Four Cases for Panspermia

Star formation peaked around 4Gyr after the Big Bang, Earth formed around 5.5Gyr later, and Earth is now 4.5Gyr old. The usual theory is that life arose within Earth’s first 0.4Gyr, but another possibility is that life first arose on a planet Eden around a star that formed near that 4Gyr peak. A rock then smashed into Eden, kicking off another rock holding life, which drifted to seed Earth’s stellar nursery.