An astrophysicist named Cosimo Bambi has proposed a bold idea: to use a miniature research spacecraft to travel to distant black holes for a close, on-the-ground exploration.
Black holes are among the strongest known sources of gravity in the universe and are considered ideal locations to test Einstein's theory of general relativity. Professor Bambi notes that while this mission is not currently technically feasible, it could become a reality within the next 20 to 30 years after overcoming two key challenges: finding a sufficiently close target black hole and developing a suitable detector.
The closest known black hole is Gaia BH1, discovered in 2022, approximately 1,560 light-years from Earth. However, Bambi believes that there are likely undiscovered, even closer black holes. Various models predict that the nearest black hole could be as close as 20 to 25 light-years from Earth. While invisible to conventional telescopes, it might be possible to detect it by observing its gravitational effects on nearby stars.
For interstellar travel, Professor Bambi is pinning his hopes on "nanocrafts." Weighing only a few grams, these detectors essentially consist of a microchip and a light sail. Powerful laser beams deployed on Earth will propel the light sail with photons, accelerating the detectors to one-third the speed of light. At this speed, the detectors could reach their target, 20 to 25 light-years away, in about 70 years. Transmitting the measurement data back to Earth would then take another 25 years (depending on the distance), bringing the total mission lifespan to approximately 80 to 100 years.
The experiments conducted upon arrival by the detectors promise to answer some of physics' greatest mysteries: Do black holes truly have event horizons? Do the known laws of nature still apply in such extreme conditions? Or do Einstein's theories break down there?
However, the challenges remain enormous. Building the required laser facilities alone is currently estimated to cost around €1 trillion, and the technology required does not yet exist. Professor Bambi remains optimistic: "It sounds crazy today. But gravitational waves were also thought to be unobservable—until we successfully detected them a century later. Fifty years ago, who would have believed we could image the shadow of a black hole?"
