Do we have proof aliens exist? Interstellar object ‘Oumuamua ‘the first sign of intelligent life’, says Harvard professor

• A seemingly self-propelled object that visited our solar system in 2017 may be the first sign of intelligent life beyond Earth, says one astronomer
• ‘People found it unacceptable to discuss this possibility,’ Avi Loeb says, but he has stood by his claim, and explains the reasoning for it in a new book