What don't we know about zombies? There's actually a lot we don't know about zombies, because we're not in the middle of a zombie outbreak right now. We don't have a zombie we can put on a lab table, and dissect and figure out exactly how the brain works and exactly how it's haunting us. It's important to note that anyone that tells you they know exactly how zombies will behave and exactly what the coming zombie plague will be like, is doomed to be wrong. If you take their advice as gospel, they're the jerks that gave you bad advice, but you're the one getting your leg chewed off. All zombie research is theoretical. We can develop models. We can try to figure out exactly what it will be like, but until a zombie actually shows up at your front door, we're not going to know. It's inevitably going to be different than what we see in movies, books, and video games.
We see in zombie movies, books, and video games that zombie's are represented in many different ways. We're never going to know exactly what the outbreak's going to be like until it actually happens. It's important to develop theories, to debate, to research zombies, to try to close that gap of knowledge as much as we can before zombies actually come, because once that happens, it's run-and-scream time.