It isn't a live and dead cat, a blatant contradiction which cannot arise. Bob observes the cat and knows if it is dead or alive. Alice measures the cat still in superposition. That's very different than Alice measuring a dead cat and Bob a live one. — noAxioms
Takes a theory to beat a theory — Andrew M
Now they’ve performed the first experiment that proves it
— Wayfarer
is this not a an objective realisation? — Mr Phil O'Sophy
Wigner’s friend is a well-known feature of QM — boundless
QM, according to Bitbol is perspectival: it makes predictions of what the experimenter herself will observe. This does not mean that the observer creates reality but, rather, that the measurement is made by a peculiar perspective, namely that of the observer's. According to Bitbol this was also the position of Bohr himself. Note, however, that this interpretation does not take an ontological position on the 'objective reality'. In some sense, CI, in this 'flavor', is a statement on the limitations of science. Science cannot give us knowledge of 'reality as it is', but in its relation to the observations (in the first paper Bitbol compares Bohr's views on QM with Kant's philosophy). — boundless
So, Schroedinger's cat is either alive or dead and never both. — Dfpolis
I think the Copenhagen interpretation is not compatible with the usual folk notion of 'objective reality'. It denies that there is any fact of the matter about where a particle is between observations.If you reject "objective reality", is there any interpretation other than Many Worlds which is acceptable? — Metaphysician Undercover
However the point of the article is the claim that what was previously only a thought experiment has now been experimentally realised. — Wayfarer
I have been reading those papers from Bitbol, and this is the interpretation that makes the most sense to me also. A point that Bitbol makes is that there is an ineliminably subjective aspect to knowledge, generally - measurements are always made from a point of view or perspective. But scientific philosophy doesn’t want to acknowledge that, it wants to believe that it’s seeing reality as it is in itself, as Boundless notes. This the conceit that is being exposed by these conundrums. — Wayfarer
Given that, it appears to me that the article says nothing new.But Proietti and co’s result suggests that objective reality does not exist. In other words, the experiment suggests that one or more of the assumptions—the idea that there is a reality we can agree on, the idea that we have freedom of choice, or the idea of locality—must be wrong.
So, according to the article, the notion of objective reality has not been unequivocally undermined, as your headline asserts. It might be the notion of freedom of choice or the idea of locality which have been undermined; the article only claims that it must be that one of the three is wrong. — Janus
Presumably quantum phenomena were happening long before there were people. — fdrake
This is the issue at the heart of the 'observer problem'. — Wayfarer
Except 'observation' has been occurring since before humans existed — fdrake
But you're not seeing why there is a controversy about this issue. You're simply adopting, or assuming, the perspective of scientific realism, without showing any indication that you understand what exactly about the discoveries of 20th c physics threw this into question. — Wayfarer
Tell me why people are required for the natural formation of salt (which requires quantum mechanical effects due to the ionic bond). — fdrake
'Does the moon continue to exist if we're not looking at it?' — Wayfarer
Isolated material particles are abstractions, their properties being definable and observable only through their interaction with other systems.
Presumably quantum phenomena were happening long before there were people. — fdrake
People gonna keep thinking quantum observers are people. — fdrake
Agree. MWI says there is an objective reality, but it is entirely in superposition, and measurement just entangles the measurer with the measured thing. It does not collapse any wave function. Hence there is no defined state of anything (like dead cat), and hence no counterfactual (or even factual) definiteness.I agree that QBism, Copenaghen interpretation (CI), RQM in their own ways reject 'realism'. But how about MWI. In MWI, the only 'truly real thing' is the universal wave-function (UW). The UW never collapses in MWI. It rejects counterfactual definiteness. But the UW is still objective. — boundless
Instruments take measurements, but only humans are observers, which is why Niels Bohr would say things like 'nothing exists until it is measured'. — Wayfarer
In quantum mechanics the departure from this ideal (of nature as an inert 'objective' substrate - me) has been even more radical. We can still use the objectifying language of classical physics to make statements about observable facts. For instance, we can say that a photographic plate has been blackened, or that cloud droplets have formed. But we can say nothing about the atoms themselves. And what predictions we base on such findings depend on the way we pose our experimental question, and here the observer has freedom of choice. Naturally, it still makes no difference whether the observer is a man, an animal, or a piece of apparatus, but it is no longer possible to make predictions without reference to the observer or the means of observation. To that extent, every physical process may be said to have objective and subjective features. The objective world of nineteenth-century science was, as we know today, an ideal, limiting case, but not the whole reality. — Bohr, Remarks after the Solvay Conference
↪fdrake I think the section you have underlined actually mitigates against your argument, don’t you? — Wayfarer
It denies that there is any fact of the matter about where a particle is between observations. — andrewk
What if the theory that needs to be ‘beaten’ is not a theory at all but an untestable metaphysical postulate? Then it might be better to simply ignore it, or proceed as if it says nothing. — Wayfarer
No interpretation is a cop out, but MWI cannot have those observers in different world branches since they communicate. Alice knows the polarity and tells Bob that she does. Bob knows that the particle is still in superposition and tells Alice so. That cannot happen if the two are in different branches. — noAxioms
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