Algr said:Nothing gets out of the black hole. The vacuum fluctuation occurs just outside the event horizon. One particle escapes, and the other enters the black hole. The anti-particle negates whatever is in the hole, forming nothing, as in 1+(-1)= zero.
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Of course I may be wrong, as it seems to me that particles and anti-particles would have an equal chance of entering the hole, thus negating each other instead of anything in the hole. What am I missing?
George Jones said:When virtual matter-antimatter pairs are created, the probability that the antimatter particle has positive energy is equal to the probability that the matter particle has positive energy, i.e., both probalilities are 1/2.
Hawking radiation does not come about because antimatter particles sometimes fall into black holes; it comes about because negative-energy particles (both matter and animatter) sometimes fall into black holes. Some popular-level treatments of black holes obscure this, and even sometime get this completely wrong.
Sometimes it is difficult to give accurate non-mathematical descriptions of processes that involve advanced physics. This is particularly true for Hawking radiation - it is very hard to see the correspondence between the non-mathematical description involving virtual matter-animatter pairs and the actual mathematical description.
Steve Carlip is a physicist who tries hard to make physical concepts clear, both for laypersons and for experts. You should read his non-mathematical description of Hawking radiation, which is more challenging than most non-mathematical descriptions, but which also is more accurate than most non-mathematical descriptions. If you have questions about his description, just post them.
What happens, very roughly, is this. Energy is associated with time and spatial momentum is associated with space. When an matter-antimatter pair of virtual particles is created *outside* the event horizon, they can become a little bit separated in the time that the Heisenberg uncertainty principle allows them to live. Tidal forces caused by the curvature of spacetime help them to separate, and, sometimes, the negative-energy particle (which could be either matter or anitimatter) wanders over the event horizon and into the black hole. Inside the event horizon, the roles of time and space coordinates get interchanged. Thus, according to what I wrote above, the roles of energy and spatial momentum get interchanged. What was negative energy becomes a negative spatial component of a local (for an observer inside the horizon) momentum vector. Only a virtual particle can have negative energy, while any particle, real or virtual, can have a negative component of spatial momentum.
Bottom line: the whole process can become a real process. In this real process, an observer outside a black hole "sees" the black hole hole swallow a negative-energy particle while emiitting a positve energy particle (the other member of the matter-antmatter pair). The balck hole radiates.
Regards,
George
Algr said:So I should have said " negative energy particle" instead of anti-particle. But that doesn't change the basic question - aren't negative and positive energy particles equally likely to fall into the event horizon? Wouldn't they just cancel each other out?
Steve Carlip said:Note that this doesn't work in the other direction -- you can't have the positive-energy particle cross the horizon and leaves the negative- energy particle stranded outside, since a negative-energy particle can't continue to exist outside the horizon for a time longer than h/E. So the black hole can lose energy to vacuum fluctuations, but it can't gain energy.
Hawking Radiation is a phenomenon proposed by physicist Stephen Hawking in which black holes emit radiation due to quantum effects near the event horizon. This radiation causes the black hole to lose mass and eventually evaporate. This concept is important in understanding the dynamics of black holes and their eventual fate.
The idea of a black hole being "perfectly black" means that no light or radiation can escape from it. However, Hawking Radiation suggests that black holes actually emit radiation, which goes against this notion. This has caused some confusion and debate among scientists, but the concept of Hawking Radiation has been supported by various experiments and observations.
Hawking Radiation is caused by the interaction between quantum effects and the intense gravitational pull of a black hole. According to quantum mechanics, particles and antiparticles are constantly being created and destroyed in pairs. Near the event horizon of a black hole, one particle may fall into the black hole while the other escapes as radiation. This process causes the black hole to gradually lose mass.
As of now, Hawking Radiation has not been observed or harnessed for any practical applications. However, the concept has played a crucial role in the study of black holes and has contributed to our understanding of the universe.
No, there are other proposed mechanisms for black holes to lose mass, such as the Blandford-Znajek process and the Penrose process. These processes involve the extraction of energy from the rotation of the black hole. Additionally, as black holes interact with matter and other black holes, they can also gain or lose mass. Hawking Radiation is just one way that black holes can lose mass over time.