The mysterious FRB 121102 radio burst has just woken back up, right on schedule, beaming radio waves out into space. FRBs, or fast radio bursts, are some of the most pervasive things in astronomy, with researchers struggling to come up with an exact cause for these mysterious signals. FRB 121102 is a radio burst that repeats roughly every 157 days and is said to be coming from a dwarf galaxy 3 billion light-years away.
Astronomers have come across many Fast Radio Bursts over the past decade, but not every FRB is made equally. Appearing for only a fraction of a millisecond, most of these deep space signals are random, making them very difficult to study. FRB 121102 could help researchers close in on the cause of these mysterious signals, but there is still so much we don't know, and from the looks of it, space is much more "chatty" than we might have thought.
Could some of these signals be alien civilizations, or are they just an astronomical phenomenon? Let's start by looking at the signal that first wowed us all.
"Wow" what is that?
SETI, the Search for Extraterrestrial Intelligence, has been searching our skies for decades, on the constant hunt for any sign of alien life. It uses thousands of telescopes, in locations around the world, to accomplish this massive task. As you can imagine, the mountains of data collected from SETI need to be analyzed.
Sadly, SETI cannot afford a supercomputer, so they have created SETI at home, a downloadable program that allows you to use a tiny part of your home computer's power to process the data. This solution has proven to be effective.
Unfortunately, back in the 1970s, this was not the case. Though on a much smaller scale, data collected decades ago had to be reviewed by hand, which could be an extremely tedious task. This is where our story begins.
In 1963 The Big Ear, a telescope the size of two football fields, went into operation for the United States Ohio Sky Survey. This massive telescope scanned the night sky for radio waves in space. Throughout its lifetime, The Big Ear was able to catalog nearly 20,000 sources of radio waves, identifying the star or galaxy in which it originated. However, there was one signal that rocked the world of astronomy.
On August 18th, 1977, while reviewing one of the daily data print-outs from the sky scans, Jerry Ehman noticed a massive spike in a specific frequency of a radio wave, about 30 times what he was used to seeing.
Ehman was so taken back by his discovery that he wrote "Wow" on his print-out, hence why astronomers often call it the "Wow signal" The 72-second signal was odd for multiple reasons aside from its strength. First, the signal only occurred on one frequency, 1420MHz.
This frequency is banned from users across the world because researchers are so positive that if aliens were to contact us, they would use 1420MHz. Secondly, the "Wow Signal" seemed to behave like a telescope from a distant world scanning the sky, similar to how we scan the sky here on earth.
Next, astronomers tracked down the signal source to a place somewhere in the constellation of Sagittarius. However, they found no evidence of an astronomical event that would cause the 72-second radio burst.
For the past 40 years, researchers have been trying to solve this mystery. Researchers have even pointed to the comet 266P as a potential culprit, as the comet was somewhere in the region during the time of the Wow signal event.
However, astronomers have never seen a comet generate these specific types of radio waves. So, aliens? Perhaps. It has not been ruled out. Nevertheless, this would not be the first radio signal to leave astronomers dumbfounded.
Fast Radio Bursts are bizarre and don't make much sense
In 2007, a group of astronomers discovered one of the first FRBs, dubbed the Lorimer burst, a powerful, very brief burst of radio emission coming from an unidentified source in space. As mentioned above, FRBs have been an elusive mystery in the astronomy community.
Unlike the Wow signal discussed above, these radio signals are incredibly short, or "fast" lasting anywhere from a fraction of a millisecond to just a few milliseconds, and usually disappearing just as quickly as they appear. What is even more strange is that most of these fast radio bursts tend to occur without warning.
The elusive and random nature of these strange astronomical events has made them extremely difficult to study. Over the past decade, astronomers have identified dozens of potential FRBs. Yet the actual number of FRBs is believed to be much higher. Even more so, some of these signals from space seem to be repeating a bit like clockwork, i.e., FRB 121102.
This has led to wild speculation as the cause of these signals ranges from black holes and to, yes, aliens.
We have identified a repeating FRB from 500 million light-years away
A new piece of the puzzle was added to the FRB mystery in 2018 when Canadian researchers found not only 28 new bursts, but one radio frequency burst that repeats exactly every 16.35 days. Coming from a spiral galaxy 500 million light-years away, the mysterious source sends out one or two bursts of radio waves every hour, over four days. Then it goes quiet for 12 days, only to repeat the process. However, this may just be the beginning.
In 2020 the puzzle appeared to get even messier. Using the CHIME radio telescope, the same group of researchers has detected around 700 bursts from FRB sources, with nine of them repeating. This list of FRBs seems to be growing, as well as the theories surrounding them. Nevertheless, we are no closer to understanding what causes the radio bursts of energy. However, astronomers do have some guesses.
Are neutron stars and black holes the potential culprit?
For the uninitiated, neutron stars are like the stellar phoenixes of the universe. When a star approximately 8 to 29 times more massive than our own sun explodes in a stunning supernova, they can leave behind a small dense core of neutrons that continues to collapse in on itself, forming a roughly city-sized object called a neutron star.
These objects are so dense that it has been said a single teaspoon would weigh a billion tons. Also known as the Tolman Oppenheimer Volkov Limit, these city-sized stars can collapse in on themselves after acquiring more mass, leading to the formation of a black hole.
But, that is not the only way a neutron star can become a black hole. On the rare occasion when two neutron stars collide, this is thought to create a black hole releasing tremendous amounts of energy and radio waves across the universe. Researchers believe this could be one potential explanation for the mysterious periodic FRB signals from space.
There is also an argument that two colliding black holes would have a similar effect, sending off massive amounts of energy in all directions in space. However, at the moment, these are all just theories and do not explain repeating signals like FRB 121102.
So it must be aliens, right?
Let's be honest. We have a tendency to write-off any odd astrological phenomena as "aliens" when we can't explain it adequately. Yet, the universe is a massive place filled to the brim with phenomena we have yet to witness or understand. But, some researchers have not ruled out this possibility. There is a theoretical paper by astrophysicists Avi Loen and Manasvi Lingam that argues that the FRB patterns could be from extraterrestrials.
Nonetheless, there is a big issue with the alien argument, energy. These signals are insanely powerful explosions of energy, which is why stars and black holes are considered the most likely culprits. FRBs release about as much energy as our sun does in 80 years. It is highly unlikely that an alien civilization would create pulses of energy that strong.
At the moment, researchers at CHIME are finding more and more of these mysterious signals and believe that these FRBs are far more common than were previously thought. Repeating signals like the famous FRB 121102 have given researchers a little more to work with, allowing them to speculate on the cause of these mysterious signals. At the moment, black holes and neutron stars could be the culprit. Only time will tell. Nevertheless, things like the Wow signal still offer us a little bit of extraterrestrial hope.