What are wormholes ? Explain like i am 5
Some people think there are those things called wormholes that allow people to travel very-very far very quickly, faster than anything else, even faster than light. 
Imagine a caterpillar in the middle of a big leaf, and it needs to be on the other side of it. It can crawl to the edge and then turn around it. But if it chews a hole though the leaf then it is a much shorter path. Wormholes work the same way.
Is this physically possible or is it purely theoretical?