The concept of virtual particles does exist in string theory, but they are not the same as virtual particles in traditional quantum field theory. In string theory, particles are not considered to be point-like objects, but rather tiny strings or loops. These strings can vibrate at different frequencies, giving rise to different types of particles.
In string theory, virtual particles are considered to be excitations of the string that are not observed directly, but can have an effect on the behavior of the string. They do not have the same properties as point particles, such as definite position and momentum, but rather exist in a probabilistic "fuzzy" state.
As for black holes in string theory, they are described as tiny strings that have collapsed into a singularity. According to string theory, black holes do not emit Hawking radiation in the same way as point particles. Instead, they emit radiation through the vibration of strings on their event horizon. This radiation is known as "Hagedorn radiation" and is thought to be responsible for the evaporation of black holes in string theory.
There are indeed multiple types of black holes in string theory, including "fundamental" black holes, which are made of a single string, and "solitonic" black holes, which are made of multiple strings. These different types of black holes have different properties and behaviors, but they all follow the same fundamental principles of string theory.
Overall, the concept of virtual particles and black holes in string theory is still a subject of ongoing research and debate, and there is much that is still unknown. However, string theory offers a unique and intriguing perspective on these phenomena, and continues to be a fascinating area of study in theoretical physics.
