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posted by chromas on Thursday September 20 2018, @04:30PM   Printer-friendly
from the depends-on-how-you-look-at-things dept.

Theoretical physicists at ETH (Eidgenössische Technische Hochschule) Zurich have come up with a real puzzler in Searching for Errors in the Quantum World:

The theory of quantum mechanics is well supported by experiments. Now, however, a thought experiment by ETH physicists yields unexpected contradictions. These findings raise some fundamental questions – and they’re polarising experts.

There is likely no other scientific theory that is as well supported as quantum mechanics. For nearly 100 years now, it has repeatedly been confirmed with highly precise experiments, yet physicists still aren't entirely happy. Although quantum mechanics describes events at the microscopic level very accurately, it comes up against its limits with larger objects -- especially objects for which the force of gravity plays a role. Quantum mechanics can't describe the behaviour of planets, for instance, which remains the domain of the general theory of relativity. This theory, in turn, can't correctly describe small-scale processes. Many physicists therefore dream of combining quantum mechanics with the theory of relativity to form a coherent worldview.

[...] Thought experiments... can be used to transcend the boundaries of the macroscopic world. That’s exactly what Renato Renner, Professor for Theoretical Physics, and his former doctoral student Daniela Frauchiger have now done in a publication that appears in Nature Communications magazine today. Roughly speaking, in their thought experiment, the two consider a hypothetical physicist examining a quantum mechanical object and then use quantum mechanics to calculate what that physicist will observe. According to our current worldview, this indirect observation should yield the same result as direct observation, yet the pair’s calculations show that precisely this is not the case. The prediction as to what the physicist will observe is exactly the opposite of what would be measured directly, creating a paradoxical situation.

[...] "Our job now is to examine whether our thought experiment assumes things that shouldn't be assumed in that form," Renner says, "and who knows, perhaps we will even have to revise our concept of space and time once again." For Renner, that would definitely be an appealing option: "It's only when we fundamentally rethink existing theories that we gain deeper insights into how nature really works."

Journal Reference:
Daniela Frauchiger, Renato Renner. Quantum theory cannot consistently describe the use of itself. Nature Communications, 2018; 9 (1) DOI: 10.1038/s41467-018-05739-8

See also: Ars Technica Quantum observers with knowledge of quantum mechanics break reality.


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  • (Score: 2) by takyon on Thursday September 20 2018, @05:48PM (9 children)

    by takyon (881) <reversethis-{gro ... s} {ta} {noykat}> on Thursday September 20 2018, @05:48PM (#737620) Journal

    Devil's advocate: We get the "why is the universe here?" question regardless of whether we are living in a simulation or not. But living in a simulation could explain weird things that are going on in our layer.

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  • (Score: 0) by Anonymous Coward on Thursday September 20 2018, @05:52PM

    by Anonymous Coward on Thursday September 20 2018, @05:52PM (#737623)

    This "reality is a simulation" talk is metaphysics, not physics.

  • (Score: 0) by Anonymous Coward on Thursday September 20 2018, @06:24PM (7 children)

    by Anonymous Coward on Thursday September 20 2018, @06:24PM (#737640)

    But living in a simulation could explain weird things that are going on in our layer.

    What sort of simulation though? I don't see how the math used by most of our simulations can explain stuff like consciousness and qualia. There's no need for such stuff to exist based on that math. In theory the math and simulation would be the same whether consciousness actually exists or not[0]. Couldn't you simulate stuff without consciousness being produced? Or is it always[1] produced? What law of Physics addresses that?

    [0] But I know I experience consciousness. But I suspect some people don't, at least not the same way I do, based on their responses on this subject.

    [1] There are some who suggest that consciousness is a fundamental in our Universe but resorting to that doesn't explain much any more than the people claiming that everything is God and God is everything.

    • (Score: 2) by takyon on Thursday September 20 2018, @06:33PM (6 children)

      by takyon (881) <reversethis-{gro ... s} {ta} {noykat}> on Thursday September 20 2018, @06:33PM (#737647) Journal

      I don't think there's anything preventing us from simulating a virtual brain, including emergent consciousness, other than hardware requirements (could need neuromorphic architecture, will probably need transition to 3D chips), and a lack of understanding of how the brain works. Once you have that down, you can scale it up, simulate multiple minds at a time, create a virtual world to trick the simulated brain/creature, etc.

      Humans are just biological machines that are more advanced than other biological machines.

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      • (Score: 0) by Anonymous Coward on Thursday September 20 2018, @07:29PM (4 children)

        by Anonymous Coward on Thursday September 20 2018, @07:29PM (#737679)

        Humans are just biological machines that are more advanced than other biological machines.

        So says modern science without being able to actually explain consciousness. Maybe we are just emergent phenomena from mechanistic processes, maybe not. You can't say one way or another, time to admit that is a belief you hold and stop going around stating it as fact until we have the evidence to back it up.

        • (Score: 2) by takyon on Thursday September 20 2018, @07:34PM (3 children)

          by takyon (881) <reversethis-{gro ... s} {ta} {noykat}> on Thursday September 20 2018, @07:34PM (#737681) Journal

          Meh, I can wait a decade or two to be proven right.

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          • (Score: 0) by Anonymous Coward on Thursday September 20 2018, @07:57PM (2 children)

            by Anonymous Coward on Thursday September 20 2018, @07:57PM (#737696)

            Ah yes arrogance, such a wonderful trait that has never led to embarrassment /s

            • (Score: 2) by takyon on Thursday September 20 2018, @08:05PM (1 child)

              by takyon (881) <reversethis-{gro ... s} {ta} {noykat}> on Thursday September 20 2018, @08:05PM (#737704) Journal

              Skins v. Souls

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              • (Score: 0) by Anonymous Coward on Thursday September 20 2018, @08:43PM

                by Anonymous Coward on Thursday September 20 2018, @08:43PM (#737723)

                I'm not into sports, I just try to be objective. You've lost your objectivity and your faith is blinding you to that fact because Science! with the big s!

      • (Score: 2) by cosurgi on Friday September 21 2018, @12:21PM

        by cosurgi (272) on Friday September 21 2018, @12:21PM (#738066) Journal

        There's is actually a short story written by Stanisław Lem exactly about this. IIRC it was in the adventures of Ion Tichy. He visited a crazy scientists who simulated a scientist inside a computer, and this simulated scientists was performing experiments inside his simulated reality and was slowly becoming more confident that he is not in a real world.

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