# Is there a better explanation of Hawking radiation?

I'm writing a piece on Hawking radiation, and find I have something of a problem. The "given" explanation which I find on Wikipedia and elsewhere is unsatisfactory:

"Physical insight into the process may be gained by imagining that particle–antiparticle radiation is emitted from just beyond the event horizon. This radiation does not come directly from the black hole itself, but rather is a result of virtual particles being "boosted" by the black hole's gravitation into becoming real particles[10]. As the particle–antiparticle pair was produced by the black hole's gravitational energy, the escape of one of the particles lowers the mass of the black hole[11]. An alternative view of the process is that vacuum fluctuations cause a particle–antiparticle pair to appear close to the event horizon of a black hole. One of the pair falls into the black hole while the other escapes. In order to preserve total energy, the particle that fell into the black hole must have had a negative energy..."

It relies on virtual particles and an negative-energy particles. However vacuum fluctuations are not the same thing as virtual particles, which only exist in the mathematics of the model, and we know of know negative-energy particles. So I'm looking for a better explanation. The Wikpedia article also says this:

"In another model, the process is a quantum tunnelling effect, whereby particle–antiparticle pairs will form from the vacuum, and one will tunnel outside the event horizon[10]."

However that suggests pair production is occurring inside the event horizon, which seems to disregard the infinite gravitational time dilation, and that one of them a) appears outside of the event horizon and b) escapes as Hawking radiation when pair production typically involves the creation of an electron and a positron. Again it's unsatisfactory. So:

Is there a better explanation of Hawking radiation?

• The particle falling in doesn't require negative energy. All that matters is that some photons escape to infinity, which means that some of the energy that was "borrowed" from the gravitational field is lost (in the form of those photons). So the gravitational field weakens, which reduces the apparent mass/energy. But "apparent" is just what we see as distant observers. What happens inside the event horizon is...in the range of conjectural to nothing. That said, I don't think there's a majority opinion on how the radiation arises, or if it even exists... – zibadawa timmy Mar 22 '17 at 10:03
• You might find more on Physics SE given the fairly esoteric nature of this material. – StephenG Mar 22 '17 at 10:54
• Noted Stephen. @zibadawa timmy : but how does you "borrow" energy from a gravitational field? And if you do, how does energy then leak out of the event horizon for more of the same until you end up with no black hole at all? – John Duffield Mar 22 '17 at 12:36
• John, from your questions it sounds like you don't understand the concepts of potential energy or energy stored in fields (gravitational, electric, etc). I'd start by reading about those concepts. – Carl Witthoft Mar 22 '17 at 12:57
• 1. All these verbal explanations are just metaphors. The real deal is doing the Hawking calculations - that's the real explanation. 2. Here's another metaphor: The black hole is nothing but a tremendous spacetime curvature tied into itself - and the name we have for spacetime curvature is "gravity". The black hole is nothing but gravity, intense enough to persist itself. The p / anti-p pairs are brought into existence the same way that any extremely intense field can generate particles: when you have plenty of energy, particles can pop out of it. E.g. electromagnetic radiation could do it too. – Florin Andrei Mar 22 '17 at 18:35

• It was an interesting read, but I noted this on page 5: ”One may now consider doing an experiment first proposed by Geroch$^{[8]}$. One adiabatically lowers a perfectly reflecting box filled with electromagnetic radiation at a temperature T >> T$_{BH}$ to a Schwarzschild radius r, close to the event horizon. One then exchanges radiation with the hole…” Surely there’s no exchange because of the infinite gravitational time dilation? Geroch’s gedankenexperiment from the 1971 Princeton colloquium seems to be widely referenced but unpublished. An interesting lead, thanks again. – John Duffield Mar 23 '17 at 13:12