This was a book series I read when I was younger.
It featured a boy in his early teens who was contacted by aliens in a miniature space ship. He is soon shrunk down to their size and becomes a member of the ships crew. I believe they are some sort of galactic police force.
They go on several adventures over the course of a few books.
I believe the main villain in the story attempts to freeze time in his moment of ultimate triumph. There might also be some sort of search for the boys father.