Robots could replace humans within the next few hundred years, Astronomer Royal predicts

"My guess is that if we do detect an alien intelligence, it will be nothing like us. It will be some sort of electronic entity," he said. "If we look at our history on Earth, it has taken about 4 billion years to get from the first protozoa to our current, technological civilisation. "But if we look into the future, then it's quite likely that within a few centuries, machines will have taken over – and they will then have billions of years ahead of them. "In other words, the period of time occupied by organic intelligence is just a thin sliver between early life and the long era of the machines. "Because such civilisations would develop at different rates, it's extremely unlikely that we will find intelligent life at the same stage of development as us.