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Fun idea, but "according to scientists" and "according to prevailing quantum theory" are questionable. The many worlds interpretation isn't as mainstream as thi

Fun idea, but "according to scientists" and "according to prevailing quantum theory" are questionable. The many worlds interpretation isn't as mainstream as this implies (and many non-physicists think). Personally I don't think it makes any sense at all, although I have a mere batchelor's degree in physics so I'm not particularly well qualified to judge. I've never had a satisfactory answer to the simple emperor's new clothes question, which requires no knowledge of QM to ask, "If every outcome happens, in what sense is one outcome more probable than another?" Because it is (experimentally, based on repeat trials), and QM furnishes us with the probabilities. This is sometimes stated as "How do you get the Born rule?" but it's a simple and obvious question as soon as any sort of multiverse is proposed. I'm aware of the attempts to answer the question using decision theory but while they produce the right numbers they fail to provide a convincing justification for or interpretation of them (vs the simple, experimentally falsifiable frequentist view "if you repeat the experiment you'll see the frequencies approach these probabilities").

Closi 5y ago
> Fun idea, but "according to scientists" and "according to prevailing quantum theory" are questionable. Well it is certainly up there in terms of quantum theory along with the Copenhagen interpretation, and some quantum physicists definitely believe this, so considering it is a joke app and mostly a thought experiment I think we can say these statements are accurate enough. > I've never had a satisfactory answer to the simple emperor's new clothes question, which requires no knowledge of QM to ask, "If every outcome happens, in what sense is one outcome more probable than another?" I've never had a satisfactory answer to how a cat can be both alive and dead at the same time with the competing Copenhagen interpretation - however I will leave this debate to researchers in quantum mechanics who understand the maths of quantum physics better than my knowledge of quantum dead cats.
beecafe 5y ago
One outcome being more probable than another in MW can be interpreted as that outcome being more likely to have occurred in your past. That is also what the frequentist example is measuring, not which outcome is more likely but which outcome is more likely to be in your history. There is also Quantum Bayseianism in which an outcome being more likely is due to that state being better at copying itself to neighboring states. In all interpretations (including Copenhagen) the mapping from the unobservable wavefunction is taken as axiom (well, one could argue that Relational QM/Transactional interpretation avoids this, but just adds another axiom).
- dumbfounder 5y ago
  But how do I use this when I bet at the track? Can I tell them my horse did win, but just in a different universe?
ravi-delia 5y ago
I mean, fair's fair, many worlds doesn't give you probabilities. On the other hand, I'm not convinced saying "and then collapse happens" is an explanation for the Born rule anyway, seeing as collapse is just something magic that turns amplitudes into probability in the same way (mathematically) decoherence does. Meanwhile, collapse remains totally unmoored from the rest of quantum mechanics. It could definitely be decided either way, whether by a satisfying explanation of collapse or a solid explanation for the Born rule, but as of now I'd say the weight of evidence is behind many worlds.
- nobody9999 5y ago
  >I mean, fair's fair, many worlds doesn't give you probabilities. On the other hand, I'm not convinced saying "and then collapse happens" is an explanation for the Born rule anyway, seeing as collapse is just something magic that turns amplitudes into probability in the same way (mathematically) decoherence does. An alternative explanation with as much physical evidence as the Many Worlds (MW) interpretation (i.e., none) could be that we are, in fact, part of a simulation[0] and the "wave function" properties of quanta aren't "real" (what is "real" in a simulation?), but rather are artifacts of speculative execution[1] on the part of the CPU executing the aforementioned simulation. The idea there being that all possible branches are followed, but only the [correct|selected|randomly arrived at|etc.] events are incorporated into "reality." That, of course, raises a number of questions: 1. How is it that we can perceive such speculative branch execution from inside a simulation executing on such a CPU? 2. What mechanism (algorithm? [pseudo]-random number generation? lookup table?) would be used to determine "actual" outcome from executing all possible code branches? 3. Like the "Many Worlds" hypothesis, treating quantum uncertainty as an artifact of "speculative execution" of all possible branches of simulation code isn't testable (at least not as far as I'm aware). As such, how do we use the scientific method to identify the most likely scenario? I'm not advocating the position that we do, in fact, live in a simulation. Nor am I advocating the MW, Copenhagen or even Pilot-wave interpretations. Rather, my point is that none of these interpretations are "science" in the sense of having falsifiable hypotheses. Unless and until we have the appropriate concepts/technology to test such hypotheses, all are just speculation/metaphysics. That said, I also think it's useful to examine and (where possible) investigate such hypotheses, as that might give us a better understanding of the universe(s) we occupy. [0] https://en.wikipedia.org/wiki/Simulation_hypothesis https://en.wikipedia.org/wiki/Simulation_hypothesis [1] https://en.wikipedia.org/wiki/Speculative_execution https://en.wikipedia.org/wiki/Speculative_execution Edit: Clarified prose.
mhh__ 5y ago
In my experience at least many worlds seems to be popular amongst physicists who avoid the "shut up and calculate" philosophy.
- speakeron 5y ago
  It's like the old joke about Vegans. "How do you know if a physicist is an MWI proponent? Don't worry, they'll tell you soon enough..."

