Friday08 November 2024

ru

en

ua

Black holes encode information on their surfaces, yet they evaporate through Hawking radiation. Does this information persist, and if so, in what manner?

https://focus.ua/technologies/673319-paradoks-hokinga-pochemu-fiziki-do-sih-por-ne-reshili-informacionnuyu-zagadku-chernyh-dyr2024-10-16 09:05:47

Back in 1974, the renowned physicist Stephen Hawking discovered that black holes are not eternally stable objects; rather, they lose mass through radiation, which later became known as Hawking radiation, until they completely evaporate. It was subsequently proven that black holes encode a vast amount of information on their surfaces, while Hawking radiation should contain no additional information. So, is the information that contributed to the formation of a black hole destroyed? Or is it somehow encoded in the outgoing radiation? This is known as the black hole information paradox or Hawking's paradox. Even in 2024, physicists have yet to solve this mystery, as reported by Big Think.

It is known that entropy in the universe always increases. On the other hand, the total amount of information in a physical system can only remain the same or increase, but it can never decrease.

However, a paradox arises for black holes. If any object is thrown into a black hole, it will retain information. This information will enter the black hole, adding to its mass and size. When the black hole evaporates through Hawking radiation, the information encoded in this radiation, as theories predict, will be completely random, as if the information has been erased. Despite constant claims that the black hole information paradox has been resolved, this is not entirely accurate.

Every particle and system of particles that exist in the universe have a certain amount of information. Some of these properties are static, such as mass, charge, the number of protons, neutrons, and electrons, etc. But other properties depend on the system to which the particle belongs, as well as its interaction history. If physicists could know the exact quantum state of each particle involved in the system at any given moment, they could obtain all the information about that particle. In reality, this is neither physically nor practically possible.

Instead of thinking of entropy as a measure of disorder, it is more accurate to think of it as the amount of missing information needed to determine a specific microstate of the system. This definition of entropy is key to understanding the concept of quantum information.

In our universe, the entropy of an entire physical system can never decrease; it can only increase or remain the same. This is why the black hole information paradox is a genuine puzzle.

What happens to the information that enters a black hole? In principle, it could be encoded on the surface of the black hole itself. However, the entropy of a black hole does not allow information to be preserved indefinitely. Over time, the black hole disappears due to Hawking radiation. Yet, this radiation does not encode the information that originally went into the formation of the black hole. Somewhere, the information has been destroyed. This is the key mystery behind the black hole information paradox. This information exists, just like entropy, and it enters the black hole both at its creation and as it grows. The contentious issue, and the real big question behind the paradox, is whether this information returns or not.

The way physicists calculate what comes out of a black hole via Hawking radiation has not significantly changed in the last 50 years. It utilizes Einstein's theory of relativity and quantum theory. From this, it is understood that Hawking radiation has temperature, spectrum, entropy, and other properties, including the fact that it does not encode the initial information. Over time, the black hole loses mass, resulting in an increase in the intensity of the radiation, as well as its temperature and entropy, until the black hole completely disappears.

So, where has all the initial information gone if it somehow does not appear in the radiation? Or does it still exist in the radiation? Three possibilities are suggested:

- Information loss occurs, but it is not a problem due to some process that scientists do not understand, allowing for information loss to happen without paradoxes.
- Despite black holes emitting radiation as believed, information is not lost and is somehow encoded in this radiation, meaning that physicists are likely drawing incorrect conclusions based on their assumptions.
- It is quite possible that something is wrong with the fundamental assumptions made when formulating the information paradox, and physicists do not understand black hole entropy correctly at all.

Although the proposed solutions are not necessarily limited to these three options, most physicists generally expect that something interesting is happening in either the second or the third case.

The space outside a black hole is extremely complex, even when considering it as an idealized rather than a realistic system. An important fact is that this space behaves as a non-static, self-moving entity. Physicists suggest that the laws of general relativity remain perfectly accurate for describing the dynamics of space at the quantum level. It is assumed that the quantum effects that create Hawking radiation are significant. However, any quantum effects arising when considering space as a classical background, which it may or may not be, can be ignored. Physicists work with this approach to explain Hawking's paradox. But it is not entirely correct.

Despite periodic and repeated statements from scientists that the black hole information paradox is nearly resolved, this is not the case. Accurate answers to questions regarding the correct quantum properties of the outgoing Hawking radiation and where exactly the information goes when the black hole has completely disintegrated are still lacking. Physicists have yet to determine whether black hole information is preserved, and if so, how?

The good news is that scientists have made progress in addressing the fundamental question of the black hole information paradox. It can now be stated with a fair degree of confidence that one of the assumptions underlying the problem is incorrect. One cannot simply look at the space outside the black hole when calculating the outgoing radiation. There is a continuous interaction between this radiation and the inner part of the black hole. As the black hole evaporates, the inner part begins to contain information related to the outgoing radiation, and thus, the inner part of the black hole can no longer be ignored.

However, physicists are still far from precisely defining where this information goes and how, and whether it actually leaves the black hole at all.