Home→ Exoplanets FAQ → What are the prospects of receiving signals from alien life-forms?
The Drake equation is usually introduced for answering the kind of question posed in the title. However, the Drake equation is fairly useless because the critical quantities that appear in it are completely unknown. By plugging in suitable values for the unknowns you get the number of intelligent civilizations in our Galaxy that could potentially communicate with us to be less than or greater than 1, as you please.
I will say, however, that the term in the Drake “equation” that corresponds to the “length of time that intelligent civilizations send out signals for other aliens to receive” is really a financial term, and the financial reality is rarely discussed. How much money is a species prepared to put into transmitting signals into space, as a planet-wide effort? On Earth, the planet-wide financial commitment to send signals into space for aliens to receive is exactly zero (making the rest of the Drake “equation” irrelevant). Whilst millions of individuals are prepared to make a financial commitment to send signals to aliens, for humans as a species the activity has zero priority. The number-one planet-wide financial commitment is for humans to make weapons designed to exterminate other members of the species. These are facts. If other alien species exist, and their financial priorities are the same as humans, then the chance of us finding them is exactly zero.
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There are also other reasons why intelligent life-forms may not be contacting us (which are again similar to the reasons why are making no effort to contact them).
The various incarnations of SETI (search for extraterrestrial intelligence) on Earth have received limited support of various kinds, and you can read about the various activities and financial woes on a variety of websites (for example seti.org). Still, it is true to say that there has never been a project that vows to continuously pump signals at astronomically “serious” power levels into space. Also, it is important to remember that SETI-type activities predominantly aim to receive signals, not to send them. If we are not sending out signals, why should we expect an alien species to do so? It would be very hard for any species to inject serious money into something that will likely have no result for generations, and certainly no financial return.
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File under: Prospects of contact with extraterrestial life-forms; SETI; Drake equation.