A new study has suggested that aliens might be shooting a laser at the gravity mirror of a fast-moving black hole in a binary black hole system to travel across galaxies.
The lead author of the study, published in the pre-print journal arXiv, David Kipping has termed this technique 'Halo Drive,' and he believes that this technique has a big advantage when compared to traditional light sails, as it demands very less energy.
It should be noted that current light sail proposals demand a huge amount of energy to accelerate the spacecraft to a speed that is actually a significant fraction of light speed. Interestingly, this amount of energy is much more than the total energy humanity has produced in its entire history.
Kipping argues that using the technique of halo drive, all the energy required could be sapped from black holes, and no extra fuel source is needed.
Kipping admitted that the technique of halo drive too has its limits. As per Kipping, at a certain point in time, the spacecraft will start moving so quickly away from the black holes and as a result, it will fail to absorb enough energy to add up additional speed. In order to solve this problem, the laser can be moved off the spaceship on to a nearby planet. Thus without reabsorbing the laser light, the planet would have to burn fuel to generate beams continuously, and would eventually dwindle away.
Kipping believes that such a technique might be used by advanced alien civilizations to navigate across the Milky Way. As per Kipping, there are many black holes around, and if an alien civilization is so advanced, they might be already using sophisticated techniques like this to travel across.
The scientist also added that extraterrestrial life can be searched from this dimension too. As alien civilizations might be sapping energy from black holes, humans could detect signs of alien life from the eccentric orbits of binary black holes.
Kipping added that if no alien civilizations are using this technique now, then humans could be the first species to this sophisticated travel method.