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Science

More Than One Reality Exists (in Quantum Physics) (livescience.com) 114

Zorro (Slashdot reader #15,797) quotes Live Science: Can two versions of reality exist at the same time? Physicists say they can -- at the quantum level, that is.

Researchers recently conducted experiments to answer a decades-old theoretical physics question about dueling realities. This tricky thought experiment proposed that two individuals observing the same photon could arrive at different conclusions about that photon's state -- and yet both of their observations would be correct.

For the first time, scientists have replicated conditions described in the thought experiment. Their results, published Feb. 13 in the preprint journal arXiv, confirmed that even when observers described different states in the same photon, the two conflicting realities could both be true. "You can verify both of them," study co-author Martin Ringbauer, a postdoctoral researcher with the Department of Experimental Physics at the University of Innsbruck in Austria, told Live Science.

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More Than One Reality Exists (in Quantum Physics)

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  • by kiviQr ( 3443687 ) on Sunday March 24, 2019 @11:39AM (#58324914)
    ...we knew it for long time
  • by NoNonAlphaCharsHere ( 2201864 ) on Sunday March 24, 2019 @11:56AM (#58324962)
    Every time I talk to my boss, I know there's more than one reality.
    • by Tablizer ( 95088 )

      Every time I talk to my boss, I know there's more than one reality.

      The Milton Effect: You are fired and working at the same time. The boss just hasn't told you yet.

    • by rtb61 ( 674572 )

      I am going with three inter related realities. One of normal space us, one of quantum space where matter is small enough to go faster than the speed of gravity and exist massless until such time as sufficient quantum particles come together to exhibit mass and slow below the speed of gravity. There third one, macro space, multiple universes, bound within a greater verse, one going much slower than us, much like we go much slower than quantum space. Us caught in between, normal space stretched between quantu

  • by Roger W Moore ( 538166 ) on Sunday March 24, 2019 @12:00PM (#58324984) Journal
    The paper indicates that one of three assumptions must be wrong with the other two being: free choice and non-locality. My bet is on the latter. However, one aspect of this particularly dense paper that I do not quite grasp yet is that it seems that the suggested experiment requires measuring the state of an entangled photon non-destructively which I understood to be impossible...but it is possible I misunderstood.
    • I think this is terribly mischaracterized even in the paper. They say that the assumption they think is violated is something like "there is an objective reality" and so the reality can be different for the two observers. But, as best I can tell, what they mean by an "objective" answer is that there is a hidden variable [wikipedia.org]. We already knew that there are no hidden variables, so it's not surprising that this experiment also shows the assumption of a hidden variable must be violated. While this is a really n
      • Actually, we don't know that there are no hidden variables. Quite the contrary, lots of hidden variable theories are still consistent with all known experiments. You've probably been misled by the nonsense that gets published every time someone tries to do a new test of Bell's inequality. Most of those articles are just as confused as this one. Remember that all those "experimental proofs" that the wavefunction is real, that measurements are random, that hidden variables don't exist, and so on are actua

  • I tried to read the paper but my brain melted about halfway through it.

    Can someone produce a lay explanation?

    • by Anonymous Coward

      I tried to read the paper but my brain melted about halfway through it.

      Can someone produce a lay explanation?

      Really small things are hard to measure, and even really smart people read WAY too far into the language used to describe really small things bumping into each other.

  • Wigner's friend (Score:5, Informative)

    by Okian Warrior ( 537106 ) on Sunday March 24, 2019 @12:03PM (#58325006) Homepage Journal

    For a little more clarity on the subject, this is a physical realization of the "Wigners Friend" [wikipedia.org] experiment. The "state" referred to in the summary is "superposition/collapsed waveform", and not the specific information about the photon such as its spin.

    In the experiment, one scientist ("Wigner's friend") observes a photon in a superposition of states, which collapses the state, while a second scientist observes the first scientist. This uses entangled photons, so that observing the first photon collapses the state of the second.

    The first scientist observes one photon, thereby collapsing its state to reveal information. Does the second scientist see his photon in a superposition or collapsed state? The first scientist might even tell the 2nd that he has observed the photon, collapsing its state - but not sating what state information was seen.

    According to the experiment, the 2nd scientist still sees his photon in a superposition of states even though he knows that the first scientist has observed the photon and that the first scientist knows what the collapsed state is.

    • Re: (Score:2, Interesting)

      by Anonymous Coward

      None of which suggests what the article summary implies: parallel realities. Everything in your experiment involves two people interacting with one another in one shared space-time continuum.

      The whole "multiverse" thing annoys me because it is intrinsically non-falsifiable. It gets a lot of attention because a specific group of physicists who favor this model happen to be famous and popular. So people think this is a done deal. And it's not. Just as many, just as smart and just as prominent physicists

      • by Binestar ( 28861 )

        I care, but I'm not smart enough in particle physics to know what to search for. Would you give *me* links?

