I’ve been taking another look at the Arecibo message recently. It is, so far, the only attempt by humans to send a message out into space with the sole intention of identifying ourselves, our biology and our location. Details of the actual message can be found here:
The Arecibo Message
Such attempts are increasingly considered unwise. The Arecibo message, despite its apparent simplicity, contains enough information for an extra-terrestrial civilisation to develop weapons and technology to subdue or destroy humans, whilst leaving our planet’s resources and atmosphere intact.
Professor Stephen Hawking has recently expressed his concerns regarding attempts to contact aliens, stating that if we were visited the outcome would be similar to when Columbus discovered North America:
Stephen Hawking warns over making contact with aliens
The Native Americans did not fair well after the arrival of the Europeans. Extra-terrestrial beings visiting Earth may condemn us to a similar fate or simply use up the planet’s resources (including humans themselves as slaves or food) and then move on.
We should do all that we can to remain hidden. We should work to limit the radio emissions from Earth to minimize the chance of being discovered. Fortunately this is happening almost ‘accidentally’ as we move to a completely digital communications network, and make more and more use of cable and satellite transmissions and less use of traditional broadcasting:
Earth Becoming Invisible to Aliens
There are plenty of scientists listening for signals that could originate from alien civilisations, but if the development of technology by our civilisation is typical, then there will only be about a 50 to 100 year window in which to detect strong unidirectional analogue radio signals, such as our ‘old-style’ televisions broadcasts, and after that the strength of the emissions will reduce dramatically, and become digital in nature. Such a window of time is miniscule, and the chances of a civilisation being at the same stage as us as far as technological development goes is almost zero. This, I believe, is why we appear to be ‘alone’ as far as radio transmissions are concerned.
Given the age of the universe almost all alien civilisation will be much older than ours. They will all have concealed their broadcasts (due to fears of discovery and invasion, amongst others). Any signals that are transmitted beyond their domains will be very weak and digital in nature. Even if we could detect those signals, without the right decoding algorithms (CODECS) we would be unable to decipher any of the information.
Unless a message is intended for discovery we are unlikely to detect one. Perhaps humans are the only civilisation foolish enough to send such a message? Let's hope we are not punished for our innocence and openness.
If you would like to know what a possible reply to the Arecibo message could contain I recommend reading this chilling short story I found at the Palace of Amino free science fiction website (make sure you have a stiff drink close at hand):
The Arecibo Response
The intended destination of the Arecibo message was the M13 star cluster, 25,000 light-years away meaning a response would not be expected from that location for at least 50,000 years (actually one will never arrive from there, as the M13 cluster will not be in that location when the message arrives). The above story has a reply being received towards the end of this century, meaning the recipient intercepted the message only 50 light-years away.
You never know who's going to be listening...