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Can I feed enough spin up electrons to a black hole to affect its angular momentum?

How can a particle with no size have angular momentum?Why can't I just think the spin as rotating?What the quantum spin refers to? How we calculate the angular momentum $omega$ from the spin quantum number?What is the significance of electron spin quantum number?What's is the origin of Orbital Angular Momentum of electrons in atoms?How does the Gordon Decomposition of Dirac Current give rise to spin angular momentum?Orbital angular momentum of electronsWhat all has intrinsic spin?Relationship Between Magnetic Dipole Moment and Spin Angular MomentumWhat is the angular momentum of an electron? And how can it be zero?

5

$begingroup$

I was reading classical spin vs quantum field spin. I know spin in quantum mechanics is just a quantum number. But what happens if I try to intentionally feed many electrons all in the same spin state into a rotating 5 solar mass blackhole? Can I affect its angular momentum eventually?

black-holes angular-momentum electrons conservation-laws quantum-spin

share|cite|improve this question

edited Apr 23 at 20:35

Jens

2,44811632

asked Apr 22 at 10:45

user6760user6760

3,16612145

$endgroup$

add a comment | 

5

$begingroup$

I was reading classical spin vs quantum field spin. I know spin in quantum mechanics is just a quantum number. But what happens if I try to intentionally feed many electrons all in the same spin state into a rotating 5 solar mass blackhole? Can I affect its angular momentum eventually?

black-holes angular-momentum electrons conservation-laws quantum-spin

share|cite|improve this question

edited Apr 23 at 20:35

Jens

2,44811632

asked Apr 22 at 10:45

user6760user6760

3,16612145

$endgroup$

add a comment | 

$begingroup$

I was reading classical spin vs quantum field spin. I know spin in quantum mechanics is just a quantum number. But what happens if I try to intentionally feed many electrons all in the same spin state into a rotating 5 solar mass blackhole? Can I affect its angular momentum eventually?

black-holes angular-momentum electrons conservation-laws quantum-spin

share|cite|improve this question

edited Apr 23 at 20:35

Jens

2,44811632

asked Apr 22 at 10:45

user6760user6760

3,16612145

$endgroup$

share|cite|improve this question

edited Apr 23 at 20:35

Jens

2,44811632

asked Apr 22 at 10:45

user6760user6760

3,16612145

share|cite|improve this question

edited Apr 23 at 20:35

Jens

2,44811632

asked Apr 22 at 10:45

user6760user6760

3,16612145

edited Apr 23 at 20:35

Jens

2,44811632

edited Apr 23 at 20:35

Jens

2,44811632

asked Apr 22 at 10:45

user6760user6760

3,16612145

asked Apr 22 at 10:45

user6760user6760

3,16612145

2 Answers
2

active

oldest

votes

6

$begingroup$

I infer that you are asking whether spin angular momentum can accumulate to a macroscopically significant amount.

It is generally claimed that spin angular momentum does not have a classical counterpart. So maybe there is no connection with macroscopic angular momentum at all? In fact, there is a connection with macroscopic angular momentum, which is vividly demonstrated by an effect called the 'Einstein-De Haas effect'. I'll get to that in a second.

About the black hole in your thought experiment: my guess is that you added that element to the picture because nothing escapes a black hole. That is, the fact that the electrons enter a black hole ensures that it is a one way trip.

Check out this youtube video titled Einstein De Haas effect, uploaded by the University of Michigan Demo lab

The demo shows a torsion pendulum.

The amplitude of the swing is back and forth around a vertical axis. The amplitude of the swing increases because the swing is pumped. The current in the surrounding coil is reversed in resonance with the natural frequency of the torsion pendulum. The Einstein De Haas effect is very small, the resonance setup accumulates the effect to a significant amplitude.

The particular metal in the setup, presumably iron, has a significant population of electrons with a spin that can be reoriented by an external magnetic field. Every time the current is reversed the direction of the magnetic field is reversed, and the alignable electrons realign. But angular momentum cannot change, so the electrons must exchange angular momentum with external mass.

