ELI5: Explain Like I'm 5

Hamilton–Jacobi equation

Okay kiddo, have you ever seen those movies where the bad guys are chasing the good guys in their cars, and the good guys have to figure out the best way to get away and find their way to safety? Well, there's a fancy math equation called the Hamilton-Jacobi equation that can help the good guys figure out the best way to escape!

Now, imagine a robot that wants to move from point A to point B, and it has to make sure it doesn't hit any obstacles or run out of energy along the way. The Hamilton-Jacobi equation can help the robot figure out the best way to move from A to B while avoiding obstacles and using the least amount of energy possible.

But how does it work? Basically, there's a function called the "action" function that describes how much energy the robot needs to use to move from one point to another. The Hamilton-Jacobi equation tells the robot how to find the best action function to use by calculating the optimal paths that minimize the energy used and avoid obstacles along the way.

So in simpler terms, the Hamilton-Jacobi equation is like a map that helps robots and other machines figure out the best paths to take to reach their destinations while avoiding obstacles and using the least amount of energy possible. Pretty cool, huh?