ELI5: Explain Like I'm 5

Zeta function regularization

Okay kiddo, let me tell you about zeta function regularization. You know how sometimes equations can give us very strange or infinite answers? Well, zeta function regularization is a way to make sense of those answers by giving them a new meaning.

Let's start with the zeta function itself, which looks like this: ζ(s) = 1 + 1/2^s + 1/3^s + 1/4^s + ... This equation adds up all the numbers in the series, where each number is the reciprocal (or 1 divided by) a specific number raised to the power of s.

Now, when s=1 (which means we're adding up all the reciprocals of every positive integer), the zeta function gives us an answer of infinity. That seems really strange, right? But wait, there's more.

What zeta function regularization does is take that infinity and give it a new meaning. Instead of saying it's an infinitely big number, we say it's a special kind of number called a pole. A pole is really just a way to show us that the equation gets really big when s=1, but it also helps us work with the equation more easily.

So, by using zeta function regularization, we're able to take equations that might give us confusing or infinite answers and turn them into equations that make sense to us. And that's pretty cool, even for a 5-year-old!