brash_stryker:
You keep saying that he's falling down the lift shaft not the reactor core shaft. Please explain how you know it to be a "lift shaft".
It might be because he's right next to the lift!
And if you look at the scene it's crystal clear that the Emperor is electrifying Luke next to the railings on the lift shaft, and Vader throws him down it.
Watch the scene, it's indisputable.