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Reimagining of Schrodinger's Cat Breaks Quantum Mechanics -- and Stumps Physicists (nature.com)
In a multi-'cat' experiment, the textbook interpretation of quantum theory seems to lead to contradictory pictures of reality, physicists claim. New submitter Lanodonal shares a report: In the world's most famous thought experiment, physicist Erwin Schrodinger described how a cat in a box could be in an uncertain predicament. The peculiar rules of quantum theory meant that it could be both dead and alive, until the box was opened and the cat's state measured. Now, two physicists have devised a modern version of the paradox by replacing the cat with a physicist doing experiments -- with shocking implications.
Quantum theory has a long history of thought experiments, and in most cases these are used to point to weaknesses in various interpretations of quantum mechanics. But the latest version, which involves multiple players, is unusual: it shows that if the standard interpretation of quantum mechanics is correct, then different experimenters can reach opposite conclusions about what the physicist in the box has measured. This means that quantum theory contradicts itself.
The conceptual experiment has been debated with gusto in physics circles for more than two years -- and has left most researchers stumped, even in a field accustomed to weird concepts. "I think this is a whole new level of weirdness," says Matthew Leifer, a theoretical physicist at Chapman University in Orange, California. The authors, Daniela Frauchiger and Renato Renner of the Swiss Federal Institute of Technology (ETH) in Zurich, posted their first version of the argument online in April 2016. The final paper [PDF] appears in Nature Communications on 18 September.
Quantum theory has a long history of thought experiments, and in most cases these are used to point to weaknesses in various interpretations of quantum mechanics. But the latest version, which involves multiple players, is unusual: it shows that if the standard interpretation of quantum mechanics is correct, then different experimenters can reach opposite conclusions about what the physicist in the box has measured. This means that quantum theory contradicts itself.
The conceptual experiment has been debated with gusto in physics circles for more than two years -- and has left most researchers stumped, even in a field accustomed to weird concepts. "I think this is a whole new level of weirdness," says Matthew Leifer, a theoretical physicist at Chapman University in Orange, California. The authors, Daniela Frauchiger and Renato Renner of the Swiss Federal Institute of Technology (ETH) in Zurich, posted their first version of the argument online in April 2016. The final paper [PDF] appears in Nature Communications on 18 September.
Is this just another way of saying "Number 7 will shock you!"
Aren't the physicists in the box collapsing the function already by observing the coin? Unless we are saying that the system would behave like nested functions where the internal function collapses when the internal observation is made and a secondary function that includes the 1st one as a variable also collapses when the external observer performs their observation.
We replaced the cat with Folgers Crystals. Let’s see if anyone notices.
In the world's most famous thought experiment, physicist Erwin Schrodinger described how a cat in a box could be in an uncertain predicament.
Compared to the second most famous, but ironically similar: "Does this dress make me look fat?"
Where your relationship is also in an "uncertain predicament" -- being both dead and alive -- until the question is answered.
It must have been something you assimilated. . . .
The whole point of the Schrodinger's cat thought experiment was that quantum physics can apply to large scale things like cats and people, indirectly, if you design a mechanism to make it so. It's not about the whole cat decaying. The experiment is that if a geiger counter detects a single atom decaying it triggers the release of a poison to kill the cat. Thus the quantum state of the single atom determines the life or death of the cat.
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I don’t think it’s possible to KNOW precisely at any given moment whether quantum mechanics is broken, and to what degree it IS broken if indeed it is. That’s kind of the point of quantum mechanics.
OR...
If a mechanic breaks your quantum, he should have to fix it, theoretically.
I cant decide which joke to go with, so I've decided on a quantum superposition of both:
If don’t mechanic it’s your to he preciesly have any fix...
Hehehehe... quantum humor... simultaneously both really funny, and not funny at all, but you won’t know WHICH it is unitl you read the joke and collapse the wave-function.
Our reign has gone on long enough. Indeed. Summon the meteors.
The whole point of Schrodinger's cat experiment was to show that trying to apply certain quantum physics theories to reality resulted in absurd results.
To him (and Einstein), it was obvious that the cat could not be both alive and dead, and therefore the people pushing the superposition theory were obviously wrong.
It's a shame that his thought experiment has been taken to mean the exact opposite of what he was originally talking about.
The whole point of the Schrodinger's cat thought experiment was that quantum physics can apply to large scale things like cats and people, indirectly, if you design a mechanism to make it so.
No, the whole point was to point out the absurdity of the Copenhagen interpretation. Unfortunately, most people tend to miss this part and think that Schrödinger espoused the point of view that he was actually arguing against.
