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Can quantum computers work at all? They need an observer to collapse all possibilities. Does this depend upon which observer is observing?
Yes, by definition of the probability distribution of possible outcomes using qubits, you may get different results each time you run the algorithm. However, certain outcomes will be highly favored depending on the algorithm (think Schor's algorithm). Also, by running it several times, you can use statistics to decide the most likely result to be taken as the outcome (think Grover's algorithm).
As a side note, the observer analogy is a bit misleading. There is no conscious being looking at the sample and collapsing the wavefunctions. It's simply the measurement that leads to a probability distribution of outcomes.
Oh, no conscious being? Many people believe that the whole Universe is a conscious being.
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:)
I used to read a lot of books on how to interpret quantum mechanics (think many-worlds, etc). All very interesting things to think about, but for practical use in my daily life, I'm fully content with just thinking of it as a probability of outcomes. Same thing with how I think about freewill. In all likeliness, there is no freewill, but I am content with thinking there is freewill and I am charge of my destiny. It's too depressing otherwise.
All this to say that I don't worry too much about the philosophical interpretations of the world and the universe. Until we can bring these considerations into the real world using tangible experiments, that is.
Still, all very fun to read about in my free time.
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Yes, the problem is being caught in a world of only tangible experiments and tangible anything else. There are too many intangibles in the world to deny them. Is consciousness one of them, intangibles, that is?
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I'm fully ok with saying "I don't know" as a scientist (I say that at least a few times a week to students and colleagues during discussions). Lots of things that were intangible have become tangible over time, so I believe there are even more such transitions to come in centuries ahead. I like to observe these intangibles, and ponder about them, but I specifically try to avoid making definite claims. I don't need a higher power (God, etc) to make sense of them, I just accept them as things we can't explain yet (or may never be able to explain). I'm happy with this worldview, it works for me. And it may not work for others.
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The "I don't know." part always works. Some things are just beyond our ken. Although, it is kind of hard to "observe" intangibles, you can ponder them but observation is very difficult.
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