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Question69
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Has there been so far any prediction validated in experimental outcomes that these theories make as a result of the modification of the Schrodinger equation?
As far as I'm aware, no. Though looking at macroscopic superposition states (eg 40kg mirrors) and gravity in the future, they can test models whereby gravity is the cause of wave function collapse.Question69 said:Has there been so far any prediction validated in experimental outcomes that these theories make as a result of the modification of the Schrodinger equation?
And for the CSL and GRW models?StevieTNZ said:As far as I'm aware, no. Though looking at macroscopic superposition states (eg 40kg mirrors) and gravity in the future, they can test models whereby gravity is the cause of wave function collapse.
Yes, no experiments to report that differ from quantum theory.Question69 said:And for the CSL and GRW models?
No. I've yet to see an experiment that's been performed and reported that conforms to one of their predictions that differ from quantum mechanics.Question69 said:so the CSL and GRW models have kind of been falsified?
Yes that's what falsified means.They have made predictions that do not stand up to future scrutiny.StevieTNZ said:No. I've yet to see an experiment that's been performed and reported that conforms to one of their predictions that differ from quantum mechanics.
Also, do you believe many worlds could be the right interpretation, as we have seen no evidence(so far) of the non-linearity of the wavefunction?StevieTNZ said:No. I've yet to see an experiment that's been performed and reported that conforms to one of their predictions that differ from quantum mechanics.
As far as I know, an experiment has not been performed that tests the prediction difference between collapse theories and quantum theory.Question69 said:Yes that's what falsified means.They have made predictions that do not stand up to future scrutiny.
No. But interpretation discussions belong in the sub-forum.Question69 said:Also, do you believe many worlds could be the right interpretation,
Not yet, they have to get up the scale.Question69 said:Has there been so far any prediction validated in experimental outcomes that these theories make as a result of the modification of the Schrodinger equation?
vanhees71 said:This simply implies that the particle's position is not too well determined, but it doesn't say the particles where at those "two places at once".
I hope they spend the 13 M€ for something more profound than such wrong ideas, which are indeed not only "in contradiction to common sense" but also in contradiction to quantum theory.
vanhees71 said:Well, I meant this a bit ironically. I'm pretty sure that they'll do very high-quality work within this project. I'm only always a bit disappointed, why people who know QT as well as the PIs of this project do, cannot write a somewhat better explanation for the public but repeat over and over again the bad popular-science writing of decades ago.
vanhees71 said:Well, I meant this a bit ironically. I'm pretty sure that they'll do very high-quality work within this project. I'm only always a bit disappointed, why people who know QT as well as the PIs of this project do, cannot write a somewhat better explanation for the public but repeat over and over again the bad popular-science writing of decades ago.
Question69 said:And for the CSL and GRW models?
I wonder in many worlds, does it make sense to ask for a branching speed?vanhees71 said:To decohere, say two entangled photons, you don't need faster-than light propagation. It's sufficient that one of the photons interact with something else, and then usually the two photons are no longer entangled but now the larger system consisting of the two photons and the other stuff the one photon was interacting with are now entangled.
If is of course very difficult to find relativistic "objective collapse models", because you always run into trouble with causality since it's very difficult to find non-local relativistically causal models.
vanhees71 said:To decohere, say two entangled photons, you don't need faster-than light propagation. It's sufficient that one of the photons interact with something else, and then usually the two photons are no longer entangled but now the larger system consisting of the two photons and the other stuff the one photon was interacting with are now entangled.
That's interesting, what interpretation do you hold to?vanhees71 said:In these papers, the selection made to prepare entanglement between "quantum systems that never interacted" is due to local measurements.. In the first paper in the diagram in the first column it's the joint measurement on Bob's two particles (local at his place) that enable to select ensembles representing entangled states of Alice's and Charlie's particles, although these never interacted. In the 2nd paper it's the local joint measurement of the two photons labelled with IV in Fig. 1.
