Boy: Can I dig a hole?
Dad: Well sure, why not?
Boy: Can I climb a tree?
Dad: Yes, sir!
Boy: Can I jump off the roof?
Dad: Of course!
Boy: Can I fly in the sky?
Dad: Yes, son, you can!
Boy: Can I go into space?!
Dad: Erm. No, I'm sorry, son. You can't do that.
What is this conversation means?