Learning Of Information, Non An Interaction, Induces The Collapse

The dishonest Bohmist crackpot filth continued to endure everywhere – on the Physics Stack Exchange, the Quanta Magazine, too elsewhere – too then it was pleasant to run across a new, one-week-old YouTube video yesteryear Inspiring Philosophy well-nigh quantum mechanics, a video I may fully endorse.



Last time, inwards a give-and-take amongst him on this blog, I was annoyed yesteryear his stance that philosophers such as Kant or Hegel or their ideas should "stand above" the physics question which I consider totally ludicrous because physics must role its ain philosophy too persistently upgrade it as the evidence arrives too is evaluated inwards improve ways. And the one-time guys' philosophy is clearly outdated plenty to endure unusable inwards the context of modern physics.

I receive got also disliked just about basic technical misunderstanding – I forgot what it was – but all these things are forgotten yesteryear now.




In the novel 5-minute video that I recommend you lot to watch, Inspiring Philosophy to a greater extent than oftentimes than non talks well-nigh a fun 1994-95 paper

Experimental Realization of Interaction-free Measurements (full PDF)

by Zeilinger et al.




Some people oftentimes receive got the wishing to "restore just about realism". So they tell that the collapse of the moving ridge percentage isn't tightly linked to just about observer or his deed of an observation. Instead, it's a final result of an interaction. Well, the interaction amongst a bigger object etc. may endure a grooming for the mensuration – too for the collapse – but it's non the mensuration too it doesn't crusade the collapse yet. After all, the collapse may receive got house without an interaction.

Zeilinger et al. receive got used a Michelson interferometer inwards their experiment but Inspiring Philosophy has shown a simpler prototypical illustration of the same idea. All deep novel ideas well-nigh quantum mechanics may endure extracted from the double slit experiment if you lot recollect well-nigh it deeply enough, Feynman i time said, too this regulation is applied here, too.

H5N1 double slit experiment creates an interference designing when both slits are open. But it's plenty to house a detector/counter inwards slit H5N1 – too no detector inwards slit B – too the final result is just the same as if you lot house detectors/counters inwards both slits, H5N1 too B.

You know, this actually contradicts the thought that the collapse – too its experimental consequence, namely the devastation of the interference designing – is caused yesteryear an interaction of the photon amongst the "which way detector". Why? Because if this were the instance too if you lot studied the organization amongst i detector solely inwards slit A, in that location would endure a 50% probability that the interaction amongst the detector doesn't occur (because the particle may receive got gone through slit B which has no detector). So the final result should endure something inwards betwixt the interference designing too the "two shadows" interference-free result.

However, quantum mechanics predicts too the experiment shows that you lot acquire the exact same final result without whatever interference fifty-fifty if you lot solely role i counter inwards slit A. The interference disappears because you lot (an observer who also observes the dots at the photographic plate at the end) receive got learned the which-way information, too that's what forced you lot to role the collapsed moving ridge percentage behind i of the slits. And the absence of the interaction amongst the detector (and the audio that accompanies it) is plenty to learn.

In other words, if there's solely a detector inwards the slit A, 50% of the particles collapse into a parcel close this detector, but the remaining 50% of the particles collapse into a moving ridge parcel behind slit B, a house which contains no detector too where no interaction of the particle amongst a detector has taken place.

Zeilinger et al. receive got also proposed a modification of the experiment inwards which an overwhelming bulk of the objects collapses to places where no interaction has taken place. And because it was a few years later on the "weak measurements" receive got introduced, they also discussed a weak-measurement interpretation of such modifications, something that is jump to atomic number 82 to to a greater extent than confusion too misinterpretations.

Don't acquire me wrong: just about potential for an interaction of the observed physical scheme amongst a macroscopic object is a necessary status for a measurement. But:

• in principle, an arbitrarily large physical scheme may endure described yesteryear exact quantum mechanics too then that no collapse takes house earlier the actual observer looks at it (there is no "unavoidable collapse") when macroscopic systems are included
• it is of import to include the words "potential for an" inwards the business higher upwards because inwards many/most of the actual collapses, i may tell that the collapse took house away or without whatever interaction of the observed particle(s) amongst a detector or just about other macroscopic system

Many people beloved to speak over the unproblematic Everettian events inwards which a measured particle gets entangled amongst an apparatus, too both of them may acquire entangled amongst something else, perchance amongst a truthful cat or a human, or just about other human, too and then forth. They speak over these fiddling things too they believe that they solve something well-nigh what they consider to endure a mensuration "problem".

Needless to say, they don't solve whatever occupation at all. They are solely "solving" as many "problems" as the position out of novel unnecessary "problems" they receive got added. They are just postponing the discussion. H5N1 measured particle may indeed acquire entangled amongst an apparatus, a cat, a human, or something else, but at the end, in that location nevertheless needs to endure an observer who makes the observation. And the actual collapse to i of the a priori possible outcomes is always associated amongst the modify of the cognition of an observer because the collapse is zero else than a generalization of Bayesian inference described yesteryear the probability amplitudes according to the quantum mechanical rules.

Just similar the Bayesian probabilities don't modify without mortal who subjectively learns well-nigh just about information, the probability amplitudes inwards quantum mechanics don't modify without an observer who is learning just about data from a quantum measurement!

Now, the people who just loathe the (no longer too) novel foundations of physics may tell that the interaction is taking house all the time, fifty-fifty if the detector is solely inwards the slit A, because just about object (the wave) objectively existed close both slits when in that location was the potential to abide by the particle inwards detector A. However, if you lot encompass this attitude, it way that you lot are demonstrably pretending that just about objects that are clearly unphysical are physical.

The argue is that you lot are proverb that "something existent exists close the slit A" (namely the "wave") whenever the particle has the potential to endure seen either inwards slit H5N1 or B. However, you're admitting that this "real thing" can't receive got whatever touching on on whatever experiments you lot are doing inwards the given situation. Pretty much yesteryear Definition of the intelligence "unphysical", a physicist must tell that because this "something" isn't observed fifty-fifty inwards principle, this "something" is unphysical – just similar the detail value of the potential \(A_\mu\) inwards a guess theory. And when something is unphysical (in this sense), it's absolutely essential – actually a affair of honesty – to acknowledge that all the descriptions where this unphysical "something" has unlike values or properties are as existent or as truthful inwards the scientific sense.

Because \(A_\mu\) isn't straight measured, nosotros tell that all the configurations of \(A_\mu\) related yesteryear guess transformations to each other are as existent too as true. The realists inwards full general too Bohmists inwards detail violate this dominion – that descriptions amongst the same understanding amongst all the empirical evidence are as existent too as truthful – which actually proves that they are beingness dishonest.

Also banking concern complaint that the thought that "something is close the slit A" regardless of the reaction of the detector inwards the slit H5N1 implies a huge nonlocality of the most roughshod kind. The collapse to a moving ridge parcel close the slit B was caused yesteryear just about wave's presence close the detector inwards the slit A. Once you lot consider similar nonlocal classical theories, you lot should consider the most generic values of all of their parameters – non solely the values of the parameters that are to a greater extent than useful for counterfeiting of the right theory (quantum mechanics). If you lot practise so, you lot volition unavoidably predict that this nonlocal classical theory predicts easily visible nonlocal phenomena amongst the probability approaching 100%, something that is clearly ruled out yesteryear the experiments.

So fifty-fifty inwards this sense, the people who maintain on insisting on "realism addition nonlocality" are just failing to acquit as honest scientists. They are ideologically driven filth.