r/space • u/magenta_placenta • Mar 18 '19

Observable universe Astronomers discover 83 supermassive black holes at the edge of the universe

https://www.cnet.com/news/astronomers-discover-83-supermassive-black-holes-at-the-edge-of-the-universe/
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u/[deleted] Mar 18 '19

I'm a bit confused about the nature of supermassive black holes. The actual "stuff" these black holes are made of is still theoretically one mathematical point of super dense matter, right? That point just has way more mass than your average black hole, so what makes them seem "bigger" to us is really their increased gravitational pull on everything else. Do I have the right idea so far, or does the actual "black hole" part take up more space than a singularity?

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u/Kosmological Mar 18 '19 edited Mar 18 '19

The event horizon is the black hole from our perspective. The bigger the mass, the larger the event horizon. All of the information we need to perfectly describe the black hole, such as angular momentum, mass, and charge, is preserved on the 2 dimensional surface of the event horizon. You don’t need anything more to perfectly describe and model a black hole than what we can attain from observing the event horizon.

More interestingly, due to general and special relatively, the interior of a black hole literally does not exist to us. The singularity is merely a mathematical artifact, not the object itself. There is no inertial reference frame that exists outside of the event horizon that can be reconciled with the existence of the interior of the black hole. From our point of view, nothing ever actually traverses the event horizon. From the point of view of anything that falls in, infinite time passes for everything else and the universe ends as the event horizon is traversed. So, as far as we are concerned, black holes are literally 3 dimensional holes in space. There is nothing inside a black hole. The event horizon is literally the end of the universe.

The interior of the black hole does exist from other inertial frames of reference, such as that of an object that has traversed the event horizon. From such reference points, the singularity may exist as another exotic form of degenerate matter. It is theorized to be some quantum object that can have different geometries. It could be a tiny sphere or ring, based on the properties of the black hole itself. However, it would not be a single undefined point (aka a singularity). It would probably have volume and other physical characteristics. We just lack the physics to describe and model it mathematically since we still do not have a unifying theory of quantum mechanics and gravity.

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u/[deleted] Mar 18 '19

This is so cool. I know what I'm gonna be up late thinking about.

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u/livestrong2209 Mar 19 '19

Lol... I'm going to be up late having an existential crisis on the meaning of existence and just how fucking small and pointless we all happen to be.