Why is Hawking Radiation not probabilistically symmetric?

[MWresearch]

Hawking Radiation, where virtual particles form near the event horizons of black holes, normally posing no measurable effect due to annihilation can be sucked into the black hole. Since energy must be conserved, if positive mass escapes the black hole's gasp outside the event horizon, then the black hole must lose energy. But, in all of this, is there not a 50/50 chance of a black hole absorbing either a positive energy particle or negative energy particle? If there is, why would a black hole shrink over time? Shouldn't it stay the same size because of positive and negative energy gain have the same probability? If they don't have the same probability, well how?

[John Cuthber]

"But, in all of this, is there not a 50/50 chance of a black hole absorbing either a positive energy particle or negative energy particle? "

No.

The particles may have positive or negative charge, but they have positive mass and that's all that matters.

No particle has negative energy.

[MWresearch]

I kind of wanted you to elaborate more on why it's "no," hence me saying "...well how?" Also, there are multiple articles stating that a black hole can in fact absorb negative energy from a virtual particle pair that is created near the event horizon leading to its eventual evaporation. A black hole absorbing positive mass would cause it's mass to increase, not decrease. Even in the tunneling model whereby somehow the distribution of the virtual pair exceeds the infinite time dilation and length contraction of a black hole, there is still positive mass and negative mass.

A black hole must lose mass in order to keep the conservation laws the same if a real positive mass particle escapes.

Furthermore, opposite charged positive mass particles annihilating each other still have net energy. Matter and anti matter that collide leave photons behind. Yet, we are not seeing gamma rays everywhere despite that virtual particles exist almost everywhere.

Although it is primarily in a vacuum that virtual pairs exist, but virtual pairs don't produce gamma rays, their net measured effect is usually 0 as with other virtual particles that are not measured.

[Strange]

This has been discussed recently: http://www.scienceforums.net/topic/87841-hawking-radiation-question/

[swansont]

Hawking Radiation, where virtual particles form near the event horizons of black holes, normally posing no measurable effect due to annihilation can be sucked into the black hole. Since energy must be conserved, if positive mass escapes the black hole's gasp outside the event horizon, then the black hole must lose energy. But, in all of this, is there not a 50/50 chance of a black hole absorbing either a positive energy particle or negative energy particle? If there is, why would a black hole shrink over time? Shouldn't it stay the same size because of positive and negative energy gain have the same probability? If they don't have the same probability, well how?

 

There is no "negative energy particle".

[MWresearch]

But if there's no negative mass despite article upon article upon article upon article stating that there is, what is the mechanism for a black hole losing mass, seeing as how no new information can ever escape a black hole? And, if virtual pairs are both positive mass, why isn't the vacuum of space constantly emitting gamma rays?

Edited March 2, 2015 by MWresearch

[Strange]

But if there's no negative mass despite article upon article upon article upon article stating that there is, what is the mechanism for a black hole losing mass, seeing as how no new information can ever escape a black hole? And, if virtual pairs are both positive mass, why isn't the vacuum of space constantly emitting gamma rays?

 

My simple version: the gravitational field of the black hole provides the energy to create a pair of particles - this is equivalent to the mass of two particles. One of the particles then falls through the event horizon contributing its mass back to the black hole. The other escapes taking its mass/energy away. So the black hole loses the net mass of one particle. This can only occur near an event horizon where the pair of virtual particles can be permanently separated. In the vacuum of space the pair immediately annihilate again.

 

And, from the other thread, a much better explanation:

 

The original calculation is based on a very important 'difficulty' with quantum field theory on a curved space-time. That is different observers will not agree on the vacuum. This is the true origin of Hawking radiation; one man's empty state is another man's filled state! An observer hovering just above the horizon will see something different that an external observer at infinity. This is due to the fact that the observer near the horizon needs to keep accelerating just to maintain his position. The Unruh effect states that an accelerating observer will observe black body radiation while an inertial one will see none. Thus, the Unruh effect and Hawking radiation are deeply tied. (Both effects were predicted independently at about the same time)

 

Only later was the originally heuristic picture of particle and anti-particle pairs with one falling in shown to be a reasonable way to picture the process. It was Parikh and Wilczek who showed that tunnelling can be used to explain Hawking radiation. I forget the year, but a quick search of the arXiv will give you the paper.

