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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.

7 of 273 comments (clear)

  1. Re:Well, this is dumb by Gavagai80 · · Score: 4, Informative

    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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  2. Collapsing wave functions? by dlleigh · · Score: 2, Informative

    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/...

  3. Re:Well, this is dumb by surfcow · · Score: 3, Informative

    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]

  4. Still has credence by aepervius · · Score: 3, Informative

    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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  5. Re:Well, this is dumb by novakyu · · Score: 4, Informative

    The interpretation of QM, called the Copenhagen interpretation, was clearly wrong which is why nobody believes it today.

    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.

  6. Re:A dumber question. by SqueakyMouse · · Score: 3, Informative

    Look up Bell's theorem.

  7. Original paper by burtosis · · Score: 4, Informative

    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.