Closi 5y ago

> Fun idea, but "according to scientists" and "according to prevailing quantum theory" are questionable. Well it is certainly up there in terms of quantum theory along with the Copenhagen interpretation, and some quantum physicists definitely believe this, so considering it is a joke app and mostly a thought experiment I think we can say these statements are accurate enough. > I've never had a satisfactory answer to the simple emperor's new clothes question, which requires no knowledge of QM to ask, "If every outcome happens, in what sense is one outcome more probable than another?" I've never had a satisfactory answer to how a cat can be both alive and dead at the same time with the competing Copenhagen interpretation - however I will leave this debate to researchers in quantum mechanics who understand the maths of quantum physics better than my knowledge of quantum dead cats.

beecafe 5y ago

One outcome being more probable than another in MW can be interpreted as that outcome being more likely to have occurred in your past. That is also what the frequentist example is measuring, not which outcome is more likely but which outcome is more likely to be in your history. There is also Quantum Bayseianism in which an outcome being more likely is due to that state being better at copying itself to neighboring states. In all interpretations (including Copenhagen) the mapping from the unobservable wavefunction is taken as axiom (well, one could argue that Relational QM/Transactional interpretation avoids this, but just adds another axiom).

dumbfounder 5y ago
But how do I use this when I bet at the track? Can I tell them my horse did win, but just in a different universe?

ravi-delia 5y ago

I mean, fair's fair, many worlds doesn't give you probabilities. On the other hand, I'm not convinced saying "and then collapse happens" is an explanation for the Born rule anyway, seeing as collapse is just something magic that turns amplitudes into probability in the same way (mathematically) decoherence does. Meanwhile, collapse remains totally unmoored from the rest of quantum mechanics. It could definitely be decided either way, whether by a satisfying explanation of collapse or a solid explanation for the Born rule, but as of now I'd say the weight of evidence is behind many worlds.

nobody9999 5y ago
>I mean, fair's fair, many worlds doesn't give you probabilities. On the other hand, I'm not convinced saying "and then collapse happens" is an explanation for the Born rule anyway, seeing as collapse is just something magic that turns amplitudes into probability in the same way (mathematically) decoherence does. An alternative explanation with as much physical evidence as the Many Worlds (MW) interpretation (i.e., none) could be that we are, in fact, part of a simulation[0] and the "wave function" properties of quanta aren't "real" (what is "real" in a simulation?), but rather are artifacts of speculative execution[1] on the part of the CPU executing the aforementioned simulation. The idea there being that all possible branches are followed, but only the [correct|selected|randomly arrived at|etc.] events are incorporated into "reality." That, of course, raises a number of questions: 1. How is it that we can perceive such speculative branch execution from inside a simulation executing on such a CPU? 2. What mechanism (algorithm? [pseudo]-random number generation? lookup table?) would be used to determine "actual" outcome from executing all possible code branches? 3. Like the "Many Worlds" hypothesis, treating quantum uncertainty as an artifact of "speculative execution" of all possible branches of simulation code isn't testable (at least not as far as I'm aware). As such, how do we use the scientific method to identify the most likely scenario? I'm not advocating the position that we do, in fact, live in a simulation. Nor am I advocating the MW, Copenhagen or even Pilot-wave interpretations. Rather, my point is that none of these interpretations are "science" in the sense of having falsifiable hypotheses. Unless and until we have the appropriate concepts/technology to test such hypotheses, all are just speculation/metaphysics. That said, I also think it's useful to examine and (where possible) investigate such hypotheses, as that might give us a better understanding of the universe(s) we occupy. [0] https://en.wikipedia.org/wiki/Simulation_hypothesis https://en.wikipedia.org/wiki/Simulation_hypothesis [1] https://en.wikipedia.org/wiki/Speculative_execution https://en.wikipedia.org/wiki/Speculative_execution Edit: Clarified prose.

mhh__ 5y ago

In my experience at least many worlds seems to be popular amongst physicists who avoid the "shut up and calculate" philosophy.

speakeron 5y ago
It's like the old joke about Vegans. "How do you know if a physicist is an MWI proponent? Don't worry, they'll tell you soon enough..."