    • Re:Wigner's friend (Score:5, Interesting)

      by burtosis ( 1124179 ) on Sunday March 24, 2019 @12:34PM (#58325122)
      It's a bit clickbaity as the experimenters themselves say

      In contrast to standard Bell inequalities, (the probability distribution) is not concerned with the coexistence of local properties for two separate physical systems, but rather with the coexistence of facts with respect to different observers.

      Yet this apparent discrepancy in observed measurements, or "facts about the world being observer independent" has several loopholes including locality, freedom of choice, and the detection loophole (only a fraction of photons are successfully detected). The locality and freedom of choice loopholes can be removed by sufficiently seperating the events in space. Neither of these was able to be done in this experiment. Further you would need to ensure that the measurement of the observers "memory" (an observer could simply be an instrument, sensor, or interaction of matter/energy of some kind and not a person) and are clearly independent systems initially.

      Tl:dr this is less about showing multiple realities exist and more about showing how the "cut" between indeterminate quantum and deterministic classic macro systems work. A good discussion is here [arxiv.org]

      • The locality and freedom of choice loopholes can be removed by sufficiently seperating the events in space.

        How is that? If the locality assumption is wrong, that means by definition that separating them in space doesn't make any difference..

    • by Anonymous Coward

      You can't see that a photon is in a superposition of states, that is by definition, an unobserved photon. QM analogies... I swear physicists were trolling us when they came up with that stuff.

    • by Jamu ( 852752 )
      Which is the expected result. It's just disturbing that it implies that Wigner's friend must also now be in superposition and entangled with the photon state.
    • This is the thing that has always puzzled me about quantum mechanics.
      What is an observer? Is a cat an observer? What about a measuring device that displays a value, but nobody reads it?

      Surely we can't be in a situation where everyone has an entirely different universe depending on who observed what.

      Can we?

      • The measurement device is an observer. The key thing to note is that it takes a piece of information about something very small and propagates that information to a relatively large system, large enough to be human readable. There's no need to infer that there's anything special about being human or feline here.

    • And, if a photon falls in the Superposition Woods, does it make a sound?

  • by Anonymous Coward

    ... in some version of reality.

  • Quantum Physics does find more and more evidence that their theory is nonsense ans needs a major revision. But I guess they have never heard of KISS.

    • They avoid things like KISS at all costs, otherwise it is hard to keep the money flowing.
      • by gweihir ( 88907 )

        Unfortunately, that makes perfect sense. The whole complex mess we have in Quantum Physics theory may primarily server to keep some people employed.

    • by Jeremi ( 14640 ) on Sunday March 24, 2019 @01:54PM (#58325536) Homepage

      But I guess they have never heard of KISS.

      The problem is that Quantum Physics already uses the KISS method -- it's just that universe behaves strangely enough that this is the simplest theory they can (currently) come up with that hasn't been already falsified by measured results. Plenty of beautiful, simpler theories (Newtonian mechanics, aether, etc) have already been tried and found wanting.

      Correlary: if/when they ever do figure out How The Universe Really Works, it will probably be even weirder and more counterintuitive than their current theories. Buckle up!

    • But I guess they have never heard of KISS.

      If the universe were simple we would have cracked it by now, then built a system to make it less simple out of sheer boredom.
      Science doesn't have to be simple, elegant, concise, easy to convey, or any other such nonsense. In fact, the only people who look for such things are non-scientists.

    • quit thinking on the level of an anti-vaxxer

      Quantum mechanics makes useful and provable predictions, it is not nonsense.

      • by gweihir ( 88907 )

        Well, either quantum mechanics or gravity (likely both) are known to be wrong, because they are inconsistent. Hence you cannot make reliable predictions with either. Not possible. I do know they are both exceptionally well verified experimentally, but that just means their flaws are either subtle or surprising or both and they will be fundamental. There are a lot of morons that cannot see that though. You seem to be one of them.

        • by Jamu ( 852752 )
          Only one is know to be wrong (because they are inconsistent with each other). You can make reliable predictions with either. We still use Newtonian mechanics and Newtonian gravity to make reliable predictions and we know those are wrong! We only know that one must be flawed, but we don't know that they both are.
        • We know the models break down under conditions not found in our Earth (inside black holes, extreme energies, times near big bang...)

          But they are extremely useful for electronics, optics, for GPS satellite corrections...

          hardly nonsense when the computer and monitor you're using is a product of solid state physics which includes quantum mechanics.

  • Anyone who (a) has been married or (b) has kids already knows this.
  • It's too early ... (Score:4, Insightful)

    by CaptainDork ( 3678879 ) on Sunday March 24, 2019 @04:37PM (#58326324)

    ... to ink this one in.

    Recall the twin paradox and the loss of simultaneity with Special Relativity. The phenomenon are both "apparent," and "true," depending on the frame of reference.

    It took years for that to be accepted and to morph into intuition.

    Quantum mechanics is in its infancy and it will be 30-40 years before we get to the same comfortable place.

  • of "alternative facts"

If you think the system is working, ask someone who's waiting for a prompt.

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