Why should rotating black holes emit particles?

In summary, according to the uncertainty principle, rotating black holes should emit particles. However, I do not understand why this is necessary according to the uncertainty principle.
  • #1
Confuses
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In a brief history of time it says theft 'according to the uncertainty principle rotating black holes should emit particles'. However I do not understand why rotating black holes need to emit particles according to the uncertainty principle.

I do understand why black holes emit particles it is just the rotating black holes and The uncertainty principle thing that I do not understand.

Thanks in advance.
 
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  • #2
My understanding is that Hawking radiation is a theory used to explain how black holes conserve energy. For example, we think black holes grow in size as they consume matter. Any particle that enters the Schwarzschild radius (SR) of a black hole is absorbed. QM purposes that virtual particles in the quantum field 'pop' in and out of existence all the time, but that they come in particle/anti-particle pairs that quickly annihilate one another, thus conserving energy and momentum in the universe. Hawking used this notion to theorize that virtual pairs that happen to 'pop' into existence on the event horizon (SR), are split up and do not annihilate each other as they usually do. One particle 'falls' into the black hole, while the other escapes and appears as Hawking Radiation. Since the black hole grows fractionally by swallowing one particle, and since the other particle in the pair is emitted as radiation, energy and momentum are conserved.
 
  • #3
quantumtoast said:
My understanding is that Hawking radiation is a theory used to explain how black holes conserve energy.
A black hole in General Relativity alone does not emit Hawking radiation and conserves energy.

Since the black hole grows fractionally by swallowing one particle, and since the other particle in the pair is emitted as radiation, energy and momentum are conserved.
Hawking radiation causes black holes to shrink.@Confuses: There is nothing special about rotating black holes. All black holes are assumed to radiate particles (mainly photons). Rotating black holes are just the most common type of them in space.
 
  • #4
There is something called Penrose Pair Production (PPP) which occurs with static black holes but increases significantly for rotating black holes with high spin-

Penrose Pair Production (PPP) A variant of the classical Penrose process is the Penrose Pair Production. The mechanism is based on another ingredient, the photon sphere. Photons are instably trapped in the photon sphere. Other photons may now infall on radial null geodesics and hit these trapped photons. If the energy of the quanta exceeds the rest frame energy of about one MeV, gamma photons produce pairs of leptons. For rather large values of the black hole spin, a>0.7, the spherically symmetric photon sphere plunges into the oblate ergosphere. Then, the PPP is expected to occur dominantly. PPP is sketched in Fig. 3.14. Williams applied this model to explain the populations of ultrarelativistic electrons in the quasars 3C 279 and 3C 273.

'Magnetohydrodynamics on the Kerr Geometry' by A Mueller
http://www.wissenschaft-online.de/astrowissen/downloads/PhD/PhD_AMueller.pdf
pages 47 & 48
 
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  • #5


The idea that rotating black holes should emit particles is based on the concept of the uncertainty principle in quantum mechanics. This principle states that there is a fundamental limit to the precision with which certain pairs of physical properties, such as position and momentum, can be known simultaneously. This means that there is always some degree of uncertainty in the measurement of these properties.

In the case of a rotating black hole, the uncertainty principle applies to the particles that are constantly being created and destroyed at the event horizon (the point of no return for a black hole). These particles are known as virtual particles and they exist in a state of uncertainty, meaning their exact properties cannot be known.

As the black hole rotates, it creates a strong gravitational field that can affect the virtual particles near the event horizon. This interaction between the particles and the black hole's gravity can cause the particles to become real and escape from the black hole as radiation. This process is known as Hawking radiation and it is a direct result of the uncertainty principle.

Therefore, it can be said that according to the uncertainty principle, rotating black holes should emit particles. Without the uncertainty principle, this phenomenon would not occur. It is important to note that this is a theoretical concept and has not yet been directly observed, but it is widely accepted in the scientific community.

In summary, the uncertainty principle plays a crucial role in the emission of particles from rotating black holes, providing a deeper understanding of the behavior of these mysterious objects in our universe.
 

1. How do rotating black holes emit particles?

Rotating black holes emit particles through a process called Hawking radiation. This radiation is created when a particle-antiparticle pair is spontaneously created at the event horizon of the black hole. One particle falls into the black hole while the other is able to escape and be detected as radiation.

2. Why should rotating black holes emit particles?

According to Stephen Hawking's theory, a black hole must emit particles in order to maintain its temperature and energy balance. This is because black holes are not completely "black" and do have a temperature, which is inversely proportional to their mass. As a result, they must emit particles to maintain this temperature and avoid "evaporating".

3. What types of particles are emitted by rotating black holes?

The types of particles emitted by rotating black holes are primarily photons (particles of light) and gravitons (particles that carry the force of gravity). However, other types of particles such as electrons, protons, and neutrinos can also be emitted depending on the specific conditions of the black hole.

4. Can rotating black holes emit particles in all directions?

Yes, rotating black holes can emit particles in all directions. However, the amount and direction of the emitted particles can vary depending on the rotation and other properties of the black hole. For example, a rapidly rotating black hole may emit more particles along its equator compared to its poles.

5. How does the emission of particles affect the mass and size of a rotating black hole?

The emission of particles from a rotating black hole does not significantly affect its mass or size. This is because the particles that are emitted have a very small mass compared to the black hole itself. However, over an extremely long period of time, the black hole may slowly lose mass and decrease in size due to the emission of particles, but this process is very slow and difficult to measure.

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