A black hole, even in radio wavelengths alone, will exhibit a large number of different features owing to the bending of light by the curved space surrounding the black hole. Some of the material from behind the black hole, some of the material from in front of the black hole, and some photons from all around it will be bent and sent off along any particular line-of-sight. No radiation generated by quantum processes outside the event horizon, known as Hawking radiation, has ever been detected. (Credit: NASA’s Goddard Space Flight Center/Jeremy Schnittman)
According to Stephen Hawking, spontaneously emitted radiation should cause all black holes to decay. But we’ve never seen it: not even once.
Black holes represent the most extreme objects within our Universe.
Once you cross the threshold to form a black hole, everything inside the event horizon crunches down to a singularity that is, at most, one-dimensional. No 3D structures can survive intact. That’s the conventional wisdom, and has been treated as proven for over 50 years. But despite the predictions of Hawking radiation, no black holes have ever been observed to decay. (Credit: vchalup / Adobe Stock)
They’re created whenever too much mass collects inside a given volume.
In the vicinity of a black hole, space flows like either a moving walkway or a waterfall, depending on how you want to visualize it. At the event horizon, even if you ran (or swam) at the speed of light, there would be no overcoming the flow of spacetime, which drags you into the singularity at the center. Outside the event horizon, though, other forces (like electromagnetism) can frequently overcome the pull of gravity, causing even infalling matter to escape. Rotating black holes possess ring-like, not point-like, singularities. (Credit: Andrew Hamilton/JILA/University of Colorado)
An event horizon forms, and collapse down to a singularity is inevitable.
One of the most important contributions of Roger Penrose to black hole physics is the demonstration of how a realistic object in our Universe, such as a star (or any collection of matter), can form an event horizon and how all the matter bound to it will inevitably encounter the central singularity. Once an event horizon forms, the development of a central singularity is not only inevitable, it’s extremely rapid. (Credit: J. Jarnstead/Royal Swedish Academy of Sciences; annotations by E. Siegel)
Black holes can form via:
massive stellar cores collapsing during supernova events,
The anatomy of a very massive star throughout its life, culminating in a type II (core-collapse) supernova when the core runs out of nuclear fuel. The final stage of fusion is typically silicon-burning, producing iron and iron-like elements in the core for only a brief while before a supernova ensues. The most massive stars achieve a core-collapse supernova the fastest, typically resulting in the creation of black holes, while the less massive ones take longer, and create only neutron stars. (Credit: Nicolle Rager Fuller/NSF)
