It really is not possible to prove that any space contains nothing. There are possibilities of new forms of wave energy or undetectable(as yet) particles that are passing unhindered or unseen by any known means yet available. I was going to say that the detector of something new would have to be invented first but really the new phenomena and its detector would arrive simultaneously. - bit like the chicken and egg problem. Any known chemical in the space would of course have techniques for detecting it and the time from the discovery of a new elements since the last one is getting longer and longer but they also tend to last a smaller and smaller time. It is likely that our universe and others are constant in their total of matter +energy (which is interchangeable with energy ; E=mC2)
It is one of a number of concepts that one just has to get used to in science starting with things like the concept of infinity which cannot be assigned a number. I hope this does not put you and others off trying these concepts because without them we cannot make progress to any true understanding. "You get used to them " , which is probably not a very satisfactory argument to you. Black holes are very special spaces.

They are still working on the math,could have been appearance through a super massive black hole, they still don't know

They probably read it in a book.

Like so many other unbelievable events, they were bamboozled into believing. OR forced to believe by peer pressure.

Hummmmm. Where have I heard that before