Is it possible to use both Firebase and PHP for a single project?

I've a big social networking project going on and I am amateur in web back-end. Although I've programming experience, I'm a beginner in the back end support.

I was trying to make a login page and was thinking if I use Firebase to do the user authentication? Then I would use PHP to do rest of the things like chat system or post system.

Is it possible to do so? If yes, then how should I start a session in Firebase and use it in PHP?