Hawking Radiation doesn't make any sense?
March 14th, 2010 by janeHawking radiation is supposedly radiation that comes out of a black hole. It is theorized by Hawking that due to the Heinsburg uncertainty principle, a pair of particles - a "particle" and an "antiparticle" can spontaneously appear in front of a black hole. Hawking theorized that if the "antiparticle" falls into the black hole and the "particle" escapes, then the black hole loses mass and this is how over time the black hole slowly evaporates.
What my question is that, wouldn't over time a similar number of "particles" fall into the black hole as "antiparticles" therefore maintaining an equilibrium therefore not allowing the black hole to lose any mass? (In fact, wouldn't a higher number of "particles" fall into the black hole than "antiparticles" due to the fact that "particles" have mass and therefore wouldn't the black hole gain mass with Hawking radiation overtime if more "antiparticles" were emitted?)
I'm sure it makes perfect sense in Hawking's proof but I'm young and haven't yet dwelled beyond school mathematics.
Quantum mechanics states that energy and matter are in a continual dance of the energy collapsing (for lack of a better word) to create a particle and antiparticle pair, and then the particles smashing into each other again to turn back into energy. This "dance" is happening throughout the universe, even in what we consider empty space (vacuum fluctuations).
Energy, particles, and antiparticles are continuously being created and destroyed inside of the black hole. The only way for a black hole to loose mass is when this occurs near the event horizon (the edge where gravity becomes to strong for light to escape from the black hole). When energy near the edge creates a particle/antiparticle pair, quantum mechanics allows for one (or both) to materialize just beyond the event horizon and escape the black hole, taking its mass with it.
This is a very, very slow process by our time-line. In the course of a lifetime, there will not be a measurable difference in the mass of a black hole. When speaking of a cosmological time-line (hundreds of thousands to several million years - a blink of an eye to the universe), a black hole can theoretically dissipate into nothing.
Many of the particles that are radiated are in fact photons. The antiparticle for a photon is a photon. And both photons can be emitted, i think.
When the black hole absorbs one of these particles, it breaks the symmetry (symmetry is a very important thing in quantum physics). As the energy balance has to be kept zero (as otherwise the universe would slowly gain energy from nowhere), the energy has to be spent by the black hole, which is guilty of disturbing the balance.
Both have mass. Both will annihilate one of their anti-particles.
What doesn't 'make sense' is the appearance of the particle
pair in the first place, but theory does hold that it happens.
Also, both anti-matter and matter have positive mass.
The particle that falls into the black hole, again no matter which it is, has less energy than the gravitational ground at the event horizon. So the black hole is constantly soaking up particles that have less energy than the vacuum they were made in; i.e., negative energy particles.
It's not a "particle/antiparticle" pair; rather, it's an "existence/antiexistence" pair. Quantum mechanics allows particles to pop into existence "ex nihilo" (from nothing), but only for an extreeeeeeeemely short time (the so-called Planck time). They pop into existence along with another "antiexistence particle". They then pop right back out of existence, UNLESS the "antiexistence particle" meets up with an actually existent particle and annihilates it.
Now, suppose one of the existence/antiexistence pairs pops up on a black hole's event horizon:
If the existence particle is inside the event horizon, it gets sucked in. However, the antiexistence particle does not (we can assume) meet up with any existing particle, so they both pop right back out of existence after an extreeeeeeeeemely short time.
Suppose instead that the antiexistence particle is inside the event horizon. If the existence particle outside the event horizon has sufficient energy, it can escape the black hole's gravitation. The antiexistence particle, being inside the black hole, will of course be "suck in" to the singularity and will reduce the mass of the black hole by annihilating mass exactly equal to the particle that escaped.
Btw, this is called "evaporation" of a black hole. Obviously, I haven't given you any sort of proof, just a description of the idea. If you want to research it more, get into a graduate course on quantum mechanics.
1st, antiparticles (http://en.wikipedia.org/wiki/Antimatter) DO have mass. Just because they have a cool name doesn't mean they're not matter. They just happen to have the property that when it collides with ordinary matter, they annihilate eachother. So its perfectly reasonable for the gravity of a black whole to pull in antimatter.
2. (This is where I'm guessing), I think two particles you speak of are radiating from the black hole itself-- so even if the matter particle you speak of is the one that gets sucked in, the black hole does not grow at all, because the particle came from the black hole to begin with.
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