Scientists are optimistic that we will be able to find life outside of our planet within the next generation, and a new theory outlines how we could potentially detect beings travelling between stars.
If some form of life in the universe does indeed have the ability move between stars in a process called panspermia, it would likely spread in a predictable pattern that we could identify, the Harvard-Smithsonian Center for Astrophysics reported.
"In our theory clusters of life form, grow, and overlap like bubbles in a pot of boiling water," said lead author Henry Lin of the Harvard-Smithsonian Center for Astrophysics (CfA).
There are two ways for life to potentially spread in the universe: through natural processes such as "gravitational slingshotting" of comets and other objects; or through intelligent life deliberately traveling through the cosmos. The new model explained in the study suggests we would be able to detect panspermia if it does occur.
The model assumes the life "seeds" of a planet can spread outwards in every direction. If one of these seeds eventually reaches a habitable planet in a nearby solar system, it can grow and populate that planet.
"Life could spread from host star to host star in a pattern similar to the outbreak of an epidemic. In a sense, the Milky Way galaxy would become infected with pockets of life," said CfA co-author Avi Loeb.
If we successfully detect signs of life on alien worlds, we could also look for patterns indicating how the observed distribution came about. In what the researchers referred to as an "ideal" case, the Earth would be on the edge of a "life bubble" in which all nearby inhabited worlds exist on one half of the sky while the other half is uninhabited.
The researchers noted a pattern would only be able to be detected if life spreads relatively quickly because the rapid movement of stars can eliminate signs of life bubbles.
The findings were published in a recent edition of The Astrophysical Journal Letters.
