In September 2016, China announced that their new radio telescope installed in Guizhou Province became operational, with a dish the size of 30 football pitches (500m diameter dish), which makes it the biggest radio-telescope in the world, bigger than the Arecibo Observatory in Puerto Rico with its 305m dish. It took five years and $180 million to build.
What should we expect when sending messages in space?
Listening is one thing, and it is mainly what this kind of installation will be doing among other things. But there are other projects which are actively trying to send signals out there hoping for a response.
It is in 1974 that Drake transmitted the first actual CETI message using the Arecibo radio telescope. Later, different ways of communication have been tried from physical probes sent to space to messages coded following different algorithms hoping the recipient would be able to understand it.
- 1974 – Arecibo messages. Array of pixels showing the numbers one through ten, atomic numbers of H, C, N, O, P, information about DNA, human being and others.
- 1974 – Pioneer probes. Containing plaques depicturing the location of the Earth in the galaxy and the solar system, and the form of the human body.
- 1977 – Voyager probes. Diagrams depicting the human form, our solar system and its location, as well as sounds and images from Earth.
In 1950 Enrico Fermi tried to theorize the possibility of the existence by formulating it in a paradox, fit which 3 solutions have been proposed:
- They are here, but we don’t know it (we usually assume they should have a humanoid form but it could be that they are just something we cannot describe and observe).
- They exist but have not communicated with us yet (for instance they might know our existence but have decided to preserve is like a natural park).
- They don’t exist.
Is it a reasonable idea to try to communicate with extra-terrestrial intelligence?
When sending a message, we expect an answer and a contact, hopefully friendly.
The first message sent was 42 years ago meaning it has reached a distance of about 42 light-years from Earth. The Milky Way is only 100,000 light years, that means this message has covered less than .00002% of its surface (5542/31415926536), we would be very lucky to have reached someone already, and in this case we can expect the answer anything between now and the year 2056, assuming the life form we have reach is advanced enough to decode our message and send back an answer that we can detect.
So the probability to have all the conditions met is very small:
- There is a life form within the 42 light years radius of Earth.
- This life-form is advanced enough to understand our message and send a reply.
- We will not miss the reply and be able to decode it as well.
My personal opinion is that is the condition (2) is met, the civilization we made contact with is probably more advanced than us and in a position to visit Earth before we visit them. And if they do, we can expect that there technology is way more developped than ours.
Do we really expect them to be friendly when coming to say hi?
By analogy if we look back at what happened when the European civilization went to America, Africa or Australia, the answer is not so great. So I am not so excited in the idea of sending messages out in space telling everyone where to find us, and for now, I would prefer that we just keep listening to them with giant reflectors and keeping silent.
Illustration source: https://www.rt.com/news/360545-china-largest-radio-telescope/