There is a new initiative in the area of the Search for Extra-Terrestrial Intelligence (SETI). Although the SETI program has history of listening for deliberate (or accidental) messages from any potential advanced civilizations dating back more than 50 years now, we knowingly transmit messages less than 1% of that time.
Indeed some long wavelength transmissions such as TV programs do manage to leak into space, but they are too faint to decipher across interstellar distances. In all that time we have never received a message from aliens. There is also no evidence at all that aliens have ever visited us. Space appears to be empty.
Does this mean other intelligent creatures do not exist at all? The struggle to answer that question has motivated a new initiative called the Messaging Extra Terrestrial Intelligence (METI). The aim is to take action to send messages in the direction of known planetary systems. Most people at this point ask, "Is this exciting?, or Should we be worried by the possible alien response?"
It seems that fewer people consider a third question, which is, "What is the statistical likelihood of a response?" Let us imagine that planets around other stars do often cradle life. If so, then even if life first emerged on another planet 3.5 billion years ago as it did on Earth, what if the most advanced life form is still only a bacterium, or maybe a tree?
On the other side of the coin, what if 4 billion years is sufficient time for intelligent life to emerge at a faster than it did on our humble planet, resulting in an alien civilization that by now really cannott be bothered to talk to such lowly creatures as humans. We humans cannot even manage interstellar travel after all, making us potentially no better than the common potato bug. Lastly, what if there is intelligent life out there but they prioritize spending government money as well as private endowments activities other than sending and receiving messages into space?
The takeaway is that the odds of finding an alien civilization at the right age to want to play hopscotch with us requires that they be in our same child-like state of evolution. Maybe there are other intelligent 'children' out there. If so, is there a great human need to try to find them? What do you think?