Astronomer Wants to Find Alien Life By Detecting Radiation from Light Sails

Harvard astronomer Avi Loeb is known for his unusual thought experiments regarding alien life; he has suggested a search for artificial light on Pluto, in the remote chance that aliens have built a civilization there, and detecting industrial pollution on exoplanets. Now, he has proposed his next radical idea: detecting radiation from light sails that aliens use to travel between planets. 

Solar sails, or light sails, as they're frequently called, use ultra-thin mirrors to capture solar wind, using it to propel a spacecraft without the use of rockets. They don't exist yet, but scientists agree that they are theoretically possible, and a prototype is currently in the works at the Planetary Society, with a test flight planned for next year.

Theoretically, a light sail would use most of the light it absorbed in order to generate power, but there would inevitably be some leakage. According to Loeb, if aliens are more technologically advanced than humans, and have discovered how to make light sails work, then we would be able to detect residual radiation from the sails.