Low Dimensional Crisis

In fact, a black hole in three-dimensional space and time is a four-dimensional material, and the singularity observed by humans is a point where this four-dimensional material and three-dimensional space and time come into contact. This is indeed not easy to understand, because it is difficult to imagine what four dimensions look like in a three-dimensional world. It can be easily understood if it is changed to two dimensions. Here you can imagine the desktop as a two-dimensional space-time. The two-dimensional creatures on the desktop can only see things within the two-dimensional desktop. When they observe a two-dimensional black hole, they also see the singularity of the two-dimensional black hole. If we place a three-dimensional ball on the table (two-dimensional space-time), and then observe it by the two-dimensional creatures on the table, what will they see? The answer is also a point. Because two-dimensional creatures cannot observe things outside the desktop (two-dimensional), they can only see a point where the three-dimensional ball contacts the desktop (two-dimensional space-time). This point is the singular point of the two-dimensional black hole, and the three-dimensional ball is a black hole in two-dimensional space and time. Therefore, a black hole in any dimension is a high-dimensional matter.