SETI is a generic acronym that stands for the Search for Extraterrestrial Intelligence. Scientists doing SETI experiments are looking for proof, not merely of life elsewhere, but of intelligent beings in other star systems.
How is it done?
Scientists have realized that we can’t find aliens by just flying to other planets. Although movies and TV shows present this as a possibility, the vast distances to stars (the nearest is 7,000 times farther than Pluto) make such visits impossible. While the idea of warp drive is appealing, it remains just an idea.
And while some people think that the extraterrestrials, with their advanced technology, may be able to come here, this is not a popular idea among most scientists.
Credit: Third Party Reference
Consequently, most SETI these days eschews rockets and relies on radio telescopes – massive antennas outfitted with highly sensitive and specialized receivers. The idea is simple: Forget the rockets and bring on the photons. Let signals beamed via radio (or light) do the traveling.
Radio is a great way to send information over the incredible distances between the stars; it easily passes through the dust and gas that suffuse space, and it does so at the speed of light (about 20,000 times faster than our best rockets).
So, most SETI of the past 60 years has involved using large antennas to try and eavesdrop on any radio signals aliens might be transmitting.
There are also SETI experiments done with specially designed optical systems that search for flashing laser light beamed into space by other societies to convey information, to propel their rockets, or to just ping other star systems to see if anyone is home.
Note that SETI experiments do not broadcast. They just try to pick up signals that might already be threading the galaxy.
Who thought of SETI?
While early inventors like Nikola Tesla and Guglielmo Marconi thought they could listen for signals from Mars (and even believed they heard something!), modern SETI began in 1959. That year, physicists Phillip Morrison and Giuseppe Cocconi created a simple thought experiment.
They imagined taking the world’s most powerful radar transmitter and aiming it at a large receiving antenna. Of course, if you did this little experiment in your backyard, the big antenna would have no difficulty picking up the signal from the radar transmitter.
Credit: Third Party Reference
But then, in their minds, the two physicists slowly separated the transmitter and receiver. They wanted to know how far apart they could be and still reliably establish a radio link. To their surprise, it turned out that this setup would work even when the transmitter and the receiver were separated by light-years of distance!
In simple terms, even with the radio technology of the 1950s, it was possible to use radio to send signals over distances like those between stars. This idea led the two scientists to write a paper proposing that intelligent aliens might use radio to communicate, and that we should search for those signals.
The first one to actually do any looking was astronomer Frank Drake. In 1960, he used an 85-foot diameter antenna in Green Bank, West Virginia, to hunt for signals that might be coming from two very nearby star systems. In the two weeks of his experiment, Drake didn’t hear any alien transmissions. But his modest effort, known as Project Ozma, was the beginning of modern SETI.
Why hasn’t SETI picked up any alien signals?
Some people think that, after six decades of searching, the fact that SETI researchers have yet to pick up a signal from space might mean something. Perhaps the aliens don’t want to broadcast in our direction (maybe we’re not worthy!)
Others think that the apparent silence means that there are no intelligent beings out there, and humans are the smartest things in the galaxy, a circumstance that many readers might find comforting or possibly self-evident.
But there’s a more reasonable explanation for the fact that SETI receivers have so far heard nothing that’s clearly extraterrestrial. Namely, the experiments have simply not examined enough of the sky. Or perhaps the antennas don’t have enough sensitivity, or maybe they’ve not been tuned to the correct frequency.
So, if you buy into any of these explanations – which maintain that we haven’t found any aliens simply because we haven’t tried hard enough – then our future strategy is obvious. We simply have to be patient and continue to press the search.
Credit: Third Party Reference
Said another way, we continue to assume that the trillion or so planets in the Milky Way house some transmitting societies, but our experiments have to continue and continue to improve in order to succeed in picking up a signal.
There are many reasons for the “great silence.” Some suggest aliens don’t find us interesting, while others worry that sending signals into space is risky. However, the true reason why SETI hasn’t found any clear signals may only be understood once we detect something.
Who funds SETI?
Following Frank Drake’s pioneering experiment (see above), John Billingham, a British physician working at the NASA Ames Research Center in Mountain View, California, was inspired to start a small NASA project to do SETI systematically.
Over the course of a dozen years, this focused effort developed not only invaluable expertise but also cutting-edge hardware and sophisticated software that significantly advanced the field of astronomical research. The NASA project was just beginning its extensive survey of the sky, aimed at detecting signals from extraterrestrial civilizations, when it faced an unexpected setback and was canceled in 1993 by a narrow vote in the U.S. Senate.
This abrupt halt meant the cessation of a potentially groundbreaking scientific endeavor, leaving many researchers and enthusiasts disheartened. Since that time, all efforts related to the Search for Extraterrestrial Intelligence (SETI) in the United States have relied heavily on the goodwill and generosity of private donations, as government funding has remained elusive, sparking numerous debates about the importance of pursuing such a critical inquiry into the cosmos.
Reference: https://www.seti.org/research/seti-101/seti-research/
