It says a lot about how crazy our world is these days that the former president of the United States can casually say "[aliens] are real" in a podcast, and it was a story for maybe a weekend afternoon. Part of the reason this is not a bigger revelation is that Barack Obama squashed it, putting out a statement after this answer raised some eyebrows to try to lower them and downplay what he said.
Now, scientists are mulling an intriguing possibility: if aliens exist, their technology may be only marginally better than ours. And having explored their cosmic neighbourhood for a while, they simply got bored and stopped bothering, making it difficult to detect them. The scenario, described in a new paper, embraces the principle of radical mundanity, which shuns the notion of extraterrestrials zipping around the universe after harnessing physics beyond our comprehension.