Panspermia is the hypothesis that life exists throughout the Universe, distributed by space dust, meteoroids, asteroids, comets, or spacecraft. It suggests microorganisms can travel between planets, potentially seeding life on Earth, rather than originating here. While not proven, some bacteria can survive space conditions, making transfer possible.
Key aspects of the panspermia theory include:
Mechanisms: Life travels via lithopanspermia (rocks/meteors) or radiopanspermia (radiation pressure).
Directed Panspermia: The intentional transmission of microorganisms to Earth by intelligent beings from another planet.
Origin: The concept dates back to Greek philosopher Anaxagoras and was later supported by Lord Kelvin.
Viability: Research suggests some bacteria can survive for years in space, and amino acids (building blocks of life) have been found in comets, supporting the possibility.
Critique: A major criticism is that it does not explain how life began, only how it moved, and it lacks direct evidence, says New Scientist.
There are 4 main types of panspermia often discussed:
Lithopanspermia: Microorganisms are transferred through space rocks/meteorites.
Radiopanspermia: Microorganisms are transported through space by radiation pressure.
Interstellar Panspermia: Transport of life between star systems.
Intergalactic Panspermia: Transport of life between galaxies, perhaps via rogues planets, says this YouTube video.