A new paper sketches a daring plan: launch a wafer-sized spacecraft toward the nearest black hole and let it report back on the most extreme physics in the cosmos.

The author, astrophysicist Cosimo Bambi of Fudan University, places the idea “somewhere between hard engineering and science fiction,” yet he also anchors it to a timeline. The hardware might be ready in twenty to thirty years, the journey roughly seventy more, and the return signal would reach Earth eighty to a hundred years after launch.

Why bother visiting a black hole?

Black holes concentrate gravity so strongly that nothing — not even light — escapes. They provide a perfect testbed for Albert Einstein’s general relativity, where its equations strain the most. Telescopes and gravitational-wave detectors already hint that Einstein still holds sway, yet stray gas clouds and noisy data limit the precision of these checks. A close-up mission would sidestep that problem by sending instruments directly into the pristine vacuum around a lone black hole.

Currently, the champion for “closest known black hole” is Gaia BH1, a dormant stellar-mass hole about 1,600 light-years away in Ophiuchus. Bambi’s statistics suggest many black holes wander unseen far nearer — possibly just 20 to 25 light-years out. Spotting one will rely on clever tricks such as watching how starlight bends when an unseen object drifts across our line of sight or catching faint radio afterglows from gas the hole gulps down.

“There have been new techniques to discover black holes,” says Bambi. “I think it’s reasonable to expect we could find a nearby one within the next decade.” 

How will it work?

Chemical rockets crawl on interstellar scales; their fuel is too heavy. Bambi points instead to nanocrafts — gram-scale chips attached to meter-wide light sails. A ground-based laser array would pummel the sail with photons, pushing the craft to around one-third the speed of light within minutes. Breakthrough Starshot, a private effort aimed at Alpha Centauri (the closest star to Earth), relies on the same physics.

At that velocity, a probe could traverse 25 light-years in roughly seventy-five years. The science data, beamed back through the sail acting as a dish, would need another quarter-century to reach Earth.

Bambi outlines three experiments that could transform black-hole science.

To confirm the Kerr metric, scientists would send two sister probes to orbit the black hole at different heights and compare their clock beats and redshifts. Matching results would show whether the surrounding spacetime truly follows Einstein’s prediction.

A second experiment, and one of the most exciting, would watch the event horizon in real time. One probe could dive toward the invisible boundary, and if its signal fades exactly as theory expects, the presence of a classic event horizon is reinforced. A sudden cut-off, however, could hint at more exotic objects such as “fuzzballs.”

The mission would also look for shifts in nature’s constants. By examining atomic transitions whose energies depend on the fine-structure constant, the probes could reveal whether this fundamental number remains fixed inside a super-strong gravitational field.

The price tag — and the payoff

Building the laser array today would run about a trillion dollars, but the nanocraft itself still lives on engineers’ wish lists. Bambi notes, though, that laser costs fall fast and that other deep-space projects could share the same technological groundwork.

Critics will point to the century-long wait for results. History counters with two examples: gravitational waves predicted in 1916 and detected in 2015, and black-hole silhouettes doubted in the 1970s yet photographed in 2019. If Bambi’s roadmap holds, today’s high-school students may grow old reading a headline that begins, Data from a probe orbiting a black hole just arrived…

“It may sound really crazy, and in a sense closer to science fiction,” Bambi said. “But people said we’d never detect gravitational waves because they’re too weak. We did — 100 years later. People thought we’d never observe the shadows of black holes. Now, 50 years later, we have images of two.” 

That moment would hand humanity its closest look yet at the strange frontier where space, time and matter twist into something new.

The findings appeared in the journal iScience.