While watching a Walking Dead commercial I saw a vast number of zombies walking in a single uniform march in one direction. I wondered why (not knowing the show) and could only presume they heard a sound and therefore were all walking toward said sound. However, this was a large army of zombies, surely the ones in the way back didn't hear the same sound, so perhaps they just heard the moans and footsteps of the zombies in front of them and were following their movements.
This idea got me excited, I wondered if it were possible to create a story where all zombies, given enough time, could come together to the same location by following the loudest sound possible. After a certain number come together surely the sound of (a million?) moaning zombies would be the loudest thing around. Like cosmic debris in orbit fusing together after being pulled toward one another's gravity, I want the zombies to pile up in an ever growing mass, where at the end of the story a single (or close as possible) nuclear strike could wipe them out.
The only presumptions I want to make about the zombies is that they live forever aside from brain being damaged and that they move toward the loudest sound they hear.
What other presumptions about my zombies would I have to make to get as many of them as possible to the same place? i.e. should they hear a sound and walk forever in that direction or should they stop in the general area they think they heard it. I would think walking forever would be best to get the zombies out of remote locations, but I also want them to clump together which walking forever might impair.
Is it feasible to presume they could all end up in the same location given enough time or is it just too improbable that certain zombies would ever find the "main clump". Obviously they couldn't cross the ocean so is 6 continental clumps the best I could hope for?