In the search for extraterrestrial civilizations , it ’s unmanageable to have it away what to look for . During the pursuit , we have tend to search for detectable sign and planetary house that we ourselves would utter ( on determination , orby stroke ) on the presumption that aliens will use similar technology , turn over that they have approach to the same physical science .

It ’s absolutely logical to do so , but it ’s not altogether ideal . As we ’ve figure over the last few hundred years on our own satellite , well-informed civilization can rapidly vacate honest-to-goodness noticeable engineering as their understanding of the universe increase . For obvious instance , we have speedily moved from using analog signals to digital for communication . Though analogue signal in the kitchen stove we used for communicating would be a fairly ineffective way of commune with alien planet , it ’s possible that alien civilizations could go " wireless tranquil " in a cosmologic half - eye blink of 100 or so year , just like we have , making detection all the more unmanageable .

As such , scientists have speculate about what kind of sign a more ripe culture might mail , and what engineering level would be want to send off them .

While of course speculative , we do have some idea of what form of signal would make sense , as well aswhat the subject matter should containto make it clear it comes from an well-informed being .

“ In the 1960s , the thought was to focus on a part around a well - known relative frequency where achromatic atomic number 1 emits radiation in interstellar quad , 1.42 gigacycle , " astronomy grad bookman at Berkeley , Bryan Brzycki , explain toUniverse Today . " Since this lifelike expelling is prevailing throughout the galaxy , the idea is that any intelligent civilisation would know about it , and potentially place this relative frequency for transmission to maximise the chance of detecting . Since then , peculiarly as technology has rapidly advanced , radiocommunication SETI has expanded along all axes of measurement . "

Sending signal across the beetleweed or universe , particularly uninterrupted signal that would put up our honest fortune of detection , necessitate a lot of energy , far more than homo are capable of . In 1963 , Soviet stargazer Nikolai Kardashev attempt to work out the kind of vim involved in sending such information - carrying signal , and the levels of advancement that civilizations would have to be at in parliamentary law to transmit them .

Kardashev disunite these hypothetic civilisation intothree type , based on how much energy they are capable to tackle from their environs .

Type I civilization are civilisation which are able-bodied to tackle all the energy usable to them on their planet ( given at around 4 x 1019erg per second ) and employ it for their own purposes . Type II civilization are able to tackle the energy of their star , for instance by construct aDyson Sphere , theoretic megastructures construct around stars built for this purpose . Type III civilizations , meanwhile , are alien civilizations open of harnessing the energy of their whole galaxy .

Though the DOE output of Type II and III civilizations are super high , based on an increase in energy yield on Earth of 1 percent per class Kardashev calculated that humanity would hit those milestones in3,200 and then 5,800 years . An extended scale , propose in 2020 , suggests a Type IV civilization which is able to harness the energy of their observable population . accord to this squad , take care at our vitality expenditure , humans are currently a Type 0.72 culture .

Detecting Type I civilisation , with their puny yield ( though far in nimiety of our own ) would be very unlikely , according to Kardashev . But signaling sent by Type II and Type III civilization could be detect ( though not respond to ) by a Type I civilization with conventional tuner telescope not too far in progress of our own . The assumption in the work is that alien civilizations would be spread scientific info far in advance of our own , with the spirit of being heard by less advanced civilization , whichmay not be a great ideafor any civilization with the goal of staying awake .

However , the Kardashev scurf gives us an idea of what kind of civilization are capable of sending signals we may soon be able to detect . If such advanced civilizations subsist ( and give how vast the universe is , and how long it has dragged on for , it would be a reasonable presumption ) it would also give us other thing to look for , such as giantmegastructuresused for harness energy .