SETI Institute, the non-profit organization whose mission is to “to explore, understand and explain the origin, nature and prevalence of life in the universe.“, has said that the search for intelligent life in the universe has reached a new era.
After listening for signs of “life out there” for 40 years with little results, they have now said that the reason for this is because the extraterrestials are probably sending out laser or light signals, and not radio. Makes sense, no?
SETI (Search for Extraterrestial Intelligence), who unveiled a new facility last April, answer two pressing questions you’ve always wanted to know:
1. How do we know if the signal is from ET?
Virtually all radio SETI experiments have looked for what are called “narrow-band signals.” These are radio emissions that are at one spot on the radio dial. Imagine tuning your car radio late at night? There’s static everywhere on the band, but suddenly you hear a squeal – a signal at a particular frequency – and you know you’ve found a station.
Narrow-band signals, say those that are only a few Hertz or less wide, are the mark of a purposely built transmitter. Natural cosmic noisemakers, such as pulsars, quasars, and the turbulent, thin interstellar gas of our own Milky Way, do not make radio signals that are this narrow. The static from these objects is spread all across the dial.
In terrestrial radio practice, narrow-band signals are often called “carriers.” They pack a lot of energy into a small amount of spectral space, and consequently are the easiest type of signal to find for any given power level. If E.T. is a decent (or at least competent) engineer, he’ll use narrow-band signals as beacons to get our attention.
2. What happens if we find something?
Keep in mind that the receivers used for SETI are designed to find constant or slowly pulsed carrier signals? something like a flute tone against the noise of a waterfall. But any rapid variation in the signal – known as modulation, or more colloquially as the “message” – would be smeared out and lost. In order to understand anything that E.T. might be saying to us, we’ll have to build far larger instruments to look for the modulation of his signal. It’s more than likely that, once a detection is made, the money will become available to build this far larger instrument.
Until we can measure the modulation, all we’ll know is that there is intelligence out there. We can pinpoint the spot on the sky where the signal is coming from, and slow changes in its frequency will tell us something about the rotation and orbital motion of E.T.’s home planet. Even with this limited information, the detection of alien intelligence will be an enormously big story. We’ll know we’re not alone, and we’re not the smartest things in the universe. And of course there will be a loud clamor to build the big dishes that would allow eavesdropping on E.T.’s message.
Then what? Suppose we get the message? Will we understand it? No one knows, of course. It’s conceivable that an advanced and altruistic civilization will send us simple pictures and other information.
