WHAT WOULD HAP­PEN IF ALIENS CON­TACTED US?

Focus-Science and Technology - - Q&A -

1. COULD WE DE­CODE IT?

Hu­mans have only been trans­mit­ting ra­dio sig­nals for around 80 years, and al­ready we are phas­ing out ana­logue trans­mis­sion sys­tems such as AM and FM in favour of digital sig­nals. These are much eas­ier to de­tect – but only if you know the en­cod­ing sys­tem. With­out this key piece of in­for­ma­tion, any trans­mis­sion from an alien civil­i­sa­tion would just sound like back­ground static.

2. COULD WE UN­DER­STAND IT?

In 1974, the Arecibo tele­scope broad­cast a 23 x 73 pixel im­age at the M13 star clus­ter. Al­though it con­tains de­tails of our count­ing sys­tem, DNA struc­ture and place in the So­lar Sys­tem, it’s so cryp­tic that even other hu­mans prob­a­bly wouldn’t be able to de­ci­pher it. An alien mes­sage might have such an ab­stract set of pri­or­i­ties and as­sump­tions that we would never un­der­stand what they were try­ing to tell us.

3. ARE THEY STILL THERE?

Even if we re­ceived and un­der­stood a mes­sage, its senders would prob­a­bly be long gone. A 2018 study at the Uni­ver­sity of Cal­i­for­nia, Santa Cruz, found that if civil­i­sa­tions last fewer than 100,000 years, the odds of de­tect­ing a signal while the trans­mit­ting civil­i­sa­tion still ex­ists are al­most nil. So there’s not much hope of send­ing (or re­ceiv­ing) a re­ply.

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