Enjoying a round of golf or a pint down the pub could become the norm for millions in decades to come.

But all that free time might not actually be that good for us.

Speaking at the world's biggest science conference in Washington DC, Prof Moshe Vardi expressed concerns over the social impact of an economy with more than 50% unemployment.

Prof Vardi, of Rice University in Houston, Texas, told the annual meeting of the American Association for the Advancement of Science (AAAS): "We are approaching a time when machines will be able to outperform humans at almost any task.

 "I believe that society needs to confront this question before it is upon us: If machines are capable of doing almost any work humans can do, what will humans do?"