There’s something heavy in the outer reaches of our solar system. At least, it seems that way. Hints of it are scattered across the farthest reaches of our sun’s neighborhood — that something 5 to 10 times the mass of Earth tugging on nearby objects with its gravity. No one’s ever seen it, as this phantom has eluded years of searches by telescopes. In fact, not everyone believes it’s real. For now, most astronomers refer to it as “Planet 9.”
Now, the famous theoretical physicist Edward Witten has published a paper on how to track down this specter haunting our outer solar system: a fleet of tiny probes, pushed via lasers to a blistering 0.1% of the speed of light. Blanket that part of space with hundreds of little probes, Witten argued in the new paper, and the fleet should be able to pin down the lost object’s location. (The paper has not yet been peer reviewed or accepted for publication in a journal.)
Witten is a theoretical physicist and mathematician at the Institute for Advanced Study in New Jersey, best known for his work on the mathematics of quantum field theory and as the progenitor of string theory’s unifying “M-theory.” He was also the first physicist to win the Fields Medal, the most prestigious prize in mathematics. None of those accomplishments are typical bullet points on the resume of a NASA mission designer, Witten readily admits.