SCOTT SIMON, host:
For 50 years scientists have been searching the skies for some sign that somebody is out there. They call this project SETI, the Search for Extra Terrestrial Intelligence, and so, far 50 years in, there hasnt been a message, a signal, a contact, anything to be called a communication from an alien planet - with one possible exception.
Here's science correspondent Robert Krulwich.
ROBERT KRULWICH: I'm going to take you back to the moment when SETI scientists thought maybe this is it - the real deal - a signal from an intelligent alien. It happened 33 years ago, on August the 15th, 1977. And because science writer Michael Brooks has investigated this in great detail, he's going to help me.
So where are we?
Mr. MICHAEL BROOKS (Science Writer): We're in Delaware, Ohio, at an observatory, a radio telescope called The Big Ear.
KRULWICH: So picture a large curved dish-like thing standing on a platform, an aluminum covered platform. Its all alone in an empty Ohio field.
Mr. BROOKS: So youre almost at midnight. There's nobody there to listen.
KRULWICH: Though there is a computer using a very primitive code. This computer can record any unusual noises from space. At 11:16 Eastern Daylight Savings Time...
Mr. BROOKS: The receiver picks up this signal...
KRULWICH: Which based on the computer data would've sounded something like this.
(Soundbite of signal)
Mr. BROOKS: Basically a growing electric pulse that then just falls away again.
KRULWICH: And as this is going on, there is a man living nearby, just a short drive away.
Where were you at 11:16 p.m., just before midnight?
Mr. JERRY EHMAN (Astronomer): Sleeping.
KRULWICH: Youre asleep.
(Soundbite of laughter)
Mr. EHMAN: Yeah.
KRULWICH: Jerry Ehman is an astronomer.
Mr. BROOKS: So Jerry was one of many SETI pioneers who, you know, were listening at this at this stage.
Mr. EHMAN: I had been asked to look at the computer printouts for anything that looked interesting to me.
(Soundbite of laughter)
KRULWICH: So three days after the signal was received...
Mr. BROOKS: A technician comes along and takes the data, prints it out, and he delivered that to Jerry Ehman's house.
Mr. EHMAN: Yeah. I got the computer printout out of the box.
Mr. BROOKS: And Ehman sat down in the kitchen and had a look at the printout.
KRULWICH: What Jerry was looking for was a very particular kind of signal, imagined years before by two famous physicists.
Mr. BROOKS: Giuseppe Cocconi and Philip Morrison.
KRULWICH: Astronomers from Cornell who'd published an article in Nature, one of the great science journals.
Mr. BROOKS: And what they did was they went and looked at what - if you were alien, you know, what would you broadcast? If we were looking for a signal, you know, what kind of signal should we be looking for?
KRULWICH: Because radio signals can travel vast distances across space, they suggested we should look for a radio transmission at a frequency that has some kind of universal significance. So, for example...
Mr. BROOKS: The abundant molecule in the universe, hydrogen, has a very specific resonance frequency, 1420 megahertz.
KRULWICH: And apparently everybody, you know, science people, know this. Everyone.
Mr. BROOKS: And so if youre going to beam a signal, that would be the frequency to choose, because it means something to anyone in the universe who's intelligent enough to listen.
KRULWICH: So there's Jerry Ehman now sitting at the kitchen table. And what he saw...
Mr. BROOKS: Was a very, very narrow signal.
Mr. EHMAN: Just like our AM and FM radio broadcasts and so forth.
KRULWICH: It's narrowband.
Mr. EHMAN: Narrowband signal would indicate intelligence.
Mr. EHMAN: Because in order to create a narrowband signal you have to have some electronics to handle that. It's not a natural phenomenon.
KRULWICH: Well, let me ask you about the frequency. Did this signal by any chance come in near 1420 megahertz?
Mr. EHMAN: It turns out to be at 1420.4556, so it's very...
KRULWICH: Is that close? Is that...
Mr. EHMAN: That's close.
KRULWICH: Is that so close that it might look like someone intended it to be there?
Mr. EHMAN: That could be an interpretation.
KRULWICH: So if it's a narrow band radio signal, it's close to 1420 megahertz, it's loud. That kind of fits, doesn't it?
Mr. EHMAN: Yes. Sure does.
KRULWICH: So Jerry took his pen at that moment and wrote: wow, exclamation point - right there on the page.
Mr. EHMAN: Right.
Mr. EHMAN: Well, that's the nice thing about the word wow. Yeah, I was astonished.
