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Arthur T Knackerbracket has found the following story:
One of the most striking features of quantum theory is that its predictions are, under virtually all circumstances, probabilistic. If you set up an experiment in a laboratory, and then you use quantum theory to predict the outcomes of various measurements you might perform, the best the theory can offer is probabilities—say, a 50 percent chance that you'll get one outcome, and a 50 percent chance that you'll get a different one. The role the quantum state plays in the theory is to determine, or at least encode, these probabilities. If you know the quantum state, then you can compute the probability of getting any possible outcome to any possible experiment.
But does the quantum state ultimately represent some objective aspect of reality, or is it a way of characterizing something about us, namely, something about what some person knows about reality? This question stretches back to the earliest history of quantum theory, but has recently become an active topic again, inspiring a slew of new theoretical results and even some experimental tests.
If it is just your knowledge that changes, things don't seem so strange.
To see why the quantum state might represent what someone knows, consider another case where we use probabilities. Before your friend rolls a die, you guess what side will face up. If your friend rolls a standard six-sided die, you'd usually say there is about a 17 percent (or one in six) chance that you'll be right, whatever you guess. Here the probability represents something about you: your state of knowledge about the die. Let's say your back is turned while she rolls it, so that she sees the result—a six, say—but not you. As far as you are concerned, the outcome remains uncertain, even though she knows it. Probabilities that represent a person's uncertainty, even though there is some fact of the matter, are called epistemic, from one of the Greek words for knowledge.
This means that you and your friend could assign very different probabilities, without either of you being wrong. You say the probability of the die showing a six is 17 percent, whereas your friend, who has seen the outcome already, says that it is 100 percent. That is because each of you knows different things, and the probabilities are representations of your respective states of knowledge. The only incorrect assignments, in fact, would be ones that said there was no chance at all that the die showed a six.
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(Score: 2) by VLM on Wednesday May 03 2017, @06:35PM
If you take a piece of string and keep cutting it in half, it will never be eliminated as there will always be more to cut in half.
A better analogy is you take point three repeating and divide it by point nine repeating of string, you divide them and the repeating cancels out and you get 3/9 or 1/3, right? Well, point three repeating is supposed to be 1/3 so thats chill, right? I mean you've done a couple decimal places of the long division, right? I mean just humor me for a minute that dividing my point nine repeating is OK..
So you try again add a third with point six repeating and divide it by point nine repeating, you divide them and the repeating cancels out and you get 6/9 or 2/3, right? Well, one third plus one third usually comes up as two thirds, so no surprise.
So you try one last time add one more third resulting in point nine repeating (where have I seen that before?) divided by point nine repeating and the repeating cancels out and you get 9/9 or oh snap...
There's a certain implication above that you can't divide by anything but 1 and get the original result back, so doesn't that imply that dividing by point nine repeating always gets the original result back? But the only number that works for is dividing by one, anything smaller gives a bigger result and anything larger gives a smaller result, so the separation between one and point nine repeating is infinitely small, lets say... zero? Implying they're the same thing.
I'm too tired to play the analogy game where you chop a length point nine repeating length of string out of a length 1 piece of string and that itty bitty remainder of string, whatever you claim it is, has properties indistinguishable from zero, so apparently point nine repeating equals one because the gap between is a zero. The hard part of this analogy is convincing someone you're constructing the point nine repeating segment of the string correctly.