I find the Einstein De Haas effect fascinating: you get to see a quantum effect accumulate to a level where you see a physical consequence with the unaided eye.

share|cite|improve this answer

edited Apr 22 at 14:17

answered Apr 22 at 11:45

CleonisCleonis

2,446714

$endgroup$

• 
  
  
  

  
  

  
  
  
  
  
  

  
  $begingroup$
  there's something about adding "Einstein" to a name that seems to double its coolness to me... "Einstein Rosen Bridge" ... "Bose Einstein Condensate" ... Einstein-De Haas Effect" ...
  $endgroup$
  – Michael
  Apr 22 at 19:07
  

  
  
  
  

add a comment | 

3

$begingroup$

A single electron will already alter the angular momentum of a black hole by exactly $hbar/2$.

share|cite|improve this answer

edited Apr 22 at 12:49

answered Apr 22 at 10:58

my2ctsmy2cts

6,1032721

$endgroup$

• 
  
  
  

  
  

  
  
  
  
  
  

  
  $begingroup$
  This is not given unless measured, because QM and GR don't play well together. And surely you can't measure such a small change.
  $endgroup$
  – safesphere
  Apr 23 at 4:03
  
  

  
  
  
  

add a comment | 

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6

$begingroup$

I infer that you are asking whether spin angular momentum can accumulate to a macroscopically significant amount.

It is generally claimed that spin angular momentum does not have a classical counterpart. So maybe there is no connection with macroscopic angular momentum at all? In fact, there is a connection with macroscopic angular momentum, which is vividly demonstrated by an effect called the 'Einstein-De Haas effect'. I'll get to that in a second.

About the black hole in your thought experiment: my guess is that you added that element to the picture because nothing escapes a black hole. That is, the fact that the electrons enter a black hole ensures that it is a one way trip.

Check out this youtube video titled Einstein De Haas effect, uploaded by the University of Michigan Demo lab

The demo shows a torsion pendulum.

The amplitude of the swing is back and forth around a vertical axis. The amplitude of the swing increases because the swing is pumped. The current in the surrounding coil is reversed in resonance with the natural frequency of the torsion pendulum. The Einstein De Haas effect is very small, the resonance setup accumulates the effect to a significant amplitude.

The particular metal in the setup, presumably iron, has a significant population of electrons with a spin that can be reoriented by an external magnetic field. Every time the current is reversed the direction of the magnetic field is reversed, and the alignable electrons realign. But angular momentum cannot change, so the electrons must exchange angular momentum with external mass.

I find the Einstein De Haas effect fascinating: you get to see a quantum effect accumulate to a level where you see a physical consequence with the unaided eye.

share|cite|improve this answer

edited Apr 22 at 14:17

answered Apr 22 at 11:45

CleonisCleonis

2,446714

$endgroup$

• 
  
  
  

  
  

  
  
  
  
  
  

  
  $begingroup$
  there's something about adding "Einstein" to a name that seems to double its coolness to me... "Einstein Rosen Bridge" ... "Bose Einstein Condensate" ... Einstein-De Haas Effect" ...
  $endgroup$
  – Michael
  Apr 22 at 19:07
  

  
  
  
  

add a comment | 

6

$begingroup$

I infer that you are asking whether spin angular momentum can accumulate to a macroscopically significant amount.

It is generally claimed that spin angular momentum does not have a classical counterpart. So maybe there is no connection with macroscopic angular momentum at all? In fact, there is a connection with macroscopic angular momentum, which is vividly demonstrated by an effect called the 'Einstein-De Haas effect'. I'll get to that in a second.

About the black hole in your thought experiment: my guess is that you added that element to the picture because nothing escapes a black hole. That is, the fact that the electrons enter a black hole ensures that it is a one way trip.

Check out this youtube video titled Einstein De Haas effect, uploaded by the University of Michigan Demo lab

The demo shows a torsion pendulum.

The amplitude of the swing is back and forth around a vertical axis. The amplitude of the swing increases because the swing is pumped. The current in the surrounding coil is reversed in resonance with the natural frequency of the torsion pendulum. The Einstein De Haas effect is very small, the resonance setup accumulates the effect to a significant amplitude.

The particular metal in the setup, presumably iron, has a significant population of electrons with a spin that can be reoriented by an external magnetic field. Every time the current is reversed the direction of the magnetic field is reversed, and the alignable electrons realign. But angular momentum cannot change, so the electrons must exchange angular momentum with external mass.

