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Why do the pairs of virtual particles that appear at the event horizon of a black hole always fall into the negative mass and escape the positive mass? Since it is a random quantum fluctuation, shouldn't the probability of who goes in and out be the same?

Last time it was said that Hawking radiation is similar to a kind of thermal radiation, although it takes a very long time, but because of its existence, the black hole will one day "evaporate" itself clean. Because the Hawking radiation is so weak that the energy lost by the black hole is not absorbed from the background radiation, it is still safe for the black hole at this stage.

The most common explanation for how Hawking radiation comes from is the quantum fluctuations that occur at the event horizon of a black hole. This description is used in almost all popular science about Hawking radiation, including Hawking himself.

Although this description is easy to understand and easy to understand, it is also because of popularity, it is not a real physical picture. As a simplified description, it is bound to be imprecise, which leads many people to wonder at the beginning: quantum fluctuations are random, why are the results of the two particles not random?

Before answering this question, let's re-understand how Hawking radiation comes from a more scientific point of view.

Last time, Hawking applied quantum field theory to general relativity and got Hawking radiation. In fact, during the same period, Stephen Flynn, a postdoctoral fellow, was also considering the quantum field theory of curved space-time, and predicted the phenomenon that accelerated observers would see a kind of blackbody radiation that could not be seen from the outside world. The theory of this phenomenon was then further refined by Paul Davis and William Amrou, which became the later "Flynn-Davis-Unruh effect effect", also known as the "Amrou effect".

Stephen Flynn, Paul Davis, and William Ann Rouge use the most popular words to explain that if you are in a vacuum with a very accurate thermometer, when all factors that can affect the thermometer reading (including background radiation) are excluded, the thermometer reading should be infinitely close to zero, right? But when you start to accelerate, the thermometer reading will no longer be zero. In other words: you speed up the movement of you make the surrounding space "hot", and the degree of heat is proportional to your acceleration. Note: at this time, the thermal radiation generated by the surrounding space can only be seen by you in accelerated motion, and this part of the space is not getting hot for outside observers.

It is not clear whether this bizarre phenomenon really exists, because it is extremely difficult to verify. If we want to make an object (for example, an atom) warm enough to be detected, we need to accelerate it to close to the speed of light in less than 1 microsecond (that is, 1/1000000 seconds). To achieve such a high acceleration, even the most powerful particle accelerators do not have the ability to do so.

Then we first assume that the Andrew effect exists, then Hawking radiation can be regarded as a phenomenon caused by the Andrew effect.

Anyone who knows anything about general relativity should know the "equivalence principle", that is, the observer in the gravitational field and the observer in the accelerated motion, the two are indistinguishable from the effect.

Therefore, for observers near the black hole, because of the strong gravity of the black hole, the Amru effect, which is difficult to show, can be shown here. So observers near the black hole will find that the space around them is "getting hot", and the vacuum has changed from "no temperature" to "temperature". If there is temperature, there is thermal radiation, and the temperature is produced by the gravitational field of the black hole, so we can assume that the black hole is radiating energy outward, that is, Hawking radiation.

Therefore, the particles produced in Hawking radiation are not positive particles, antiparticles, let alone virtual particles, they are ordinary photons. The so-called virtual particles are only things used in the process of calculation, and only real particles with positive energy are finally reflected in reality.

Where on earth did these radiated solid particles come from? Obviously, they come not from inside the black hole, but from the space outside the event horizon of the black hole, or in a vacuum. The generation of these particles is caused by the inconsistency between the vacuum near the black hole and the vacuum in the distance, you can understand that a vacuum state produces some kind of excitation in the process of spreading far away, and this is where the positive mass particles that "escape" come from.

So at the beginning of the question, "Why only negative mass particles are swallowed up and positive mass particles escape", you can understand causality in turn: because the escaped particle is outside the event horizon, it becomes a real particle with positive mass; and the particle in a black hole, you can only think that it has negative mass, after all, energy conservation. As for what the negative mass particle is and what it looks like, it doesn't matter. Anyway, it has nothing to do with our world. Just treat it as an imaginary being.

Now, is the explanation of quantum fluctuation quite vivid? It's just that this modified popular explanation ignores a lot of details, so it also brings some problems: for example, it can make people think that the radiation is emitted entirely from the visual interface. In fact, as I just said, Hawking radiation is generated by the space around the black hole, and those particles do not just appear on the event horizon. In fact, they are born in a large area outside the event horizon and can even extend to 10 to 20 times the radius of the black hole. Because the farther away from the black hole, the weaker the gravitational field, the radiation gradually weakens from the inside to the outside. As the energy is slowly taken away by the radiation, the curvature of the space decreases slowly, showing that the black hole is slowly getting smaller.

Generally speaking, Hawking radiation is a theory based on mathematical models, and there is no corresponding very accurate and vivid physical image. If you have to give a physical image, you can also think of it this way: if the black hole swallowed positive mass particles, then the mass of the black hole would be a little larger, and the visual interface would expand outward a little bit. in this way, the escape probability of negative mass particles will be reduced a little bit. On the other hand, if you swallow negative mass particles, the mass of the black hole will decrease a little bit, and the event horizon will contract inward a little bit, so that the escape probability of positive mass particles will increase a little bit. So the end result is that positive-mass particles escape a little more. So, is this explanation vivid enough?

Finally, some friends mentioned that black holes will gradually become smaller with Hawking radiation, which is not in contradiction with the black hole area theorem of "only increasing but not decreasing".

In fact, it is not a contradiction. The area theorem is more about the macroscopic performance of black holes, such as the large-scale phenomenon of the merger of two black holes, while Hawking radiation is microscopic and belongs to the effect of quantum level. Just like general relativity and quantum mechanics, both theories are true, but the scope of application is different. In addition, the area theorem is mainly aimed at the black hole itself, while Hawking radiation takes into account the whole system that contains the black hole and the space near it. The two theories are not within the same physical framework, so there is no contradiction.

But then again, both the surface area of the black hole and Hawking radiation are related to the same thing, that is, the "temperature" of the black hole, but the "temperature" here is not the traditional temperature.

The concept of temperature is actually very broad. Sometimes it does not necessarily represent the kinetic energy of particles. For example, temperature in statistical mechanics can correspond to other degrees of freedom. If you don't consider the heat balance, you can even create a "negative temperature". Theoretically, a substance with a "negative temperature" is not "colder than absolute zero", but "hotter than any positive temperature". It is just that the level of the negative temperature system is meaningless because it does not consider the thermal equilibrium and does not satisfy the zeroth law of thermodynamics.

This article comes from the official account of Wechat: Linvo says ID:linvo001, author: Linvo

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