KRULWICH: And ever since, this signal from space has been labeled the wow signal. And even a skeptic like the director of astrobiology at Columbia University, Caleb Scharf...
Professor CALEB SCHARF (Columbia University): The gloomy...
Mr. EHMAN: Yeah, be the gloomy...
Prof. SCHARF: ...gloomy commentator on this.
KRULWICH: Even Caleb says this one felt kind of like the real deal.
Prof. SCHARF: Yeah, I think the fact that it was part of a carefully designed systematic survey gives you some hope that it's a real signal, but...
KRULWICH: This signal did have a problem, because if I were an extraterrestrial and I was trying to say hello to planet Earth, it wouldn't make a whole lot of sense to just say hello one time. I mean, if something is intentional, it would be hello, pause, and then hello, pause, and then hello. I mean, you'd do it a few times, right?
Mr. EHMAN: That's right.
Prof. SCHARF: But he looked through the rest of the printout and there was no other signal in the printout.
Prof. SCHARF: No, nothing.
KRULWICH: Has there been any pulse picked up like that in the next year?
Prof SCHARF: There has been absolutely nothing ever since of this particular type.
KRULWICH: So that's the troubling part.
Mr. EHMAN: That's troubling.
Prof. SCHARF: If I put myself in his shoes, I don't envy him.
KRULWICH: Columbia's Caleb Scharf says that scientists want confirmation when they discover something.
Prof. SCHARF: Absolutely. And that's key in scientific method. You want to see a repeat.
KRULWICH: And you want to eliminate alternate possibilities, like maybe this was a military transmission or a satellite.
Mr. EHMAN: No.
KRULWICH: Or signals bouncing off some orbital space debris.
Mr. EHMAN: No.
KRULWICH: So for 33 years, every time SETI astronomers said okay, we've eliminated all the other explanations, up popped an astronomer to say, well, have you considered...
Prof. SCHARF: Colliding black holes? Glitching pulsars? Black holes going burp? Gamma ray bursts. All this kind of stuff.
KRULWICH: Well, then how do you solve the mystery when astronomers keep handing you new clues every year? Jerry Ehman in the end says he can't really know if he saw an alien signal because he can't eliminate all these alternative possibilities.
Prof. SCHARF: But they're really interesting.
KRULWICH: Yeah, but it never ends.
Prof. SCHARF: What do you do about that? It's a very interesting problem, mate(ph). The frustration would be at some point someone's going to knock on the door and say, well, look, you're using all this time and, you know, let's stop. And I don't know if you had a really good response to that.
KRULWICH: Well, what's you're response? Do you think SETI should stop looking for aliens because it's so hard? Is that...
Prof. SCHARF: My personal take would be, yeah, you should keep doing it.
KRULWICH: Really? Why? You've been such a doomy, gloomy...
Prof. SCHARF: Well, exactly what you've said. I can't in good conscience say that you will never see something. And I know that if you did, it would be amazing.
KRULWICH: Wouldn't you like to meet an alien?
Prof. SCHARF: Of course I would. Absolutely. It would be unbelievable and incredible. But it's a long shot.
KRULWICH: So there we are. We want the amazing part, but who knows what the costs will be. We can't stop looking, so we're really kind of...
Prof. SCHARF: Kind of stuck.
KRULWICH: Yeah. And that's SETI 50 years in. The odds are next to impossible, but they're doing it anyway.
Robert Krulwich, NPR News.
Oh, I should add, because some of you might want to know this: A few hours after the signal hit the receiver in Delaware, Ohio, something a little odd did happen.
(Broadcast of TV broadcast)
Mr. DAVID BRINKLEY (News Anchor): Good evening. Elvis Presley died today.
Prof. SCHARF: Elvis died just a few hours after this signal came in. And I'm not saying there's any coincidence or any link between these events at all.
KRULWICH: But we just thought you ought to know.
(Soundbite of song, "Are You Lonesome Tonight?")
Mr. ELVIS PRESLEY (Singer): (Singing) Are you lonesome tonight?
SIMON: You can continue the search for alien life with a rare look at a baby solar system and see the computer printout, and Jerry Ehman's Wow! - at Npr.org. Wow!
(Soundbite of song, "Are You Lonesome Tonight?")
Mr. PRESLEY: (Singing) Does your...
SIMON: You're listening to WEEKEND EDITION from NPR News - wherever. Transcript provided by NPR, Copyright NPR.
Think we've never heard from an alien? A radio transmission recorded in Ohio and translated into six little numbers and letters suggests there's a chance we have.
