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BioTechproject t1_ivsmk6h wrote

Reply to comment by -domi- in A first-of-its-kind experiment simulating the cosmos with ultracold potassium atoms suggests that in a curved, expanding universe pairs of particles pop up out of empty space by marketrent

Since there are fields everywhere and particles are just disturbances of the field, there can be random particle-antiparticle creation by "borrowing" some of the energy of that field. Usually they near instantly eliminate eachother, putting that energy right back.

Near black holes there is a chance that on the event horizon those pairs are created, one particle on the inside, one on the outside. The one on the outside can escape while the one on the inside won't (as it needs to travel at more than the speed of light). Hence energy is taken out of the field at the event horizon for the creation of 2 particles, but the black hole only gains one of them, hence it is a net energy loss of the black hole. That is also called Hawking radiation.

Also those thermodynamic rules are more of like a general trend and less of a rule that applies in every single instance.

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chullyman t1_ivxy1ta wrote

My understanding of this was that there was some kind of bias to pull antimatter in over the event horizon, shrinking the black hole. Although I don’t understand how’s it works. Am I wrong to make this assumption?

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BioTechproject t1_ivyf89v wrote

There is no bias, gravity [unlike other forces] does not discriminate between particles and anti-particles [they have positive mass after all].

Simply because 2 particles are created out of the field at the event horizo, the black hole looses the energy/mass [as they are interchangeable] of 2 particles. However since it can suck one of them right in (doesn't matter which) it can gain the energy of 1 particle back, while the other is ejected. Hence it has lost the energy of 1 particle.

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chullyman t1_ivyh97g wrote

> 2 particles are created out of the field at the event horizo, the black hole looses the energy/mass [as they are interchangeable] of 2 particles.

If the particles are created outside of the black hole, at the event horizon. How is it the black hole losing mass? These particles did not originate from the blackhole, they originated in the space many miles away from the blackhole. From my understanding of what you said the blackhole would be purely gaining mass.

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BioTechproject t1_ivytlf0 wrote

everthying that is inside the event horizon is automatically part of the black hole, as nothing sub-light can escape. Since the particles are created at the boundary, one can be barely on the inside while the other is barely on the outside. The one outside can escape while the one inside is doomed. Since the energy comes from the point at the exact boundary, which is part of the black hole, it looses that energy and thus mass.

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[deleted] t1_ivtecpq wrote

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faisent t1_ivtiyxo wrote

It is, but its also traveling at c so as long as its moving away it won't cross the horizon. It could also be created so its moving towards the horizon as well and there's no change in the system.

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[deleted] t1_ivtmj7i wrote

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Isogash t1_ivusmnm wrote

Gravity doesn't slow down light, it curves spacetime and makes the light need to travel further. The light always travels at the speed of light (in a vacuum.)

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Hanflander t1_ivuzokt wrote

No one has ever described this so concisely in my entire life, thank you.

There’s a light bulb going off above my head now but I can’t see anything because of how dense I feel.

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