I still do not see (a) any need for "objective collapse" additions, because standard local QFT explains everything without causality violations and (b) how "objective collapse" additions can be made without inducing such violations, because as you say yourself, this would imply the need for FTL signals.
Of course, if there is the possibility to check such objective collapse models one should do it (see #11). I'm pretty sure that QT will also pass this test again ;-)), but to be sure, the experiment must be done and carfully validated as usual.
So what do you think the likely interpretation to be true is?DrChinese said:As we have discussed before: You are somewhat in denial about the meaning of entangled particles that have never shared/overlapped in spacetime - and therefore have never interacted. This (per references), like an ordinary Bell test, is something that any quantum theory or interpretation should be able to describe. It is a prediction of orthodox QM, but theories like GRW and CSL - in my opinion - lack the theoretical structure to explain these phenomena. Again, they (GRW and CSL - objective collapse which is said to occur as a function of time) would need an actual FTL signal to operate, while orthodox QM merely requires generally accepted "quantum nonlocality".
https://arxiv.org/abs/0911.1314
"Quantum systems that have never interacted can become nonlocally correlated through a process called entanglement swapping. "
https://arxiv.org/abs/1209.4191
"The observed quantum correlations manifest the non-locality of quantum mechanics in spacetime."
So I am not saying that orthodox quantum non-locality involves any FTL signaling. I don't know what it involves any more than anyone else. But Objective Collapse theories, as I read them, are attempting to insert hypotheses that can't really address the full range of quantum behaviors. If you think they can address the experiments I reference above, I'd love to understand how.
If you wish to ask about interpretations, please start a new thread in this sub-forum: https://www.physicsforums.com/forums/quantum-interpretations-and-foundations.292/Question69 said:So what do you think the likely interpretation to be true is?
StevieTNZ said:If you wish to ask about interpretations, please start a new thread in this sub-forum: https://www.physicsforums.com/forums/quantum-interpretations-and-foundations.292/Question69 said:So what do you think the likely interpretation to be true is?
The collapse happens under the context of a parameter.So for example the bigger a system is, the bigger the chance of a collapse is for that.Smaller things have a very, very low chance of collapsing.If we have a big entangled system, that will have a very big chance of collapse.DrChinese said:As referenced: We have 2 distant spin-entangled particles (Alice and Bob) that are created from independent lasers, and have never interacted (and never exist within a common light cone).
Objective collapse: "Collapse theories avoid the measurement problem by merging the two dynamical principles of quantum mechanics in a unique dynamical description. The physical idea that underlies collapse theories is that particles undergo spontaneous wave-function collapses, which occur randomly both in time (at a given average rate), and in space (according to the Born rule). The imprecise talk of “observer” and a “measurement” that plagues the orthodox interpretation is thus avoided because the wave function collapses spontaneously."
1. An objective collapse theory states that the likelihood of entangled Alice and Bob decohering is a function of time. Presumably that elapsed time can occur before either encounters a measurement device that tests a Bell inequality. As we know, the coincidence rate is strictly dependent on the relative choice of measurements on the 2 entangled particles Alice and Bob, and nothing else. If either Alice or Bob had decohered into an unentangled state PRIOR to their measurement, the statistics would be distinctly different because one or both particles would have taken on a specific spin value at time/place of decoherence. This experiment has already been executed, so we know that cannot be.
What am I missing? Again: QM says decoherence occurs only when an irreversible measurement is performed, I don't see how this could be different in GRW or any "objective collapse" theory.
2. In swapping setups, the final 2 entangled particles Alice and Bob were at one time entangled with other particles, let's call those Chris and Dale. Under an objective collapse theory, when Chris and Dale are measured, certainly an objective collapse must have occurred for their then respective partners Alice and Bob. In orthodox QM, particles can be entangled on multiple bases (say spin and position/momentum). They can then be collapsed on individual bases, leaving the particles entangled on some bases. Or swapping can occur.
