Recursion in the real life

{Imported from my post in Vstretch blog}

Recursion is one of the most interesting concepts I have found in the software development, when a function calls itself in order to efficiently reach a solution. Most of the models used in the science and technology are based on the real-world entities at the first place, neural networks, artificial intelligence.. For many years now I had the thought of finding the analogy of the recursion in reality.

There are many aspects that are recursive, although your first tough usually doesn't land on those, like the parallel mirror positioned ideally so that one reflects the reflection of the other and the other one the reflection of the other one... But there are two problems with this instance, first that wherever you position the camera (viewpoint) it won't be reflecting the reflection of one mirror into the other, since it is going to be pointed onto one of the mirrors at a time. Second problem is that in the actuality there is no such thing as ideally positioned mirrors, likewise there is no such a thing as parallel lines.

Lizards - by M. C. Escher (one of the most recursive painting known)

As a kid I was amazed when on tv, the cartoon actors where watching TV. I would guess that those could be watching another cartoon on their TV, why not? That's like a wander to a kid -- recursive cartoon!

The best instance of recursion for me has been for a long time and to this day.. dreaming... Have you ever had a dream in your dream?

Think about it, and before you ever heard of  the movie Inception, but when you are dreaming inside your dream, which is the serious second level dreaming. But who restricts you to have another dream when you are dreaming in your dream? With enough imagination that is very possible and achievable.

What's your instance of real-world recursion?