we have no problem saying that the tennis ball was travelling at 100 mph and then I measured it. The tennis ball had the pre-existing property of a speed of 100 mph, which I could determine by measurement. We would never think of saying that it was travelling at 100 mph because I measured it. That wouldn’t make any sense. In quantum theory, we do have to make statements like that. And then we can’t help asking what it means. That’s when the arguments start.
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