ALIENS are likely to be “electronic entities” which have overthrown and replaced the organic lifeforms which first designed them, the British Astronomer Royal has claimed.

Lord Martin Rees said it was likely that aliens — if they exist — will be very different to humans.

He said: “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.”

Speaking during an interview at Trinity College, the Emeritus Professor of Cosmology and Astrophysics at the University of Cambridge explained that humans have taken about 4 billion years to get to our current state of civilisation.

But within a few centuries, it’s likely machines will have taken over — and they will 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,” he said.

“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.

“More likely, that life will still be either far simpler, or an already fully electronic intelligence.”

Lord Rees has previously warned that governments should be spending millions on asteroid defence annually.

He claimed that the cost was a worthwhile investment to protect humanity from a deadly space rock.

This article originally appeared on The Sun.