Right now, you’d understand if aliens didn’t want to pay Earth a visit, what with the potentially deadly Covid-19 pandemic and all.

But earlier this year, after 16 years of secrecy, the Pentagon has released footage of UFOs which has made many ask, for the zillionth time: are we really alone in the universe? Or are aliens already among us?

For years, these questions have divided scientists, sci-fi fans and conspiracy theorists. Although many explanations have been put forward for why we haven’t met aliens yet, none have been completely convincing or universally accepted.

In short, in a world where we’re obsessed with discovering every little thing, this is one big question we don’t really know.

But two years ago, when the world seemed like a very different place, Russian physicist Alexander Berezin, from the National Research University of Electronic Technology (MIET), had a theory. He suggested that once a civilisation reaches the capabilities of spreading across the stars, it will inevitably wipe out all other civilisations.

Read more: indy100