AASTRICHT, Netherlands (AFP) - Romantic human-robot relationships are no longer the stuff of science fiction -- researchers expect them to become reality within four decades.
And they do not mean simply, mechanical sex.
"I am talking about loving relationships about 40 years from now," David Levy, author of the book "Love + sex with robots", told AFP at an international conference held last week at the University of Maastricht in the south-east of the country.
"... when there are robots that have also emotions, personality, consciousness. They can talk to you, they can make you laugh. They can ... say they love you just like a human would say 'I love you', and say it as though they mean it ..."
Robots as sex toys should already be on the market within five years, predicted Levy, "a sort of an upgrade of the sex dolls on sale now".
These would have electronic speech and sensors that make them utter "nice sounds" when a human caresses their "erogenous zones".
But to build robots as real partners would take a bit longer, with conversation skills being the main obstacle for developers.
Scientists were working on artificial personality, emotion and consciousness, said Levy, and some robots already appear lifelike.
"But for loving relationships -- that is something completely different. In loving relationships there are many more things that are important. And the most difficult of all is conversation.
"You want your robot to be able to talk to you about what is interesting to you. You want a partner who has some similar interest to you, who talks to you in a manner that pleases you, who has a similar sense of humour to you."
The field of human-computer conversation is crucial to building robots with whom humans could fall in love, but is lagging behind other areas of development, said the author.
"I am sure it will (happen.) In 40 years ... perhaps sooner. You will find robots, conversation partners, that will talk to you and you will get as much pleasure from it as talking to another human. I am sure of it."
Levy's bombshell thesis, whose publication has had a ripple-effect way beyond the scientific community, gives rise to a number of complicated ethical and relationship questions.
British scholar Dylan Evans pointed out the paradox inherent to any relationship with a robot.
"What is absolutely crucial to the sentiment of love, is the belief that the love is neither unconditional nor eternal.
"Robots cannot choose you, they cannot reject you. That could become very boring, and one can imagine the human becoming cruel against his defenseless partner", said Evans.
A robot could conceivably be programmed with a will of its own and the ability to reject his human partner, he said, "but that would be a very difficult robot to sell".
Some warn against being overhasty.
"Let us not exaggerate the possibilities!" said Dutch researcher Vincent Wiegel of the Technological University of the eastern town of Delft.
"Today, the artificial intelligence we are able to create is that of a child of one year of age."
But Levy is unyielding. He is convinced it will happen, and predicts many societal benefits.
"There are many millions of people in the world who have nobody. They might be shy or they might have some psychological hang-ups or psycho-sexual hang-ups, they might have personality problems, they might be ugly ...
"There will always be many millions of people who cannot make normal satisfactory relationships with humans, and for them the choice is not: 'would I prefer a relationship with a human or would I prefer a relationship with a robot?' -- the choice is no relationship at all or a relationship with a robot."
They might even become human-to-human relationship savers, he predicted.
"Certainly there will be some existing human-human relationships where one partner might say to the other partner: 'if you have sex with a robot I'm leaving you'.
"There will be others who say: 'when you go on your business trip please take your robot because I happen to worry about the red light district'."