Normally, black holes have an event horizon, which stops us from seeing the black hole directly. However, we still know it is there due to gravitational lensing.
In general relativity, a naked singularity is a gravitational singularity that is viewable from the outside. The event horizon is like a bubble which surrounds a black hole. Inside the event horizon, the pull of the light cannot escape, so we are unable to view objects inside the event horizon. This includes the event horizon itself. Naked singularities do not have an event horizon, hence the term 'naked'.
The existence of naked singularities is a very important topic in physics, because it would mean we could actually see phenomena made by black holes that we wouldn't be able to see otherwise. In addition, naked singularities would pose big problems for general relativity, since scientists still have not figured out a working idea for what happens to space-time in and around a black hole. Quantum mechanics, the main other scientific theory scientists turn to in physics, is also unable to explain how space-time would behave in such a situation.
Although the cosmic censorship hypothesis says that naked singularities cannot exist, some research says that if loop quantum gravity (a scientific theory that says the universe is made of small 'loops') is correct, naked singularities could exist in nature. Other calculations and arguments have been made to support this.
Possible formation
There are black holes known as Kerr black holes which have spin (they rotate). But, there is a maximum spin rate. If it spins faster than that maximum, its horizon disappears, leaving the singularity inside it wide open.
Mathematician Demetrios Christodoulou has shown that naked singularities also occur in nature.[1] However, he then showed that such "naked singularities" are unstable.[2]
