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Published 3 years ago by AdelleChattre with 10 Comments

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  • leweb
    +3

    This is the sort of thing you get when you let a philosopher of science write about science. They love to tell scientists how they should think about science, while not understanding the science itself.

    The dice example is an enormous straw man. The author seems to suggest that because one of the people can see the state of the dice, there is an objective reality that the other guy doesn't know, except in a probabilistic sense. The problem is that you cannot observe that supposed objective reality in a quantum system without changing the system. The moment you observe it, the reality is not the same. If you can't observe that "objective reality", you have no way to tell whether it exists or not, so whatever you say beyond that point is a matter of personal opinion, not science.

    • AdelleChattre
      +3

      Worse than that, arguably unless one eventually makes an observation, there hadn’t been a reality in the first place.

      • leweb
        +3

        There you go. The very question in the title is silly. QM is not telling you about what you know, but about what can be known. I don't see any difference between "reality" and "what can be known about reality". This is not about not knowing some detail because we haven't looked far enough or because we haven't come up with a way to figure it out. It's about the fact that the detail itself is unknowable unless you change the system in some way, and then what you know is not a fact about the original system anymore.

        • AdelleChattre (edited 3 years ago)
          +3

          What then are we to think of experiments like the one I linked, which appear to show not only that an observation in the future determines what happened in the past, but that the past may not’ve been real unless an observation is made in the future? Mind you, I know it’s silly. The tao that can be understood is not the true tao.

          • leweb
            +5

            That conclusion follows only if you assume that the particle's trajectory exists independently of the observation, which is again not true in QM. Nothing exists unless it's observed, and when you observe it, you change it.

            • Appaloosa
              +2

              This exchange reminds me of solipsism.

            • AdelleChattre
              +2
              @Appaloosa -

              You too?)

            • Appaloosa (edited 3 years ago)
              +2
              @AdelleChattre -

              Yes, it's both science and philosophy to me. If you put a ringing alarm clock into a vacuum, sound no longer exists as the medium does not support it. The clock is doing everything mechanical to produce a sound, yet it does not exist. But, if a tree falls in a forest does it make a sound if nothing is around to observe it. The tree would be in a medium, air, to support a sound, unlike a bell in a vacuum.

            • leweb
              +3
              @Appaloosa -

              This is nice, but still not quite the same thing. Alarm clocks, vacuum, trees in forests, they're all macroscopic objects that have a well defined internal state. The weird thing about QM is that there are no specific, well defined internal states, except when defined by observation. There's nothing like it in our normal, everyday (or even not so every day) experience. That's the reason for the oft-cited quote about understanding QM attributed to Richard Feynman.

            • AdelleChattre (edited 3 years ago)
              +3
              @Appaloosa -

              Physics is philosophy. Science is all philosophy of nature, right? The 'Ph' in /u/leweb's Ph.D stands for philosophy. Agreed, the tree falling in the forest makes sound, even if nobody's around to hear it. Never understood why it was supposed to be so trippy that nobody hears it. Quantum physics, on the other hand, baffles me. I think it's supposed to. They say if you think you 'get it' then think again, because nobody does. Nobody can. I'm right there with you about the "sound of one hand clapping" woo woo, but this stuff is spooky. For real.

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