Hidden variables

Definition

Hidden variables refer to unobserved factors or parameters that could potentially explain the behavior of quantum systems, particularly in relation to measurements and outcomes. These variables are central to debates about the completeness of quantum mechanics, especially when discussing phenomena like entanglement and the EPR paradox, which challenges the idea of local realism by suggesting that distant particles can instantaneously affect each other’s states.

5 Must Know Facts For Your Next Test

1. Hidden variable theories were proposed as a way to restore determinism to quantum mechanics, suggesting that underlying factors dictate the outcomes of quantum experiments.
2. The EPR paradox, formulated by Einstein, Podolsky, and Rosen, questioned whether quantum mechanics provides a complete description of physical reality by introducing the concept of hidden variables.
3. If hidden variables exist, they would need to comply with the constraints imposed by Bell's Theorem, which states that any local hidden variable model can be contradicted by experimental results showing entangled particles.
4. Experimental tests, such as those involving Bell's inequalities, have shown results consistent with quantum mechanics but inconsistent with local hidden variable theories.
5. The search for hidden variables has led to various interpretations of quantum mechanics, including the many-worlds interpretation and pilot-wave theory.

Review Questions

• How do hidden variables challenge the interpretation of quantum mechanics regarding entangled particles?
  • Hidden variables propose that there may be underlying factors influencing the outcomes of measurements on entangled particles, suggesting a more deterministic view of quantum events. This challenges standard interpretations of quantum mechanics that rely on probability and randomness. The EPR paradox exemplifies this challenge by arguing that if such hidden variables existed, they could provide a more complete description of reality than what is offered by conventional quantum mechanics.
• Discuss how Bell's Theorem relates to hidden variable theories and its implications for our understanding of quantum mechanics.
  • Bell's Theorem shows that any theory based on local hidden variables cannot reproduce all the predictions of quantum mechanics. This theorem has profound implications because it suggests that if hidden variables exist, they must allow for non-local influences, contradicting the principle of locality. Thus, experiments testing Bell's inequalities have supported the predictions of quantum mechanics over local hidden variable theories, leading to significant philosophical debates about determinism and reality.
• Evaluate the significance of experimental tests on hidden variables in shaping current interpretations of quantum mechanics.
  • Experimental tests on hidden variables are crucial because they have consistently supported quantum mechanics while undermining local hidden variable theories. These tests provide evidence for phenomena like entanglement and non-locality, which challenge classical intuitions about separability and independence. As a result, these findings have prompted deeper inquiries into alternative interpretations of quantum mechanics, such as pilot-wave theory or many-worlds interpretation, reshaping our understanding of reality at a fundamental level.

Related terms

Local Realism: The philosophical viewpoint asserting that objects have definite properties independent of observation, and that influences cannot travel faster than the speed of light.

Bell's Theorem: A theorem that demonstrates the incompatibility of local hidden variable theories with the predictions of quantum mechanics, showing that if hidden variables exist, they must be non-local.

Quantum Entanglement: A phenomenon where two or more particles become interconnected in such a way that the state of one particle instantly influences the state of another, regardless of the distance separating them.