They prey on their own kind. Some might call it cannibalism, but
it’s the only way they can survive. Indeed, the zombie
apocalypse is here. So-called “zombies” exist throughout nature,
but unlike their fictional counterparts, these zombies serve a
good purpose. For example, our very own galaxy has gobbled up
smaller galaxies for over ten billion years. Astronomer Jeff
Zweerink tells me that this regular diet of galactic food keeps
star formation at a steady pace. Continual star formation might
not seem like a big deal, as though non-continual star formation
just means fewer objects to spot in the night sky. But, as Jeff
puts it, “a galaxy must form multiple generations of stars” in
order to host life. “On the other hand,” he continues, “a
collision with a galaxy that was too large would have disrupted
the MWG’s [Milky Way Galaxy’s] spiral structure and led to
conditions hostile to life.” Collisions with the just-right size
galaxies affect our galaxy’s structure and add energy to the
outer part of the Milky Wa