Before I say anything else I have no intention to make a game of any kind. I just got a question from a random web user and I was curious as the answer.

He asked if it was possible make a graphics engine with php. I told him that I cannot be certain but I am pretty sure that php cannot be used to make a graphics engine.

Can PHP theoritcally be used to make a graphics engine? If not what is the language missing to create one?

A graphics engine? Perhaps when you are using PHP as a command line, local programming language but not any other way like Java. The closest I could think that PHP could come would be with the GD module (or some of the newer 3D rendering modules) and ajax sending image specifications to PHP to generate and return. I can only imagine how slow this would be.

Another was would to have PHP generating images that are loaded into flash to be animated and used in actionscripts and movies.

I would never attempt it though, I would use a language much more suited to the task -- Java, C etc.