Black holes have arguably been my favorite food for thought in the past decade or so. However, there is one glaring issue with them that has been bugging me lately.
Einstein described in significant detail everything that should, in theory, happen in a black hole. The only thing he admitted to having no clue about is also the reason why black holes might not even exist -
the singularity.
That point of infinite density and absurd amounts of mass that sits in the geometric center of the black hole is allowed to exist within the confines of Einstein's theory of general relativity, but there is one other major worldview on modern-day physics that would disagree with Einstein - quantum mechanics.
If the world as we know it does indeed abide by the rules of quantum mechanics, a singularity should
not be possible at all. This introduces the idea of the so-called "dark star" - currently the only alternative to a black hole that makes any sense in a universe governed by the unwavering laws of quantum mechanics.
Technically, the only reason physicists believe black holes exist is that
"nothing else can do what this dark spot in the universe does". It doesn't take a theoretical physics Ph.D. to reach the conclusion that such reasoning is far from convincing or built on anything resembling a remotely solid foundation. Well, a dark star
can exist both in general relativity
and quantum mechanics, and it has pretty much the same characteristics as a black hole, minus the magic happening in the middle.
A dark star would be born from a massive regular star that has collapsed in on itself because its inner balance has been disrupted. The intense gravity squeezes all of its matter tightly until it "extinguishes" it - no visible light comes out of it at all, and its surface temperature drops drastically.
However, this doesn't mean that no light at all comes out of it. In fact, photons are most likely streaming out of it in all directions, but because of the extreme conditions around an object so massive and dense, this light gets redshifted to an extreme degree. The photons' wavelength becomes so long that it can, in fact, span the entire galaxy, making it virtually undetectable by any detector smaller than the galaxy. In a sense, this photon becomes invisible to us, but it is there.
If black holes are in fact dark stars, this solves one of the hairiest problems in the hitherto accepted view on those mysterious objects - there is no need for an ineffable singularity in the center to achieve the same physical properties. Stars can still orbit a dark star, and it can still aggregate an accretion disk of superheated matter that emits light in a variety of wavelengths, including x-rays.
A lot more research and data is needed before we have anything close to an answer to all these questions. The bottom line is that we're still so early in our cosmic exploration, barely at the foothill of this towering mountain of knowledge about the universe. We just don't know and can only guess. But so far, the tantalizing mystery of a black hole seems rather implausible when measured against a much more grounded explanation, such as a dark star.
If you're interested in this topic, you can check out
this fantastic episode of the podcast "Daniel and Jorge explain the Universe" where
Daniel Whiteson, a brilliant particle physicist, goes into this subject in excellent depth.
The more we learn about the Universe, the more we expand our awareness of how little we actually know. Be well, friends.