When the original paper about planet 9 being a black hole came out a year ago, everybody thought it was a cool-sounding but just completely wild idea -- both physicists and pop science articles. Not impossible by any means, but not within the top 250 new physics ideas in plausibility. Then the discussion died down. I figured it would end up being one of those forgotten but cool gems.

Then the most authoritative string theorist in the world, who hasn't worked on anything relating to experiments in decades, suddenly writes a very short, simple, single-author paper to use this idea to promote Yuri Milner and Mark Zuckerberg's space probes. Now it's the conjunction of two crazy ideas, and it's really taking off. I just don't know why this is happening, or what to make of it.