However, in the end they found that even in the worst case scenarios, the entire Milky Way could be exchanging biotic components across vast distances. In short, they determined panspermia is viable on galactic scales, and even between galaxies. As Ginsburg said:

“Smaller objects are more likely to be captured. If you consider Saturn’s moon Enceladus (which is very interesting in itself) as an example, we estimate that as many as 100 million such life-bearing objects may have traveled from one system to another! Again, I think it’s important to note that our calculation is for life-bearing objects.”

The study also bolsters a possible conclusion raised in two previous studies conducted by Loeb and James Guillochon (an Einstein Fellow with the ITC) back in 2014. In the first study, Loeb and Guillochon traced the presence of hypervelocity stars (HVSs) to galactic mergers, which caused them to leave their respective galaxies at semi-relativistic speeds – one-tenth to one-third the speed of light.

In the second study, Guillochon and Loeb determined that there are roughly a trillion HVSs in intergalactic space and that hypervelocity stars could bring their planetary systems along with them. These systems would therefore be capable of spreading life (which could even take the form of advanced civilizations) from one galaxy to another.

“In principle, life could even be transferred between galaxies, since some stars escape from the Milky Way,” said Loeb. “Several years ago, we showed with Guillochon that the Universe is full of a sea of stars that were ejected from galaxies at speeds up to a fraction of the speed of light through pairs of massive black holes (formed during galaxy mergers) which act as slingshots. These stars could potentially transfer life throughout the Universe.”