우주학 개론 제 16강 3부 (블랙홀 정보의 역설 해결 방법 - 영어더빙, 한국어 자막)

Introduction to Cosmology, Lesson 16, Part 3 (How to solve the black hole information paradox - English dubbing, Korean subtitles)

Einstein and Rosen published a paper titled "Can Quantum-Mechanical Description of Physical Reality be Considered Complete?" in 1935. In this paper, they introduced the concept of a hypothetical passage called a wormhole, connecting black holes and white holes. A wormhole is a theoretical pathway that allows for rapid transit from one point in space to another, assuming that the entrances of a black hole and a white hole are connected. Black holes act as objects that pull matter in, while white holes expel matter.

According to this theory, it was claimed that traveling through a wormhole would enable movement to different spaces or times. In other words, an object crossing the event horizon of a black hole could exit through the entrance of a white hole, potentially allowing for time travel. However, this theory has not been substantiated by scientific evidence. The existence of wormholes appears feasible under General Relativity, but it encounters contradictions with quantum mechanics. Additionally, wormholes are highly unstable, and their short lifespan raises the possibility of destruction for anything passing through them. Therefore, the feasibility of time travel through wormholes remains unknown.

The black hole information paradox refers to a contradiction between the predictions of General Relativity and quantum mechanics regarding black holes. According to General Relativity, black holes pull all matter and information beyond the event horizon. The event horizon is the boundary from which even light cannot escape. In contrast, quantum mechanics dictates that information must be conserved.

Therefore, the matter and information that fall into a black hole must be preserved somewhere. However, if a black hole evaporates, its event horizon disappears. This raises the question of what happens to the matter and information that fell into the black hole. If all the information inside the black hole is destroyed when it evaporates, it violates the law of information conservation. On the other hand, if the information inside the black hole is preserved when it evaporates, it implies that information can move beyond the event horizon. This contradicts general relativity.

Therefore, the black hole information paradox presents a fundamental challenge to our understanding of black holes. Various attempts have been made to resolve the paradox, but a definitive solution remains elusive.

One proposed solution suggests that information swallowed by a black hole is preserved at the singularity. The singularity is a point at the center of a black hole where gravity is infinite and spacetime is highly warped. Since our known physical laws do not apply at the singularity, it is suggested that information could be conserved there.

Another solution proposes that when a black hole evaporates, the information inside it is emitted in a copied form. Hawking radiation is the energy emitted when a black hole evaporates, consisting of various particles such as photons and neutrons. Therefore, the information absorbed by the black hole might be copied into these particles and emitted.

The black hole information paradox is a paradox concerning the fate of information that falls into a black hole. When applying both general relativity and quantum mechanics, it leads to the conclusion that information that falls into a black hole can be completely destroyed. However, the law of information conservation states that information cannot be destroyed. Therefore, it appears that these two laws contradict each other.

This paradox was first introduced in 1974 when Stephen Hawking published a paper on Hawking radiation. Hawking radiation is the phenomenon where a black hole emits radiation and loses mass. Hawking argued that a black hole would eventually disappear due to Hawking radiation, and in the process, the information that fell into the black hole would also be destroyed.

However, the law of information conservation explicitly states that information cannot be destroyed. Thus, Hawking's claim that information falling into a black hole would be completely destroyed violates the law of information conservation.

The black hole information paradox remains an unsolved mystery to this day. It is still unclear whether one of the two laws needs to be abandoned or if a new physical law can be discovered that satisfies both laws.

The black hole information paradox holds significant importance in our understanding of the fundamental physical laws of the universe. If this paradox is resolved, it is expected that our understanding of the nature of the universe will advance significantly.