There could be evidence of dead alien civilisations out there and humans might find one if we go out exploring the galaxy, says SpaceX CEO Elon Musk.

In a 2021 discussion on the Joe Rogan podcast, Musk said that many extra-terrestrial civilisations might have failed to advance as a multi-planetary species and perished as a result of it. And all that is left are 'ghost towns.'

"It might turn out that when we go out there exploring the galaxy, we might find a whole bunch of dead, one-planet civilisations and they just never made it to the next planet," Musk told Rogan.

He even theorised about the lost civilisations leaving behind traces of their existence like heiroglyphs by ancient Egyptians.

"It's like if you go through the archaeological ruins of ancient Babylonians and Sumerians, trying to decode their writings," Musk added. That being said, the billionaire, has said in the past that he has not seen any evidence of extra-terrestrial life so far and that we might probably be alone.

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Making humanity multiplanetary is one goal Musk has pursued relentlessly and it is also the foundation stone of SpaceX. Apart from Musk, many experts the likes of physicist Stephen Hawking and former NASA advisor and scientist Carl Sagan have pushed to strive for spreading out in the universe.

Hawking believed that spreading out into space will "completely change the future of the human race and maybe determine whether we have any future at all."

Renowned science-fiction authors like Isaac Asimov and Arthur C. Clarke were also in favour of space colonisation as it is only way to ensure humanity survives.

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