Discussion Overview
The discussion centers on the concept of decoherence in quantum mechanics and its effect on superpositions, particularly in the context of the two-slit experiment. Participants explore the implications of decoherence for probability distributions and the nature of quantum states, touching on interpretations of quantum mechanics and the relationship between amplitudes and probabilities.
Discussion Character
- Debate/contested
- Conceptual clarification
- Technical explanation
Main Points Raised
- Some participants propose that decoherence leads to the disappearance of superpositions, suggesting that the particle is described by a probability distribution that appears more classical and lacks interference effects.
- Others argue against the notion of "negative probabilities," clarifying that while amplitudes can be negative, probabilities must remain positive according to the Kolmogorov axioms.
- A participant introduces the Wigner quasi-probability distribution, noting that it can have negative values in certain regions but results in positive observable probabilities after decoherence.
- There is a suggestion that the original poster may be conflating probability with probability amplitudes, as interference effects arise from the cancellation of amplitudes.
- Some participants express confusion over whether a particle remains in a superposition of classical probabilities after decoherence or if it definitively occupies one state, reflecting on the implications of different interpretations of quantum mechanics.
- One participant questions the role of entanglement and decoherence, suggesting that decoherence prevents entanglement with the measuring device, while others assert that entanglement occurs as a result of decoherence.
- There is a discussion about the arbitrary nature of collapse interpretations and the implications for predicting future states of particles post-measurement.
- Some participants clarify that decoherence destroys interference between alternatives rather than converting amplitudes into probabilities, emphasizing the mathematical processes involved in quantum mechanics.
Areas of Agreement / Disagreement
Participants express multiple competing views regarding the nature of decoherence, superpositions, and the interpretation of quantum mechanics. There is no consensus on the implications of decoherence or the definitions of superposition in this context.
Contextual Notes
Participants reference various interpretations of quantum mechanics, including wave function collapse and entanglement, without resolving the underlying assumptions or definitions that may affect their arguments.
and that's how 'textbook' QM answers it too - we get something, somehow. I guess I see decoherence, as applied to measurement theory, as an attempt to resolve the unitary dynamics, non-unitary measurement issue of QM. I've not really seen any interpretation of QM that I'm personally 100% happy with, they all seem to me to have this character of sweeping something under a rug - they just use different rugs.