The book follows the protagonist to the edge of the Solar System where he discovers a quantum gateway for interstellar travel. And that gave Gillon, who led the team that discovered the planets in the TRAPPIST-1 system, a real-world idea straight out of sci-fi.
“I had this idea of assuming an ancient civilization that would have explored the whole galaxy using self-replicating probes,” Gillon tells Inverse. “And they would use this gravitational lensing technique to communicate from one system to the other.”
Gillon thought of a galactic scale communication network that uses stars to boost its communication. In a study posted on the preprint server Arxiv, Gillon and his colleagues suggest one star as the ideal candidate to intercept that interstellar communication line. And it’s one that Star Trek: The Next Generation fans will recognize instantly.
HERE’S THE BACKGROUND — The study presupposes that aliens not only exist, but they are far more advanced than human civilization. This hypothetical ancient alien civilization uses self-replicating probes known as the von Neumann probe.
The idea was proposed by Hungarian-American mathematician and computer scientist John von Neumann in 1966, who suggested that the most effective way of space exploration would be to design self-replicating robots.
These robots would seek out raw material from asteroids or moons, and even entire planets, to create copies of themselves. The replicas would travel across the cosmos, going from one star system to the next.
Once they have explored the entire Milky Way galaxy, Gillon also suggests that the super-advanced aliens would use stars to improve their communication network through gravitational lensing.
Gravitational lensing was first predicted by Einstein’s Theory of Relativity. It occurs when a large object like a star or galaxy passes in front of an object in the background, distorting and amplifying the light coming from a distant source within the same line of sight.
Theoretically, a civilization could use the same effect to amplify transmissions. By aligning the beam of communication with a star, they would use gravitational lensing to create a focused beam of outgoing information to another star.
WHAT’S NEW — Taking this scenario one step further, the scientists behind the new study also assume that our own Sun is part of the communication network.
Artem Burdanov, postdoctoral associate at MIT’s Department of Earth, Atmospheric & Planetary Sciences, and co-author of the study, explains how this could be taking place unbeknownst to us.
“Under this hypothesis, our Sun should also have such probes,” Burdanov tells Inverse. “And these local probes should communicate with the nearest stellar systems to us, so it could be Proxima Centauri, Barnard’s star, or Wolf 359.”
The scientists decided to focus on neighboring star Wolf 359 as a prime candidate for detecting interstellar communication. The star is about 7.9 light years away, and has two candidate planets, though neither are believed to be habitable. It also is the site of a confrontation between the Federation and the Borg in Star Trek: The Next Generation.
“I noticed that one of the nearest stars, in fact the third nearest star, Wolf 359 is kind of special because it lies in the mean orbital plane of the Earth,” Gillon says.
Considering Earth’s position from the star Wolf 359, the planet should cross the beam of communication traveling towards the star every year, “meaning that we have an opportunity every year to eavesdrop on the communication from the probe,” Gillon says. That beam would be detectable in infrared wavelengths.
The team then went hunting for these signals, using the telescopes TRAPPIST and SPECULOOS to try and detect this beam of interstellar communication. However, their first attempted search came up empty.
“But it still doesn’t mean that it doesn’t exist,” Gillon says. “Maybe the probe is using another wavelength.”
WHAT’S NEXT — Gillon is not giving up yet.
The team will continue their search using different telescopes. Although they have not jumped back in just yet, they are eyeing small ultraviolet telescopes known as nanosatellites.
But as far as how long it would take the human civilization to reach the same amount of technological advancement as this galactic exploring alien civilization, there’s still a bit of time left.
“Theoretically, nothing prevents us now from making such a probe and to have it in our Solar System,” Burdanov says. “But we need to be quite more advanced to really explore our galaxy with such probes.”
Abstract: Under the hypothesis that self-reproducing probes have formed a galactic-scale communication network by direct Gravitationally-Lensed (GL) links between neighboring systems, we identify Wolf 359, the third nearest stellar system, as an excellent target for a search for alien interstellar communication emitted from our Solar System. Indeed, the Earth is a transiting planet as seen from Wolf 359, meaning that our planet could pass in an alien communication beam once per orbit. We present a first attempt to detect optical messages emitted from the Solar System to this star, based on observations gathered by the TRAPPIST-South and SPECULOOS-South robotic telescopes. While sensitive enough to detect constant emission with emitting power as small as 1W, this search led to a null result. We note that the GL-based interstellar communication method does not necessarily require to emit from the so-called "Solar Gravitational Line" (SGL), starting at ~550 au from the Sun, and that the probe(s) could be located closer to the Sun and off-center relative to the SGL, at the cost of a smaller but still significant gain compared to a non-GL-boosted communication strategy. Basing on this consideration, we searched in our data for a moving object whose motion would be consistent with the one of the hypothesized alien transmitter, assuming it to use a solar sail to maintain its distance to the Sun. We could not reliably identify any such object up to magnitude ~23.5, which corresponds to an explored zone extending as far as Uranus' orbit (20 au).