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/sci/ - Science & Math

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2118681 No.2118681 [Reply] [Original]

From another thread, I was talking about vacuum energy and its relationship to hawking radiation.

I need someone to critique what Im remembering:

Particle pairs rely on some kind of field of energy to pull from to come into existance, right? They're more prevalent in high gravity? And they convert this energy into the mass/energy of the pair?

>> No.2118708
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2118708

Bump, this is an actual question about actual science.

>> No.2118769
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2118769

Bump, does /sci/ not know?

>> No.2118815

Thinking in concepts like 'particles' and 'high gravity' can be treacherous as the underlying theories, quantum field theory and general relativity, can be very counter-intuitive.

This isn't going to answer your question but I've got to go now.
Look into the basics of QFT, GR and check upon the Unruh effect.

As long as there isn't one of very few people that actually know something about science left around here shows up, your chances of getting a good and correct answer are low. Retards and trolls have ruined /sci/...

>> No.2118934

>>2118815
I dont like Wikipedia for these sorts of things, getting pointed to one page necessitates I read three more pages first, and each one of those pages requires a few pages of background reading, and so on ad infinitum. It sounds like you have a grasp of the concept, can you explain it?

>> No.2119086

Hawking radiation occurs when paired (part-antipart) particles pop into existence near a black hole which captures one but not t'other. The free particle recoils, taking a little energy away from grav field.

It's now thought to have been simulated in the lab,

Hawking radiation from ultrashort laser pulse filaments
http://arxiv.org/abs/1009.4634

>> No.2119117

>>2119086
I understand the particle and antiparticle are sent off in different directions, but how does the gravity field affect that?

>> No.2119186

>>2119117

The created pairs will be oriented randomly. Some pairs will have a particle just just close enough to event horizon that the time uncertainty, dt, of pair life is comparable to time take to capture closest particle. Non captured particle then has nothing to annihilate with and recoils from the grav field, taking some of field's energy with it.

And no, I don't know the math.

>> No.2119209

>>2119117
The end result of a very large amount of math I don't feel like going into is that the universe kind of "cheats" in that it "borrows anti-entropy" and spontaneously generates pairs of particles that then annihilate with each other. Sometimes this happens right at the edge of a black hole, and one particle escapes but the other gets pulled in. Since you can't just create energy and have it persist more than a tiny fraction of a second, the escaping particle pulls energy from the black hole in order to permanently exist.

That's the third-grade explanation.

>> No.2119220

I'm getting conflicting responses here. One person is saying the free particle robs the black hole of energy by recoiling off its gravity field (still don't understand how that is supposed to work), and the other is saying the gravity field contributes to the pair coming into existance in the first place. Im interested in how the energy is transferred from the gravity field (and therefore the mass beyond the event horizon), into the escaping particle.

>> No.2119262

It's both. During the time the pair is in existence, total energy is the same, field energy + pair energy. If pair is destroyed then its energy returns to field and none is lost. If one particle is captured then Newtons 3rd - surviving particle recoils.

>> No.2119287

If you actually try to study this stuff, you'll learn that particles don't objectively exist.

>> No.2119313

>>2119262
The use of "recoil" confused me, like the free particle was being accelerated by the field AFTER it was spawned. But the momentum is imparted during the creation process, with random direction. And the free/non-captured particle doesn't go any faster BECAUSE the other particle gets sucked it, it just continues going its normal speed, correct? Recoil makes me think its pushing off of something, but its just exhibiting the normal speed it was imparted with.

>> No.2119400

>>2119313

Yep, recoil energy will be some fraction of: E - annihilated particle energy.