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Aliens can shoot lasers to black holes to travel the galaxy

(NASA/JPL-Caltech)

An astronomer from the University of Columbia has a new guess about how the hypothetical extraterrestrial civilizations could be invisible to navigate in our galaxy: the Firing of lasers in binary black holes two black holes orbiting one another).

The idea is a futuristic upgrade of a technology NASA has used for decades.

Now, spacecraft all navigate our solar system using the gravity wells as catapults. The spacecraft itself will orbit around a planet, throws himself in as close as possible to a planet or the moon to pick up speed, and then that extra energy to travel even faster to his next destination. In doing so, it saps away a small fraction of the planet is sailing through space — but the effect is minimal, and it is almost impossible to notice. [9 Strange, Scientific Reasons why We Haven’t Found Aliens Yet

The same principles work in the intense gravity wells around black holes, bend not only the paths of objects, but light itself. If a photon, or light particle, is in a certain region in the vicinity of a black hole, a partial circuit around the black hole and slammed back in exactly the same direction. Physicists call these regions “gravity mirrors,” and the photons they fling back “boomerang photons.”

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Boomerang photons are already moving at the speed of light, so they don’t get an speed of their travel through black holes. But they pick up energy. That energy takes the form of a higher wavelength of light, and the individual photon “packets” more energy than they had when they in the mirror.

That comes at the expense of the black hole, sapping some of its momentum.

In a paper published in the preprint journal arXiv on March 11, David Kipping, the Columbia astronomer, proposed that an interstellar spaceship would be able to fire a laser at the gravity mirror of a fast moving black hole in a binary black hole system. When the new energy of the photons of the laser whipped around again, it could re-absorb them, and convert all that extra energy — impulse for firing the photons back at the mirror again.

This system, that Kipping is called the “halo drive” has a big advantage compared to more traditional lightsails: It is not necessary to be a great source of energy. Current lightsail proposals need more energy to accelerate the space shuttle “relativistic” speeds (in the sense of a significant fraction of the speed of light) than mankind has produced in all of history.

With a halo drive, all that energy can only be undermined, of a black hole, rather than on the basis of a fuel.

Halo disks have limits — at a certain point, the spacecraft would move so quickly away from the black hole that it would not absorb enough light energy to extra speed. It is possible to solve this problem by moving the laser from the spaceship and on a nearby planet, he noticed, and just exactly focus the laser as it turns out from the black hole, the gravity well to hit the spaceship. But without re-absorbing the laser light from that planet would have to burn fuel to generate new beams constantly, and would eventually dwindle away.

A civilization can be with the help of a system like this to navigate in the Milky way now, Kipping wrote. There are certainly enough black holes out there. If that is the case, that the civilization could be undermining so much momentum of black holes that would mess with their jobs, and we can detect the signs of alien civilization from the eccentric orbits of binary black holes.

And if there are no other civilizations are there to do, he added, perhaps humanity would be the first.

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Originally published on Live Science.

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