Everything Everywhere Daily: History, Science, Geography & More - The WOW! Signal

Starting point is 00:00:00 On August 15, 1977, for a period of 72 seconds, the search for extraterrestrial intelligence had its greatest moment. A signal was received like none other before or since. However, in the over 45 years since the signal was recorded, astronomers have been unable to relocate it or even figure out what it was. Learn more about the wow signal, why it was important and what it could have been on this episode of Everything Everywhere Daily. What if your perceptions about the past were wrong? ThruLine is a podcast that takes you back in time to uncover the parts of the story that may have gone unnoticed. It effectively turned day into night and how it shaped the world now.

Starting point is 00:00:57 Time travel with us every week on the ThruLine podcast from NPR. In a previous episode, I discussed the search for extraterrestrial intelligence or the SETI project. To very quickly summarize, SETI was established to try to find signals from extraterrestrial civilizations using radio astronomy. Why try to detect civilizations using radio waves? Different wavelengths of light travel through space differently. And if you remember back to my episode on the electromagnetic spectrum, radio is just a form of light. While space is in near vacuum, there are gas and dust molecules that can inhabit interstellar space, which can block or absorb certain frequencies of light.

Starting point is 00:01:40 There are certain frequencies in the microwave range from about 1 to 10 gigahertz, which can pass through relatively unimpeded. Frequencies above this range tend to get absorbed in the atmosphere or in interstellar space. Frequencies below this range tend to be drowned out by the enormous amount of radio waves created by the core of the galaxy. The noise in this region is so great that it would be difficult to filter out a real signal from the noise. The band where communications would be possible, not being drowned out and not being absorbed, is known as the microwave window. So if we were to communicate with some civilization far away, this is the most likely place to check for messages. However, simply looking for radio waves really isn't enough.

Starting point is 00:02:25 Back in 1967, radio astronomers Jocelyn Bell and Anthony Hewish discovered something unexpected. They found something at the same point in the sky that pulsed with a little bit of the sky that pulsed with they signal every 1.337 seconds. Its signal was so regular that it was actually more accurate than atomic clocks at that time. At first, it was thought to be a signal from an extraterrestrial civilization. However, they soon found others like this and realized that it was a natural phenomenon. What they had found were dubbed pulsars, which stand for pulsating radio source. They result when extremely rapidly spinning neutron stars emits radio waves from its magnetic poles.

Starting point is 00:03:05 It's basically like a rapidly spinning lighthouse, and we can only see the signal when the beam of light hits us. In addition to spinning rapidly, it also tends to emit radio waves over a rather large region. In fact, spewing radio waves over a large band of radio spectrum is pretty much a hallmark of naturally occurring radio sources. When humans broadcast radio waves, we tend to do so over very narrow bands of frequency. That is why you can listen to different radio station, so close to each other on the dial. So a good place to look would be in the microwave window and a good thing to look for would be some sort of narrow band communication. However, there's one other thing. The microwave window is still pretty big. One to 10 gigahertz is a lot of spectrum to search. Within that window

Starting point is 00:03:54 is a smaller range of frequencies that hold special significance. Hydrogen is the most abundant element in the universe by a wide margin. When excited, hydrogen can emit electromagnet, genetic waves at 1.42 gigahertz at a wavelength of approximately 21 centimeters. Another important molecule is the hydroxyl molecule, which consists of one oxygen and one hydrogen. It has a wavelength of 1.612 gigahertz to 1.72 gigahertz. What do hydrogen and hydroxyl molecules make when you put them together? Water. This range from 1.42 gigahertz to 1.72 gigahertz is known as the water.

Starting point is 00:04:35 hole. This is a relatively short range of frequencies in the microwave window that correspond to two very important and common substances, hydrogen and water. I mention all of this, because there is a very specific place where astronomers are looking, and there is a very specific thing that they are looking for. They aren't just randomly listening to every radio signal in the sky. If there's some extraterrestrial civilization trying to send messages, a very narrow band signal, somewhere in the watering hole, seems like a very good place to search. With that, the story now turns to Ohio State University.

Starting point is 00:05:15 In the 1960s, they created one of the largest radio telescopes in the world known as the Big Ear. If you've ever seen a radio telescope or a photo of one, the Big Ear looks nothing like it. The Big Ear was the size of a football field. On one end was a 33-meter-long flat structure that could, tilt up and down, but not right to left. On the other end of the field was a parabolic structure that didn't move at all. And in between, the field was covered in tinfoil, and in the middle there were two radio receivers. The way it worked was that the flat end would bounce radio waves from space

Starting point is 00:05:49 towards the parabolic structure. The parabolic structure would then focus the radio waves into the radio receivers. The difference between it and a parabolic antenna was that you couldn't point it anywhere you wanted. You could only adjust it up and down. However, that was okay because you could use the rotation of the earth to move it right and left over time. The big ear was designed to conduct a survey of radio signals over the entire sky. The reflecting section would be set at a particular angle and the earth would revolve about its access, allowing an entire strip of sky to be analyzed. They could adjust the angle and just do it again, and they could just keep doing it until the entire sky was covered. And that's exactly what they