Most physicists don't give much credence to the Copenhagen Interpretation. There are better ways to think about quantum mechanics.
https://en.wikipedia.org/wiki/...
No, the whole point was to point out the absurdity of the Copenhagen interpretation. Unfortunately, most people tend to miss this part and think that SchrÃdinger espoused the point of view that he was actually arguing against.
And the Copenhagen interpretation is the new "Bohr atom model" - almost no one believes it this century, but it's still widely discussed and often taught in intro-level classes, out of simple tradition.
Anyhow, measurement devices collapse the wave state, removing this sort of uncertainty at the point of measurement.* It was never a very good thought experiment in the first place. The fact that you can't scale up quantum uncertainty to the macro scale in any straightforward way is the answer to SchrÃdinger's question.
* That's usually explained very early on even in describing "quantum weirdness" in lay terms. The two slit experiment stops giving a diffraction pattern as soon as you measure which slit the photons/electrons/whatever go through.
Socialism: a lie told by totalitarians and believed by fools.
Schrödinger's point about the cat thought experiment is that that cat is NOT in two separate states at the same time. That was his expressing his aggravation about the contradiction of the results of his work and reality.
The question remains, "How does potential get resolved?"
Until we open up Schrödinger's coffin, we can't know whether he was arguing for or against the Copenhagen interpretation.
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"Conscious observer" has nothing to do with it. The Geiger counter rigged to the poison is the observer that collapses the wave state.
Socialism: a lie told by totalitarians and believed by fools.
Observation / interaction have NOTHING to do with being conscious. It could be a rock and a can of spray paint.
Because he could be spinning in his grave in either direction. (sorry).
Where are we going and why are we in a handbasket?
I think they're trying to talk about boundaries across which things have NOT been interacting (in a quantum-state destructive way) yet.
No matter how complex the thing inside a boundary is, you could in principle (t least in a thought experiment) have the whole thing not entangled in any way with the observer and their entangled environment. So can that complex but isolated thing be in a quantum state/superposition, FROM THE PERSPECTIVE of the outside observer?
I suspect that was the idea of the box concept.
Where are we going and why are we in a handbasket?
I believe you are mistaken.
Schrödinger’s point was that the Copenhagen Interpretation led to absurd conclusions. See below.
https://en.wikipedia.org/wiki/Schr%C3%B6dinger%27s_cat#Origin_and_motivation
Schrödinger did not wish to promote the idea of dead-and-alive cats as a serious possibility; on the contrary, he intended the example to illustrate the absurdity of the existing view of quantum mechanics. However, since Schrödinger's time, other interpretations of the mathematics of quantum mechanics have been advanced by physicists, some of which regard the "alive and dead" cat superposition as quite real. Intended as a critique of the Copenhagen interpretation, the Schrödinger's cat thought experiment remains a defining touchstone for modern interpretations of quantum mechanics.[citation needed] Physicists often use the way each interpretation deals with Schrödinger's cat as a way of illustrating and comparing the particular features, strengths, and weaknesses of each interpretation.[citation needed]
Yes, but everything I've read about this in the past few years suggests that the simplest explanation is that the Geiger counter acts as the "observer" and "collapses the wave function" which determines at that point if it'll release the poison or not. From the Geiger counter (and the cat's) perspective, the cat is either alive or dead. All of this quantum weirdness goes away when the wave collapses, which means the particle (or pair of entangled particles) interacts with something else.
"I have never let my schooling interfere with my education." - Mark Twain
Let's see if I have this straight. Quantum physics is in an undefined state between valid and invalid and we must wait for a cat to resolve the state? Is that roughly right?
You can't see ANYTHING from a car, You've got to get out of the goddamned contraption and walk...Edward Abbey
I think that the description is one of those things that's absurd in a way that makes people pause, but doesn't seem to trigger the thought that was intent to be conveyed. To most people, they're still imagining that there's a cat in the box, and being alive or dead doesn't matter because they imagine the cat about the same way. Maybe there's some other part of what does it mean to be both alive and dead at the same that makes their mind stray into philosophical territory that doesn't matter.
I think it was Einstein who used a similar metaphor only with a barrel of gunpowder that could either be set off or left alone. When people imagine an exploded barrel of gunpowder, the mental image is completely different than that of a barrel of gunpowder and it's easier to say that it doesn't make sense to say that a barrel of gunpowder is both states since they're so vastly different. With a cat, the cat is still there and its form hasn't really changed. It still looks the same and could be mistaken for sleeping perhaps.
And the Copenhagen interpretation is the new "Bohr atom model" - almost no one believes it this century
A 2011 survey of attendees of a conference on quantum physics would disagree with you, with 42% of the respondents (a plurality) listing the Copenhagen interpretation as their favorite interpretation of quantum mechanics.
