ELI5: Explain Like I'm 5

Segal–Shale–Weil distribution

Okay, so imagine you have a box of 100 candies. Each candy has a number on it, from 1 to 100. Now imagine you want to know how many candies have an odd number on them. One way you could do this is to look at each candy one by one and count them. But, if you're very smart, you could figure out the answer without actually looking at each candy.

This is kind of like what mathematicians do when they use something called the Segal-Shale-Weil distribution. It's a fancy way of figuring out how many odd numbers there are in a certain group, without actually having to count them one by one.

Here's how it works: imagine you have a really big group of numbers, called a "Lie group". Just like our box of 100 candies, each number in this group has a certain property, called a "representation". In our candy example, the property was the number being odd or even. In the Lie group, the property is something different, but it's still a way of telling each number apart based on its properties.

Now, the Segal-Shale-Weil distribution lets us figure out how many of the numbers in this Lie group have a certain property. It's like counting the odd candies in our box, but with a much bigger and more complex group of numbers.

This might not seem very useful, but it turns out that mathematicians use Lie groups and their representations to study all kinds of things in physics, like subatomic particles and gravity. So being able to count the number of something in a Lie group is a really powerful tool.

And that's basically what the Segal-Shale-Weil distribution does - helps us count things in big and complex groups of numbers, without having to actually look at each one individually.