Let us ask a simple question: When you look up at night and "see" a star, what is "really" going on? A Newtonian philosopher might answer that you are "really seeing" the star, since, in Newtonian physics, the speed of light is reckoned as being infinite. An Einsteinian philosopher, on the other hand, would answer that you are seeing the star as it was in a past epoch, since light travels with finite velocity and therefore takes time to cross the gulf of space between the star and your eye. To see the star "as it is right now" has no meaning since there exists no means for making such an observation.
A quantum philosopher would answer that you are not seeing the star at all. The star sets up a condition that extends throughout space and time--an electromagnetic field. What you "see" as a star, is actually the result of a quantum interaction between the local field and the retina of your eye. Energy is being absorbed from the field by your eye, and the local field is being modified as a result. You can interpret your observation as pertaining to a distant object if you wish, or concentrate strictly on local field effects.
Friday, February 5, 2010
Strictly local field effects
This is quoted in the fairly poetic wikipedia entry on the observer in quantum physics. It comes from somebody at NASA, but it's a bit unclear who actually wrote it. I have nothing to say about it, I just like it.