Warning: Don't read this in front of the kids

Here's a prediction that'll make you squirm: In the future, people will fall in love with robots. Robots will not be cold, predictable machines, but actual lovers - precocious, sexy and remarkably humanlike in appearance. Humans will even marry robots in certain obliging jurisdictions. Now send the kids into the other room while we mention the obvious, bizarre implication: Someday, people will have sex with robots.

And not just cold, mechanical sex that barely incites a feeble meep-meep-meep from your robot lover: No, we're talking about real elbow-pads-and-helmets sex. Electrifying sex! (And afterward the robot will take a drag on a cigarette and say, "That really recharged my batteries.")

We learn all this from robot enthusiast David Levy in his intriguing but very strange new book, Love and Sex with Robots, which if nothing else gets points for the straightforward title. Levy, whose previous book, Robots Unlimited, outlined the coming era of ubiquitous robotics, has taken his scenario to its logical, if not entirely persuasive, conclusion:

"Love with robots will be as normal as love with other humans," Levy writes, "while the number of sexual acts and lovemaking positions commonly practiced between humans will be extended, as robots teach us more than is in all of the world's published sex manuals combined."

Levy goes on to imagine a world of robot prostitutes, or "sexbots," which would offer people a chance to practice their technique before entering a human relationship. "With a robot prostitute," he writes, "the control of disease is implicit - simply remove the active parts and put them in the disinfecting machine."

At this point you are likely holding up both hands with palms outward in the internationally recognized gesture meaning "Stop." This sounds crazy. Clearly robots are not going to become plausible objects of sexual relationships, much less actual romance and genuine love, until they have a serious makeover. Human love isn't so shallow that we'll fall for the first machine with a nice pair of antennae.

But Levy's thesis isn't as silly as you might initially think. We are living in a period of revolutionary advances in computer software and processing speeds. The Japanese already have a multibillion-dollar robot industry, including robots used to keep an eye on - and even bathe - the elderly. Sony has invented a robotic dog named AIBO. Honda has created an android that can climb stairs. Carnegie-Mellon University invented a robot, Grace, that managed to register by itself (herself?) for an academic conference. Meanwhile, researchers are experimenting with flexible polymers that can be used as artificial skin, an essential leap for the creation of robots you might actually want to cuddle. Most important, robots will have to learn to act like humans; one researcher, Levy reports, has designed robots that can exhibit 77 human behavior patterns.

The key is that these technological advances will someday be complemented by cultural changes, and cavorting with robots just won't seem weird anymore. "It would not surprise me if a significant proportion of readers deride these ideas until my predictions have been proved correct," Levy writes, and then makes a cheap analogy to people who once were hostile to the idea that the Earth was round rather than flat.

Levy's book is entertaining in parts, such as the eye-opening (even climactic) section on the evolution of vibrators. "A steam-driven vibrator invented in the United States in 1869 was inconvenient for doctors to use because they repeatedly had to shovel coal into its boiler," he writes. (Who among us has not heard the command, "Keep shoveling"?)

But throughout Love and Sex with Robots, there's a recurring sense of the writer trying a little too hard: Every brick must be carefully laid as he builds the great edifice of his thesis. Thus, we must labor through long sections on why people fall in love, why they love their pets, how they become attached to their computers, and so on, before we can get to the good stuff on sex toys. And it's not clear that Levy - described on the book jacket as "an internationally recognized expert in artificial intelligence" - is truly an expert on the subject of human love. He seems more like a partisan in a technological debate most of us didn't realize was going on.

No doubt it is a good bet that technology and sexual desire will continue to have a mutually supporting relationship. But Levy is not merely saying that sex toys will be more elaborate in the future. He is envisioning robots as essentially interchangeable with people. The problem is, a robot programmed to fall in love with a person is essentially a fancy inflatable doll. Imagine the awkward moments:

Robot: I love the clever way you comb those few, thin, feeble locks of hair all the way over the vast bald region of your head.

Human: You're just saying that.

Levy stipulates, near the end of the book, that an important part of sexuality is "the possibility of failure or denial," and thus sexbots will need to be able to mimic human "capriciousness." But at some point you wind up with sexbots out of control, which, come to think of it, is a great idea for a science-fiction movie.

If Levy is right, the era of rambunctious robot love is not far in the future. But I'd advise everyone to hang on to a flesh-and-blood backup.