Stephen Hawking's chilling warnings to the world

Stephen Hawking fears for the future of the human race. Photo / Getty

Stephen Hawking has issued a chilling warning to the world, saying humanity should be wary of seeking contact with alien civilisation.

The astrophysicist has warned that intelligent aliens may one day roam between fertile planets and conquer and colonise at will.

In his documentary called Stephen Hawking's Favourite Places, he stresses humans need to tread carefully, or face extinction.

"One day, we might receive a signal from a planet like this," Hawking says in the documentary, referring to a potentially habitable alien world known as Gliese 832c.

"But we should be wary of answering back. Meeting an advanced civilisation could be like Native Americans encountering Columbus. That didn't turn out so well."

In 2010 Hawking warned that if intelligent alien life forms did exist, they may not be the friendly cosmic neighbours humans are looking for.

He said advanced space-faring extraterrestrial civilisations could wander the universe in spaceships after consuming the natural resources of their own planets, which could threaten our own existence on Earth.

"Such advanced aliens would perhaps become nomads, looking to conquer and colonise whatever planets they could reach," Hawking said.

"If so, it makes sense for them to exploit each new planet for material to build more spaceships so they could move on. Who knows what the limits would be?"

The famous scientist also predicts the death of mankind, saying he believes "Earth may become as hot as Venus, the oceans will boil, there will be acid rains and the temperature of the air will reach 250 degrees on the Celsius scale."

The theoretical physicist recently slammed Donald Trump's decision to pull the US out of the Paris Climate Accord, warning it could have devastating consequences for the planet.

According to Hawking one of the possibilities for the salvation of the human race will be colonisation of other planets and the Moon.

Recently he urged humankind to hurry up with developing strategies for colonisation of other planets because there are no more than 50 years left before there is some global cataclysm.