I'm bored so I'm going to write about zombies. Zombies get my attention! But, as this is a science and newsletter, I'll look at them from a scientific viewpoint. More or less. Trust me! I might even be able to work in a tech angle.

To begin with, you should know that George A. Romero did not invent zombies. Long before he directed Night of the Living Dead¹ there were schlock horror pics like White Zombie which dates from 1932!

Since Romero's first classic, there have been hundreds, maybe even thousands of zombie movies, TV shows, video games, books and - I love this one - there's even a sporting organization called The Zombie Shooters Association of America. Most of the stories have zombies created by some kind of virus, sometimes one that has been bioengineered to be deadly. That's what I wanted to get to in this post. Could there really be a zombie virus that destroys civilization, leaving the world full of a few pitiful survivors constantly on the run from undead flesh-eating monsters?

Let's take a look. Here's the way it works in a standard zombie movie:

1) Something bad kicks it off. Maybe a nuclear war. Maybe bioterrorism. Maybe a weird comet. Something spreads the zombie virus far and wide, infecting everyone.

2) And then nearly everyone dies. It doesn't usually take but a few weeks. In 28 Days Later that's all it took. After just four weeks, civilization was gone along with most of the population. Only a few humans survive to carry on in the ghost of a world.

3) But the dead people all (or mostly) come back as zombies, craving human flesh. Or brains. It depends who's writing. Normally, they are attracted to moving people and to sounds because. No, that wasn't poor grammar on my part. Well, okay, it was, but I didn't finish the sentence because the reasons for things are usually glossed over in these stories. It just happens. Enjoy the carnage, paying audience. Now!

4) Zombies are fast and attack in packs. If they bite you but fail to kill you, after a little while you'll turn into a zombie too. This is actually a decent dramatic device because it forces characters to make hard choices in a hurry, or die.

5) In most of the stories, people who die of some other cause than being killed by zombies, also turn into zombies. This is another dramatic device. The people closest to them have to shoot them in the head to keep them from murdering their friends and neighbors².

Some of these stories are actually pretty good. 28 Days Later and World War Z are at the top of my list of watchable zombie movies. About 99.99999% of the rest are truly awful. But that's not important. I'm not here to make movie recommendations! I'm here to tell you that every single step in that list is scientifically ridiculous. Wanna know why?

1) Nuclear weapons incinerate everything close to them. For the most powerful nukes, "too close" might translate to "on the same continent." So If you're trying to spread a virus to the populace, putting it on a nuke is not going to work. But, you ask, what if the virus is released into the atmosphere before the bomb explodes so it isn't flash fried? Then it will be take a monster dose of radiation, which will cause it to mutate and probably die. It definitely won't be the same horrible disease you loaded onto that missile in the first place³.

Besides, like we saw with covid, airborn transmission isn’t very efficient. Too much sunlight might kill the disease. Or a gust of wind might keep it from spreading too much. And let’s not even talk about wearing masks, okay?

2) Point 2 is where everybody dies in maybe just a few weeks. For this one, let's have a (really really simplified) look at the SIR model of disease spread. I learned this one in a class a few years ago. I don't remember why I took it. Anyway, there are three terms to the SIR model. S, I and R. Let me know if I'm going too fast for you.

S is for Susceptible. Wouldn't that make a good title for a mystery novel?⁴. Anyway, it means how many people can possibly catch the disease? For the zombie apocalypse to work, S has to mean everybody.

I is for Infected. I might have to write this series, even if they are mysteries about zombies! Sorry. I'm easily distracted. The more people there are in the infected category, the more chances the uninfected (S) have to be exposed. Got that? If no one in town has a cold, then no one can pass it on to you. You might still get one because colds are at least as sneaky as zombie viruses but your odds are pretty low.

R is for Recovered. In general, diseases aren't fatal to everyone all the time. There are some people who won't get much of a dose or who have spectacular immune systems, or who are just genetically lucky and have bodies that can fight off some particular disease. Even the Black Death didn't kill everyone who got it⁵.

Here's the thing: If a disease killed everyone, some people would never come in contact with someone who was infected. Because they would have died, see? Death reduces the number in the I category. So a zombie virus that kills everyone is actually too strong to kill everyone. It would burn out too fast.

The best thing, from the disease's point of view, is for the victims to get just a little sick, so they still go to school or to work where they can spread it around to more people (S: the susceptible, remember them?), who will do the same. Then, once they've infected a lot of other people, they can die. But all that "getting a little sick and spreading it around" takes time. You're not going to see the whole human race infected in a couple weeks. It took covid a lot longer to spread around the whole population and there are still some people who haven't caught it yet⁶.

And now I'm out of room for the rest. That’s annoying. I still have to talk about the zombie elephant in the room: How does a virus bring the dead back to life? I'll get to that and more in part 2 of this strange and unintentional series about the science of the zombie apocalypse.

Here's that prompt: "A surreal scene in a medical setting where zombies, dressed as doctors and nurses in white coats and scrubs, are treating patients. The zombies appear happy and content, with exaggerated smiles and bright eyes, as they go about their work with enthusiasm. The medical environment is clean and modern, with hospital beds, medical equipment, and charts on the walls. The patients, who are also zombies, look relaxed and comfortable, receiving care from the medical staff. The overall mood is unexpectedly cheerful and professional, with a slight touch of dark humor."

I thought about making this all one post and putting it up for paying-subscribers only. But I haven't done one of those for a while and, anyway, if I did then I’d have to come up with another idea for a post for everybody else. That’s a lot of work.