Anyhow, measurement devices collapse the wave state, removing this sort of uncertainty at the point of measurement.
Sorry -- what's your definition of the Copenhagen interpretation? Because, to my understanding, wave function collapse on measurement *is* the Copenhagen interpretation: "Here's the quantum regime. Here's the classic regime. The result of a 'measurement' is always classical. -- How do you go from quantum to classical? It doesn't matter, it just does. We have well defined procedures to extract the empirical (classical) measurement results from a given quantum result. Throw a black box over the 'how', then shut up and calculate."
You are correct.
And, by "measurement," we don't mean "humans looking at it."
The "measurement problem" was settled long ago in that there are a shit load of "measuring devices."
When a quantum interacts with anything , that's a measurement.
It little behooves the best of us to comment on the rest of us.
The whole point of Schrodinger's cat experiment [phys.org] was to show that trying to apply certain quantum physics theories to reality resulted in absurd results.
No, it is more subtle than that. It was designed to show that one interpretation of the results of QM was wrong by showing that it leads to an absurd explanation for every-day scale objects like cats. Nobody ever believed that the cat was in some weird superposition: that was indeed the entire point. The interpretation of QM, called the Copenhagen interpretation, was clearly wrong which is why nobody believes it today. However, everyone believes in quantum mechanics itself and that it works when describing reality (it's the second most precisely tested scientific theory that has ever existed). The problem is trying to get brains that are used to a world that works in the large-scale limit of QM to really grasp the rather different underlying reality.
The mathematical equation are still used. What your itnerpret them as MW, copenhagen wave collapse , or angel on a pin is pretty much unfalsifiable. Among my colleague copenhagen is still the majorly used interpretation , just look at QM article they speak of measurement and collapse. Not other world or angel on a pin.
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Of course it's right. Clearly we can't rely on a physicist is resolve it, and cats are well known for having a definite opinion on everything.
If you believe that, you haven't taken a single course in quantum mechanics. Copenhagen interpretation is still taught as the orthodox interpretation of quantum mechanics—maybe everyone has an issue with the whole idea of non-local collapse of wavefunction (or what makes up a "measurement"), but it's more widely believed than any of the other cooky theories, including some that Einstein proposed.
Anyhow, measurement devices collapse the wave state, removing this sort of uncertainty at the point of measurement
Yeees. And it only requires probability wave states that "collapse" at literally infinite speeds... nothing can possibly go wrong with this final, slayer-of-all-others, supreme, holy "interpretation", no-seree-bob, nothing, I tell ya!
Look up Bell's theorem.
Most people also believe that 'observation' is the universe caring about human consciousness.
Telling, is that you provide no citation of a poll.
I'm in this field (see what I did there) and science is not not a democracy wherein a 51% majority settles matters.
The wave collapse is instantaneous across any distance because the quantum measured is a single object (a wave).
There is no "information," transmitted during collapse, and therefore, no violation of the speed limit of light in a vacuum.
It little behooves the best of us to comment on the rest of us.
FFS the linked article didn't mention the original paper, thank goodness they even mentioned the authors. After tracking down the authors publications, I have located the original paper on arxiv. It's interesting to read, and seems to lend more thought experiment evidence to the many world interpretation.
Orthodox. When a physicist uses that word he is pointing up the element of faith involved, and probably implying that he doesn't believe it.
There is around a dozen interpretations (what does it mean, really?) of quantum mechanics.
I remember reading a while back about a convention where they took an anonymous poll of which interpretations the attendees favoured. To everyone's surprise Many Worlds was the most popular.
Copenhagen interpretation is still taught as the orthodox interpretation of quantum mechanics
Perhaps in some of the more backward, remote realities, but it has long been abandoned in the more sophisticated worlds.
FTFY
Many worlds makes quick work of this whole thing. Referencing original explanation, 3 subsets of multiverse: AA,AB & B. In subsets starting with A, Alice in her box sets up spin sideways, in B, spin down. In AA, Bob measures spin up, in AB & B, spin down.
The contradiction is supposed to be in AB Alice is in superposition to Bob, but not to herself. But in many worlds, everyone was always in AB, but they couldn't know that until diverging from copies of themselves in parallel worlds, which they only do when information about choices occurs. It's all beautifully consistent.
-The art of programming is the pursuit of absolute simplicity.
I'd agree with him: the entangled pair of states is a "single object". Can't think of a better way to say it in English. |Up Down > is a "single object" as is " |Down Up>. That's how you get cos^2.
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