he called an “image dissector.”

“That’s it folks. We’ve done it,” Farnsworth said to his assistants. “There you have electronic television.” Harold Evans (in They Made America) also quotes Farnsworth’s belief in the positive power of the new medium: “If we were able to see people in other countries and learn about our differences, why would there be any misunderstandings? War would be a thing of the past.” But only a few years later, in 1935, another forecast, advanced by the philosopher Rudolph Arnheim, was decidedly mixed: “Television is a new, hard test of our wisdom. If we succeed in mastering the new medium it will enrich us. But it can also put our mind to sleep” (quoted in Steven Lubar’s InfoCulture).

But the New York Times was not worried. Reviewing a demonstration of television at the 1939 World’s Fair, it declared “The problem with television is that people must sit and keep their eyes glued on a screen; the average American family hasn’t time for it.”

In 1996, this prediction has finally started to become true, as the Scientific American observed: “Something intriguing is happening in American homes. Computers seem to be luring away people from the television set. It’s still too early to tell if this is the long-heralded end of the 50-year obsession with the ‘idiot box.’ But it does seem to be the beginning of an affair with CD-ROMs and the World Wide Web, and as it heats up, the door is thrown open for another generation of stars.”

And today, according to the Pew Research Center, “The internet is slowly closing in on television as Americans’ main source of national and international news. Currently, 41% say they get most of their news about national and international news from the internet, which is little changed over the past two years but up 17 points since 2007. Television remains the most widely used source for national and international news — 66% of Americans say it is their main source of news — but that is down from 74% three years ago and 82% as recently as 2002.”

And tomorrow? In 2010, for the first time according to Pew, “the internet has surpassed television as the main source of national and international news for people younger than age 30.”