So: we live on the earth. The earth is in the galaxy. The galaxy is in the universe. the universe is a kind of black hole because no light can escape. A kind of multi-dimensional sphere. But, what’s behind that? If this happens like a normal black hole, there should technically be matter (or some other source of energy) feeding the black hole. Is this so? And if so, where does that energy come from? Is there some kind of other black hole like our sky out there? or is it just fueled by dark energy?
Answer
You say it rightly: a ‘sort of’ black hole, because the light (by definition) cannot escape.
Where your reasoning goes too far is when you state that with a ‘normal black hole’ there must be matter to feed the black hole. That is not true. What is true is that we can only ‘see’ that black hole when matter falls on it: before that matter falls into the black hole (and thus disappears), it emits a lot of energy, which we just barely see. But if it weren’t for that energy, the black hole would still be there, we just didn’t see it.
In that sense too, describing the universe as a black hole is a bit misleading. It’s true, the light can’t get out, simply because all space is in the universe. Actually, it is a ‘white’ hole for those standing in the universe.
Answered by
prof. Christopher Waelkens
Astronomy
Old Market 13 3000 Leuven
https://www.kuleuven.be/
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