Is Conservation of Momentum Overlooked in Bells Inequality Violations

In summary: Otherwise, who cares if conservation of spin holds on a single particle?In summary, the EPR scenario involves the application of classical mechanics and conservation laws to explain correlation results and derive Bell type inequalities based on expected spin values. However, the violations of these inequalities are then explained by quantum mechanics, specifically the forbidden simultaneous knowledge of mutually non-commuting observables and the collapse of the wave function due to non-locality. The question is raised whether a more complete understanding of conservation of momentum in relation to spin and non-parallel detector settings could explain these violations classically. The possibility of a particle or classical physics mechanism being responsible for these violations is also considered.
  • #1
morrobay
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In the EPR scenario the correlation results are explained with the conservation laws of classical mechanics as applied to spin. The Bell type inequalities are derived on expected spin values.
But the violations of these inequalities are then explained with QM: That simultaneous knowledge of mutually non commuting observables is forbidden, collapse of wave function , non locality ...
If there were a more complete understanding of conservation of momentum as applied to the physics of spin with non- parallel detector settings could violations of the inequalities be explained classically ?
 
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  • #2
morrobay said:
If there were a more complete understanding of conservation of momentum as applied to the physics of spin with non- parallel detector settings could violations of the inequalities be explained classically ?

What's incomplete about our understanding of conservation of momentum in these situations?
 
  • #3
morrobay said:
In the EPR scenario the correlation results are explained with the conservation laws of classical mechanics as applied to spin. The Bell type inequalities are derived on expected spin values.
But the violations of these inequalities are then explained with QM: That simultaneous knowledge of mutually non commuting observables is forbidden, collapse of wave function , non locality ...
If there were a more complete understanding of conservation of momentum as applied to the physics of spin with non- parallel detector settings could violations of the inequalities be explained classically ?

the spins come opposite (in case of anti-correlated)...momentum is conserved

why do you feel it's overlooked?
 
  • #4
Momentum is conserved with this inequality with perfect anti correlation at parallel detector settings
n[x-z+] + n[y+z-] ≥ n[x+y+] The spin values derived from entangled particles created at the source with total spin, when measured at A and B, equal to zero.
In accord with the conservation laws.
One of eight:
..A::::::::::::::B..
x y z :::::::::x y z
+ + -::::::::::- - +
But when the above inequality is violated with non parallel settings the total spin at A and B does not equal zero, in conflict with conservation laws. So the question is about the interaction at detector with particle at time of measurement. Given that particles were created with total spin of zero at source and the inequality was violated (spin change ) Then can spin change be related to an interaction with the detector and conservation of momentum for total system ? Again, with non parallel detector settings can the spin be affected by the conservation laws in such a way that the inequality is violated ? And if so then is a particle or classical physics mechanism the explanation?
 
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  • #5
As an example for the above, with a 4 out of 8 table of spins with parallel detector settings
A:::::::::::::::B
x y z:::::::x y z
+ ++:::::::- - -
- + +:::::::+ - -
- - +:::::::+ + -
- - -:::::::+ + +
n[x+y-] + n[y-z+] ≥ n[x-y-] The Bell type inequality with expected spin values is applied in experiments when detector settings are not aligned. If only the spin on axis for x in first term of inequality:n[x+y-] changes spin to n[x-y-] during measurement due to particles interaction with magnetic field in detector and angle of detector, then the inequality is dis proven. Maybe a particle physicist can explain a mechanism for this spin change in terms of state of particle, detector angle/field interaction and the conservation laws.
 
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  • #6
morrobay said:
... But when the above inequality is violated with non parallel settings the total spin at A and B does not equal zero, in conflict with conservation laws. ...

Ah, this is not quite correct. There is conservation for the system of A+B. This system no longer exists after one is measured, say you found A=-1 at 0 degrees. You now know B=+1 at that same angle. But instead you measure B at 15 degrees. The answer may or may not be +1, exactly as you imagine.

But now the question is: is there conservation of spin on a single particle? So you are really asking what happens to the spin of the observation apparatus when a particle's known spin is measured on a different basis. Ie is that somehow affected when it comes into contact with B? I would answer: sure, precisely *because* there is conservation.
 

FAQ: Is Conservation of Momentum Overlooked in Bells Inequality Violations

What is the conservation of momentum?

The conservation of momentum is a fundamental principle in physics which states that the total momentum of a closed system remains constant, unless acted upon by an external force. This means that the total amount of momentum before and after an event or interaction must be the same.

What is Bell's inequality?

Bell's inequality is a mathematical expression used to test the validity of local hidden variable theories in quantum mechanics. It states that if local hidden variables exist, then certain statistical correlations between distant events should not exceed a certain value. Violations of this inequality have been observed in experiments, suggesting that local hidden variables do not exist and that quantum mechanics is a more accurate description of reality.

How is conservation of momentum related to Bell's inequality violations?

The conservation of momentum is indirectly related to Bell's inequality violations because it is one of the fundamental principles of physics that is assumed to be true in Bell's inequality tests. If the conservation of momentum were violated in these experiments, then it would call into question the validity of the entire framework of physics.

Is the conservation of momentum overlooked in Bell's inequality violations?

No, the conservation of momentum is not overlooked in Bell's inequality violations. In fact, it is a crucial aspect of these experiments and is carefully considered and accounted for in the analysis of the results.

Why is the conservation of momentum important in physics?

The conservation of momentum is important in physics because it is a fundamental principle that governs the behavior of particles and systems in the universe. It allows us to make accurate predictions and understand the motion of objects, from the smallest subatomic particles to the largest celestial bodies.

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