Authored by Rupendra Brahambhatt via Interesting Engineering,
For more than half a century, the search for extraterrestrial intelligence has been built on the assumption that if aliens exist and try to communicate, their signals will be faint, scattered, and easy to miss.
So astronomers have spent decades scanning narrow slices of the radio spectrum, hoping to catch a weak signal buried in cosmic noise. However, a new study suggests something totally different-if an advanced civilization actually wanted to be noticed, it would not broadcast weak, unfocused emissions.
It would do the opposite -concentrate its power into tightly aimed, high-intensity beams directed at specific targets.
“Our principal assumption is that a purposely communicative technological civilization will do its technological best to establish communication with other extraterrestrial technological intelligences (ETIs),” Benjamin Zuckerman, study author and an astrophysicist from the University of California, Los Angeles,said.
If this idea is even roughly right, then the silence in our data is not just a lack of evidence. It actually limits how many nearby civilizations could be sending signals we could detect.
The traditional logic behind SETI comes from a simple constraint-interstellar communication is hard. If a civilization has limited power, the most efficient strategy is to broadcast in all directions.
However,this makes any signal extremely weak by the time it reaches another star.This is why SETI searches have focused on extremely narrow frequency bands.
“Radio search programs have employed very narrow (few Hz) bandwidths (BWs)-because, if an ETI has a given (limited) amount of power to transmit, then the way to maximize the signal-to-noise ratio at the receiving antenna is to use very narrow transmission and reception BWs,” Zuckerman notes.
The difficulty is that no one knows which frequency to listen to, so even decades of work have covered only a tiny fraction of possibilities.
Source: ZeroHedge News
