Why haven't we met aliens? Gamma-ray bursts may hold the answer

NEW DELHI: Astronomer Frederick Walter from Stony Brook University in New York has proposed that

extraterrestrial civilizations

might have been wiped out by

gamma-ray bursts

(GRBs), offering a possible explanation for the absence of contact with

alien life

. His views were reported in the Daily Mail on Tuesday.
GRBs, which Nasa describes as short-lived but extremely bright eruptions of light, possess a luminosity a quintillion times that of the Sun.

"It’s a tightly focused beam. And, if it’s directed through the plane of the galaxy, it could basically sterilize about 10% of the planets in the galaxy," Walter explained. He estimates that such bursts occur roughly every 100 million years in any given galaxy.
Over the span of a billion years, this could mean significant devastation for potential civilizations. "Over a billion years, on average, you might expect a significant number of civilizations to be eradicated, should they exist... It’s just one of many possible explanations, sort of morbid, I suppose," he remarked.
Despite the potential threat GRBs pose, Walter reassured that the probability of Earth being hit by such an event is low. "They’re rare, and they’re directed," he stated, indicating that the direct trajectory makes them unlikely to impact Earth.

Walter also discussed other potential reasons why humans have not yet detected extraterrestrial life. He speculated that some alien worlds could harbor life forms akin to aquatic species, such as whales and dolphins, which would be incapable of developing technology necessary for space travel or communication.
Furthermore, he suggested that some civilizations might avoid contact with other potentially dangerous life forms. Another grim possibility he mentioned is that technologically advanced alien societies might destroy themselves. "Just look around, you know? We’re polluting the atmosphere. We’re making it questionable as to whether we’re going to have a viable civilization in a century, unless we do something drastic. If civilizations tend to evolve in the same way that they have on our planet, then that’s going to hit everybody," he warned, noting the risk of not surviving another 150 years at our current pace.
This theory of gamma-ray bursts adds another layer to the ongoing debate about the

Fermi Paradox

and why, despite the vastness of the universe, humanity still stands seemingly alone.