“Our galaxy may be teeming with technologically active life or populated by a single very long-lived civilization. In either case, we should be incredibly lucky to get a detection one day,” wrote physicist Claudio Grimaldi in an email to The Daily Galaxy about the possibility of there being a fundamental flaw in why we have not received a signal from an advanced alien civilization.
In contrast to Harvard astrophysicist Avi Loeb’s optimism that extraterrestrials are less speculative than dark matter or extra dimensions, a study posted in September of 2018 conducted by three scholars from the Future of Humanity Institute (FHI) at Oxford University, suggesting that although we exist in a universe with a potential 50 quintillion habitable planets, the expectation that life — from inorganic to bacteria to sentient beings —abiogenesis– has or will develop on other planets as it has on Earth, might be based more on optimism based on a sample of one.
It is conceivable that a civilization advanced enough to see itself in a cosmological context would think of a way to make itself known to the universe. In “The Messenger: A Galactic Center Gravitational-Wave Beacon” pre-print on Arxix, an international team of researchers have proposed a hypothetical alien craft, a beacon at the Milky Way’s Galactic Center, “The Messenger”, that emits gravitational waves that are “unambiguously artificial”.