Originally posted by KingDubya
If I remember correctly, in Episode V, someone directly called the Emperor "Emperor Palpatine". When Episode I came out, I hadn't seen any of the others for about two years, but then hearing Palpatine's name struck a chord in my memory, so I watched the movies again. And there was the mention of the name Palpatine, so I knew far before most people that he was the Emperor, and since Sidious and the Emperor shared many physical qualities it was common sense that they would be one and the same. And I was right.

If there's anyone out there who thinks that they can directly prove me wrong, I dare you.

that and, on the movie itself it says that palpatine is sidious.