In the decades-long search for extraterrestrial intelligence, there has never been validated proof of an alien signal. There have, nevertheless, been a couple of tantalizing secrets. Possibly the biggest of these is referred to as the Wow Signal.
Observed on 15 August 1977 by the Big Ear radio telescope at Ohio University, the signal was a strong, continuous, narrow band radio signal lasting a minimum of 72 seconds. Our knowledge of the signal is limited given the design of Big Ear. Rather than being able to track radio signals like a lot of modern radio telescopes, Big Ear was set to a specific elevation and count on Earths rotation to scan throughout the sky. Since thats how long it took the source to sweep throughout Big Ears observation range, the factor the Wow Signal lasts 72 seconds is.
Astronomers simply set it up, and it would run on its own, taping the strength of signals as it goes. Because of this, the signal was only discovered days after the event when taped observations were evaluated.
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Observed on 15 August 1977 by the Big Ear radio telescope at Ohio University, the signal was a strong, continuous, narrow band radio signal lasting at least 72 seconds. Since of this, the signal was only found days after the occasion when taped observations were reviewed. Regardless of having simply one observation, the Wow Signal is thought about the greatest prospect for an extraterrestrial signal. The most standard concept is that the signal was of terrestrial origin, maybe an airplane passing overhead, or a radio signal spread off area debris. A scattered signal is possible, however the strength of the signal would be uncommon, and the frequency of the Wow Signal is within a range where transmissions are restricted.
An aerial view of the Big Ear telescope. Credit: Bigear.org/ NAAPO
Regardless of having simply one observation, the Wow Signal is thought about the greatest prospect for an extraterrestrial signal. A scattered signal is possible, but the strength of the signal would be unusual, and the frequency of the Wow Signal is within a range where transmissions are limited.
A number of years ago it was proposed that the signal may have been triggered by comets that were near the observed location of the sky, however this has because been disproven. While 2 comets were close to the source area, they werent really within the observed range. And comets arent likely to release such a strong narrowband signal.
One interesting aspect of the signal is that its frequency was very close to that of the so-called 21-centimeter line. If you desired to get the attention of alien astronomers, a strong signal near that frequency would be a great method to do it.
Plot of signal strength vs time of the Wow! signal on August 15, 1977. Credit: Maksim Rossomakhin
Provided the alluring nature of the Wow Signal, there have been several efforts at repeat observations. Every observation in that location since has turned up absolutely nothing. Well, one method to take on the problem is to look at what your observations omit.
In this work, the authors argue that the source might be some kind of stochastic repeater. Astronomers have considered this idea, and have made observations that rule out a source with a regular periodicity. Rather than having a quantifiable duration, stochastic repeaters repeat somewhat randomly.
Using Bayesian stats to a most likely outcome. Credit: Wikipedia
On the face of it, this looks like a silly concept. Weve never seen the Wow Signal repeat, and weve proved it cant be duplicating regularly, however maybe its been repeating non-randomly such that weve never ever observed it. It sounds like the authors are arguing that it must be a non-random repeater since weve never observed it repeat. However the concept isnt as ridiculous as it sounds. The authors take a look at when an unnoticed burst might have taken place, and apply Bayesian data to compute when a future burst might take place.
Understanding of one burst occasion, and knowing when other burst occasions have not taken place, the authors compute the times at which future occasions are most likely. If the Wow Signal was a stochastic repeater, then well likely capture a new event. If we dont see another occasion, we can rule out stochastic repeaters as a likely cause.
Referral: David Kipping and Robert Gray. “Could the Wow signal have originated from a stochastic repeating beacon?” arXiv preprint arXiv:2206.08374 (2022 )
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