An interstellar spacecraft designed to explore a black hole could transmit data back to Earth in roughly 100 years.

Cosimo Bambi from the University of Hudang in Shanghai has devised a framework for such missions utilizing technologies projected to be available within the next 20 to 30 years.

By approaching a black hole, we can validate Albert Einstein’s theory of general relativity and uncover the behavior of fundamental physical constants in extreme gravitational fields.

The nearest well-known black hole is approximately 1500 light years away. However, within our Milky Way galaxy, there is estimated to be one black hole for every 100 ordinary stars. This suggests a significant likelihood of locating a black hole within 20 to 25 light years, says Bambi.

Identifying a black hole poses challenges, as these entities do not emit light; astronomers must infer their existence by observing their gravitational influence on surrounding stars.

Reaching a black hole within 25 light years of our solar system will require advanced technological developments, but according to Bambi, “it’s achievable.” Within a century, spacecraft could be minuscule, featuring sails that cover 10 square meters and propelled by light. Such crafts could theoretically accelerate to about one-third the speed of light through pulses from high-powered lasers.

“Currently, light sails and nanocrafts appear to be the most viable options for interstellar travel since they can achieve speeds approaching that of light,” Bambi states. However, he estimates that the power required for an effective laser system could reach approximately 1 trillion euros today.

To validate predictions concerning general relativity, it may be necessary to dispatch two miniature spacecraft or release a secondary probe as the primary nanocraft nears a black hole. The secondary craft would venture closer to the black hole, while the primary craft remains at a safe distance, gathering data and relaying it back to Earth.

Gerlan Lewis from the University of Sydney acknowledges that while the challenges are significant, the proposal is far from impossible.

However, the extensive time frame for the proposed mission introduces a possibility that nanocrafts could become outdated by the time they reach their destination. Lewis remarks, “Considering 100 years of technological advancement, can we truly predict what kind of propulsion system might exist then?”

“A mission to black holes would likely resemble this proposal, akin to how we might imagine the advancements of the 20th century, 500 years in the past,” he adds.

Lewis points out that Bambi’s plans do not address how to decelerate the nanocrafts upon arrival at the black hole. Bambi suggests that the simplest approach is to not slow the vehicle at all, but rather deploy a probe to transmit data back to the main craft for Earth delivery.

“In such scenarios, the probes won’t stop around the black hole; they will merely pass by. Some may be drawn into the black hole, which should provide sufficient data to analyze the black hole’s gravitational field,” he explains.

Sam Baron at the University of Melbourne describes Bambi’s framework as one of the most “speculative” research papers he has encountered, but notes that a century ago, the construction of the Large Hadron Collider would have seemed like science fiction.

“I believe utilizing small-scale technologies is likely the way forward,” he observes. “The question remains whether we can indeed engineer something that meets all the criteria outlined in this paper.”

Bambi emphasizes that human beings cannot personally venture to black holes due to the extreme accelerative forces—around 10,000 g—that nanocraft would need to endure. “Unless we discover a wormhole in the fabric of space-time to provide a shortcut,” he notes.

“We really need a nearby wormhole like in the movie Interstellar” to facilitate human missions,” he concludes. “Unfortunately, my assessment is that wormholes are purely theoretical at this point.”

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