Yes. See the citations in this SEP article. If I recall correctly, you upload a human into a quantum computer, and then that uploaded human observes a system that is in a superposition of states xy. The human can be decomposed into two factors, aotimesb, where the second factor is capable of remembering the result of the observation and the first factor is only capable of remembering the fact that an observation has been made. Before the observation, the system is
%20)
and afterwards, it’s
a′otimesb_xotimesxa′otimesb_yotimesy
Now the evolution
%20\mapsto%20b_x%20\otimes%20x%20+%20b_y%20\otimes%20y) is a unitary transformation, so you can undo that process without affecting the state a′. Then we’re left with the state
)
Now we communicate with the human, who tells us that they remember observing the mixed state, but they cannot remember what they observed. Then we verify that indeed, the mixed state is still mixed, despite having been observed by a human. That’s what MWI predicts, anyways.
This is one of those models fighting a “straw collapse”. The orthodox approach is “this is the math, shut up and calculate”. Until the MWI math is different from “unitary evolution+Born rule”, it’s indistinguishable from collapse.
I think a better way of phrasing it is, ‘Is there any scenario in which a collapse postulate would be testable...’
We have done tests far more sensitive than this one and not found any collapse behaviors separate from decoherence. The sort of experiment proposed would not be as sensitive because we would not expect coherence in the first place—you can’t get any sort of quantum effect out of a person just because of its size and inhomogeneity.
What if you have an automated setup perform the double slit experiment with and without detectors at each slit and observe the interference pattern.
After the experiments, the humans/ems in the simulation are only told whether the interference patterns are different, they are given no other information about the outside world and are especially not told what the detectors read.
I was hoping to ask a really vague question so I displayed less of my total ignorance of QM.
Well wouldn’t it determine whether wave function collapse happens because of scale or because a human observed it or because you yourself observed it?
If neither having other humans outside the simulation nor having detectors changes the interference pattern, then the wave function collapse happens only if you yourself are effected by the information from the detectors.
If having other humans outside the simulation changes the interference pattern, then wave function collapse happens because any human is effected by the information from the detectors.
If having detectors changes the interference pattern even when no humans were effected by the information from the detectors, then wave function collapse happens at certain scales.
If having detectors changes the interference pattern even when no humans were effected by the information from the detectors, then wave function collapse happens at certain scales.
Having detectors present is already known to destroy the interference pattern, even if the detected information is silently and automatically erased right after (though I have trouble locating a relevant reference right now). A similar example is the experiment by Anton Zeilinger with hot bucky balls. The hotter they are, the less self-interference is observed, because the black-body radiation they emit gives away their position to some degree, even if this radiation is not specifically measured by anyone. Not sure what it says about your models.
If the detected information is silently and automatically destroyed, the interference pattern is recovered ..
Indeed, but it would take a lot more than a single polarizer to destroy all traces of thermal radiation from a fullerene molecule. Once those thermal photons are out, you cannot really destroy all traces of their interaction with the rest of the Universe. Well, maybe you can, somehow, but that was not attempted in the experiment. My original point was that entanglement with the environment (=possibility of detection) is enough to destroy the interference pattern. Hence my puzzlement by Incorrect’s statement that “wave function collapse happens at certain scales”.
even if the detected information is silently and automatically erased right after
Yes but it can still effect the humans through butterfly effects. If we put the humans in a digital simulation, nothing short of data corruption will effect them.
Is there any scenario in which many-worlds would be testable by placing humans in a simulation and restricting the information they receive?
Yes. See the citations in this SEP article. If I recall correctly, you upload a human into a quantum computer, and then that uploaded human observes a system that is in a superposition of states x y. The human can be decomposed into two factors, aotimesb, where the second factor is capable of remembering the result of the observation and the first factor is only capable of remembering the fact that an observation has been made. Before the observation, the system is
and afterwards, it’s
a′otimesb_xotimesx a′otimesb_yotimesy
Now the evolution
Now we communicate with the human, who tells us that they remember observing the mixed state, but they cannot remember what they observed. Then we verify that indeed, the mixed state is still mixed, despite having been observed by a human. That’s what MWI predicts, anyways.
This is one of those models fighting a “straw collapse”. The orthodox approach is “this is the math, shut up and calculate”. Until the MWI math is different from “unitary evolution+Born rule”, it’s indistinguishable from collapse.
Those computations wouldn’t really be humans doing their regular human thing… you’d have to suspend the ‘human’ program for parts of that experiment.
I think a better way of phrasing it is, ‘Is there any scenario in which a collapse postulate would be testable...’
We have done tests far more sensitive than this one and not found any collapse behaviors separate from decoherence. The sort of experiment proposed would not be as sensitive because we would not expect coherence in the first place—you can’t get any sort of quantum effect out of a person just because of its size and inhomogeneity.
Feel free to elaborate on what you mean by this.
What if you have an automated setup perform the double slit experiment with and without detectors at each slit and observe the interference pattern.
After the experiments, the humans/ems in the simulation are only told whether the interference patterns are different, they are given no other information about the outside world and are especially not told what the detectors read.
What would you expect to happen differently depending on whether the MWI is more than an interpretation?
I was hoping to ask a really vague question so I displayed less of my total ignorance of QM.
Well wouldn’t it determine whether wave function collapse happens because of scale or because a human observed it or because you yourself observed it?
If neither having other humans outside the simulation nor having detectors changes the interference pattern, then the wave function collapse happens only if you yourself are effected by the information from the detectors.
If having other humans outside the simulation changes the interference pattern, then wave function collapse happens because any human is effected by the information from the detectors.
If having detectors changes the interference pattern even when no humans were effected by the information from the detectors, then wave function collapse happens at certain scales.
Having detectors present is already known to destroy the interference pattern, even if the detected information is silently and automatically erased right after (though I have trouble locating a relevant reference right now). A similar example is the experiment by Anton Zeilinger with hot bucky balls. The hotter they are, the less self-interference is observed, because the black-body radiation they emit gives away their position to some degree, even if this radiation is not specifically measured by anyone. Not sure what it says about your models.
Doesn’t this contradict it though? If the detected information is silently and automatically destroyed, the interference pattern is recovered ..
Not sure where you see a contradiction.
Indeed, but it would take a lot more than a single polarizer to destroy all traces of thermal radiation from a fullerene molecule. Once those thermal photons are out, you cannot really destroy all traces of their interaction with the rest of the Universe. Well, maybe you can, somehow, but that was not attempted in the experiment. My original point was that entanglement with the environment (=possibility of detection) is enough to destroy the interference pattern. Hence my puzzlement by Incorrect’s statement that “wave function collapse happens at certain scales”.
Yes but it can still effect the humans through butterfly effects. If we put the humans in a digital simulation, nothing short of data corruption will effect them.