[Marxism] Quantum Experiment

Jim Farmelant farmelantj at juno.com
Sun Nov 17 06:35:41 MST 2019



Ever since quantum mechanics began, there have been many physicists and others who have insisted on interpreting the results of quantum experiments as supporting idealist interpretations of the theory. In the West, most people seemed to have been perfectly happy with that outcome because the rejection of materialism supported the prevailing political ideologies. In the Soviet Union, quantum mechanics  (along with relativity) struggled for some years to gain acceptance there precisely because so many Soviet physicists and philosophers also interpreted the theory in idealist terms.

More about that here:

www.quora.com/Does-quantum-mechanics-disprove-materialism/answer/Jim-Farmelant 



Jim Farmelant
http://independent.academia.edu/JimFarmelant
http://www.foxymath.com 
Learn or Review Basic Math


---------- Original Message ----------
From: John Edmundson via Marxism <marxism at lists.csbs.utah.edu>
Subject: Re: [Marxism] Quantum Experiment
Date: Sun, 17 Nov 2019 09:47:13 +1300


It;s ironic that the outcome of this would be to objectively prove the
subjectivity of science :-)

Cheers,
John

On Sun, Nov 17, 2019 at 4:53 AM Louis Proyect via Marxism <
marxism at lists.csbs.utah.edu> wrote:

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> On 11/16/19 10:19 AM, Marla Vijaya kumar via Marxism wrote:
> >
> > Louis,            The subject is extremely interesting and I am working
> on the philosophical aspect of it.
> > But unfortunately, it requires subscription.
> > Can you post the text?
> > Vijaya Kumar M
>
> Vijaya, this was from Alternet, which does not have paywalls. In any case:
>
> Quantum physics: our study suggests objective reality doesn’t exist
> November 14, 2019 7.40am EST
>
> Authors
> Alessandro Fedrizzi
> Professor of Quantum Physics, Heriot-Watt University
>
> Massimiliano Proietti
> PhD Candidate of Quantum Physics, Heriot-Watt University
>
> Alternative facts are spreading like a virus across society. Now it
> seems they have even infected science – at least the quantum realm. This
> may seem counter intuitive. The scientific method is after all founded
> on the reliable notions of observation, measurement and repeatability. A
> fact, as established by a measurement, should be objective, such that
> all observers can agree with it.
>
> But in a paper recently published in Science Advances, we show that, in
> the micro-world of atoms and particles that is governed by the strange
> rules of quantum mechanics, two different observers are entitled to
> their own facts. In other words, according to our best theory of the
> building blocks of nature itself, facts can actually be subjective.
>
> Observers are powerful players in the quantum world. According to the
> theory, particles can be in several places or states at once – this is
> called a superposition. But oddly, this is only the case when they
> aren’t observed. The second you observe a quantum system, it picks a
> specific location or state – breaking the superposition. The fact that
> nature behaves this way has been proven multiple times in the lab – for
> example, in the famous double slit experiment (see video below).
>
>
> In 1961, physicist Eugene Wigner proposed a provocative thought
> experiment. He questioned what would happen when applying quantum
> mechanics to an observer that is themselves being observed. Imagine that
> a friend of Wigner tosses a quantum coin – which is in a superposition
> of both heads and tails – inside a closed laboratory. Every time the
> friend tosses the coin, they observe a definite outcome. We can say that
> Wigner’s friend establishes a fact: the result of the coin toss is
> definitely head or tail.
>
> Wigner doesn’t have access to this fact from the outside, and according
> to quantum mechanics, must describe the friend and the coin to be in a
> superposition of all possible outcomes of the experiment. That’s because
> they are “entangled” – spookily connected so that if you manipulate one
> you also manipulate the other. Wigner can now in principle verify this
> superposition using a so-called “interference experiment” – a type of
> quantum measurement that allows you to unravel the superposition of an
> entire system, confirming that two objects are entangled.
>
> When Wigner and the friend compare notes later on, the friend will
> insist they saw definite outcomes for each coin toss. Wigner, however,
> will disagree whenever he observed friend and coin in a superposition.
>
> This presents a conundrum. The reality perceived by the friend cannot be
> reconciled with the reality on the outside. Wigner originally didn’t
> consider this much of a paradox, he argued it would be absurd to
> describe a conscious observer as a quantum object. However, he later
> departed from this view, and according to formal textbooks on quantum
> mechanics, the description is perfectly valid.
>
> The experiment
> The scenario has long remained an interesting thought experiment. But
> does it reflect reality? Scientifically, there has been little progress
> on this until very recently, when Časlav Brukner at the University of
> Vienna showed that, under certain assumptions, Wigner’s idea can be used
> to formally prove that measurements in quantum mechanics are subjective
> to observers.
>
> Brukner proposed a way of testing this notion by translating the
> Wigner’s friend scenario into a framework first established by the
> physicist John Bell in 1964. Brukner considered two pairs of Wigners and
> friends, in two separate boxes, conducting measurements on a shared
> state – inside and outside their respective box. The results can be
> summed up to ultimately be used to evaluate a so called “Bell
> inequality”. If this inequality is violated, observers could have
> alternative facts.
>
> We have now for the first time performed this test experimentally at
> Heriot-Watt University in Edinburgh on a small-scale quantum computer
> made up of three pairs of entangled photons. The first photon pair
> represents the coins, and the other two are used to perform the coin
> toss – measuring the polarisation of the photons – inside their
> respective box. Outside the two boxes, two photons remain on each side
> that can also be measured.
>
>
> Researchers with experiment. Author provided
> Despite using state-of-the-art quantum technology, it took weeks to
> collect sufficient data from just six photons to generate enough
> statistics. But eventually, we succeeded in showing that quantum
> mechanics might indeed be incompatible with the assumption of objective
> facts – we violated the inequality.
>
> The theory, however, is based on a few assumptions. These include that
> the measurement outcomes are not influenced by signals travelling above
> light speed and that observers are free to choose what measurements to
> make. That may or may not be the case.
>
> Another important question is whether single photons can be considered
> to be observers. In Brukner’s theory proposal, observers do not need to
> be conscious, they must merely be able to establish facts in the form of
> a measurement outcome. An inanimate detector would therefore be a valid
> observer. And textbook quantum mechanics gives us no reason to believe
> that a detector, which can be made as small as a few atoms, should not
> be described as a quantum object just like a photon. It may also be
> possible that standard quantum mechanics does not apply at large length
> scales, but testing that is a separate problem.
>
>
> There may be many worlds out there. Nikk/Flickr, CC BY-SA
> This experiment therefore shows that, at least for local models of
> quantum mechanics, we need to rethink our notion of objectivity. The
> facts we experience in our macroscopic world appear to remain safe, but
> a major question arises over how existing interpretations of quantum
> mechanics can accommodate subjective facts.
>
> Some physicists see these new developments as bolstering interpretations
> that allow more than one outcome to occur for an observation, for
> example the existence of parallel universes in which each outcome
> happens. Others see it as compelling evidence for intrinsically
> observer-dependent theories such as Quantum Bayesianism, in which an
> agent’s actions and experiences are central concerns of the theory. But
> yet others take this as a strong pointer that perhaps quantum mechanics
> will break down above certain complexity scales.
>
> Clearly these are all deeply philosophical questions about the
> fundamental nature of reality. Whatever the answer, an interesting
> future awaits.
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