How does emberfire maintain authentication sessions when restarting the app?

This is a very noobie question, but there is something I don't really understand.

Whenever I have an authenticated session with emberfire, I'm able to stay logged in, even if I do something like refresh the page or go hit the back button on my browser. The reason I find that strange is because Ember is a single page application. That means by hitting refresh I'm essentially restarting the app and I feel like I should be losing all my sessions and states. How is it then that my login state is preserved even when I refresh the page? Shouldn't my login information be lost when refreshing?