When something truly startling happens, people say: "OMG!" or the dreaded, "Awesome!" But when Jerry Ehman sat at his kitchen table on Aug. 18, 1977, and saw six numbers and letters on the computer printout in front of him — six symbols that have become one of the grandest riddles in modern science — he chose the simplest expression of all. He took a red pen, circled the letters and then wrote:
When Jerry Ehman wrote that three-letter word, "wow," he was a professor at Ohio State University volunteering with SETI, the Search for Extra Terrestrial Intelligence. Every few days, a messenger would bike over from "The Big Ear," Ohio State's giant radio telescope in Delaware, Ohio, and hand Jerry computer records of sounds coming in from deep space. If something surprising popped up, he was to notify the other SETI folks.
What he saw that day was like an answered prayer.
If I Were An Alien ...
Eighteen years earlier, two Cornell physicists, Philip Morrison and Giuseppe Cocconi, had tried to imagine how an intelligent alien civilization might try to signal Earth. We should look, they said, for a radio transmission. Radio waves are cheap to produce, don't require much energy and travel vast distances across space.
Cocconi and Morrison guessed that the aliens would choose a frequency that would mean something to creatures who know math and chemistry. Hydrogen is the most common element in the universe. Zap a hydrogen atom and it will resonate at a particular rate: 1420 megahertz (MHz). So look, they said, for a signal coming in at 1420 MHz. And look for something loud, something that would catch our attention.
And on Aug. 15, in it came, exactly as predicted.
What Jerry saw was, yes, a radio signal and, yes, a radio signal very, very close to 1420 MHz (it was 1420.4556, just a smidge from where it was expected). It lasted 2 to 2 1/2 minutes. It was loud. And the transmission had the shape that Cocconi and Morrison had predicted. If you look at this printout, you will see this sequence of letters and numbers: 6EQUJ5.
According to science writer Michael Brooks in his book 13 Things That Don't Make Sense, "The letters and numbers are, essentially, a measure of the intensity of the electromagnetic signal as it hit the receiver. Low power was recorded with numbers 0 to 9; as power got higher, the computer used letters: 10 was A, 11 was B and so on." So by the time you get to the last letters of the alphabet, you are getting a very powerful signal.
That's why when Jerry saw this letter U on his printout (U is the 21st letter of the alphabet) he knew something was up.
"I had never seen any signal that strong before," Jerry says. "U," in a logarithmic way, means about 30 times louder than the ordinary noise of deep space. That's kind of a "Hello!" level. And that explains Jerry's reaction.
"That's the nice thing about the word 'wow.' I was, uh ... I was astonished," he says.
The Universe Is A Noisy Place
As surprised as he was, Jerry was also puzzled. Where did the signal come from? SETI scientists traced it back to the constellation Sagittarius, just to the northwest of the globular cluster M55. But when they looked for the source, there was nothing there, no planet, no star. Still, the shape of the signal, its narrow AM/FM-like focus, not to mention its surprisingly tantalizing frequency suggested intentionality. Maybe whoever or whatever sent the signal had moved on?
Or maybe not. Maybe there was no signal. Jerry and his colleagues checked all the alternative explanations they could think of. Was it a satellite transmission (no), a military signal (no), an aircraft signal (no), a broadcast beam (no), an accidental beam ricocheting off space debris (no)? Could it have been something natural? A pulsating star? That's where things began to unravel.
Astronomers keep discovering new noisemakers in space: colliding black holes, glitching pulsars, gamma ray bursts. Columbia University astronomer Caleb Scharf says it is very hard to exhaust the possibilities when we are learning more every year about the universe.
For Jerry Ehman, the big puzzle is: Why only one signal? If an alien intelligence is trying to send a message somewhere, wouldn't it make sense to send the message a few times? The signal landed once on Aug. 15, 1977. It never repeated.
"That's key in the scientific method," says Columbia's Scharf. "You want to see a repeat." That way, other scientists can confirm the finding.
And yet, the "Wow!" signal is the only reliably recorded sound apparently received from deep space that has the quality of an intentional signal. Jerry Ehman has never claimed he'd heard from E.T. Where the signal came from is still an open question for him. All Jerry Ehman will say is that having eliminated (as best he can) every other explanation, a message from E.T. is one possibility he can't dismiss.
Michael Brook's account of the "Wow!" signal is probably the best I've ever read. It can be found in chapter seven of his book "13 Things That Don't Make Sense," published in 2008.