Searching for extraterrestrial intelligence can turn out to be quite frustrating as the area to be searched is too vast. From the 1960s, researchers have gone through several billions of radio channels to find anything abnormal as it could suggest not only a different life form but also advanced intelligence. However nothing different has been found yet.
A relatively new astronomical program, Breakthrough Listen searches for signs of alien life in the local Universe which is 160 light years from our planet Earth. After finding no sign of alien life, the researchers from the University of California Berkeley released the data on the public domain before going through a peer review, and the complete analysis consists of 1 petabyte of information about 1327 local stars which is nearly 80 percent of their local star sample. The study has been submitted to The Astrophysical Journal.
Radio and optical telescope observations were used from Green Bank Radio Telescope (GBT) situated in West Virginia, CSIRO’s Parkes Radio Telescope located in Australia. This data set is the representation of the most comprehensive, sensitive search for extraterrestrial life (SETI) in the entire human history.
After removing millions of events which may have been caused due to human interference or forces of nature such as cosmic radiation -only few events were left. But on deeper analysis, the team did not find any event indicating possibility of an alien life.
According to the principal author, Danny Price this data represents a giant milestone for the Breakthrough Listen team. He added that the team went through several thousands of hours of observations from local stars, spread across billions of frequency channels but did not find any evidence of artificial signals. This does not draw any conclusion about the existence of alien life, it could mean that the right place has not yet been searched for, or weaker signals have not been detected.
To classify a signal as extraterrestrial or from human interference, researchers used a technique known as “nodding” telescope technique. Selecting a target, telescopes focus there for 5 minutes also called as ON and then shifts to a nearby spot for another 5 minutes known as OFF. This ON-OFF technique is repeated thrice and it helps to classify whether a signal is from a fixed spot or is coming from other directions, wherein it indicates an event due to human interference. Additional methods of machine learning were also employed for further filtering out the signals.
This is not the end for the Breakthrough team, as it will now move on to multi-wavelength analysis of the nearby stars and galaxies while searching for higher frequencies. Scientists are optimistic as there are many more stars and approaches for consideration.