Edited March 2, 2015 by Strange

[swansont]

 

My simple version: the gravitational field of the black hole provides the energy to create a pair of particles - this is equivalent to the mass of two particles. One of the particles then falls through the event horizon contributing its mass back to the black hole. The other escapes taking its mass/energy away. So the black hole loses the net mass of one particle. This can only occur near an event horizon where the pair of virtual particles can be permanently separated. In the vacuum of space the pair immediately annihilate again.

 

 

Taking a step back, one has to realize that the creation of a virtual particle pair does not conserve energy, it just does not violate the energy uncertainty [math]\Delta E \Delta t > \hbar/2[/math] , i.e. they can have any energy as long as they exist for a short enough time

 

It takes energy to make these into real particles.

[MWresearch]

Right, virtual particles themselves can violate physics because they aren't directly measured while they are virtual. But, when they become real, the ultimate effect abides by the laws of physics, like the conservation of energy. So, if both virtual particle possess positive mass which would be modeled by matter-antimatter annihilations, why aren't there measured violations in the conservation of energy all the time?

Edited March 2, 2015 by MWresearch

[Strange]

Because, as swansont says, they exist for less than the time defined by the Heisenberg uncertainty principle. Therefore no violation of conservation of energy.

[MWresearch]

Which would make sense but only if negative mass exists within the pairs and if John was wrong, that they aren't just typical matter-antimatter pairs that annihilate each other, because that type of interaction releases photons which virtual pairs obviously don't do. As pointed out, the virtual pairs can only violate conservation laws for brief periods of time and if they aren't interacting. If they interact with an object measurably, then conservation laws have to be upheld.

Edited March 2, 2015 by MWresearch

[Strange]

Which would make sense but only if negative mass exists within the pairs and if John was wrong, that they aren't just typical matter-antimatter pairs that annihilate each other, because that type of interaction releases photons which virtual pairs obviously don't do.

 

No, virtual pairs are a particle and anti-particle both with (positive) mass. They don't annihilate and produce photons because that would violate conservation of energy. They only exist for a short time as defined by the relationship between energy and time in the HUP.

[swansont]

Which would make sense but only if negative mass exists within the pairs and if John was wrong, that they aren't just typical matter-antimatter pairs that annihilate each other, because that type of interaction releases photons which virtual pairs obviously don't do. As pointed out, the virtual pairs can only violate conservation laws for brief periods of time and if they aren't interacting. If they interact with an object measurably, then conservation laws have to be upheld.

 

No, not really. The existence of virtual particles is already part of interactions. Negative mass is not required, nor is it part of the model.

[MWresearch]

But, the particles only exist for a short time because they annihilate each other over a time interval dictated by that uncertainty. If they annihilate each other and they still possess the properties of charged particles such as positive mass and opposite charge, they must emit photons upon annihilation. You're not showing me anything anywhere that shows the addition of matter and antimatter ads up to total nothingness. Existing for a short time doesn't mean they can violate every single possible aspect of physics, just a very limited part.

Edited March 2, 2015 by MWresearch

[John Cuthber]

I kind of wanted you to elaborate more on why it's "no," hence me saying "...well how?"

 

I thought you might have.

that's why I elaborated a bit.

 

"But, in all of this, is there not a 50/50 chance of a black hole absorbing either a positive energy particle or negative energy particle? "

No.

The particles may have positive or negative charge, but they have positive mass and that's all that matters.

No particle has negative energy.

There's really not a lot more to say

Your question was

is there not a 50/50 chance of a black hole absorbing either a positive energy particle or negative energy particle?

and the answer is no because, as I pointed out, no particle has a negative energy.

[MWresearch]

But you're explanation still doesn't explain the anti symmetry anyway. Even if black holes lose mass through virtual pairs containing real mass and then tunneling out which later produces a real effect that upholds conservation laws, why aren't there an equal number that stay trapped inside the black hole? That question is relevant regardless of if there's negative mass or not, because in either scenario there's still some particles that are trapped inside and anothers that aren't. You didn't address that main point of the paragraph.

Edited March 2, 2015 by MWresearch

[Strange]

But, the particles only exist for a short time because they annihilate each other over a time interval dictated by that uncertainty.

 

They don't annihilate; they just cease to exist: they are living on borrowed time and borrowed energy.

