Predicting the future ain't easy. That's why astrologers and fortune tellers tend to keep their forecasts as vague as possible. But in the high-stakes world of high technology, the future belongs to those who see it coming well in advance.

Of course, even the most successful tech prognosticators make their share of foolish predictions, multiplying the candidates for inclusion in this article. In any case, here are a few of my favorite forward-looking flubs of the past 65 years.

Foolish Tech Prediction 1

"I think there is a world market for maybe five computers."

Thomas Watson, president of IBM, 1943

At the dawn of the computer industry, nobody really knew where this new technology would take us. But the explosion of desktop computing that put a PC in nearly every American home within 50 years seems to have eluded the imagination of most mid-century futurists.

After all, when IBM's Thomas Watson said "computer," he meant "vacuum-tube-powered adding machine that's as big as a house." It's fair to say that few people ever wanted one of those, regardless of the size of their desk.

(IBM did stay in the business, of course. For details, see our retrospective, "The IBM Personal Computer's 25th Anniversary.")

Foolish Tech Prediction 2

"Television won't be able to hold on to any market it captures after the first six months. People will soon get tired of staring at a plywood box every night."

Darryl Zanuck, executive at 20th Century Fox, 1946

By 1946, movie executive Darryl Zanuck had already cemented his place in entertainment history as the producer of more than 100 films for the big silver screen. So who could have blamed him for underestimating the power of the small blue screen? I'm guessing that if Zanuck were alive today, he'd find himself just as mesmerized as the rest of us by the mind-crushing distortion loop that modern TV programming has become.

(But the TV sets rock!)

Foolish Tech Prediction 3

"Nuclear-powered vacuum cleaners will probably be a reality within ten years."

Alex Lewyt, president of Lewyt vacuum company, 1955

In the 1950s, the only thing more certain than the red menace was the inevitability of atomic power. So when New Jersey-based vacuum cleaner honcho Alex Lewyt heralded a tomorrow in which nuclear-powered appliances would suck up dirt in every American household, the news probably caused few eyebrows to rise. Remember, this was the era of radium-impregnated paint for glow-in-the-dark dials. Peaceful radioactivity seemed as safe as asbestos.

Of course, Lewyt's vision has yet to come true, and it likely won't until well after nuclear reactors are enlisted to power all of the terminator robots in our post-SkyNet future.

(Interested in robots? Take a look at "The Robots of 2008" for a video appreciation of the coolest and most innovative of Gort's great-great-grandchildren.)

Foolish Tech Prediction 4

"There is no reason anyone would want a computer in their home."

Ken Olsen, founder of Digital Equipment Corporation, 1977

Photograph: Erik Klein (vintage-computer.com) Digital Equipment Corporation was acquired by Compaq more than a decade ago, but in the 1970s the company was a major force in the world of computing. Apologists argue that DEC president Ken Olsen made this quip before the advent of the PC as we know it, but ready-made personal computers like the MITS Altair had hit the market a couple of years earlier. And within four years of Olsen's remark, the release of the IBM PC had enshrined this prediction in the high-tech hall of shame.

(The MITS Altair 8800 pictured above is one of "The Most Collectible PCs of All Time.")