In the search for Habitable Worlds, there is a kind of "loopback address" as well. Our loopback address is Earth--the local host of life.
Recently, we have used some of our space probes to look back at our planet from millions of miles away. As if from a mirror, we've learned new things by watching Earth--giving us initial insights on what to look for on exoplanets for prospects of habitability.
One of these crafts, EPOXI has helped scientists to come up w/ a potential technique in detecting features on the surface of exoplanets. They based their findings on how the oceans and continents of the Earth appears from 30 million miles away. The same team also found out that "sun glints" are reflected from the oceans of the Earth.
And from a little farther away, the Voyager spacecraft has shown us that our planet is a tiny speck of pale blue dot, which has evoked lucid reflections from the late Carl Sagan.
With all these beginner insights of what to look for on other planets, we've alternately began to think of how other alien civilizations would see us. By some recursive loop of "Exoplanetary thinking", we now think about how they would think of us thinking about them thinking about us.
And in turn, any extraterrestrial in the same curious endeavor of finding life elsewhere would naturally begin their quest by also looking back at their homeworld--their loopback address.
Perhaps there is a cosmic rule, that for Civilizations which starts to think about other habitable worlds, they will find that the loopback address begins at home.
"... and the end of all our exploring will be to arrive where we started and know the place for the first time." --T.S. Elliot
Links:
The New Exoplanetology
Seeing Earth from an Alien Perspective
Sun Glints
Pale Blue Dot