Again, for objective collapse theories: Presumably the time at which the objective collapse occurs applies to all bases, not just one - else it wouldn't be an objective collapse, would it? But that cannot be either, else swapping is not possible at all quantum entanglement would have decohered once Chris and Dale are brought together. Alice and Bob would not end up with an entangled relationship.
What am I missing? My reasoning applies equally to the hypothesis that gravity induces collapse. Time, gravity, it's doesn't make any difference. It should be obvious that the standard quantum viewpoint - that collapse occurs within the context of an irreversible measurement context - is the only explanation that fits with experiment. Bell tests to date show no dependence on time.
3. There have even been experiments performed where a photon is "stored" for an hour, and collapse does not occur. Not exactly an absolute disproof of time based objective collapse, but certainly bring the concept into question.
https://www.nature.com/articles/s41467-021-22706-y
Where is there a place for objective collapse when entanglement is brought into the picture?
Please give a specific reference for what experiments, or what predictions using only the basic math of QM or some other model that makes different experimental predictions (such as the "objective collapse" theories that modify the dynamics), you are talking about that show this. Please bear in mind that this is not the interpretations subforum, so talking about what some particular collapse interpretation says is out of bounds here.Question69 said:The collapse happens under the context of a parameter.
Question69 said:The collapse happens under the context of a parameter.So for example the bigger a system is, the bigger the chance of a collapse is for that.Smaller things have a very, very low chance of collapsing.If we have a big entangled system, that will have a very big chance of collapse.
Well, wouldn't it explain those ill-defined terms? An observer here is a system of particles, and the collapse happens because you are a big system that gets entangled to the small system that is in superposition because it's not big enough.DrChinese said:OK, I can see that objective collapse might not occur often if the parameter was "small" for a single particle. But that essentially means such theories don't explain anything useful in the quantum regime. I thought the whole point was to explain away the need for defining "observer" and "measurement". If it comes back to explaining entangled particle behavior using orthodox quantum definitions in 99% of cases, what's the point?
The minimal statistical interpretation, i.e., QT without unnecessary philosophical extensions.Question69 said:That's interesting, what interpretation do you hold to?
So it's forbidden to discuss about alternative ansatzes like the here discussed objective-collapse postulates?PeterDonis said:Even in the interpretations subforum, that question is off limits. All QM interpretations make the same predictions for all experiments, so there is no way of testing by experiment which ones are "true". The interpretations subforum is for discussion of what the different interpretations say, not for expressing opinions about which ones people think are "true". Please refer to the guidelines for the interpretations subforum.
The objective collapse postulate is a theory in quantum mechanics that suggests that the wave function of a particle collapses spontaneously due to an external interaction or measurement. This theory is an alternative to the more commonly accepted Copenhagen interpretation, which states that the wave function only collapses when observed by a conscious observer.
The main difference between the objective collapse postulate and the Copenhagen interpretation is in their explanation of the collapse of the wave function. The objective collapse postulate suggests that the collapse is a physical process that occurs due to an external interaction, while the Copenhagen interpretation states that the collapse is a result of the observation by a conscious observer.
Currently, there is no direct evidence that supports the objective collapse postulate. However, some experiments have shown results that are consistent with this theory. For example, the double-slit experiment has shown that particles behave differently when observed, which could be explained by the collapse of the wave function due to an external interaction.
If the objective collapse postulate is true, it would suggest that the universe is not entirely deterministic, as the collapse of the wave function would introduce an element of randomness into quantum systems. It would also have implications for our understanding of consciousness and the role of the observer in quantum mechanics.
Yes, there are some criticisms of the objective collapse postulate. One of the main criticisms is that it is not a complete theory and does not fully explain the collapse of the wave function. Additionally, some argue that it is not testable and therefore cannot be considered a scientific theory. Further research and experimentation are needed to fully understand the validity and implications of the objective collapse postulate.