What is "Emptiness"?

There is a lot of stuff in various sutras and holy books about "emptiness".

But what is it? And does this emphasis on "emptiness" mean that I have to be empty inside? Or that the world is just imaginary?

Perhaps "emptiness" refers merely to the absence of the need for a persona, a homunculus running the show. It is the absence of the need for a "me" in there somewhere. It is the absence of the need for a "mind" in charge. No observer.

That's all. No wonder Jesus spoke of the fullness of a cup overflowing - perhaps removal of the  need  for a persona, creates an opening through which the universe rushes in to fill the gap.

No big deal