Amri Wandel, an astrophysicist from Hebrew University of Jerusalem, has recently published a scientific paper that has yet to be reviewed by peers. His paper offers a new resolution to the Fermi paradox - which has long been a topic of debate among scientists. According to Live Science, Wandel's paper suggests that extraterrestrial civilizations only seek out planets that are teeming with highly advanced technologies, and because Earth doesn't host such technology, they have not reached out to us. In other words, they have not found any signs of intelligent life on our planet. For years, researchers have sought to understand why aliens have not made contact with humans, and Wandel's paper adds another possible explanation to the mix.
He put forward four hypotheses. The first supposes that aliens could have come to Earth in the distant past before humans created the first civilizations, however, it appears their interest in our planet declined after that. The second theory suggests that interstellar travel may be more challenging than thought and alien civilizations may not have the technology to reach such distant locations. The third supposes that a certain alien civilization may have recently discovered how to explore its closest area of space, but they have not yet ventured beyond their own solar system. Finally, the fourth proposes that these aliens do not wish to explore more distant galaxies, or maybe a disaster destroyed them before they had the chance.
Wandel suggests that while intelligent life in our galaxy is not only present, but rather abundant, extraterrestrial civilizations likely send signals that are directed towards planets they deem interesting, with species they consider to be capable of cognition. Earth's signals, sent out only relatively recently, could be indicative of the intelligence of our species; however, their reach is limited, as they can only reach planets orbiting about 15,000 stars, compared to the estimated 400 billion stars in our galaxy. This implies that our signals may not be capable of reaching other civilizations, possibly meaning that even if aliens are aware of the presence of life on Earth, they might not be aware of its intelligence.
Despite the likelihood that the aliens have picked up our signal, the reply may not have travelled back to Earth yet. Furthermore, Wandel suggested that aliens may not be able to decipher the message that was sent. Thus, even though there may be a limited quantity of advanced civilizations in our galaxy, the signal from Earth could still be grasped by those further out and comprehended. Therefore, a potential explanation is that they are waiting for recognition of our species as a space-exploring society.