The hypothetical Planet Nine, a potential massive object lurking beyond Neptune, has captivated astronomers. While telescope searches continue, some scientists have entertained the intriguing possibility that Planet Nine might not be a planet at all, but a primordial black hole. Physicist Edward Witten has proposed a novel approach to detect this hypothetical black hole: a fleet of miniature spacecraft armed with precise clocks.
While the existence of a ninth planet beyond Neptune has long been speculated, direct observation remains elusive. The gravitational influence on trans-Neptunian objects suggests the presence of a massive body, five to ten times the mass of Earth. Traditional telescope searches have yielded no definitive results, leaving room for alternative theories. In 2019, researchers James Unwin and Jakub Scholtz proposed the possibility of Planet Nine being a primordial black hole captured by the Sun’s gravity. This audacious idea prompted a search for evidence using gamma-ray telescopes.
Building on this concept, Edward Witten, a renowned theorist at the Institute for Advanced Study, envisioned a dedicated mission to locate Planet Nine if it were indeed a black hole. His proposal, detailed in a paper published on the arXiv preprint server, leverages the technology envisioned for the Breakthrough Starshot initiative. This initiative proposes using Earth-based lasers to propel and guide ultra-lightweight spacecraft, weighing mere grams, across interstellar distances.
Witten’s concept involves launching a thousand of these miniature spacecraft towards the outer reaches of our solar system, targeting a distance of 500 AU (Astronomical Units). For comparison, Pluto’s average distance from the Sun is around 40 AU. Each spacecraft would be equipped with highly accurate clocks, constantly transmitting timing data back to Earth. Any minute deviation in a spacecraft’s clock could indicate the subtle gravitational influence of a small black hole.
While this idea is theoretically compelling, it’s not without significant challenges. Witten himself acknowledges that achieving the required precision in timekeeping aboard such small spacecraft presents a major hurdle. Other technical obstacles also need to be overcome. He suggests prioritizing traditional telescope searches and other less conventional detection methods before embarking on such an ambitious mission.
Fortunately, advancements in space-based atomic clocks, such as those being tested by NASA, offer a glimmer of hope. These highly precise clocks could pave the way for future missions to explore the furthest reaches of our solar system and potentially uncover the true nature of Planet Nine. While the search continues, Witten’s proposal provides a fascinating backup plan should traditional methods fail to unveil the secrets of this mysterious celestial object.
