Astronomer says aliens might zap black holes with lasers to travel the galaxy

nbc ^ | 03/15/2019 | Rafi Letzter, Live Science

[BenLurkin]

Spacecraft already navigate our solar system using gravity wells as slingshots.

The same basic principles operate in the intense gravity wells around black holes, which bend not only the paths of solid objects, but light itself. If a photon, or a light particle, enters a particular region in the vicinity of a black hole, it will do one partial circuit around the black hole and get flung back in exactly the same direction. Physicists call those regions "gravitational mirrors" and the photons they fling back "boomerang photons."

Boomerang photons already move at the speed of light, so they don't pick up any speed from their trips around black holes. But they do pick up energy. That energy takes the form of increased wavelength of the light, and the individual photon "packets" carry more energy than they had when they entered the mirror.

Kipping, the Columbia astronomer, proposed that an interstellar spacecraft could fire a laser at the gravity mirror of a fast-moving black hole in a binary black hole system. When the newly energized photons from the laser whipped back around, it could re-absorb them, and convert all that extra energy into momentum...

This system, which Kipping termed the "halo drive," has a big advantage over more traditional lightsails: It doesn't require a massive fuel source.

[samtheman]

Seems like it would only work while you’re reasonably close to the black hole. Even slightly far away — let’s say 10 light years — it takes the light beam 20 years to whip around and get back to you. I guess that is overcome by having a steady stream “in the pipeline”, however, the article does mention the effect weakening over distance and I bet that effect is huge and that this method would only be practical for moving around in the vicinity of a black hole. But then again, I am not a rocket scientist, so what do I know?

[Beowulf9]

I’m pretty skeptical of these claims but I have to say I don’t honestly know, but it seemed pretty incredible to think that would work.

I was just playing around with creative writing and sarcasm. Still skeptical of outlandish claims but you’re right, it takes ideas and imagination yet I think these are more ‘look at me’ than real ideas.