For most of us, snipers evoke some unsettling imagery—a lone cold-blooded gunman, undetectable, and on the hunt. Operating from afar, these marksmen eliminate their target with precision. Without hesitation.
Now, let’s scale it further. Imagine a cosmic sniper, packing the fire power of billions of stars from thousands of galaxies, firing its weapon towards us. What'd happen you ask? We'd be totally obliterated.
As explained by Kurzgesagt's latest episode, cosmic snipers, in the form of black holes, can actually emit extremely powerful energies called gamma ray bursts (GRB). So powerful that if it was shot even a few thousand light-years away from us, it would totally overwhelm our ozone layer, stripping it off completely, leaving the planet scorched by the Sun's radiation.
Understanding Gamma Ray Bursts
Gamma rays are electromagnetic waves that carry energy just like visible light, only that a single photon of it packs more energy than a million visible photons combined. These rays are feared, even in small and dispersed amounts, as it disrupts the delicate biochemical machinery that keeps humans alive. Much like a drunk old man running over your Jenga tower.
Fortunately, our beloved ozone shields us from most gamma rays before they can harm us—but that's not the case for the extremely focused GRB's.
Using NASA's Fermi Gamma-ray Space Telescope, we have observed two types of these GRB's—the short and long GRB'S. While causes are different, both scenarios still end with the same thing, with a black hole that's surrounded by a magnetised disk of gas left over from its parent star, capable of shooting out extremely focused jets of gamma rays that erupt out of the black hole like a laser gun.
Perhaps, these gamma ray bursts provide the reason as to why we haven't seen any unambiguous signs of extraterrestrial life yet. Its destructive power alone is believed to be wiping out huge chunks of ET life on a regular basis, firing blindly and randomly into the dark.
Fortunately, all the bursts we’ve detected so far are too far away to hurt us. Seeing as gamma-ray bursts travel at the speed of light, we have no way of detecting it until it hits us and kills us all. As a matter of fact, one could be heading towards us right now, undetected and unexpected.