Starting point is 00:06:31 did. From 1963 to 1971, the Big Ear conducted the Ohio Sky Survey. They discovered almost 20,000 radio sources during this period. However, once the survey was completed, the Big Year was no longer a state-of-the-art instrument. But rather than dismantle it, in 1973, it was repurposed for the search for extraterrestrial intelligence, or SETI. The events which are the subject of this episode took place on August 15, 1977. The way that the system worked is that the radio telescope would listen for about 10 seconds near the 1.4 gigahertz frequency. An IBM 1130 computer would then take two seconds to analyze the data. It would then output a single alphanumeric character to indicate the strength of the signal to the background

Starting point is 00:07:18 noise. If the signal it heard was between zero and one standard deviations from background noise, it would just print a space, like literally nothing. If it was between one and two standard deviations it would publish a one. After nine, it used the letters of the alphabet. A was 10, B was 11, and so on. It would print out the results on paper, which humans would then analyze to look for any patterns. Most of the printouts were nothing but spaces and the number one, with an occasional two and maybe a three. Several days after the recording took place, a SETI volunteer physicist by the name of Jerry Eamon was reading the recordings taken on August 15th at 10.16 p.m. Eastern Daylight Time. On the printout, amongst the blank spaces ones and twos were six consecutive characters that had never been seen before.

Starting point is 00:08:07 6 EQUJ5. This was an enormous narrow band signal located right near the 1.4 gigahertz frequency. The exact thing that SETI researchers had been looking for. Jerry Eamon took a pen and circled the data on the printout and wrote next to it, Wow. Hence the name, the wow signal. I should note that 6EQ UJ5 was not some sort of code sent by aliens. 6EQ UJ5 is just how the computer system recorded the strength of the signal.

Starting point is 00:08:40 The six characters represented a full 72 seconds of the signal. The U part of the signal was the point where the signal was a full 30 standard deviations above the background noise. There is no known natural way for a narrow band signal of that strength to be sent. So the first question was, where did the signal come from? At the time the signal was recorded, the telescope was pointed towards the constellation Sagittarius in a particular section near the Messiae object number 55. Messier objects are points in the sky that aren't stars and are usually nebulae or galaxies,

Starting point is 00:09:17 and they'll be the subject of a future episode. The area of the signal came from couldn't be pinpointed exactly due to the dual receiver setup of the big ear. However, in the part of the sky, we can narrow the location down to, it contains over a million stars. While we know roughly where the signal came from, the other big question is, what was it? If there was any information contained in the signal, it couldn't have been recorded because that wasn't what the radio telescope was set up to do. Information in a radio signal would be sent through modulation of the signal, and as the system

Starting point is 00:09:50 was set up to average everything out over 10 seconds, the modulation would have been lost. No other radio telescope has ever detected anything like this in that area of the sky. There have been at least 50 different attempts to try to find the signal in the same patch of space. In May of 2022, several radio telescopes were pointed at this patch of sky for an extended period of time, and they found nothing. One theory holds that this was in fact some sort of extraterrestrial signal. However, whoever sent it is sending the signal out like a lighthouse beam. They're covering the sky, and our observation sweeping the sky,

Starting point is 00:10:25 just crossed their beam at the right point for only those 72 seconds. If this is the case, then why haven't we seen the signal since then? One problem could be that we're only looking intermittently. One of the longest searches ever conducted was done by the very large array in New Mexico, which only looked for 14 hours. One proposed theory that made the news back in 2017 was that it could have been a comet that it saw. That theory has pretty much been discredited because it wasn't actually in that part of the sky

Starting point is 00:10:53 at the time of the recording, and comets don't behave that way. The other theory, which seems the most likely, is that it came from some human source. The 1.427 gigahertz frequency is supposed to be dedicated to radio astronomy. However, it's possible somebody was broadcasting in that part of the spectrum,

Starting point is 00:11:10 even if it was accidentally. It could be that there was some piece of space junk that reflected a radio signal which was picked up by the ultrasensitive instrument. The truth is, we don't know. All we do know is that for, one brief moment in 1977, the exact sort of strong narrow band signal at the exact frequency astronomers were searching was recorded. And since then, it has never been seen again. Wow.

Starting point is 00:11:38 The executive producer of Everything Everywhere Daily is Charles Daniel. The associate producers are Thor Thompson and Peter Bennett. Today's view comes from listener Zell McGrane over on Apple podcasts in the United States. They write, so great. I love it. I have listened to every single episode twice. Thanks, Zell Mugran. I'm happy to announce that having listened to every episode twice, you have achieved elite platinum status in the Completionist Club. As an elite platinum member, you will get priority seating at the Completionist Club. You'll get to use the Elite Platinum member entrance and 24-hour access to the Completionist Club concierge. Remember, if you leave a review or send me a boostogram, you two can have it read on the show.

Everything Everywhere Daily: History, Science, Geography & More - The WOW! Signal

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