I find the Einstein De Haas effect fascinating: you get to see a quantum effect accumulate to a level where you see a physical consequence with the unaided eye.

share|cite|improve this answer

edited Apr 22 at 14:17

answered Apr 22 at 11:45

CleonisCleonis

2,446714

$endgroup$

• 
  
  
  

  
  

  
  
  
  
  
  

  
  $begingroup$
  there's something about adding "Einstein" to a name that seems to double its coolness to me... "Einstein Rosen Bridge" ... "Bose Einstein Condensate" ... Einstein-De Haas Effect" ...
  $endgroup$
  – Michael
  Apr 22 at 19:07
  

  
  
  
  

add a comment | 

$begingroup$

I infer that you are asking whether spin angular momentum can accumulate to a macroscopically significant amount.

It is generally claimed that spin angular momentum does not have a classical counterpart. So maybe there is no connection with macroscopic angular momentum at all? In fact, there is a connection with macroscopic angular momentum, which is vividly demonstrated by an effect called the 'Einstein-De Haas effect'. I'll get to that in a second.

About the black hole in your thought experiment: my guess is that you added that element to the picture because nothing escapes a black hole. That is, the fact that the electrons enter a black hole ensures that it is a one way trip.

Check out this youtube video titled Einstein De Haas effect, uploaded by the University of Michigan Demo lab

The demo shows a torsion pendulum.

The amplitude of the swing is back and forth around a vertical axis. The amplitude of the swing increases because the swing is pumped. The current in the surrounding coil is reversed in resonance with the natural frequency of the torsion pendulum. The Einstein De Haas effect is very small, the resonance setup accumulates the effect to a significant amplitude.

The particular metal in the setup, presumably iron, has a significant population of electrons with a spin that can be reoriented by an external magnetic field. Every time the current is reversed the direction of the magnetic field is reversed, and the alignable electrons realign. But angular momentum cannot change, so the electrons must exchange angular momentum with external mass.

I find the Einstein De Haas effect fascinating: you get to see a quantum effect accumulate to a level where you see a physical consequence with the unaided eye.

share|cite|improve this answer

edited Apr 22 at 14:17

answered Apr 22 at 11:45

CleonisCleonis

2,446714

$endgroup$

share|cite|improve this answer

edited Apr 22 at 14:17

answered Apr 22 at 11:45

CleonisCleonis

2,446714

answered Apr 22 at 11:45

CleonisCleonis

2,446714

answered Apr 22 at 11:45

CleonisCleonis

2,446714

3

$begingroup$

A single electron will already alter the angular momentum of a black hole by exactly $hbar/2$.

share|cite|improve this answer

edited Apr 22 at 12:49

answered Apr 22 at 10:58

my2ctsmy2cts

6,1032721

$endgroup$

• 
  
  
  

  
  

  
  
  
  
  
  

  
  $begingroup$
  This is not given unless measured, because QM and GR don't play well together. And surely you can't measure such a small change.
  $endgroup$
  – safesphere
  Apr 23 at 4:03
  
  

  
  
  
  

add a comment | 

3

$begingroup$

A single electron will already alter the angular momentum of a black hole by exactly $hbar/2$.

share|cite|improve this answer

edited Apr 22 at 12:49

answered Apr 22 at 10:58

my2ctsmy2cts

6,1032721

$endgroup$

• 
  
  
  

  
  

  
  
  
  
  
  

  
  $begingroup$
  This is not given unless measured, because QM and GR don't play well together. And surely you can't measure such a small change.
  $endgroup$
  – safesphere
  Apr 23 at 4:03
  
  

  
  
  
  

add a comment | 

$begingroup$

A single electron will already alter the angular momentum of a black hole by exactly $hbar/2$.

share|cite|improve this answer

edited Apr 22 at 12:49

answered Apr 22 at 10:58

my2ctsmy2cts

6,1032721

$endgroup$

share|cite|improve this answer

edited Apr 22 at 12:49

answered Apr 22 at 10:58

my2ctsmy2cts

6,1032721

answered Apr 22 at 10:58

my2ctsmy2cts

6,1032721

answered Apr 22 at 10:58

my2ctsmy2cts

6,1032721