But his latest comment has sparked a frenzy of tweets, with many people claiming in their responses aliens must exist.
One person tweeted: “No, we are not. But consider this. Civilisations advance, on the whole, exponentially. This is because knowledge breeds more knowledge.
“The y values of the exponential function samples at two randomly chosen values of x have about zero chance of being comparable…
“So what should we conclude: that no two civilisations are comparable.
“Also ... Read even more
