alainprice: Sorry, I copied ravens cry's remark from your quotation of his statement without noticing that I was doing so. When I said, "The mass, being kinda stupid", I goofed. I meant to say, "The negative energy, being kinda stupid".

I'm aware that the description involving particle pairs just outside the event horizon is an oversimplification, but the more rigorous analysis involves more quantum field theory than I'm prepared to deal with. I'm led to understand that the particle-pair picture is a rough approximation of what quantum field theory describes.

My answers to your three points are:

1- It's annihilation of the particle or antiparticle falling through the event horizon that returns "negative" energy to its source whether it happens inside or outside the event horizon.

2- The "borrowed" energy that goes into generation of the particle pair is said to have been loaned not from the gravitational field of the black hole but from space itself, suggesting that space has the ability to perform short-term loans of real energy.

3- The "negative" in negative energy is not to be taken too literally. It merely implied that it is loaned and must be returned to its source.