But you're explanation still doesn't explain the anti symmetry anyway. Even if black holes lose mass through virtual pairs containing real mass and then tunneling out which later produces a real effect that upholds conservation laws, why aren't there an equal number that stay trapped inside the black hole? That question is relevant regardless of if there's negative mass or not, because in either scenario there's still some particles that are trapped inside and anothers that aren't. You didn't address that main point of the paragraph.

 

The energy required to split a pair of virtual particles up and "convert" them to real particles is, not surprisingly, the equivalent of their combined mass - that comes from the black hole. When one particle tunnels through the event horizon and one escapes, it means that the mass-energy of one particle is "repaid" to the black hole and the mass-energy of one particle escapes. Net loss: the mass of one particle.

[John Cuthber]

But you're explanation still doesn't explain the anti symmetry anyway. Even if black holes lose mass through virtual pairs containing real mass and then tunneling out which later produces a real effect that upholds conservation laws, why aren't there an equal number that stay trapped inside the black hole? That question is relevant regardless of if there's negative mass or not, because in either scenario there's still some particles that are trapped inside and anothers that aren't. You didn't address that main point of the paragraph.

OK, I didn't explain it; science isn't generally good at answering questions about why.

But the asymmetry is a direct consequence of that act that all particles have positive mass.

If the pair production gave rise to particles of + and - mass then you would have a point.

It doesn't: you don't.

[ajb]

Loosely, the energy needed to create a real particle from a virtual pair comes from the black hole's mass. This does not depend on if it is a particle or antiparticle that escapes.

[swansont]

But, the particles only exist for a short time because they annihilate each other over a time interval dictated by that uncertainty. If they annihilate each other and they still possess the properties of charged particles such as positive mass and opposite charge, they must emit photons upon annihilation.

 

Where did the energy for the photons come from?

[MWresearch]

Oh wait, I think I finally figured out Hawking radiation, it comes from the fact that virtual pairs need energy to become real. When a virtual particle tunnels out from the event horizon of a black hole, it becomes real, and that act steals energy from the black hole. But, I don't really know how the energy is transferred.

I could see how no new information is obtained from within the black hole since the virtual pairs themselves are random, but I can't see how the energy moves from within the black hole to this tiny particle virtual particle. I also don't understand how its possible to tunnel out of a black hole, because that concept was created before there was a formal quantized model of space, Hawking Radiation must be using the version of a black hole where space is infinitely contracted and time ends at the event horizon.

[Mordred]

The trick is quantum tunnelling, unfortunately this is still a grey arena. Einstein's spooky action at a distance is still an apt description.

Quantum tunnelling afaik is a problematic influence of locality vs global influence.

Unfortunately I have no definitive explanation.

 

Best I understand it, a particle pair develops from an energy state, that pair conserves the laws of conservation of energy/momentum. (I loosely treat each entangled particle as one particle, with different localities) and think of the communation between the two as a shared state.

 

That's the gist of my understanding,

What happens to one influences the other regardless of locality.

 

ain't science fun lol

(PS) the owner of this site is an excellent guide, I met him via another forum.

 

Might help looking through his articles

 

http://www.drchinese.com/Bells_Theorem.htm

[swansont]

The trick is quantum tunnelling, unfortunately this is still a grey arena. Einstein's spooky action at a distance is still an apt description.

 

 

Spooky action was his description of entanglement, not AFAIK tunneling.

[MWresearch]

Oh wait, never mind, there's still something that doesn't add up.

 

I asked why the particle-antiparticle pair doesn't produce a photon as in a normal matter-antimatter collision. Someone told me they don't collide, they just cease to exist, which would seem to only make sense if one had negative mass thereby not producing a photon. But if that were true that both particles had properties of regular mass-bearing particles, then why would the pair need to consist of a particle and an antiparticle? Why not a neutral particle and a neutral particle or a positive and a positive non-antimatter particle?

[Strange]

I asked why the particle-antiparticle pair doesn't produce a photon as in a normal matter-antimatter collision. Someone told me they don't collide, they just cease to exist

 

That is for a virtual pair, which never really exist in the first place.

 

 

But if that were true that both particles had properties of regular mass-bearing particles, then why would the pair need to consist of a particle and an antiparticle? Why not a neutral particle and a neutral particle or a positive and a positive non-antimatter particle?

 

They need to be a particle-antiparticle pair because of other conserved properties (charge, spin, lepton number, etc.)