Long-lasting civilizations may have various motivations to relocate elsewhere in the galaxy. For instance, they might need to escape an impending supernova. They could also be scouting for new natural resources.
However, considering the vast distances between stars, interstellar travel is extremely challenging and time-consuming. Therefore, instead of leaving their own system, extraterrestrial beings might choose to bring their star system with them. The primary advantage of accelerating their own star is that they can keep it close as they move. They would achieve this by causing their star to emit or evaporate material in one direction, which would push the star, along with all its planets, to a new position in the galaxy.
Illustration of a Dyson Sphere, a hypothetical structure that aliens could use to harness the power of stars.
In a recent paper, Clement Vidal, a philosopher at Vrije Universiteit Brussels in Belgium, pointed out that most stars are not solitary but belong to binary star systems. This means we might be overlooking half of the stars that could potentially be artificially accelerated. Vidal examined a model system consisting of a neutron star with a low-mass star orbiting it. This setup provides the most flexibility in terms of maneuverability and thrust.
Extraterrestrial civilizations would need to figure out how to expel material from the star. The goal is to cause the star to push more material in one direction than another. This would create thrust, pushing the binary star system in the opposite direction, Vidal explains.
If a civilization places machinery on or near the neutron star, where the strong gravitational pull could provide readily available energy, they could control the binary system by carefully turning the machinery on and off. They might even steer their system in new orbital directions by changing the orientation of the machinery.
Remarkably, there are actually systems in the universe that fit these characteristics, such as the black widow pulsar PSR J0610-210 and redback pulsar PSR J2043+1711. Both of these systems exhibit significant acceleration. Although they are unlikely to be caused by extraterrestrial technology, they are worth studying, Vidal concludes. At least as long as they continue to exist.
