In 1977, the Ohio State University’s Big Ear radio telescope captured a signal from space so strange that scientists are still baffled by it almost 50 years later.
For decades, scientists have struggled to find any natural process capable of producing the 72-second burst which prompted astronomer Jerry Ehman to write ‘WOW!’ on the telescope’s readout.
Now, new analysis of the so-called WOW! signal has revealed that it might have been caused by a hugely powerful laser slamming into Earth.
Experts say this was not the first salvo of an alien invasion, but rather the entirely natural product of a rare alignment between a collapsed star and a cloud of cool hydrogen.
Unfortunately for alien-hunters, scientists from the University of Puerto Rico at Arecibo say this new evidence shows that the WOW! signal is not evidence of life beyond Earth.
For decades, scientists have struggled to find any natural process capable of producing the 72-second burst which prompted astronomer Jerry Ehman to write ‘WOW!’ on the telescope’s readout
When the WOW! signal hit Earth, many scientists put forward the idea that this could have been the first ‘hello’ from a distant alien civilisation.
The signal was not only uniquely powerful but also arrived in an unusually narrow band of frequencies around 1420 MHz – similar to those produced by atomic hydrogen.
Since hydrogen is so abundant in the universe, some suggested that advanced civilisations might be using its frequency as a calling card for signalling to other intelligent species.
Other natural explanations for the signature have been proposed, such as passing comets releasing clouds of gas.
In the absence of any good natural explanation, the idea that the WOW! signal was a ‘technosignature’ from another world became widespread.
Now, Professor Abel Méndez and his colleagues believe they have identified a series of similar signals which could explain the WOW! signal’s origin.
The made the discovery by combing through the archives of the now-collapsed Arecibo Observatory’s Radio Emissions from Red Dwarf Stars (REDS) project.
Since this telescope had a similar experimental set-up to the Big Ear radio telescope, he hoped that it would be able to reveal if anything like the WOW! signal had ever been spotted.
The researchers spotted several signals which appeared to be extremely similar to the WOW! signal, albeit considerably fainter.
In 1977, the Ohio State University’s Big Ear radio telescope (pictured) captured a signal from space so strange that scientists are still baffled by it almost 50 years later
Researchers have used data from the now defunct Arecibo Observatory (pictured) to find signals that match the original WOW! signal. This evidence suggests it could be been the product of a giant space laser
Four of those originated from the tiny red dwarf star, Teegarden’s Star, which is just 12.5 light-years from Earth.
Professor Méndez says: ‘Our latest observations, made between February and May 2020, have revealed similar narrowband signals near the hydrogen line, though less intense than the original Wow! signal.’
What makes Teegarden’s star unique, however, is that it is surrounded by clouds of cool atomic hydrogen.
When intense light from the red dwarf hits these clouds of hydrogen atoms, they are stimulated to produce a powerful burst of microwave energy in the 1420 MHz.
Researchers spotted similar bands of energy (pictured) being produced at fainter levels from a nearby red dwarf star called Teegarden’s Star. Importantly this star is surrounded by clouds of atomic hydrogen
The result is an entirely natural microwave laser, or maser, within the hydrogen range which looks extremely similar to that of the WOW! signal.
The researchers argue that the WOW! signal was likely produced when an even more powerful burst of energy collided with a similar hydrogen cloud, producing an even bigger maser.
A burst that powerful is rare, but could have been produced by a type of neutron star called a magnetar.
These are formed when a star collapses and explodes into a supernova, leaving behind an ultra-dense, fast-spinning core with an extremely powerful magnetic field.
If the burst from a neutron star hit a cloud of cool hydrogen gas it could trigger a colossal maser burst just like the WOW! signal.
The signal may have been produced by a microwave laser triggered by the collision of energy from a magnetar (artists impression pictured) and a cloud of hydrogen gas. This means that the Wow! signal is not evidence for alien life
Since it would be extremely rare for a magnetar to line up with a hydrogen cloud in just the right way, this also explains why we haven’t heard the signal again.
If true, this would mean there is no need to suppose that the WOW! signal is evidence of alien life.
In their paper, published on arXiv, Professor Méndez and his colleagues write: ‘Our hypothesis accounts for all observed characteristics of the Wow! signal introduces another source of false positives in technosignature searches, and suggests that this signal represented the first recorded astronomical maser flare in the hydrogen line.
‘We will continue with Arecibo Wow! exploring our extensive sets of observations from Arecibo REDS. Future studies will incorporate archival data from the Arecibo Observatory.’
WHAT IS THE FERMI PARADOX?
The Fermi Paradox questions why, given the estimated 200bn-400bn stars and at least 100bn planets in our galaxy, there have been no signs of alien life.
The contradiction is named after its creator, Italian physicist Enrico Fermi.
He first posed the question back in 1950.
Fermi believed it was too extraordinary that a single extraterrestrial signal or engineering project has yet to be detected in the universe — despite its immense vastness.
Fermi concluded there must a barrier that limits the rise of intelligent, self-aware, technologically advanced space-colonising civilisations.
This barrier is sometimes referred to as the ‘Great Filter’.
Italian physicist Enrico Fermi devised the so-called Fermi Paradox in the 1950s. It explores why there is no sign of alien life, despite the 100 billions planets in our galaxy
If the main obstacle preventing the colonisation of other planets is not in our past, then the barrier that will stop humanity’s prospects of reaching other worlds must lie in our future, scientists have theorised.
Professor Brian Cox believes the advances in science and engineering required by a civilisation to start conquering the stars ultimately lead to its destruction.
He said: ‘One solution to the Fermi paradox is that it is not possible to run a world that has the power to destroy itself and that needs global collaborative solutions to prevent that.
‘It may be that the growth of science and engineering inevitably outstrips the development of political expertise, leading to disaster.’
Other possible explanations for the Fermi Paradox include that no other intelligent species have arisen in the universe, intelligent alien species are out there — but lack the necessary technology to communicate with Earth.
Some believe that the distances between intelligent civilsations are too great to allow any kind of two-way communication.
If two worlds are separated by several thousand light-years, it’s possible that one or both civilisation will be extinct before a dialogue can be established.
The so-called Zoo hypothesis claims intelligent alien life is out there, but deliberately avoids any contact with life on Earth to allow its natural evolution.
