In everyday life, it’s easy to forget that the Universe is busy smashing together objects more massive than the Sun, creating unimaginably small and dense singularities. It’s out there, making new stars out of gas and dust, building planets of every imaginable size and composition, and (at least once) making little creatures that can look up at the night sky and ask, “What the hell is that? ”
Scattered among the stars, planets, nebulae, and galaxies that astronomers study, they sometimes pick up rare and short-lived radio signals from outer space. These Fast Radio Bursts (FRBs) last only milliseconds and most of them never appear again. Despite their rarity and short lifespan, FRBs have incredible power. It is estimated that some of the FRBs we have detected were the result of an energy release on the order of half a billion suns.
They’re powerful, they come unannounced, and we don’t know exactly what’s causing them. They’re the kind of cosmic phenomenon that practically begs for an extraterrestrial explanation. When Harry Vanderspeigle (played by Alan Tudyk in SYFY’s Resident Foreigner, streaming now on Peacock!) were here, he would surely tell us they are the result of some incredible alien weapon or communications system beyond our imagination. But he’s not here, so we must rely on the talents of mankind’s brightest minds. You can find them at the beginning of an article recently published in the magazine natural astronomy.
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Due to their rarity, astronomers cannot simply point their detectors at an incoming FRB because they don’t know where to point. All of our discoveries, more than 600 to date, are due to serendipity when astronomers happened to point their instruments at the right part of the sky at the right time.
The leading hypothesis for their cause is young magnetars, a type of neutron star with an overactive magnetic field. The field wants to expand, but is pulled in by the intense, almost overwhelming pull of the neutron star’s gravity. The result is a flickering, flickering field that occasionally sends intense bursts of radio into space. That could explain some FRBs, and indeed appears to explain one that occurred in our own galaxy in 2020, but scientists aren’t convinced that’s the whole story.
Now, however, thanks to another happy coincidence, scientists have another lead, this time in two separate labs. On April 25, 2019, scientists from the Canadian Hydrogen Intensity Mapping Experiment (CHIME) imaged a bright FRB coming from about 520 million light-years away. Two and a half hours earlier, scientists at the Laser Interferometer Gravitational-Wave Observatory (LIGO) had detected a gravitational-wave event from roughly the same location. The fact that they both appeared around the same time and from roughly the same region of space seemed like too much of a coincidence. In fact, scientists calculated the probability to be about half a percent.
That’s about as close to a smoking gun as you can hope. The LIGO detection occurred when two orbiting neutron stars collided and merged, sending ripples through spacetime itself. It is the collision that would have caused the gravitational waves and would have been picked up by LIGO, but the FRB resulted from what happened over the next few hours.
The two neutron stars were already incredibly dense, which is one of their key distinguishing features. Neutron stars are made up of densely packed neutrons, all packed together like sardines. Neutron stars are the densest stars (read: the densest three-dimensional objects) in the universe. They cannot get denser and still have dimension because their particles are already as close as they can physically be. They are prevented from collapsing further by the quantum degeneracy pressure, which basically requires that no two particles exist in the same space at the same time. After the collision, the same rules apply, but now the combined object has to deal with a lot more mass. So much mass that it’s able to overcome the pressures of quantum degeneracy and collapse into a singularity, but it doesn’t, at least not for a while.
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Immediately after the collision, the new and more massive star is still spinning rapidly. The twist pulls material away from the center, like a ball being swung at the end of a rope. As the spin slows, the outward pull decreases, fails, and the system collapses. The magnetosphere is ejected, creating an FRB as the neutron star collapses into a shiny new black hole.
The time lag of 2.5 hours between gravitational-wave detection and FRB detection is consistent with the combined neutron star’s pre-collapse survival time. By pointing the right instruments at the right objects at the right time, you can receive both signals in quick succession, like the distant rumbles and crackles of cosmic thunder and lightning.
The universe is wonderful and exciting, even if it’s full of aliens who want to take over our planet. Prevent the alien apocalypse with Resident Alien, streaming now on Peacock!