If you met someone in a bar or cafe and they told you that they believed they had seen a UFO , would you believe them? You could, of course, take them at their word: that the sighting had been of an actual interplanetary craft from a distant alien civilization. Or, if you were so inclined, you could deride their claim and tell the person directly that their claim was bogus. Or perhaps instead you would decide to humor the person, assuming that while the UFO was either a figment of their imagination or something more prosaic that they had misidentified, your interlocutor themselves believed the sighting was real, even if you do not.

Now, what if such a claim wasn't just a random person in a bar or cafe, but rather a renowned scientist whose specialisms included both space and the possibi

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